ORGANIC CHEMISTRY.1. INTRODUCTION.BY using a " plastic " model for initial and transition states, the contributionof steric strain to the energy of activation and the entropy of activation ofnucleophilic bimolecular halogen exchange in alkyl halides has been cal-culated from first principles.Phenanthrophenanthrene has been resolved and becomes the firstknown optically active hydrocarbon which owes its asymmetry to molecularovercrowding.Impressive progress has been made in the identification of naturallyoccurring amino-acids and in the study of benzotropylium and allied cations,azulene synthesis, and the structure of the extraordinary growth factormycobactin.The common stereochemical pattern of many naturally occurring sesqui-and di-terpenes is being exposed from year to year by a combinatior, ofdirect correlation with substances of known configuration and use of opticalrotations.A valuable theory to explain the stereochemistry of steroids andtriterpenes has been published ; this theory is probably applicable to thesmaller terpenes.The structure of a-amyrin has been the subject of much discussion andexperiment. Evidence has been described suggestive of the presence in thea-amyrins of a five-membered ring (E), with an attached isopropyl group.However, more evidence in favour of the older structure has also appeared.The position is still fluid, but the Reviewer is of the opinion that on balancethe evidence favours the older structure.In the steroid field one of the principle achievements has been the totalsynthesis of aldosterone.Important progress has also been made in thestereochemistry of the trimethyl-steroids.Two outstanding events of the year were the deduction of the detailedstructure of vitamin B,,, an excellent example of the use of chemical andX-ray techniques, and a brilliant two-stage synthesis of usnic acid from asimple derivative of acetophenone. The latter has cast light from a newangle on the oxidation of phenols.G. B. w. c.2. THEORETICAL,Sterically Hindered Unip1anarity.-In numerous unsaturated compounds,changes in configuration , usually out-of-plane displacements , which decreasethe intramolecular compression (destabilising) energy between non-bondedatoms also decrease the resonance (stabilising) energy.The preferred con-figurations, i.e. , those of lowest energy content, are those in which the ratesof change of compression and resonance energy, with change of configuration ,are equal. In these preferred configurations the molecules have energy inexcess of what they would have had in the absence of steric interaction132 ORGANIC CHEMISTRY.the excess comprises loss of resonance energy and gain of compression energyand is referred to as the steric strain.It is generally found that non-bonded carbon atoms do not approachcloser to each other than about 3.0 A, and that the shortest distance betweenhydrogen atoms in aliphatic hydrocarbon crystals is about 2 4 A . Indianthronylidene (1) the centre-to-centre distance between the over-crowded carbon atoms 4 and 4, and 8 and 8', is 2.90 A; it is achieved bya 40" rotation of the benzene rings out of the plane of the central ethylenicsystem.The observed bond lengths and angles indicate that resonanceinteraction is considerably reduced, the molecule consisting of an isolatedethylenic group attached by single bonds to normal benzene rings1The overcrowding in 3 : 4-5 : 6-dibenzophenanthrene (2) is partiallyrelieved by out-of-plane buckling of the molecule, which decreases the com-pression energy at the expense of the resonance energy. This bucklingdisplaces the various carbon and hydrogen atoms in a direction normal tothe original undisturbed molecular plane and is distributed over the fivefused rings in such a manner as to cause the minimum distortion in anyindividual ring.It provides2 a clearance of about 3-0A between thenon-bonded carbon atoms 4' and 1". The loss of resonance energy causedby the deformation is about 18 kcal. mole-l, while the total steric strainenergy may be about 28 kcal. moled1.These deformations affect chemical properties. It appears that foraromatic compounds, increase in departure from a uniplanar structureincreases the localisation of the electrons which are usually delocalised inaromatic rings and hence leads, for example, to increased availability ofelectrons for reaction with free radicals. Methyl radicals add to aromaticcompounds (A + CH, __t ACH,), and the relative rate constants arereferred to as methyl affinities. Those of benzene, naphthalene, anthracene,and naphthacene are 1, 22, 820, and 9250 respectively; * their logarithmsvary linearly with the singlet-triplet excitation energies.Now, whereasthe methyl affinities of 2-, 3-, 4-, 5-, and 6-methylbenzo[c]phenanthrene areroughly the same and about equal to that of the parent hydrocarbon (3),overcrowding causes the methyl affinity to rise somewhat in the l-methyland considerably in the 1 : 12-dimethyl derivative. Again, the logarithmsE. Harnik and G. M. J. Schmidt, J., 1954, 3295.A. 0. McIntosh, J. M. Robertson, and V. Vand, J., 954, 1661.C. A. Coulson and S. Senent, J., 1955, 1813, 1819.M. Levy and M. Szwarc, J . Chem. Phys., 1954, 22, 1621; J . Amer. Chem. SOC.,M. Szwarc, J . Chem. Phys., 1955, 23, 204.M. Levy, M. S.Newman, and M. Szwarc, J . Amer. Chem. SOL, 1955,77, 4225.1955, 77, 1949BADDELEY : THEORETICAL. 133of the reaction constants for interaction of l-chloro-2 : 4-dinitrobenzene andamino-naphthalenes, -anthracenes, and -phenanthrenes in ethanol are in-versely proportional to the localisation energy as calculated for the hydro-carbon analogues of the amines. 4-Aminophenanthrene is an exception ;this misfit is caused by the steric strain in this amine.'Strain similar to that in (2) would arise if 1 : 1'-diisoquinoline (4) par-ticipated in the ferroin reaction; the essential condition for this reaction isthe specific grouping *N:C*C:N-, forming part of an aromatic system andcapable of forming a five-membered chelate ring with ferrous ion. In fact,the base (4) does not give the reaction 8 whereas 1-2'-pyridylisoquinoline doessSpectroscopic evidence for the steric inhibition of uniplanarity withconsequent reduction of conjugation has recently received further attentionwith a view to a quantitative interpretation.There are two different typesof spectral manifestation : (i) decrease in absorption intensity (transitionprobability) without appreciable increase in the frequency (transitionenergy) ; and (ii) change in both. o-Substituted acetophenones, benzo-phenones,l* and styrenes exhibit steric effects of type (i), o-substituteddiphenyls those of type (ii), and 5-o-substituted 2 : 4-diaminophenyl-pyrimidines those of both types.11 It is reasonable to assume that those oftype (ii) are associated with transitions between the non-planar ground stateand the non-planar excited state, whereas the former are associated withtransitions between the non-planar ground state and the planar or near-planar excited state.12 This assumption leads to the conclusiorr that inmanifestations of type (i) the absorption process is mainly concerned withthose molecules in which, during vibration, the interplanar angle 0 2i 0" ;for in accordance with the Franck-Condon principle the relative positions ofthe atomic nuclei, including the value of 0, do not change during the processof absorption. The absorption intensity (E) depends on the populationdistribution and the transition probability as functions of 0, and if we assumethat the transition probability for 0 = 0" is not affected appreciably by stericstrain, the decrease in the absorption (as measured by &/so = r ) may betaken as a measure of the fraction of the molecules which, at any instant,have 6 N 0". Thus Y may be a measure of the energy required to imposeuniplanarity.Calculation has, however, taken another course : on theassumption that r is related to O,, the interplanar angle for the molecule inits lowest energy state, by Y = cos2 0, (a relation which may be difficult tojustify), r has been used in calculations of interplanar angles.13, 14One condition for the display of steric effects of type (i) is that sterichindrance to planarity should not exceed about 3 kcal. mole-l. It is pleasingto find that when the hindrance is expected to be about the same in differentcompounds, i.e., when changes of resonance and compression energy severallywith change of 0 are similar in different compounds, the absorption intensitiesof these compounds afford similar values of Y. For example, the absorptionF. L. J Sixma, Rec. Trav. chinz., 1956, 74, 168.F. H. Case, J . Org. Chem., 1952, 17, 471.H. Irving and A. Hampton, J., 1955, 430.E. A. Braude, F. Sondheimer, and W. Forbes, Nature, 1954,175, 117.lo R. F. Rekker and W. T. Nanta, Rec. Trav. chim., 1954, 73, 969.l1 P. B. Russell, J., 1954, 2951.lS E. A. Braude and F. Sondheimer, J., 1955, 3754.l4 L. H. Klemm, H. Ziffer, J. W. Sprague, and W. Hades, J . Org. Chem., 1955,20,190134 ORGANIC CHEMISTRY.intensity of styrene is decreased by an o-methyl substituent l5 (r = 0.78) tothe same extent as by an a-methyl substituent (r = 0.78) [cf.(5) and (S)].The absorption intensity of a-alkylstyrenes decreases progressively withincrease in bulk of the alkyl substituent ; this indicates that steric inhibi-tion of uniplanarity exists here. There is a small but significant hypso-chromic effect. The absorption intensities of the compounds Ph*OR,17Ph*NHR, and Ph*COR decrease with increase in the bulk of the alkylgroup (R) and are similarly interpreted.Unlike benzamide and its N-methyl derivative, the NN-dimethylderivative (7) cannot have a completely planar structure because of inter-ference between one of the methyl groups and the benzene ring. This inter-ference, which is apparent in the ultraviolet absorption of the compound, isprobably relieved mainly by rotation about the Ph-CO bond since resonanceinteraction, and hence the need for uniplanarity, is greater about the Me,N-CO bond.la The electric moments of N-monosubstituted benzamidesindicate that the amide group is planar and that the less strained conform-ation has the substituent in the cis-position with respect to the carbonylgroup.As a conseq~ence,~~ these compounds seem to associate to formlinear complexes (8) whereas the unsubstituted amides form ringcomplexes (9).Ar.An interesting problem arises when attempting to relate steric hindranceof uniplanarity in cyclahexenyl derivatives with that in the correspondingphenyl derivatives. It has been argued 2o that l-acetyl-2-methylcyclo-hexene is more stable in the s-traas-conformation (10) than in the s-cis-conformation (11).There is, however, no reason for the benzenoid analogueto have a conformation other than one approximating to (12). Analysis 21of the electronic moments of a number of @-unsaturated aldehydes andl5 P. Ramart-Lucas and J. Hoch, Bull. SOC. chim. France, 1935, 327; 1938, 848;l6 P. Ramart-Lucas, Proc. XIth Inst. Congr. Pure Appl. Chem., London, 1947,l7 G. Baddeley, N. H. P. Smith, and M. A. Vickers, in the press.l8 J. T. Edwards and S. C. R. Meacock, Chem. and Ind., 1955, 536.l9 J. E. Worsham, jun., and M. E. Hobbs. J . Amer. Chem. Soc., 1954, 76, 206.*O E. A. Braude and C. J. Timmons, J . , 1955, 3766.81 G. K. Estok and J. S. Dehn, J .Amer. Chem. SOL, 1955, 77, 4769.E. A. Braude and F. Sondheimer, J., 1955, 3773.Vol. 11, p. 267; C. G. Overberger and D. Tanner, J . Amer. Chem. Sac., 1955, 77, 360BADDELEY : THEORETICAL. 135ketones indicates that the p-disubstituted unsaturated ketones have pre-dominantly the s-&-conformation, eg., see ( l l ) , that the aldehydes havethe s-trans-, and that the p-monosubstituted unsaturated ketones haveapproximately equal contributions from both the s-trans- and the s-cis-conformation. The quasi-theoretical and experimentally establishedstability sequence of five stereoisomeric perhydro-1 : 4-dioxophenanthrenes(13) indicates 22 that the energy increment due to the non-bonded inter-action of the oxygen atom of a carbonyl group and a p-situated C-H bondin an eclipsed (equatorial) position is 0.8-1-2 kcal.mole-l. The energy ofnon-bonded interaction of carbonyl and o-methyl group in (11) and (12) willnot be greater than this amount and may be appreciably less.a:.Me a!:o O@"M I Me Me(10) ( 1 ' ) (1 2) (13)A qualitative correlation has been made 23 of Amax. values for up-un-saturated carbonyl compounds in which there is bond deformation in onepart of the chromophore. The excitation energy is found to be lower forcompounds in which the electron displacement of excitation is away froma site of strain. This relationship is in accordance with the idea2* thatgreater electronegativity is associated with greater s-character of the carbonbonds and hence with less directional and more deformable bonds.The absorption intensity for the o-halogenonitrobenzenes is in theorder F > Cl > Br > I, which is the reverse of that for the absorptonintensity of the p-halogenonitrobenzenes and the 2-halogenopyridines.Thedifference is interpreted as being caused by steric inhibition of uniplanarityof nitro- and phenyl-groups by the o-halogen substituent; a similar effectis not possible in the 2-hal0genopyridines.~~Polymethylene chains have conformational preferences which mayoppose the uniplanarity required for maximum conjugation. Compoundsof type (14) and (15), in which X = )CO, )C:N-NHAr, )C:N*OH,)C:N*NH*CO*NH,,15* 26a 2 7 3 2* )NH, )NMe, )N*COR, )O ; l7 XY =-CH:CH-,26, 27 -NH*CO- ; 29 and n = 5-9 ; and those of type (16), in whichY =)CO and )C:N*OH, and w = 13-18,30 have been studied and theirproperties discussed.The data do not, however, provide a quantitativelyconsistent pattern. The spectroscopic results for compounds of type (16),where Y is a carbonyl group, show the interplanar angle of the carbonyl and22 P. A. Robins and J. Walker, J., 1955, 1789; Chem. and Ind., 1955, 727.23 W. M. Schubert and W. A. Sweeney, J. Amer. Chem. SOC., 1955, 77, 2297.24 A. D. Walsh, Discuss. Faraday SOC., 1947, 2, 18.2 5 H. C. Brown and D. H. McDaniel, J. Amer. Chem. SOC., 1955, 77, 3752; H. E.26 G. Baddeley and J. Chadwick, J., 1951, 368.27 R. Huisgen, W. Rapp, I. Ugi, H. Walz, and E. Mergenthaler, Annalen, 1954,28 F. Ramirez and A. F. Kirby, J. Amer. Chew SOC., 1954, 76, 1037.2o R.Huisgen, I. Ugi, H. Brade, and E. Rauenbusch, Annalen, 1954, 586, 30.30 R. Huisgen, W. Rapp, I. Ugi, H. Walz, and I. Glogger, ibid., p. 52.Ungnade, ibid., 1954, 76, 1601.586, 1136 ORGANIC CHEMISTRY.the phenyl group to be wide (Y = 0.45) when n = 13, to decrease with in-crease in n, and to be negligibly small (P = 0.99) when n = 18. In com-pounds (14) and (15) the steric strain is least when n = 5 and increases withincrease in the value of n up to 8. Values of 9 or higher for n probablycause less strain by providing a rotation which is greater thanIt should be noted that the carbonyl frequencies of the benzocycl-anones (14, X = )CO) vary with increase in n, as do those of the correspond-ing cyclanones, and therefore do not afford evidence for steric hindrance ofuniplanarit y .The alicyclic moiety of these compounds has been shown by both physicaland chemical methods to cause no significant bond fixation of the typeproposed by Mills and Nixon.The frequency shifts, Av(CO), in theinfrared carbonyl vibration frequency arising from conjugated chelation ofadjacent hydroxyl and carbonyl groups are the same when these groups arein the 4 : 5- or the 5 : 6-position in indane as in the corresponding positionsin o-~ylene.~~ Again, comparison of the spectra of 3 : 4- and 4 : 5-dimethyl-,3 : 4- and 4 : 5-cycZopenteno-, and 3 : 4- and 4 : 5-cycZohexeno-pyridazine,~and of the rates of unimolecular solvolysis of the chlorides (17; n = 5,6, or 7) 34 demonstrates that the Mills-Nixon effect is not significantlyoperative.Ph 'SO, , ,CH;CO,HPh 'CHCI LCH2 I,, dMe (17) -$is c H2 Z (1 8 )The effect of ring-size on the steric inhibition of uniplanarity is indicatedby the study of the optical stability and ultraviolet absorption spectra ofbridged diphenyls : 35 the passage through the planar conformation of amolecule of the ortho-substituted diphenyl type is facilitated by the joiningof the two blocking groups into a ring; further, the planar conformationis more easily achieved the shorter the bridging chain of atoms.In accord-ance with expectation, the extent to which conformational preference of apolymethylene chain prevails over that of conjugation in the compounds (14)decreases with increase in the capacity of X to conjugate with the benzenering.Thus change of f i from 5 to 7 has less effect on the absorption intensity31 G. Baddeley, G. Holt, N. H. P. Smith, and F. A. Whittaker, Nature, 1951,168,386.32 I. M. Hunsberger, D. Lednicer, H. S. Gutowsky, D. L. Bunker, and P. Taussig,33 R. H. Horning and E. D. Amstutz, J . Org. Chem., 1955, 20, 1069.34 G. Baddeley and M. Gordon, J., 1952, 2190.35 D. M. Hall and E. E. Turner, J., 1955, 1242; G. H. Beaven, G. R. Bird, D. M.J . Amer. Chew. SOC., 1955, 77, 2466.Hall, E. A. Johnson, J. E. Ladbury, M. S. Leslie, and E. E. Turner, J., 1955, 2708BADDELEY : THEORETICAL. 137when X is )CO (r = 0.82) than when X is )O (Y = 0.23). This relation isalso apparent in the optical stabilities of diphenyls and related compounds,e.g., electron-withdrawing substituents 2 in the amine (18) increase theconjugation of the nitrogen atom and the benzene ring and thereby increasethe rate of racemisation. Electron-supplying substituents have the oppositeeffect .36These considerations cast doubt on the significance of interplanar anglesderived from scale models, and of calculations in which the conformationalpreference of polymethylene chains is assumed to prevail over that ofcon jugation. l3 Conventional steric considerations can be misleading, e.g. ,systems containing tram-fused cyclopentane rings are more readily formedthan steric cmsiderations would suggest 37 and optically active 1 : 1'-di-naphthyl derivatives racemise even when a mechanical interpretation by useof models indicates this to be inipos~ible.~~ Further, there is need for cautionin ascribing to steric hindrance of uniplanarity small differences of intensityof absorption between even closely related compounds : 39 e.g., whereas thecis- and the trans-forms of penta-1 : 3-diene and pent-3-en-1-yne absorbwith practically equal intensity, extension of the chromophore by additionof a methoxycarbonyl group in each case results in an appreciable differencebetween geometrical isomers, the ratio being remarkably constant.Stericinhibition of uniplanarity can be discounted here ; apparently other factorsare involved.39 It should be noted that stereoisomeric hexa-2 : 4-dienoicesters differ appreciably in both h,,, and absorption intensity, the trans-trans-isomer absorbing maximally at the shortest wavelength, exactly theopposite behaviour to that predicted on the basis of one of Zechmeister'sgeneral is at ion^.^^ This rule must be inverted for simple, laterally unsubsti-tuted polyenes.39s 41Steric hindrance of uniplanarity in 1 : 1 : 2 : 5 : 6 : 6-hexachlorohexa-1 : cis-3 : 5-triene (19) and 3 : 4-dibromohexachlorohexa-1 : trans-3 : 5-triene(20) is clearly indicated by their absorption spectra.42Intermolecular Strain.-Most chemical reactions involve one or more ofa number of possible steric effects and, for any one reaction, it is seldomapparent which will be the most important one and whether it will outweighelectronic influences. A complete theory of the effect of substituents on thecourse and rate of reaction and on equilibrium will incorporate a quantitativetreatment of spatial and electronic influences ; in the meantime, evidence fors6 R.Adams and K. V. Y. Sundstrom, J . Amer. Chem. SOC., 1954, 76, 5474.37 L. N. Owen and A. G. Peto, Chem. and Ind., 1955, 65.38 F. Bell and W. H. D. Morgan, J., 1954, 1716.40 L. Zechrneister, Experimentia, 1954, 10, 1.41 P. Nayler and M. C. Whiting, J., 1954, 4006.4z A. Roedig and K. Kiepert, Chem. Bey., 1955, 88, 733.J. L. H. Allan, E. R. H. Jones, and M. C. Whiting, J., 1955, 1862138 ORGANIC CHEMISTRY.the relative importance of the various influences and their dependence onreaction mechanism is rapidly accumulating.This sub-section is concerned with recent examples of reactions in whichnon-bonding interaction of one reactant with another (intermolecular strain)increases the energy content of the transition state or product and therebyinfluences reaction rate or equilibrium.Other types of strain are discussedin later sub-sections.This intermolecular strain has a pronounced influence on the interactionof iodine monochloride with 1 : 3 : 5-tri-tert.-butyl- and pentaethyl-benzene 43and on the methyl affinity of chloranil 44 and di-tert.-butyl-1 : 4-benzo-q~inone.*~ The structure of the product of the primary addition of themethyl radical is still undetermined and it is not clear whether the reactingradical attacks initially at an oxygen atom or at an ethylenic bond of thequinone. The latter is indicated by the steric effect : it seems that wheneverthe ethylenic bond is shielded by bulky atoms or groups the reactivity ofthe quinone decreases.The methyl affinities of styrene (792), trans-stilbene(105), triphenylethylene (46), and tetraphenylethylene (< 10) show thatsteric strain is more important than resonance stabilisation of the resultingradicals in determining these relative rates.46 o-Methyl substituents havetwo mutually opposing steric effects on the dissociation of hexaphenyl-ethane : by imposing a greater degree of non-planarity on the triphenyl-methyl radical they lower its stability and thereby hinder dissociation, whilefacilitating this process by providing additional overcrowding in the ethane.The latter effect outweighs the former.47Whereasthe alkaline rearrangement of 3- and 4-chlorobenzil48 and 2- and 3-chloro-phenanthraquinone 49 results in the preferential migration of the substitutedring, that of 2-chlorobenzil and l-chlorophenanthraquinone results in the pre-ferential migration of the unsubstituted ring.50 Apparently, steric hindranceby an adjacent chlorine atom overshadows electronic effects transmittedwithin the molecule, and the hydroxide ion attacks more readily at thecarbonyl group adjacent to the unsubstituted ring. However, o-substituentsare expected to provide only little hindrance to the approach of a nucleophileto a carbonyl group which is held in the plane of the benzene ring, for the lineof approach is perpendicular to this plane. Thus alkaline hydrolysis ofphthalide is only little affected sterically by substituents in the 7-positioi~~lThe product of the condensation of aryl aldehydes with phenylaceticanhydride in the presence of sodium phenylacetate is mainly the tram-cinnamic acid (22); in this the bulkiest groups are cis with respect to oneanother.REP.-VOL.LII 226 ORGANIC CHEMISTRY.analogous euphadiene by oxidation and partial Meystre-Miescher degradationinto products carrying the 17-side chain -CMe:CHCH:CPh,, in which theasymmetry of Ctzo) has been eliminated. The identity of the two productsshows that the starting materials differed in stereochemistry only at C(,l.yMe =C-RThe name " tirucallane " has been proposed 163 for the fundamentalhydrocarbon (88) 13a : 14p : 17a : 20-efilanostane (configuration a t Ct8) andC(9) uncertain), instead of " elemane " which might cause confusion with thesesquiterpenes.The important members of the tirucallane series are :Tirucallol Tirucalla-8 : 24-dien-38-01Elemadienolic acid 3a-Hydroxytirucalla-8 : 24-dien-21-oic acidEuphorbol 24-Methylenetirucal1-8-en-3/3-01Euphol 20-epiTirucalla-8 : 24-dien-315-01Butyrospermol (89) is one of the A7:24-isomers of euphol. Dihydro-butyrospermol, on treatment with acid, yields dihydroeuphol ( A7+As),and with perbenzoic acid gives 7-oxo-20-e~itirucal1-8-en-3~-ol. 165 " Bas-seol " is a mixture of butyrospermol and fi-amyrin.9 : 1 O-secosteroids (Calciferol and its Isomers).-Many papers have beenpublished in the last two years on the numerous isomers of calciferol whichhave been obtained by irradiation, heat, and partial synthesis.Theseisomers, which differ in configuration about double bonds, (perhaps) con-formation about single bonds, and, in some cases, the position of the doublebonds, offer a confusing picture at present and it seems profitable to deferdiscussion until workers in the field are agreed. A review 166 of the positionat the end of 1953 summarises the older literature. Among the factors usedas evidence for configurations are ultraviolet absorption (combined withsynthesis of simple reference compounds and/or theoretical arguments) andreactions with maleic anhydride.The views of various schools are given in the references165 D. S. Irvine, W. Lawrie, A. S. &Nab, and F. S. Spring, Chem.and Ind., 1955,626; M. C. Dawson, T. G. Halsall, E. R. H. Jones, G. D. Meakins, and P. C. Phillips,ibid., p. 918.lBB H. H. Inhoffen and K. Bruckner, Fortschr. Chem. org. Naturstoffe, 1954, 11, 83.187 I. T. Harrison, B. Lythgoe, and S. Trippett, J., 1955, 4016.lB8 F. Sondheimer and 0. H. Wheeler, Chem. and Ind., 1955, 714.169 E. A. Braude and 0. H. Wheeler, J , , 1955, 320, 329.l7O L. Velluz, G. Amiard, and B. Goffinet, Bull. SOC. chirn. Frunce, 1955, 1341.171 H. H. Inhoffen, K. Bruckner, G. F. Domagk, and H. M. Erdmann, Chem. Ber.,1955, 88, 1415; H. H. Inhoffen, K. Briickner, K. Irmscher, and G. Quinkert, ibid.,p. 1424; H. H. Inhoffen, K. Briickner, R. Griindel, and G. Quinkert, ibid., 1954, 87,1407; H. H. Inhoffen and G. Quinkert, ibid., p.1418; H. H. Inhoffen and J. Kath,ibid., p. 1589.17a E. Havinga, A. L. Koevoet, and A. Verloop, Rec. Truv. chirn., 1955, 74, 1230.173 L. Velluz and G. Amiard, Bull. SOC. chim. France, 1955,205 ; L. Velluz, G. Amiard,and B. Goffinet, Compt. rend., 1955, 240, 2076, 2326KLYNE STEROIDS. 227The configuration (90) of calciferol suggested by Lythgoe and his colleagues167agrees with that proposed on X-ray evidence seven yearsAmong the new compounds discussed may be noted (i) the pre-calciferolof Velluz and his colleagues 1703 173 which is apparently the immediateprecursor of calciferol and is transformed into the latter by a non-photo-chemical reaction, (ii) the " trans "-vitamins D, of Havinga 175 andInhoffen,176 (iii) the dihydrovitamin D,-I1 of Schubert,l77 (iv, v) the iso-tachysterol 178 and a(" umgelagertes ")-tachysterol 171 of Iiihoffen.The Leiden school have employed isotopically labelled 'I-dehydro-cholesterol to follow the pattern of the photochemical conversion of thevarious provitamins D.172Total Synthesis.-New work includes many improvements in synthesesdiscussed in the two previous revie~s.l7~~ 180 A general review by Cornforthhas recently appeared.ls1The Monsanto group have given details of their total synthesis ofcortisone based on the Harvard method (cf.ref. 180), and have described theresolution of the bicyclic intermediate (91) and its correlation with naturalsteroids.ls3have described a numberof lines of work directed towards a more elegant synthesis within the frame-work of their original method.A stereospecific synthesis of a trans-anti-trans-perhydrophenanthrene derivative takes the course (92-95).The Wisconsin school 185 have extended their ingenious total synthesis ofepiandrosterone to prepare an 1 l-hydroxy-compound from the intermediateCornforth, Robinson, and their colleagues(96).174 D. Crowfoot and J. D. Dunitz, Nature, 1948, 162, 608.175 A. Verloop, A. L. Koevoet, and E. Havinga, Rec. Trav. chim., 1955, 74, 1125.176 H. H. Inhoffen, J. l?. Kath, and K. Briickner, Angew. Chem., 1955,67, 276.17' K. Schubert, Naturwiss., 1954, 41, 231; Biochem. Z . , 1954, 326, 132.178 H. H. Inhoffen, K. Briickner, and R. Griindel, Chem. Ber., 1954, 87, 1.17O Ann. Reports, 1952, 49, 190.180 Ibid., 1953, 50, 21:;181 J.W. Cornforth, Progress in Organic Chemistry," ed. J. W. Cook, Butter-worths, London, 1955, Vol. 111, p. 1.182 L. B. Barkley, M. W. Farrer, W. S. Knowles, and H. Raffelson, J . Amer. ChewSOC., 1954, 76, 5017.183 A. J. Speziale, J. A. Stephens, and Q. E. Thompson, ibid., p. 5011 ; L. B. Barkley,M. W. Farrer, W. S. Knowles, H. Raffelson, and Q. E. Thompson, ibid., p. 5014.lE4 A. R. Pinder and (Sir) R. Robinson, J., 1955, 3341 ; J. W. Cornforth, 0. Kauder,J. E. Pike, and (Sir) R. Robinson, J., 1955, 3348.185 W. S. Johnson, R. Pappo, and A. D. Kemp, J . Amer. Chem. SOC., 1954,76, 3353228 ORGANIC CHEMISTRY.Reagents: 1, KOEt. 2, Li-NII,. 3, H,-Ni(94)Hon the ketal.AcOI(961(101") @a)* And AIB-isomer.Reagents : 1, Li-EtOH-NH,. 2, Pb(OAc),.3, AcOH. 4, H*CO,H.5, ( a ) Li-EtOH-NH,; (b) Hf. 6, Ha-Pd.Then as in ll-deoxy series.The introduction of the ll-hydroxy-group via 12-acetoxy-, All-, 11 : 12-diol groupings is noteworthy. Other papers from the same school deal with18 : 19-bisnor-D-homotestosterone lS6 and testosterone.187A number of papers from the Merck laboratories have described in detaillater stages in the total synthesis of cortisone (cf. ref. 179) and its subse-quent refinements,lsg~ lgo Two new methods of closing ring D are note-worthy. In the first,la9 oxidation of the primary alcohol (103) to an alde-188 W. S . Johnson, H. C. Dehm, and L. J. Chinn, J . Org. Chem., 1954, 19, 670.187 W. S. Johnson, B. Bannister,-R. Pappo, and J. E. Pike, J .Amer. Chem. SOC.,1955, 77, 817.188 G. E. Arth. G. I. Poos, R. M. Lukes, F. M. Robinson, W. F. Johns, M. Feurer,and L. H. Sarett, J . Amer. Chezn. Soc., 1964, 16, 1715; W. F. Johns, R. M. Lukes, andL. H. Sarett, ibid., 5026; G. I. Poos, R. M. Lukes, G. E. Arth, and L. H. Sarett, ibid.,p. 5031.189 G. I. Poos, W. F. Johns, and L. H. Sarett, ibid., 1965, 77, 1026.180 G. E. Arth, G. I. Poos, and L. H. Sarett, ibid., p. 3834WILSON : HETEROCYCLIC COMPOUNDS. 229hyde is followed by removal of the 20-methylene group by known pro-cedures ; cyclisation of the &-keto-aldehyde (105) with aqueous potassiumhydroxide (free from oxygen) then yields a A16-20-ketone (106). The secondCOMc Y Y Yo13 J '* CH,OH J A j'# 7""u. bHo & ~ ti H r5 l i(103) (1041 (*s) (*6)C OMcb o 2 k Y 'fa Yo T0,Me fi.0 4- 5,i ri k( 0 7 ) (lo@ ( 109)Reagents : 1, Cr03-pyridine.2, (a) OsO,, (b) HIO,. 3, KOH. 4, as 1 and 2.5, NaOMe.method 190 starts from the methoxycarbonyl compound (107) correspondingto (103). Cyclisation of the E-keto-ester (108) with sodium methoxide inbenzene gives the 16 : 20-diketone (log), which can then be transformed intothe A16-20-ketone and the saturated 20-ketone.The Ciba group,lgl continuing their total synthesis which has led to a~-homo-17a-ketone (1 lo), have described a method of contracting a six-membered to a five-membered ring which involves ring-opening of a hydr-oxyimino-ketone (1 11).Reagents : 1, C,H,,*O*NO-ButOK. 2, p-C,H,Me*SO,Cl-NaOH. 3, (a) KOH ;( b ) CH,N,.4, NaOMe.An extensive series of papers by Nazarov and his colleagueslg2 dealsOther work on poly- chiefly with bicyclic and tricyclic intermediates.hydrophenanthrenes has been reported.lg3W. K.8. HETEROCYCLIC COMPOUNDS.Small Rings.-The oxetanones (1; R = Me and Ph) have been made,the latter in 47% yield by autoxjdation of sym.-tetraphenylacetone inacetic acid.1 Azetidine-2-carboxylic acid ( 2 ) has been isolated from Con-vallaria majalis Lin., and its structure established by ring scissions2 Certainlgl P. Wieland, G. Anner, and K. Miescher, Helv. Chim. Ada, 1953, 56, 1803.lg2 I. N. Nazarov, L. D. Bergelson, I. V. Torgov, and S. N. Ananchenko, Izvest.193 C . A. Grob and 0. Schindler, Experientia, 1954, 10, 367; N. Chaudhuri and P. C.1 B.L. Murr, G. B. Hoey, and C. T. Lester, J . A m y . Chew SOC., 1955, 77, 4430;Akad. Nauk, S.S.S.R., Otdel. Khim. Nauk, 1953, 889, and subsequent papers.Mukharji, Sci. and Cult., 1954, 19, 463.G. B. Hoey, D. 0. Dean, and C. T. Lester, ibid., p. 391.L. Fowden, Nature, 1955, 176, 347230 ORGANIC CHEMISTRY.P-lactones are formed surprisingly easily from @-hydroxy-acids in diluteacids3Simple Lactones, Fwans, and Pyrans.-Glutaconic anhydrides formdihydro-oxopyridazines (4) with diazonium salts, hydrazones (3) probablybeing intermediate^.^ An analogous mechanism operates in the formationof pyrazolines from a-acetobutyrolactone and diazonium compounds.5%Lactones have given hydroxymethylene derivatives (e.g., 5), which areconverted, with rearrangement, into the esters (6) in methanolic hydrogenchloride ; 6 y-lactones behave similarly.7 a-Carboxy-y-phenylbutyrolactoneforms a Mannich base with simultaneous decarboxylation ; exhaustivemethylation of the product affords the methylene-lactone (7). Anothermethylene-lactone, protoanemonin (€9, has been obtained in 99% yield bytreating a-angelicalactone dibromide with q~inoline.~Passage of mixtures of 2-alkyltetrahydropyrans and primary amines overalumina at 300" affords piperidines, pyrrolidines, and acyclic unsaturatedbases. l o The dimers of several @-unsaturated carbonyl compounds are2-acyl-2 : 3-dihydr0pyrans.1~A large number of 2-substituted 3-hydroxypyridines has been made l2from 2-fury1 ketones and alcoholic ammonia at 165". Electrolytic methoxyl-ation of furan gives potential bdicarbonyl compounds, which have beenused in a number of interesting syntheses.13* 14* l5 For example,l3 electro-lysis of 2-acetamidomethylfuran in methanol gives the dihydrodimethoxy-furan (9), which is converted into 3-hydroxypyridine (93%) in N-hydro-9 J.H. Wotiz and J. S. Matthews, J. Org. Chem., 1955, 20, 155.4 R. H. Wiley and C. H. Jarboe, J. Amer. Chern. SOC., 1955, 77, 403; R. H. Wileyand H. G. Ellert, ibid., p. 5187.6 G. F. Duffinand J. D. Kendall, J., 1955, 3470.6 F. Korte and H. Machleidt, Chem. Bey., 1955, 88, 136, 1676.7 Idem, ibid., p. 1685.8 E. E. van Tamelen and S. R. Bach, J. Amey. Chem. Soc., 1955, 77, 4683.9 C. Grundmann and E. Kober, ibid., p. 2332.10 H. P. Richards and A.N. Bourns, Canad. J. Chem., 1955, 33, 1433.11 J. Matti and M. Perrier, Bull. SOC. chim. France, 1955, 525; J. Dreux, ibid.,p. 521 ; M. Delepine, G. Amiard, M. Badoche, P. Compagnon, A. Horeau, J. Jacques,and A. Willemart, Ann. Chim., 1955, 10, 5 ; R. H. Hall, J., 1954, 4303.12 W. Gruber, Chem. Ber., 1955, 88, 178.13 N. Clauson-Kaas, N. Elming, and 2. Tyle, A c f a Chem. Scand., 1955, 9, 1.14 J. T. Nielsen, N. Elming, and N. Clauson-Kaas, ibid., p. 9; N. Clauson-Kaas andP. Nedenskov, ibid., p. 14; P. Nedenskov, N. Elming, J. T. Nielsen, and N. Clauson-Kaas, ibid., p. 17; N. Clauson-Kaas and P. Nedenskov, ibid., p. 27; J. T. Nielsen,N. Elming, and N. Clauson-Kaas, ibid., p. 30; J. T. Nielsen, N. Clauson-Kaas, andP. Dietrich, ibid., p. 182.15 N.Elming and N. Clauson-Kaas, ibid., p. 23WILSON : HETEROCYCLIC COMPOUNDS. 231chloric acid.from a suitably substituted furan.15Pyridoxine has been made by a similar method in 76% yieldp p 2 3 , . C O P fi lG%7 ,'CO2H(13)s-s(I 2)SuZ+hur Com$oztnds.-Recent developments in thiophen chemistry havebeen reviewed.16 Several long-chain acids have been made from substitutedthiophen acids (e.g., 10 + 11) by Raney nickel des~lphurisation.~~ Di-and tri-carboxylic acids of thiophen, furan, and pyrrole have been de-scribed.l* There has been continued interest 1 9 9 2 0 in the synthesis ofa-lipoic (6-thioctic) acid (12) ; one ingenious synthesis 2o employs theintermediate (13), made by Prins condensation of formaldehyde withhept-6-enoic acid. 1 : 2-Dithiole-3-thiones (14) appear to be fairly stable;they have been made from p-oxo-esters and phosphorus pentasulphide,21and by heating a-methylstilbenes 22 or cumenes 23 with sulphur.The dioxide(15) is a much weaker base than 4-aminotetrahydrothiopyran, probablybecause of the intramolecular interaction shown.%0 9 -"'NH, R'!,-i +.. O + ~ H H ~ N ~ ; ; no/ V0 C H2ClC y04) (1 5) (16) (17)Five-membered Rings containing Nitrogen.-Good yields of N-alkyl-pyrrolidones are obtained from y-alkylbenzylamino-acid hydrochlorides inboiling acetic anhydride, debenzylation occurring sim~ltaneously.~~ Re-ductive condensation of hydroxyiminomalonic ester with p-dicarbonylcompounds, effected with zinc dust in acetic acid, provides a valuable newsynthesis of substituted pyrrole-2-carboxylic esters.26 Several relativelysimple pyrroles form stable crystalline salts with hydrogen bromide in dryether.27l6 F. F. Nord, A. Vaitiekunas, and L. J. Owen, Forlschr. chem. FOYSC~., 1955, 3,l7 M. Sy, Bull. SOC. chim. France, 1955, 1175; G. M. Badger, H. J. Rodda, and1* R. G . Jones, J . Amer. Chem. Soc., 1955, 77, 4069, 4163.1s L. J. Reed and C . Niu, ibid., p. 416; E. Walton, A. F. Wagner, F. W. Batchelor,20 E. A. Braude, R. P. Linstead, and K. H. R. Wooldridge, Chem. and Ifid., 1955,21 L. Legrand and N. Lozac'h, Bull. SOC. chim. France, 1955, 79; J. Teste and22 J. Schmitt and M. Suquet, ibid., p. 84.28 E. K. Fields, J . Amer. Chem. SOC., 1955, 77, 4255.24 C. Barkenbus and J. A. Wuellner, ibid., p.3866.26 M. W. Gittos and W. Wilson, J., 1955, 2371.26 G. G. Kleinspehn, J . Amer. Chem. SOC., 1955, 77, 1546.27 R. J. Stedman and S. F. MacDonald, Canad. J . Chem., 1955, 33, 468.309-333.W. H. F. Sasse, J., 1954, 4162.L. H. Peterson, F. W. Holly, and K. Folkers, ibid., p. 5144.608.N. Lozac'h, ibid., p. 437232 ORGANIC CHEMISTRY.2-Aryloxazolines are obtained from p-azido-alcohols and aromaticaldehydes in concentrated sulphuric acid.28 The chemistry of oxazol-5-onehas been reviewed,29 and linear polyamides made by the reaction of 2 : 2'-bis (oxazolones) with diamines30 Oxazolid-2-ones are conveniently made byheating substituted et hanolamines with ethyl trichloroacet at e, chlorof o mbeing formed simultaneously ; whilst y-aminopropanols similarly give thesix-membered cyclic analogues, 8-aminobutanols behave differently andafford pyrr~lidines.~~ The isooxazolid-%one structure (16) for the anti-biotic oxamycin, which is identical with cycbserine, has been established bydegradative studies and by total synthesis.32 2-Aminothiazole hydro-chloride can be made in 91% yield from thiourea and 2-chloromethyl-1 : 3-dioxolan (17), which is readily ac~essible.~~ The infrared absorption pro-perties of thiazolines have been recorded,34 and it has been found thatthiazol-5-ones, obtained by heating a-thioacylamino-acids with aceticanhydride, resemble oxazolones in reactions with carbonyl compounds andwith a m i n e ~ .~ ~A series of novel glyoxaline derivatives (20) has been made, in additionto previously recognised products, by treating 4-alkylidene-2-thiothiazolid-5-ones (18) with ammonia, thioamides (19) being probable intermediate~~6The nitration of pyrazoles has been studied ; N-nitro-compounds areformed first, and rearrange in acid media to 4-nitropyra~oles.~' Pyrazolesare easily iodinated 38 and br~rninated.~~ Bromine affords crystallineadducts (e.g., 21) ; in the presence of iron powder, 4-bromo-, 3 : 4-dibromo-,and 3 : 4 : 5-tribromo-pyrazoles are obtained.Several condensation pro-ducts are formed from pyrazoles and aqueous sodium hypobromite; forexample, the complex compound (22), m. p. 278", is one of the productsfrom 3 : 4-dimethylpyra~ole.~~ The formation of furoxans (23) from arylmethyl ketones and nitric acid probably involves 40 dimerisation of inter-mediate nitrile oxides (24).28 J.H. Boyer and J. Hamer, J . Amer. Chem. SOL, 1955, 77, 951.2@ E. Baltazzi, Quart. Rev., 1955, 9, 150.80 C. S. Cleaver and B. C. Pratt, J . Amer. Chem. SOL, 1955, 77, 1544, 1541.31 G. Y. Lesher and A. R. Surrey, ibid., p. 636.32 F. A. KueN, F. J. Wolf, N. R. Trenner, R. L. Peck, E. Howe, B. D. Hunnewell,G. Downing, E. Newstead, R. P. Buhs, I. Potter, R. Ormond, J. E. Lyons, L. Chaiet,and K. Folkers, ibid., p. 2344; P. H. Hidy, E. B. Hodge, V. V. Young, R. L. Harned,G. A. Brewer, W. F. Phillips, W. F. Runge, H. E. Staveley, A. Pohland, €3. Boaz, andH. R. Sullivan, ibid., p. 2345; C. H. Stammer, A. N. Wilson, F. W. Holly, and K.Folkers, ibid., p. 2346.33 M. J.Astle and J. B. Pierce, J . Org. Ckem., 1955, 20, 178.94 W. Otting and F. Drawert, Chem. Ber., 1955, 88, 1469.95 J. B. Jepson, A. Lawson, and V. D. Lawton, J., 1955, 1791.9s F. P. Doyle, D. 0. Holland, and J. H. C. Nayler, J., 1955, 2265.87 R. Huttel, F. Buchele, and P. Jochum, Chem. Ber., 1955, 88, 1577; R. Huttel38 R. Huttel, 0. Schafer, and P. Jochum, Annalen, 1955, 593, 200.89 R. Huttel, H. Wagner, and P. Jochum, ibid., p. 179.40 H. R. Snyder and N. E. Boyer, J. Amer. Chem. SOC., 1955, 77, 4233.and F. Buchele, ibid., p. 1586WILSON : HETEROCYCLIC COMPOUNDS. 233Several 1 : 2 : 4-oxadiazoles have been made by heating amidoximes withacetic anhydride or benzoyl chloride,41 and 1 : 3 : 4-oxadiazoles (25) fromacylhydrazines and orthoesters, via alkoxymethylenehydrazides.42 1 : 3 : 4-Oxadiazol-2-ones (26) are best made from hydrazides and carbonyl chloride,MemMe(24) A r -CO*CIN-tObut they can be obtained by treating N-acyl-N'-chloroureas with sodiumcarbonate ; the products undergo ring scission with amines, yielding semi-carbazides and finally hydrazide~.~~ Substituted 1 : 2 : 4-thiadiazoles (27;X = O R and N q ) are obtained from O-alkylureas 44 or NN-dialkyl-guanidines 45 by N-chlorination and reaction with sodium thiocyanate ;and 5-alkylamino-3-amino-compounds (27 ; X = NH,) from N-alkyl-N'-amidinothioureas and hydrogen peroxide in aqueous ethan01.4~ Thereaction of thionyl chloride with certain acylhydrazones gives photosensitive1 : 2 : 3-thiadiazoles (e.g., 28 + 29), which thus become readilyacce~sible.~' The acids (30; R = H) are cyclised in alkali to 1 : 3 : 4-oxadiazoles (25; R' = SH), whereas the corresponding benzyl esters (30;R' = CH,Ph) yield 1 : 3 : 4-thiadiazoles (31) in concentrated sulphuricacid .48Current usage of theIt has been stressed 50+(31) (32 (33)term '' mesoionic " has been strongly critici~ed.~~that mesoionic compounds have true benzenoidaromatic structures, as seen in the betaine forkulations (32) or (preferably)(33) for N-phenylsydnone.If the description " mesoionic " is retained, itshould be applicable to all mesomeric aromatic betaines, including suchcompounds as (34) and tropone. Acid hydrolysis of alkylsydnones has beendl K. Clarke, J., 1954, 4251.42 C. Ainsworth, J . Amer.Chem. Sot., 1955. 77. 1148.O3 A. Stempel, J. Zelauskas, and J. A. Aeschlimann, J . Org. Chem., 1955, 20, 412.44 J. Goerdeler and F. Bechlars, Chem. Ber., 1955, 88, 843.O6 J. Goerdeler and M. Willig, ibid., p. 1071.O6 F. Kurzer, J., 1955, 1, 2288.O7 C. D. Hurd and R. I. Mori, J . Amer. Chem. Sot., 1955, 77, 5359.48 R. W. Young and K. H. Wood, ibid., p. 400.6o W. Baker and W. D. Ollis, ibid., p. 910; T. I. Bieber, ibid., p. 1055; W. J. 0.A. R. Katritzky, Chem. and Ind.. 1955, 521, 1391.Thomas, ibid., p. 533234 ORGANIC CHEMISTRY.used for the preparation of substituted hydrazines ; 51, 52 3-3'-pyridyl-sydnone is reversibly phototropic, the normal colourless form becomingdeep blue in sunlight.52 A new series of mesoionic compounds (36) has beenmade from alkylsemicarbazides and nitrous acid.53The extensive chemistry of tetrazolium salts has been reviewed.=Six-membered Nitrogenous Rings.-The properties of six-memberedaromatic rings containing nitrogen have been discussed,55 also the mechanismC\aAcRON - N Q- A!$)*- 0 & Re41 (35 1 (36 1 (37)of nucleophilic substitution in these and related compounds. 56 Passingmixtures of alkyl or aryl cyanides or cyanogen with 1 : 3-dienes over aluminaat 400" affords useful quantities of substituted pyridines ; 57 and 2-2'-pyridylethylamines are conveniently made by the addition of secondaryamines to 2-~inylpyridine.~* Results are now available on the basicstrengths and ultraviolet-light absorptions of a large number of alkyl-,59halogeno-,60 and 3-hydroxy-pyridines 61 and pyridine N-oxides.62 Largea-substituents in pyridine markedly hinder quaternary salt formation.Oxidation of gaseous alkylpyridines with air at 380" over mixed vanadium-molybdenum oxides gives mainly pyridine-aldehydes. IX Moderate yieldsof pyridinecarboxylic acids are obtained from alkylpyridines and seleniumdioxide, but 3-methyl groups are not attacked.65 Dilute nitric acid is apromising reagent for the oxidation of alkylpyridines ; 66 thus, with a mixtureof 10% nitric acid and 89% phosphoric acid at 230" in a stainless-steelautoclave, y-picoline gives isonicotinic acid in yields up to 95%. Ringexpansion of pyrrole to 3-chloropyridine (33%) occurs 67 when a mixture withchloroform is passed through a glass tube at 550".It has been known forsome time that pyridine is mercurated at position 3 ; pyridine-2-sulphinicacid has now been converted into 2-pyridylmercuric chloride.68 PyridineN-oxide is sulphonated with great difficulty, to the 3-sulphonic a ~ i d . 6 ~Boiling acetic anhydride converts 70 4-methylpyridine N-oxide into a mixtureof the acetates (36) and (37).6 1 J. Fugger, J. M. Tien, and I. M. Hunsberger, J . Amer. Chem. SOC., 1955, 77, 1843.62 J. M. Tien and I. M. Hunsberger, Chem. and Ind.. 1955, 119.53 J. H. Boyer and F. C. Canter, J. Amer. Chem. SOC., 1955, 77, 1280.64 A. W. Nineham, Chem. Rev., 1955, 55, 355-483.55 A. Albert, Chem. SOC. Special Publ. No. 3, 1955, p. 124.66 N. B. Chapman, ibid., p. 155.67 G. J. Jang and W. J. H.McCulloch, J. Amer. Chem. SOC., 1955, 77, 3014, 1343.6 8 H. E. Reich and R. Levine, ibid., p. 4913.69 H. C. Brown and X. R. Mihm, ibid., p. 1723.60 H. C. Brown and D. H. McDaniel, ibid., p. 3752.61 D. E. Metzler and E. E. Snell, ibid., p. 2431.62 H. H. Jaff6 and G. 0. Doak, ibid., p. 4441; H. JaffC, ibid., p. 4451.63 H. C. Brown and A. Cahn, ibid., p. 1715.64 W. Mathes and W. Sauermilch. Chem. Ber., 1955, 88, 1276.65 D. Jerchel, E. Bauer, and H. Hippchen, ibid., p. 156.S8 E. B. Bengtsson, Actu Chem. Scand., 1955, 9, 832.67 H. L. Rice and T. E. Londergan, J. Amer. Chem. SOC., 1955, 77, 4678.68 C. D. Hurd and C. J. Morrissey, ibid., p. 4658.6@ H. S. Mosher and F. J. Welch, ibid., p. 2902.70 J. A. Berson and T. Cohen, ibid., p. 1281WILSON : HETEROCYCLIC COMPOUNDS. 235The rearrangement 71 of l-methylpynmidinium compounds, eg., (38) +(39), recalls several other rearrangements in the heterocyclic field.72 Ultra-violet-light absorption studies show that 2- and 4-hydroxypyrimidines existlargely in the lactam form in solution; these compounds afford chieflyN-methyl derivatives with diaz~methane.~~ A series of 1 : 2 : 4-triazines(41) has been made by treating or-diketone acylhydrazones (40) withammonia.74 1 : 3 : 5-Triazine can be made in fair yields by heating form-amidine hydrochloride with bases ; it is a powerful noble-metal catalystp0ison.7~Condensed Ring Systems.Naturally occurring Oxygen Ring Compounds.-Some of these compounds are discussed in a recent rn~nograph.~~ TheAuwers synthesis of 2-acylcoumaran-3-ones (43) from o-acyloxy-w-chloro-acetophenones probably involves intermediates (42) formed by a Baker-Venkataraman transformation.77 Fair yields of flavonols (45) are obtainedfrom a-chloro-o-hydroxyacetophenones in cold ethanolic potassium hydrox-ide, and 2-arylidenecoumaran-3-ones (aurones) (48) are formed at highertemperatures ; epoxides (44) are likely intermediates in this condensation. 78Aurones (48) undergo ring expansion to flavones (49) in ethanolic potassiumcyanide 79 and give either aurone epoxides or flavonols (45) with alkalinehydrogen peroxide. 80 Rearrangement of 2-acylcoumarone oxime toluene-P-sulphonates is a convenient route to chromonols (especially) and flavonols ;71 H. C. Carrington, F.H. S. Curd, and D. N. Richardson, J., 1955, 1858.7 2 Ann. Reports, 1953, 50, 238.74 R. Metze, Chem. Ber., 1955, 88, 772.7s C. Grundmann, H. Schroder, and W. Ruske, ibid., 1954, 87, 1865 (cf. C. Grund-76 Y. Asahina and S. Shibata, Chemistry of Lichen Substances,” Japanese7? E. M. Philbin, W. I. A. O’Sullivan, and T. S. Wheeler, J., 1954, 4174.J. E. Gowan, P. M. Hayden, and T. S. Wheeler, J., 1955, 862.70 D. M. Fitzgerald, J. F. O’Sullivan, E. M. Philbin, and T. S. Wheeler, J., 1955,W. E. Fitzmaurice, W. I. O’Sullivan, E. M. Philbin, and T. S. Wheeler, Chem.D. J. Brown, E. Hoerger, and S. F. Mason, J., 1965, 211.mann and A. Kreutzberger, J . Amer. $ ? m . SOL, 1955, 77, 44).Society for the Promotion of Science, Tokyo, 1954.860.and Ind., 1955, 652236 ORGANIC CHEMISTRY.the mechanism of this reaction has now been studied.*l Flavonoidsfrequently rearrange in acid media [q., (46) + (47)], probably by ether-scission of the pyrone ring followed by cyclisation in the alternative way.82OHOH MeHO ij( 5 0 ) (50HO 0WM* 7 q R HO ~ ~ ~ ~ c , , i c o , ” Ma od 52) (53) O R’ (54)Infrared absorption properties of flavones and flavanones have beenreported,m and reactivity sequences in the methylation of A avone-hydroxylgroups and in the demethylation of methyl ethers established.a A newtype of flavonoid pigment, represented by distemonanthin (50) has beendi~covered.~~ Details of the synthesis of Zeztcoanthocyanidins have beenpublished,86 and the conformational structure (51) has been proposed forcatechin ; epicatechin is the 3-epimer.87The structure of mellein (ochracin) (52) has been confirmed 88 by synthesis0 0MeOHof the (&)-methyl ether, and that of isogalloflavin 8~ (53; R = CO,H,R = H; or vice versa) by degradation to the acid (54).Two groups ofworkers 90 have synthesised trimethylbrevifolin (55).81 T. A. Geissman and A. Armen, J . Amer. Chem. SOC., 1955, 77, 1623.82 S. K. Mukerjee and T. R. Seshadri, Chem. and Ind., 1955, 271.as B. L. Shaw and T. H. Simpson, J., 1955, 655.84 T. H. Simpson and J. L. Beton, J., 1954, 4065.86 F. E. King, T. J. King, and P. J. Stokes, J.. 1955, 4594.88 F.. E. King and J. W. Clark-Lewis, J., 1955, 3384.8’ F. E. King, J. W. Clark-Lewis, and W. F. Forbes, J.. 1955, 2948; J.W. Clark-Lewis, Chem. and Ind., 1955, 1218; cf. E. A. H. Roberts, zbid., pp. 631, 1551.8 8 J. Blair and G. T. Newbold, J., 1955, 2871.J. Grimshaw, R. D. Haworth, and H. K. Pindred, J., 1955, 833.*O R. D. Haworth and J. Grimshaw, Ckem. and Ind., 1955, 199; K. Bernauer and0. T. Schmidt, Annalen, 1955, 591, 153WILSON : HETEROCYCLIC COMPOUNDS. 237Structure (56) is proposed for fuscin, and the total synthesis of dihydro-Purpurogenone (probably 57) has been fuscin methyl ether reported.g1isolated Q2 from a strain of Penicillium purpurogenum Stoll.The total synthesis of usnic acid (60) has been accomplished elegantly;ferricyanide oxidation of methylphloracetophenone (58) affords the hydroxy-diketone (59), which is dehydrated by concentrated sulphuric acid to(-j-)-usnic acid;93a this had been resolved p r e v i o ~ s l y .~ ~ The mode ofdimerisation of p-cresol derivatives involved in this synthesis appears to befairly general, and is possibly significant in the biogenesis of dibenzofuranlichen s u b ~ t a n c e s . ~ ~ ~ The formation of dibenzofurans and diquinones fromquinones has been d i s c u ~ s e d . ~ ~ An important advance is the synthesis ofthe product (61) of ozonolysis of usnic acid.94Chromic acid oxidation of bergapten (62) gives ajwxanthoxyletin (63) ;methylation, and treatment with acid hydrogen peroxide, then gives fraxinol(64). Similar reactions are employed in the conversion of visnagin intobaicalein .95(65) (66)(R = 3 : 4-methylenedioxyphenyl)The structure of sesamolin (65), which with sesamin (66) is mainlyresponsible for the pyrethrum-synergistic activity of sesame oil, has beenconfirmed by degradati~n.~~ Fagarol is identical with (-!-)-~esamin.~~Condensed Ring Systems containing Nitrogen.-Ultraviolet-light absorp-tion by mono- and di-cyclic N-heteroaromatic systems has been di~cussed.~sO1 D.H. R. Barton and J. B. Hendrickson, Chem. and I n d . , 1966, 682; A. J. Birch,;bid., p. 682.O 2 J. C. Roberts and C. W. H. Warren, J.. 1955, 2092.08 (a) D. H. R. Barton, A. M. Deflorin, and 0. E. Edwards, Chem. and Ind., 1955,1039; (b) F. M. Dean, P. Halewood, S. Mongkolsuk, A. Robertson, and W. B. Whalley,J., 1953, 1250; (c) F. M. Dean, A. M. Osman, and A. Robertson, J . , 1966, 11.94 F. M. Dean and A.Robertson, J., 1955, 2166.O 6 A. Schonberg, N. Badran, and N. A. Starkowsky, J . Amer. Chem. SOL, 1955,77, 5390.O 6 M. Beroza. ibid., p. 332; E. Haslam and R. D. Haworth, J., 1956, 827; H. Erdt-man and 2. Pelchowicz, Chem. and I n d . , 1965, 567; B. Carnmalm, H. Erdtman, and2. Pelchowicz, Acia Chem. Sand., 1965, 9, 1111.O 7 B. Carnmalm and H. Erdtman, Chem. and I n d . , 1966, 670.0 8 S. F. Mason, Chem. Soc. Special Publ. No. 3, 1966, p. 139238 ORGANIC CHEMISTRY.Monographs have been published dealing with indoles and carbazoles ~9 andwith condensed thiophen ring systems.1001-Acylated products are obtained from indolylmagnesium bromide andcertain lactones. lol Indoles and oxalyl chloride readily give highly crystal-line 3-glyoxyloyl chlorides, and lithium aluminium hydride reduction of theamides therefrom is a convenient route to tryptamines.lo2 Ring scission ofindoles to o-acylamino-acids or -ketones is effected by ozone lo3 or by aut-oxidation ; l o 3 9 lo4 in the latter case, hydroperoxides (67) are intermediates.Indoles react with nitro-olefins, yielding 3-2'-nitroalkyl derivatives,105 andwith a-acetamidoacrylic acid in acetic acid-anhydride, indole gives acetyl-tryptophan.lo6 Piperidine-ring expansion occurs during the ferricyanideoxidation of the substituted derivatives (68), and the cycloheptenoindole(69) is formed.lo7Ultraviolet-light absorptions and base strengths for quinolines havebeen reported.108 The chemistry of Reissert compounds has received furtherattention,lm and this subject has been reviewed.ll0 Nitration of quinolineaffords only a small yield of nitro-compound, mainly the 3-isomer.111 1 : 2-Dihydroisoquinoline has been isolated for the first time ; 112 reactive dihydro-isoquinolines are intermediates in several interesting syntheses.113~ 114Thus, reduction 114 of the N-substituted isoquinolinium salt (71) (from09 W.C. Sumper and F. M. Miller, "Chemistry of Heterocyclic Compounds.Vol. VIII. Heterocyclic Compounds with Indole and Carbazole Systems," IntersciencePubl. Inc., New York, 1954.loo H. D. Hartough and S. L. Meisel, "Compounds with Condensed ThiopheneRings," Interscience Publ. Inc., New York, 1954.101 A. R. Katritzky and Sir R. Robinson, J., 1955, 2481.102 M. E. Speeter and W. C. Anthony, J .Amer. Chem. Soc., 1954, 76, 6209.10s G. Clerc-Bory, M. Clerc-Bory, H. Pacheco, and C. Mentzer, BUZZ. SOC. chim.104 R. J. S. Beer, T. Donavanik, and A. Robertson, J., 1954, 4139.106 W. E. Noland, G. M. Christensen, G. L. Sauer, and G. G. S. Dutton, J . Atner.106 H. R. Snyder and J. A. MacDonald, ibid., p. 1257.107 J. Harley-Mason and A. H. Jackson, J., 1955, 374.108 S. B. Knight, R. H. Wallick, and C. Balch, J . Amer. Chem. Sot., 1955, 77, 2577.109 R. F. Collins, ibid., p. 4921; R. L. Cobb and W. E. McEweo, ibid., p. 5042.110 W. E. McEwen and R. L. Cobb, Chem. Rev., 1955, 55, 511.111 M. J. S. Dewar and P. M. Maitlis, Chem. and Ind., 1955, 685.112 L. M. Jackman and D. I. Packham, ibid., p. 360.118 A. R. Battersby, R. Binks. and P. S.Uzzell, ibid., p. 1039.114 K. T. Potts and Sir R. Robinson, J., 1955, 2675.France, 1955, 1229.Chem. Sot., 1955. 77, 456WILSON HETEROCYCLIC COMPOUNDS. 239homophthalaldehyde and tryptamine) by lithium aluminium hydride, givesthe yohimbine skeleton (72). Bromine forms N-bromoacridinium bromideswith acridine in carbon tetrachloride, and 3-bromo- and 3 : 7-dibromo-compounds in acetic acid.115 Thiolutin and aureothricin are yellow crystal-line antibiotics isolated from various Streptomyces ; they have beenassigned 116 the unique pyrrolo-1 : 2-dithiole structures (70; R = Me andEt respectively).A large number of derivatives of indazole (73), including chlorination,nitration, and sulphonation products, has been de~cribed.1~' Phosphorusoxychloride cyclises 2-acylaminomethylpyridines to 2 : 3a-diazaindenes(74), which very rapidly undergo Friedel-Crafts reactions at C(l>, or at C(3)if the former position is substituted. 118 The related pyrrocoline system (75)readily undergoes Friedel-Crafts and C-alkylation reactions ; 119 in this case,07 &N2 3 mi 3 @6 (76) NO2(73) (74) (7s)substitution occurs most easily at Co).Several derivatives of the system(76) have been made from 2-aminopyridines and 2-chloro-1 : 3-dinitro-benzene.120 The chemistry of quinolizine (pyridocoline) (77) has beenreviewed.121 Dehydrobenzoquinolizinium salts (78) have been made 122by treating a-halogenated ketone-2-phenylpyridineconcentrated hydrobromic acid ; and acridiziniumquaternary salts withsalts (79) have beenprepared 123 analogously, from 2-formylpyridine and benzyl bromides.2-Aminopyridine gives the bicyclic system (80) with P-propiolactone, and2-aminothiazoles behave similarly.l% Glyoxalinothiazolium salts (81) havebeen made by several routes,125 and dihydroglyoxalinothiazolium salts have116 R.M. Acheson, T. G. Hoult, and I<. A. Barnard, J., 1954, 4142.116 W. D. Celmer and I. A. Solomons, J. Amer. Chenz. SOL, 1955, 77, 2861.117 R. R. Davies, J., 1955, 2412.11* J. D. Bower and G. R. Ramage, J., 1055, 2834.11* D. 0. Holland and J. H. C. Nayler, J., 1955, 1504.120 K. H. Saunders. J., 1055, 3275.121 B. S. Thyagarajan, Chem. Rev., 1954, 54, 1019.122 C. K. Bradsher and L. E. Beavers, J . Amer. Chem. SOC., 1955, 77, 453.128 Idem, ibid., p.4812.126 A. Lawson and H. V. Morley, J., 1955, 1695; B. Kickhofen and F. Krohnke,C. D. Hurd and S. Hayao, ibid., p. 117.Chem. Ber., 1955, 88, 1109240 ORGANIC CHEMISTRY.been made from &-halogenated ketones and tetrahydro-2-thioglyoxaline.126Derivatives of the little known 1 : 7-naphthyridine system (82) have beenmade; 12’ polyaza-naphthalene and -indene derivatives are of interest asisosteres of biologically important purines and pyrimidines.128 A numberof glyoxalino-pyridines and -quinolines have been de~cribed.1~~Kinetin (83) has been synthesised from furfurylamine and 0-methyl-thiopurine; 130 it is a cell-division factor, with the properties of a plant“wound hormone,” and has been isolated in crystalline form from auto-claved deoxyribonucleic acid.131Pteridims.-The proceedings of a symposium on pteridines have beenpublished,132 and infrared and ultraviolet absorptions for a large number ofmonosubstituted pteridines r e ~ 0 r d e d . l ~ ~ Ring scission of hydroxypteridinesby acids and alkalis has been studied carefully.134 Reaction of the chloro-pyrazines (84; R = C02Me or CN) with amidines (or guanidine) provides anew route to 4-hydroxy- and 4-amino-pteridines. 135 Many quin~xalines,~~~(84 (8 5) (86)pteridines,13’ and other polycyclic compounds 138 have been made by thecondensation of appropriate o-aminonitroso-compounds with cyanoaceticesters. Among new pterins isolated from Drosophilia species are [85;R = CH(OH)*CH(OH)*CHJ 139 and [85; R = CH(OH)*C02H].140 Theformer is probably identical with a growth factor for Crithidia fasciculata,biopterin, isolated from urine.141 The structure of urothione (86) has beenelucidated,142 and some progress made in the synthesis of related thiophano-and dihydrof~rano-pteridines.~~~Porphyrins.-The condensation product from pyrrole and acetone1z6 W.Wilson and R. Woodger, J., 1955, 2943.127 H. E. Baumgarten and A. L. Krieger, J . Amer. Chem. SOC., 1955, 77, 2438.1z8 F. L. Rose, J., 1954, 4116; C. L. Leese and H. N. Rydon, J., 1956, 303.1 Z g K. Schilling, F. Krohnke, and B. Kickhofen, Chem. Ber., 1955, 88, 1093;F. Krohnke and B. Kickhofen, ibid., p. 1103; B. Kickhofen, ibid., p. 1114.130 C. 0. Miller, F. Skoog, F. S. Okumura, M. H. von Saltza, and F. M. Strong, J .Amer.Chem. Soc., 1955, 77, 2662.131 C. 0. Miller, F. Skoog, M. H. von Saltza, and F. M. Strong, ibid., p. 1392.132 G. E. W. Wolstenholme and M. P. Cameron (Editors), Ciba Foundation Sym-posium on Chemistry and Biology of Pteridines, J. and A. Churchill, London, 1954.133 S. F. Mason, J., 1955, 2336.134 A. Albert, J., 1955, 2690.135 G. P. G. Dick and H. C. S. Wood, J., 1955, 1379; E. C. Taylor, jun., and137 Idem, ibid., p. 2036.138 F. C. Copp and G. M. Timmis, J., 1955, 2021; T. S. Osdene and G. M. Timmis,139 H. S. Forrest and H. K. Mitchell, J . Amer. Chem. Soc., 1966, 77, 4865.l 4 0 M. Viscontini, E. Loeser, P. Karrer, and E. Hadorn, Helv. Chim. Acta, 1955, 38.141 E. L. Patterson, H. P. Broquist, A. M. Albrecht, M. H. von Saltza, and E.L. R.142 R. Tschesche, F. Korte, and G. Heuschkel, Chem. Bev., 1966, 88, 1251.143 R. Tschesche, H. Barkemeyer, and G. Heuschkel, ibid., p. 1258; R. TschescheW. W. Paudler, Chem. and Ind., 1955, 1061.T. S. Osdene and G. M. Timmis, J., 1955, 2027.J., 1955, 2032, 2214.397, 1222.Stokstad, J . Amer. Chern. SOC., 1955, 77, 3167.and H. Barkemeyer, ibid., p. 976WILSON : HETEROCYCLIC COMPOUNDS. 241probably l* has the structure (87), and analogous structures are suggestedfor the anhydrotetramers obtained from furan and methyl ket0nes.1~~Factors involved in the stability of metal-porphyrins have been studiedCH;CO,H1HO,CH 0,CCH,€O N H,IMecarefully ; copper complexes are markedly stabilised, relatively to mag-nesium complexes, by the introduction of ethoxycarbonyl groups into thepyrrole residues.146 The structure of chlorophyll 14' and the hydrogenationof porphyrins 148 have been discussed; and a series of papers deals withsynthetic tetra-azaporphyrins and intermediate imidines.149P.Rothemund and C. L. Gage, J . Amer. Chem. Soc., 1955, 77, 3340.145 R. G. Ackman, W. H. Brown, and G. F. Wright, J. Org. Chew., 1955, 20, 1147.14% W. S. Caughey and A. H. Corwin, J . Amer. Chem. SOC., 1955, 77, 1609; A. H.Corwin and M. H. Melville, ibid., p. 2755.147 R. P. Linstead, U. Eisner, G. E. Ficken, and R. B. Johns, Chem. SOC. SpecialPubl. No. 3, 1955, p. 83.14* M. Whalley. ibid.? p. 98.1955, 3521;G. E. Ficken and R. P. Linstead, J . , 1965, 3525; R. P. Linstead and k Whalley, J.,1965, 8630; J.A. Elvidge and R. P. Linstead, J.. 1955, 3536.M. E. Baguley, H. France, R. P. Linstead, and M. Whalley242 ORGANIC CHEMISTRY.The proposa11501151 of a detailed structure (89) for vitamin B,, is aremarkable achievement, and a full account of this work is eagerly awaited.It was shown in a brilliant X-ray crystallographic study 151 that the hexa-carboxylic acid, previously obtained by alkaline degradation of thevitamin, has the probable structure (88), and that the vitamin itself is aporphyrin of the same type. The fine structure (89) for the vitamin issupported by chemical evidence,150 which, inter aZia, enables the conjugatedsystem to be located satisfactorily. It is noteworthy that in the conversionof the vitamin into the hexacarboxylic acid the conjugated system migratesand a lactam ring is formed.The oxidation products of the vitamin wereshown recently to include 3 : 3-dimethyl-2 : 5-dioxopyrrolidine-4-propion-amide.153 It has been recognised that “ Factor I11 ’’ isolated from fermentedsewage, is a vitamin B,, analogue, containing a 5-hydroxybenziminazolenucleotide fragment. w. w.9. ALKALOIDS.VOLUME V of ((The Alkaloids” (Manske) has appeared during the yearreviewed. It covers the pharmacology of alkaloids, including narcotics andanalgesics, cardio-active alkaloids, respiratory stimulants, antimalarials,uterine stimulants, alkaloids as local anmthetics, pressor alkaloids, mydriaticalkaloids, curare-like effects, lycopodium alkaloids, and minor alkaloids ofunknown structure., The yohimbine, corynantheine, alstonine, cinchon-amine, and Erythrina alkaloids of the indole group have been reviewed, andpossible schemes for their biogenesis discussed.lU Structural relations inthe alkaloid field have been reviewed.lb Reviews of curare alkaloids haveappeared.2 A new synthesis of bufotenine has been rep~rted.~ Theabsolute stereochemistry of the morphine, benzylisoquinoline, aporphine,and tetrahydroberberine alkaloids has been discussed ; the change of opticalrotation with polarity of solvents is of the same type in the benzyliso-quinoline and tetrahydroberberine series, but there is an inversion in theaporphine series.The benzylisoquinoline, aporphine, and tetrahydro-berberine alkaloids accompanying the morphine and sinomenine alkaloids inNature are enantiomorphous with the latter.4Tropane Group.-A review of the chemistry and biochemistry of tropane150 D.C . Hodgkin, Sir A. R. Todd, and A. W. Johnson, Chem. Soc. Special Publ. No.3, 1955, p. 109; R. Bonnet, J. R. Cannon, A. W. Johnson, I. Sutherland, Sir A. R. Todd,and E. L. Smith, Naturs, 1955, 176, 325.161 D. C. Hodgkin, J. Pickworth, J. H. Robertson, K. N. Trueblood, R. J. Prosen,and J. G. White, ibid., p . 325.162 J. R. Cannon, A. W. Johnson, and Sir A. R. Todd, ibid., 1954, 174, 1168.153 F. A. Kuehl, C. H. Shunk, M. Moore, and K. Folkers, J . Amer. Chem. Soc.,1955, 77, 4418.164 F. M. Robinson, I. M. Miller, J. F. McPherson, and K . Folkers, ibid., p . 5192.1 “ The Alkaloids,” ed. R.H. F. Man:?, Academic Press, New York, 1955, Vol. V.Progress in Organic Chemistry,” ed. J. W.Cook, Butterworths Sciettific Publications, London, 1955, Vol. 3, Chapter 5, p. 218.1b Sir R. Robinson, The Structural Relations of Natural Products,” Oxford Univ.Press, 1955.2 D. Vovet, Boll. sci. Fac. Chiin. ind. Bologna, 1954, 12, 172; P. Karrer, Nature,1955,176, 277; P. Karrer and H. Schmid, Angew. Chem., 1955, 87, 361.5 A. Stoll, F. Troxler, J. Peyer, and A. Hofmann, Helu. Chim. Acta, 1955, 88, 1452.4 K. W. Bentley and H. M. E. Cardwell, J . , 1955, 3252 ; see also refs. 84 and 85.V. Boekelheide and V. Prelog, iPINDER ALKALOIDS. 243alkaloids has appeared,5 and further investigations on their stereochemistryhave been reported.6Lupinane Grou@.-The stereochemistry of the lupin alkaloids has beendiscussed further,’ and the synthesis of ( -j-)-cytisine announced. 2-Y-Pyr-idylallylmalonic acid (1) condensed with benzylamine and formaldehyde, togive l-benzyl-5-2‘-pyridylpiperidine-3-carboxylic acid (2 ; R = C0,H).u1-.(31The derived ethyl ester with lithium aluminium hydride afforded the alcohol(2; R = CH,*OH), which with hydrogen bromide gave the derivative(2; R = CH,Br).This quaternised to the salt (3), which on mild oxidationyielded (&)-N-benzylcytisine (4 ; R = CH,Ph). Debenzylation gave(-J-)-cytisine (4; R = H), identical with the racemic natural base. This isalso a synthesis of caulophylline (4; R = Me) and rhombifoline (4; R =CH,:CH*CH,*CH,).8The alkaloid (-)-spartalupine, found in Lupinus sericeus Pursh, is oneof the enantiomorphs of the third and remaining racemic pair stereoisomericwith (&)-sparteine and ($)-a-isosparteine.The base has been epimerisedto (+)-sparteine and to (+)-a-isosparteine, an$ has been compared with(-j-)-spartalupine, synthesised by the method of Sorm and KeiLg* 10(+)-e#iLupinine N-oxide has been found in seeds of Lupinus uarius L. ;this is the first reported natural occurrence of an N-oxide in the lupinanePyridine Group.-The controversy regarding the occurrence of pelle-tierine in Punica granatum L. cannot yet be regarded as settled.12 Wibautand his co-workers l3 have established that “ base C,” isolated from theplant, is not identical with isopelletierine. It is possible that the originalgroup.11ti A.Stoll and E. Jucker, Chimia (Switz.), 1955, 9, 25.a A. Heusner, 2. Naturforsch.. 1954, 9b, 683; G. Fodor, J. Tbth, J. Lestyan, andI. W. Vincze, Szevves Kkm. Konf. Debvccen, 1953, 293 ; G. Fodor, Acta Chim. Acad. Sci.Hung., 1955, 5, 379; Experientia. 1955, 11, 129; G. Fodor, J. Tbth, and I. Vincze, J.,1955, 3504; cf. Ann. Reports, 1954, 51, 253.7 F. Galinovsky and H. Nesvadba, Monatsh., 1954, 85, 1300; F. Galinovsky,P. Knoth, and W. Fischer, ibid., 1955, 86, 1014; J. Ratusky, R. Reiser, and F. Sorm,Chem. Listy, 1954, 48, 1794; Coll. Czech. Chem. Conam., 1955, 20, 798; cf. Ann. Reports,1954, 51, 254.E. E. van Tamelen and J. S. Baran, J . Amer. Chem. Soc., 1955, 77, 4944.M. Carmack, B. Douglas, E. W. Martin, and H.Suss, ibid., p. 4435.lo F. Sorm and B. Keil, Coll. Czech. Chem. Comm., 1948, 13, 544.11 W. D. Crow and N. V. Riggs, Austral. J . Chem., 1955, 8, 136.l2 Ann. Reports, 1954, 51, 254.1s J. P. Wibaut, H. C. Beyerman, U. Hollstein, Y . M. F. Muller, and E. Greuell,Proc. k. ned. Akad. Wetenschap., 1955, 58, €3, 56244 ORGANIC CHEMISTRY.'' pelletierine " of Hess and Eichel l4 is identical with an unidentified basefound in the bark.The tobacco alkaloid myosmine is best represented as 2-3'-pyridyl-A1-pyrroline (5). It shows a strong infrared band characteristic of a )GN-group conjugated with an aromatic ring, but no band in the }NH region.15Quinoline Group.-The pyranoquinoline alkaloid flindersine has beenproved to have the angular structure (6) by a lengthy series of degradations.On distillation with zinc dust quinoline is obtained; on treatment withpotassium hydroxide the product is 4-hydroxy-2-quinolone (7 ; R= R' = H).The alkaloid has one ethylenic bond, conjugated with the quinoline nucleus.Oxidation gives flindersinjc acid (7 ; R = CMe,*CO,H ; R' = C0,H) , whichis further degraded by hydrolysis to carbon dioxide , a-hydroxyisobutyricacid, and the quinolone (7 ; R = R' = H).Flindersinic acid, when boiledwith 95% ethanol, yields the acid (7; R = H, R = C0,H) and the corre-sponding ethyl ester, and the constitution of the latter has been proved bysynthesis. Similar degradations have been carried out on chlorodeoxy-flindersine and N-methylfindersine. The analogous aldehydic degradationproducts, a-hydroxyisobutyraldehyde and the compound (7; R = H,R' = CHO) are obtained by oxidation of flindersine with osmium tetroxideto the glycol (8; R = R = OH), followed by periodate oxidation andhydrolysis.16 Final confirmation of the structure (6) is provided by syn-thesis1' Reaction of 4-hydroxy-2-quinolone (7; R = R' = H) withp-methylcrotonyl chloride gives the ester (7; R = Me,C:CH*CO, R' = H),which undergoes a Fries rearrangement and cyclisation to the pyrano-quinolone (8; R = H, R = to).Reduction of the ketonic carbonyl groupyields the alcohol (8; R = H, R' = OH), which on dehydration affordsfiindersine (6).Dictamnic acid has been proved to have structure (7; R = Me, R' =CO,H), by unambiguous synthesis; dictamnine therefore has a linearstructure.lG2 : 3 : 4-Trimethoxy-lO-methylacridone has been found in the bark ofEvodia alata F. Muell.; it was identified by synthesis.l* Evolatine, fromthe same source, is a furanoquinoline alkaloid isomeric with ev0xine.1~ Ithas been degraded by methods similar to those used for evoxine; on potashfusion it gives the phenolic base (9 ; R = H) , which on methylation affordskokusaginine (9; R = Me), and on treatment with acid it is converted14 K. Hess and A. Eichel, Bey., 1917, 50, 1192.l6 B. Witkop, J . Amer. Chem. SOC., 1954, 76, 6597.l6 R. F. C . Brown, J. J. Hobbs, G. K. Hughes, and E. Ritchie, Austra2. J . Chem.,17 R. F. C. Brown. G. K. Hughes, and E. Ritchie, Chenz. and Ind., 1955, 1385.R. J. Gell, G. K. Hughes, and E. Ritchie, Austral. J .Chem., 1966, 8, 114.lB Ann. Reports, 1954, 51, 255.1954, 7, 3.48PINDER : ALKALOIDS. 245into the ketone (9; R = Me,CH*COCH,), isomeric with evoxoidine. Evol-atine is therefore [9 ; R = Me2C(OH)-CH(OH)*CH.J.18Methyl skimmianinate has been proved by synthesis to have structure(10) ; this provides confirmatory evidence for the linear structure of skim-mianine. Similarly, methyl O-methylkokusagininate (1 1) has been syn-thesised, proving that kokusaginine has a linear, tricyclic structure.20The alkaloid maculine, from FZindersia maculosa Lindl., is 6 : 7-methylene-dioxydictamnine (12). On hydrogenolysis it yields 3-ethyl-2 : 4-dihydroxy-6 : 7-methylenedioxyquinoline, identified by synthesis.,1Indole Grou$.-A review of ergot alkaloids has appeared.22 The stereo-chemistry of lysergic and dihydrolysergic acid % and their amides 24 has beendiscussed.A series of lumi-compounds has been obtained from ergotalkaloids and other lysergic acid derivatives by ultraviolet irradiation inaqueous acid solution; the 9 : 10-double bond in the lysergic acid residue ishydrated by this procedure.25The stereochemistry of the aZZoyohimbanes,26 yohimbane, corynanthei-dane, and related compounds 27 has been discussed. The alkaloid voacan-OHIgine, C,,H,,O,N,, from Voacanga thoumsia', gives on hydrolysis methanoland an acid which is easily decarboxylated to ibogaine; it is therefore amethoxycarbonylibogaine, of probable structure (13 ; X = C0,Me) .2820 R. I;. C . Brown, Austral. J .Chem., 1955, 8, 121.21 R. J. Gell, G. K. Hughes, and E. Ritchie, ibid., p. 422.22 M. Semonsky, Cesk. Farm., 1955, 4, 198.23 A. Stoll, T. Petrzilka, J. Rutschmann, A, Hofmann, and H. H. Gunthard, Helv.2a A. Stoll and A. Hofmann, ibid., 1055, 38, 421.25 A. Stoll and W. Schlientz, ibid., p. 585.26 E. Wenkert and L. H. Liu, Experientia, 1955, 11, 302.27 W-M. Janot, R. Goutarel, A. Le Hir, G. Tsatsas, and V. Prelog, Helv. Chim. Ada,28 M.-M. Janot and R. Goutarel, Cornpi. rend., 1955, 241, 986.,Chim. Acta, 1954, 37, 2039.1955, 38, 1073246 ORGANIC CHEMISTRY.Karrer and his associates have described extensive investigations onindole alkaloids of curare.2?, 30 Of these, fluorocurine and mavacurine havebeen assigned partial structures (14) and (15), on degradative and spectro-scopic evidence.80The structure (16) is now preferred for aricine.On alkaline hydrolysisaricinic acid is obtained, which differs in molecular formula from aricine byCH,; the acid is reconverted into aricine by diazomethane. Ring E inaricine is therefore not lact~nic.~lInterest in alkaloids of Rauwolfia spp. continues to increase.32 A welcomeattempt to clarify ambiguities in nomenclature amongst alkaloids of R.serpentina Benth. has been made, the intense activity in this field havingresulted in the assignment of several names to single compounds.33New structures have been proposed for ajmaline.32 The formation of3-acetonyl-3-hydroxy-l-methyloxindole (17) on oxidation confirms thepresence of a dihydro-N-methylindole system in the alkaloid.When heatedwith nickel, both ajmaline and isoajmaline yield decarbonoajmaline,C1,H2,PN,, a secondary base giving n-butyric, propionic, and acetic acid onoxidation. The formation of this base is explained by the elimination ofcarbon monoxide from the latent aldehyde group : )N*CH(OH)*CHEt +)NH + CO + *CH2Et, further reasons being given for believing such a groupto be present. Ajmaline is reduced by potassium borohydride in aqueoussolution to dihydroajmaline [)N*CH(OH) + )NH *CH,*OH], but is notreduced by lithium aluminium hydride; a possible explanation of thisdifference is that in aqueous solution an equilibrium exists between thecarbinolamine and a small proportion of the aldehyde-imine forms. Di-hydroajmaline yields a neutral dibenzoyl derivative, which has a freehydroxyl group.34 A number of carboline bases have been obtained bydehydrogenation of deoxydihydroajmaline and deoxyajmaline ; one of theseis alstyrine, and another, probably, id-N-methylalstyrine.The structure(18) for the alkaloid best explains these and other observations.34335 Otherinvestigators prefer a cyclic semiacetal structure (19), there being some doubtabout the position of the methyl group and the form of ring E . ~ ~29 H. Asmis, E. Bachli, E. Giesbricht, J. Kebrle, H. Schmid, and P. Karrer, Helv.Chirn. Acta, 1954, 37, 1968; E. Giesbricht, H. Meyer, E. Bachli, H. Schmid, and P.Karrer, ibid., p. 1974; H. Asmis, H. Schmid, and P. Karrer, ibid., p. 1983; H. Asmis,E. Bachli, H.Schmid, and P. Karrer, ibid., p. 1993.80 H. Bickel, H. Schmid. and P. Karrer, ibid., 1955, 38, 649.31 A. Stoll, A. Hofmann, and R. Brunner, ibid., p. 270; cf. Ann. Reports, 1954,51, 258.32 Ibid., p. 256.33 D. D. Phillips and M. S. Chadha, Chem. and Ind., 1955, 414.=4 Sir R. Robinson and co-workers, ibid., p. 285.35 F. C. Finch, J. D. Hobson, Sir R. Robinson, and E. Schlittler, ibid., p. 653.36 A. Chatterjee and S. Bose, Sci. and Cult., 1955, 20, 606PINDER ALKALOIDS. 247Confirmation of the location of the three vicinal substituents in ring Eof reserpic acid (20 ; R = C02H, R' = OH) has been provided by degrad-ation. The toluene-P-sulphonic ester (20; R = CO,Me, R' = p-Me*C,H,*SO,) on removal of the sulphonyl residue yields methyl anhydro-reserpate (21), which is the enol ether of a (3-keto-ester, since it is readilyhydrolysed and decarboxylated to the ketone reserpone (22).The sametoluenesulphonate , on reduction with lithium aluminium hydride, affordsreserpinol (20; R = CH,*OH, R' = H), which on dehydrogenation yields7-hydroxy-yobyrine (23) ; the structure of the last is proved by synthesis ofits methyl ether.37A new alkaloid, deserpidine, C3&&&,N2, has been found in R. canescens.On hydrolysis it yields 3 : 4 : 5-trimethoxybenzoic acid and methyl deser-pidate. It is probably a demethoxyreserpine (24; R = H), since its ultra- .?,-. (24) McOaC OMeOMe OMeMe(25)nviolet absorption curve is almost coincident with that of yohimbine 3 : 4 : 5-trimethoxybenzoate.38 Methyl deserpidate has been converted into a-yohimbine by a simple series of reactions, an inversion occurring at C(,).37 C .F. Huebner, H. B. MacPhillamy, A. F. St. Andrd, and E. Schlittler, J. Amer.Chem. SOC., 1955, 77, 472.38 E. Schlittler, P. R. Ulshafer, M. L. Pandow, R. M. Hunt, and L. Dorfman,ExFerieniia, 1955, 11, 64248 ORGANIC CHEMISTRY.Hence deserpidine, and also reserpine, are derivatives of 3-e#i-a-y0himbine,~~which has itself been found in R. se~pentirta.~~ Structures (24; R = H)and (24; R = OMe) are proposed for deserpidine and reserpine respectively.39Amongst other alkaloids found in R. canescens are canescine 41s 42 and re-~anescine,~~ the latter identical with deserpidine and, probably, withcanescine.Several groups of workers have investigated the stereochemistry ofreserpine and related alkaloids.The D/E ring junction of reserpine is provedto be cis by the stereochemically unambiguous synthesis 45 of ll-methoxy-alloyohimbane (reserpane) (22 ; replace CO by CH,), identical, apart fromthe racemic character of the synthetic material, with the Wolff-Kishnerreduction product of reserpone (22). Considerable divergence of view isfound regarding the absolute stereochemistry of reserpine, and the mattercannot yet be regarded as 46Tetraphyllin and tetraphyllicine are two alkaloids isolated from R. tetra-ptbylla L. The former has been assigned structure (25) on spectral evidence;it is a stereoisomer of reserpinine. The latter, C,,H,,N,, is the first oxygen-free RauwolJia alkaloid.47Strychnos Group.-Strychnospermine, C,,H,,O,N,, and spermostrychnine,C,1H260,N,, are two alkaloids of Strychnos psilosperma, the former being amethoxy-derivative of the latter.Strychnospermine (two C-Me) showsultraviolet absorption characteristic of a l-acetyl-2 : 3-dihydroindole, anddeacetylstrychnospermine of a 1 : 2-dihydroindole, both with a methoxylgroup in the benzene ring; the infrared absorption confirms this. Of thetwo nitrogen atoms, one “ ( a ) ] is weakly and the other strongly basic; themethoxyl group is meta to N(a). The oxidation of demethylstrychno-spermine or spermostrychnine with chromic acid yields apospermostrychnine(26), and zinc dust distillation of both deacetyl-alkaloids gives 3-ethyl-pyridine. Deacetylspermostrychnine gives with hydrogen bromide a3g H.B. MacPhillamy, L. Dorfman, C. F. Huebner, E. Schlittler, and A. F. St. Andre,J . Anzer. Chem. SOC., 1955, 77, 1071.40 F. E. Bader, D. F. Dickel, C. F. Huebner, R. A. Lucas, and E. Schlittler, ibid.,4 1 A. Stoll and A. Hofmann, ibid., p. 820.42 M. W. Klohs, F. Keller, 13. E. Williams, and G. W. Kusserow, ibid., p. 4084.43 N. Neuss, H. E. Boaz, and J. W. Forbes, ibid., p. 4087.44 E. E. van Tamelen, P. D. Mance, K. V. Siebrasse, and P. E. Aldrich, ibid., p. 3930.45 C. F. Huebner, Chern. and Ind., 1955. 1186.4 6 P. A. Diassi, F. L. Weisenborn, C . M. Dylion, and 0. Wintersteiner, J . Amer.Chem. Soc., 1955, 77, 2028, 4687; C. F. Huebner and E. Wenkert, ibid., p. 4180; E. E.van Tamelen and P.D. Hance, ibid., p. 4692; M.-M. Janot, R. Goutarel, A. Le Hir,G. Tsatsas, and V. Prelog, Helv. Chim. Acta, 1955, 38, 1073; H. B. MacPhillamy, C.F.Huebner, E. Schlittler, A. F. St. Andr6, and P. R. Ulshafer, J. Amer. Chem. SOC., 1955,77, 4335; C. F. Huebner, H. B. MacPhillamy, E. Schlittler, and A. F. St Andre, Ex-perientia, 1965, 11, 303.p. 3547.4 7 C . Djerassi and J. Fishman, Chem. and Ind., 1955, 627PINDER : ALKALOIDS. 249bromo-derivative, which is reduced by zinc dust to deoxydihydrospermo-strychnine (27). This base has been synthesised from the Wieland-Gumlichaldehyde (28), reduction of which in two stages gives the glycol (29), whencesuccessive treatment with hydrogen bromide and zinc dust-acetic acid,followed by acetylation, yields the base (27).Spermostrychnine andstrychnospermine have therefore structures (30; R = H and OMe respec-tively) .48The methoxyl group of aspidospermine is at the 7-position, as in vomi-cine ; on demethylation N-acetylaspidosine is obtained, which shows no OHband in the infrared spectrum because of hydrogen bonding involving thephenolic group. Two structures (31) and (32) have been suggested foraspidospermine ; the latter provides the better explanation of the formationof 3 : 5-diethylpyridine and 3-ethylindole on zinc dust distillation, but ismore difficult to reconcile with Woodward’s biogenetic scheme.49Erythrina Groz@.-The structure (33) has been proposed for a-erythro-idine,50 which has been degraded by methods similar to those employed forthe isomeric @-erythr~idine.~l Dihydro-a-erythroidinol on Hofmann de-gradation gives the aromatic base (34).Oxidation of this base yieldsphthalic acid; it is an isomer of the des-base of dihydro-@-erythroidine.Further Hofmann degradation gives the vinyl derivative (36 ; R = CHXH,),which can be reduced to the ethyl derivative (35; R = Et) ; oxidation ofthe latter yields o-ethylbenzoic acid. A final stage of Hofmann decom-position affords the tetrahydrofuran (36), which on mild oxidation is con-verted into the ketone (37), and on more vigorous oxidation into o-ethyl-benzoic acid. These and other observations show that a-erythroidine has48 F. A. L. Anet and Sir R. Robinson, J., 1955, 2253.B. Witkop and J. B. Patrick, J . Amer. Chem. SOC., 1954, 76, 5603.6o J.C. Godfrey, D. S. Tarbell, and V. Boekelheide, ibid., 1956, 77, 3342.Ann. Reports, 1952, 49, 225250 ORGANIC CHEMISTRY.the same carbon skeleton as 8-erythroidine, but the two differ in the arrange-ment of the lactone ring.50The structure (38) proposed for a9oerysopine 52 has been confirmed bysynthesis of its dimethyl ether.%AporPkine Grou$.-Spath and Hromatka’s synthesis 54 of apomorphinedimethyl ether, hitherto held in considerable doubt, has been vindicated.The critical stage, the cyclisation of the amide (39), has been found 55 oncareful re-investigation to give yields of the corresponding 3 : 4-dihydro-isoquinoline of the order of 20%.Quinazolone Grou$.-The synthesis of the Hydrangea alkaloid (40) hasbeen de~cribed,~6 the route being as shown in outline.IC02.CH2.CH:CHHHCO2*CH2*CH:CH>Reagents: (1) a, Aq.NH,; b, methyln. (2) MeCHO. (3) a, 3H,; b, CrO,;(4) a, Br2-HBr ; b, Cl-CO,.CH,CH:CH,. (5) Quinazol-4-one. (6) Aq. HCl.Phenanthridine Groz@.-Further evidence in support of the structureOn periodate oxidation, dihydro- (41) for lycorine has been advanced.62 M. Carmack. B. C. McKusick. and V. Prelog, Helv. C h h . Acla, 1951, 34, 1601.K. Wiesner,-Z. Valenta, A. J . Manson, and-F. W. Stonner, J . Amer.-Chenz. Soc.,1955, 77, 675.64 E. Spath and 0. Hromatka, Bar., 1929. 62, 325.65 D. H. Hey and A. L. Palluel, Chem. and Ind., 1955, 40.6 6 B. R. Baker and F. J. McEvoy, J . Org. Chem., 1955, 20, 136PINDER : ALKALOIDS. 251lycorinone yields a 4-acylisocarbostyril derivative, the formation of whichcan be explained satisfactorily if lycorine is a disecondary glyco1.57The structure of tazettine methine has been proved to be (42) by syn-thesis.58 Reduction of tazettine with lithium aluminium hydride yieldssecot azet t ine, which on dehydration gives anhydrosecot azet t ine.Hofmanndegradation (two stages) of the latter affords a nitrogen-free product whichdoes not show an infrared carbonyl band but forms a 2 : 4-dinitrophenyl-hydrazone. On oxidation, first the lactone (43) and then the diphenic acid(44) are obtained, both structures being proved by synthesis. The pseudo-carbonyl Hofmann product therefore has structure (45), anhydroseco-0CHa- 0 IMe0l I p O "CH,*OH0CH2-0 IMe00 CHa-0 I F i& ...- a4" .....CH2-0(49)0 0 @OM*W eHO H4ii$:tazettine (46), secotazettine (47), and tazettine (48).59 The same structurehas been proposed for tazettine on different grounds 6o and is preferred to theearlier structure (49) proposed on the basis of extensive degradations.61Infrared measurements suggest that homolycorine, C,8H,10,N, an5 7 S.Takagi, W. I. Taylor, S. Uyeo, and H. Yajima, J., 1955, 4003 ; cf. Ann. Reports,58 W. I. Taylor, S. Uyeo, and H. Yajima, J., 1955, 2962.58 T. Ikeda, W. I. Taylor, and S. Uyeo, Chem. and Ind., 1955, 1088.6o R. J. Highet and W. C. Wildman, ibid.. p. 1159.61 E. Wenkert, Experientia, 1954, 10, 476.1954, 51, 261252 ORGANIC CHEMISTRY.alkaloid of Lycaris radiata Herb., is a 8-lactone 62 and not a y-la~tone.~~Lycorenine, C,,HaO,N, from the same source, gives homolycorine on mildoxidation; it is a cyclic semiacetal. Structures (50) and (51) have beenproposed for homolycorine and lycorenine respectively,62 and have beenconfirmed by Wolff-Kishner reduction of lycorenine to the dihydrodeoxy-compound (52).This on dehydrogenation affords the arylindole (53), whichhas been synthesised from the Emde base of lycorine.64OMc(52)The product formed by reaction of lycorine anhydromethine with methyliodide & the phenanthridinium salt -(54); previous workers may haveobtained anhydrolycorine methiodide, which has the same m. p. as this salt,since anhydrolycorine is known to accompany lycorine anhydromethine inthe Hofmann degradation of l y ~ o r i n e .~ ~Pyrrolizidine Group.-A review of these alkaloids has appeared. 66 Thestructure (55; R = OH) for rosmarinecine 67 has been confirmed by con-version of this alkaloid into compounds of known constitution. On de-hydration it gives anhydrorosmarinecine (56; R = OH), which with thionylchloride yields anhydrochloroplatynecine (56 ; R = Cl), reduced to anhydro-platynecine (56; R = H), identical with the product obtained by dehydrat-ing platynecine (55; R = H). Further confirmation is provided by thesynthesis of rosmarinecine from retronecine (57), which with perbenzoic acidHYL I Jo 5H2*OH HqL H iJ 5H2*0H CHMcli HO,C C CH, CM :,CMc. COfi (60) 0OHI CHMc0 (58) (59) H0,C.C- II CH,*CHMc-CMe*COfi (61)yields epoxyisatinecine (58).Reduction then affords epoxyretronecine(59) , further reduced to rosmarinecine (55 ; R = OH). The various trans-formations indicate the similarity in stereoconfiguration of the hydroxyl62 T. Kitagawa, W. I. Taylor, S. Uyeo, and H. Yajima, J., 1955, 1066.63 H.-G. Boit, L. Paul, and W. Stender, Chem. Ber., 1955, 88, 133.64 S. Uyeo and H. Yajima, J., 1955, 3392; Ann. Reports, 1954, 51, 261.6 5 T. Shingu, S. Uyeo, and H. Yajima, J., 1955, 3557.66 F. L. Warren, Fortschr. Chem. org. Naturstoffe, 1955, 12, 198.67 M. F. Richardson and F. L. Warren, J., 1943, 452PINDER : ALKALOIDS. 253groups in rosmarinecine and platynecine, where the 7-hydroxyl group is cisto the 1-hydroxymethyl group, and both are trans to the 7a-hydrogenatom .68The alkaloid rosmarinine on dehydration gives anhydrorosmarinine,hydrolysed to rosmarinecine (55 ; R = OH) and, probably, anhydrosenecicacid (60).The toluene-fi-sulphonic ester of the same alkaloid yields onhydrolysis senecic acid (61) and eihirosmarinecine (55; R = OH, and inver-sion at C,,)) ; the same ester with pyridine affords senecionine, with elimin-ation of toluene-p-sulphonic acid. Senecionine is therefore (62), andMe*CH OH Me*CH OH$.@:Ha*CHMe?Me I 70 C It * C H 2 * C H M e e II@JCH~-~ I L+J.-;H2-0 toR(62 ) (63)rosmarinine and platyphylline have structures (63; R = OH and H respec-tively) .69 Integerrimine, known to be the tram-form of ~enecionine,~~ there-fore has structure (62; Me.5I-I replaced by H$;Me).69Hieracifoline 71and pterophine 72 have been shown by paper chromatography each to bemixtures of senecionine and seneciphylline.73Diterpeize Grou$.-Interest in alkaloids related to the tricyclic diterpenesis increasing.74 On the basis of oxidation and dehydrogenation, structures(64) and (65) have been proposed for veatchine and ganyine re~pectively.~~Selenium dehydrogenation of both alkaloids gives the benzoisoquinoline (66),identified by ~ y n t h e s i s . ~ ~ ~ 76 Cuauchichicine, a new member of the group,The Senecio alkaloids also occur as their N-0xides.6~(64) ( 6 5 ) (66)found in Garrya Zaurifolia Hartw., is isomeric with veatchine, but containsno CXH, group and is ketonic. On degradation it yields products identicalwith, or similar to, those obtained from veatchine under the same conditions,and its pK value is comparable with that of veatchine, rather than of68 L.J. Dry, M. J. Koekemoer, and F. L. Warren, J., 1955, 59.M. J. Koekemoer and F. L. Warren, ibid., p. 63.7O M. Kropman and F. L. Warren, J., 1950, 700.7l R. H. F. Manske, Canad. J . Res., 1939, 17, B, 8.72 H. L. de M’aal, Nature, 1940, 146, 777.73 C. C. J. Culvenor and L. W. Smith, Chem. and Ind., 1954, 1386; R. Adams andM. Gianturco, J . Amer. Chenz. SOL, 1956, 78, 398.74 For a review, see E. S. Stem, in “ The Alkaloids,” Manske and Holmes, AcademicPress, New York, 1954, Vol. 4, p. 275.75 K. Wiesner, R. Armstrong, M. F. Bartlett, and J. A. Edwards, J . Amer. Chem.SOC., 1954, 76, 6068.7 6 M. F. Bartlett and K. Wiesner, Chem.and Ind., 1954, 542254 ORGANIC CHEMISTRY.garryine, which suggests that the oxazolidine ring is fused to CU7) rather thanto C(ls,. Structure (67) explains these and other observations most satis-factorily.77, ' 8 Laurifoline,* an isomeric alkaloid from the same source, isreadily isomerised by acids to cuauchichicine and by hot ethanol to iso-laurifoline ; it is 19-epiveatchine (64 ; with inversion at C(lg)).7* Theinfrared absorption spectra of atisine and isoatisine hydrochlorides show aband characteristic of the >C:N( group, and in the ultraviolet region thesalts show more intense absorption above 220 mp than the bases. This can+c I'be explained if the salts are quaternary chlorides of structures (68) and (69)respectively. 79 Some observations have been made on the stereochemistryof diterpenoid alkaloids, in relation to basic strength.80Morphine Groz@.-Stnictures (70) and (71) for a- and p-codeimethineshave been confirmed by considerations of their mode of formation, reactions,and spectra. 81 The four isomeric thebainone methines have been prepared,and structures assigned to them on spectral and other evidence.82 77HOMcOHONMc(70) (71) ( 7 2 )X-Ray crystallographic determinations support the view that ( -)-morphine has the stereochemistry (72) or its mirror image,83 and a con-77 C.Djerassi, C. R. Smith, S. K. Figdor, J. Herran, and J. Romo, J. Amer. Chem.SOC., 1954, 76, 5889.'8 C. Djerassi, C. R. Smith, A. E. Lippman, S. K. Figdor, and J. Herran, ibid., 1955,77, 4801.78s Idem, ibid., p.6633.7@ S. W. Pelletier and W. A. Jacobs, Chem. and Ind., 1955, 1385.80 K. Wiesner and J. A. Edwards, Experiential 1955, 11, 255.81 I<. W. Bentley and A. F. Thomas, J., 1955, 3237.82 K. W. Bentley and H. M. E. Cardwell, ibid., p. 3245.83 M. Mackay and D. C. Hodgkin, ibid., p. 3261. * Laurifoline has been re-named garryf~line.~~ASPINALL AND SCHWARZ : CARBOHYDRATES. 255sideration of molecular-rotation differences establishes that the latter formularepresents the absolute stereochemical structure of the natural alkal~id.~Similar conclusions have been reached from a study of the degradation ofthebaine 84 and of N-nora$o~odeine.~~A. R. P.10. CARBOHYDRATES.Three years have elapsed since the last Report on po1ysaccharides.lThe greater part of the Section is therefore devoted to this subject, anddiscussion of other aspects of carbohydrate chemistry has been confined toa few selected topics.A recent book 2 provides authoritative surveys of methods for the isola-tion, identification, and estimation of plant carbohydrates.Attention isalso drawn to the new edition of E. Ott’s “ Cellulose and CelluloseDerivatives.’’Monosaccharides and oligosaccharides.General Methods.-The high efficiency of a mixture of methyl iodideand silver oxide in dimethylformamide as a methylating agent has beendemonstrated with ~ucrose,~ ~-galactal,~ and a-solanine,6 where a singletreatment gave products which no longer showed the characteristic infraredabsorption of the hydroxyl group.draws attention to the value of thealkali-labile 2 : 4-dinitrophenyl residue for protecting the amino-group inglucosamine reactions.Formation of an acid-labile orthoformate has beenused to protect the reducing group of a digalacturonic acid before reductionwith lithium aluminium hydride.8 Disaccharides can be smoothly reducedwith sodium borohydride; an earlier observation that this reduction isaccompanied by fission of the glycosidic link has not been confirmed.Degradation of 3-O-methyl-aldoses with periodate provides a useful routeto 2-methyl ethers of lower sugars.Io Periodate oxidation also forms thebasis of a useful micromethod for the determination of the ring structuresof sugar residues.ll Reactions of monosubstituted aldoses (e.g., mono-methyl ethers and disaccharides) with lead tetra-acetate in the presence ofpotassium acetate follow definite oxidation patterns depending on theposition of substitution ; this enables structural determinations to beA preliminary communication84 J.Kalvoda, P. Buchschacher, and 0. Jeger, Helv. Chim. Ada, 1955, 38, 1847.85 H. Corrodi and E. Hardegger, ibid., p. 2038.E. J. Bourne, Ann. Reports, 1952, 49, 235.‘ I Modern Methods of Plant Analysis,” Ed. K. Paech and M. V. Tracey, Springer3 “ Cellulose and Cellulose Derivatives,” Ed. E. Ott and H. M. Spurlin, Interscience4 R. Kuhn, H. Trischmann, and I. Low, Angew. Chem., 1955, 67, 32.6 R. Kuhn, I. Low, and H. Trischmann, zbzd., p. 1492.* J. K. N. Jones and W. W. Reid, J., 1955, 1890.Verlag, Berlin, 1955, Vol.11.Publ., New York, 1954 and 1955.R. Kuhn and H. H. Baer, Ckem. Ber., 1955, 88, 1537.P. F. Lloyd and M. Stacey, Chem. and Ind., 1955, 917.W. J. Whelan and K. Morgan, Chew and Ind., 1955, 1449.lo G. W. Huffman, B. A. Lewis, F. Smith, and D. R. Spriestersbach, J . Amer. Chem.11 M. Viscontini, D. Hoch, and P. Karrer, Helv. Chim. A d a , 1955, 38, 642 ; see alsoSOC., 1955, 77, 4346.F. Smith and J. W. van Cleve, J . Anaer. Chem. SOC., 1955, 77, 3091256 ORGANIC CHEMISTRY.carried out on a few milligrams of material.12 As in periodate oxidation,the aldoses appear to be oxidised as cyclic hemiacetals yielding formates.The preparative value of oxidation with lead tetra-acetate is illustrated bythe production of formates of D-erythrose and L-glyceraldehyde fromD-glucose and L-arabinose , respectively.13Paper chromatography of carbohydrates has been re~iewed.1~ Chromato-graphy on paper impregnated with boric acid facilitated the separation ofcertain methyl ethers and polyols,15 and the value of borate complexes inthe preparative separation of glycosides and sugars has been emphasized.16The ionophoretic behaviour of many glucose derivatives in alkaline boratebuffer has been related to their structure.1'The classical method of separating 4-substituted monosaccharides frommixtures, by conversion of the other components into methyl furanosideswith methanolic hydrogen chloride at room temperature, has been appliedsuccessfully to oligosaccharides.18 It is noteworthy that 2 : 3 : 6-tri-O-methyl-D-mannose does not form a furanoside under the usual mild con-ditions; this can be used to separate it from 2 : 3 : 6-tri-O-methyl-~-glucose.The molecular weights of osazones of mono- and oligo-saccharides canconveniently be determined by a spectrophotometric method.20s 21Sugars from Antibiotics.-The amino-sugars , mycaminose (1 ;R = R = OH ; from magnamycin) 22 and rhodosamine (probably 1 ;R = H, R' = OH ; from rhodomycin) ,23 are closely related to desosamine(1 ; R = OH, R = H ; from erythromycin), which was discussed in lastyear's Report.% The stereochemistry of these compounds remains to be rxpH p:lHCH.OH el:' f CH I672Lf H d GC H.N Me,CHJH, 4%(2 1 (3) 0 1elucidated.Determination of the structure of cladinose (2) ,25 anotherhydrolysis product of erythromycin, shows that it is related to mycarose(3) ,26 the branched-chain sugar from magnamycin.The resemblance be-12 A. S. Perlin, Anulyt. Chem., 1955, 27, 396.13 A. S. Perlin and C. Brice, Canad. J . Chem., 1955, 38, 1216.14 G. N. Kowkabany, Adv. Carbohydrate Chem., 1954, 9, 303; F. A. Isherwood,1 5 G. R. Barker and D. C. C. Smith, Chem. and Ind., 1954, 19.16 M. V. Lock and G. N. Richards, J., 1955, 3024.1 7 A. B. Foster and M. Stacey, J., 1955, 1778.18 S. A. Barker, E. J. Bourne, and D. M. O'Mant, Chem. and Ind., 1955, 425.1s P. A. Rebers and F. Smith, J . Amer. Chem. SOC., 1954, 76, 6097.20 V. C. Barry, J. E. McCormick, and P. W. D. Mitchell, J., 1955, 222.21 R. Kuhn, A. Gauhe, and H.H. Baer, Chem. Be?., 1954, 8'7, 289.z2 F. A. Hochstein and P. P. Regna, J . Amer. Chem SOC., 1955, 77, 3353.23 H. Brockmann and E. Spohler, Nuturm*ss., 1955, 42, 154.24 J. C. P. Schwarz, Ann. Reports, 1954, 51, 262.z5 P. F. Wiley and 0. Weaver, J . Amer. Chem. SOL, 1955, 77, 3422.26 P. P. Regna, F. A. Hochstein, R. L. Wagner, jun., and R. B. Woodward, ibid.,Brit. Med. Bull., 1954, 10, No. 3, 202; D. J. Bell, ref. 2, p. 1.1953, 75, 4625ASPINALL AND SCHWARZ : CARBOHYDRATES. 267tween the amino-sugars and branched-chain sugars derived from magnamycinand erythromycin is of interest in view of their similar ‘ I microbiologicalspectra.”Phenylhydrazine Derivatives.-The formation of a formazan whensolutions of phenylhydrazine derivatives are coupled in pyridine withdiazotised aniline has been used as a diagnostic test for the groupCH:N*NHAr.27 This reaction indicates that two of the three knownmodifications of glucose phenylhydrazone have cyclic structures, while thethird is acyclic.27 The behaviour of glucose phenylosazone , which couplesin alkaline ethanol (but not in pyridine) to give a violet fonnazan, has beeninterpreted in terms of an open-chain structure in which the two phenyl-hydrazine residues are linked by a hydrogen bond.28 However, it seemsnecessary to reconcile this structure with the observation 29 that glucosephenylosazones mutarotate in dry pyridine.The close resemblance betweenthe ultraviolet absorption spectra of the sugar osazones and of glycerosazoneprovides further evidence for the open-chain structure, although it is rathersurprising that these spectra differ markedly from that of methylglyoxalbisphenylhydrazone.2* N-Alkylphenylosazones may differ in structure fromthe unalkylated compounds; in the former the hydrazine residue at C,,)is more reactive,30 while in the latter the hydrazine residue at Co) generallyshows the greater reactivity.29 The mechanism of osazone formation hasbeen discussed.31 Hydrazine exchange can be involved when two differenthydrazines are present.Inositols.-Seven of the nine possible stereoisomers of inositol werealready known ; the remaining two, rteoinositol (123/456) and cis-inositol(123456/), have now been synthesised. fieoInosito1 was prepared from(-)-inositol by inversion of the configuration of two adjacent carbon atomsvia an epoxide intermediate.32 cis-Inositol, which has been separated fromthe mixture obtained on hydrogenation of hexahydroxybenzene,= is ofconsiderable interest, as the chair conformation must involve three axialhydroxyl groups situated on the same side of the ring.A new C-methyl-inositol has been encountered in algae,% and three new 0-methylmyoinositolshave been isolated from natural sources; 35 the detailed structures of thesecompounds remain to be elucidated. The synthesis of DL-bornesitol bymethylation of 1 : 3 : 4 : 5 : 6-penta-0-acetylmyoinositol involves migrationof an acetyl residue from an equatorial to an axial hydroxyl Anumber of quercitols (cyclohexanepentols) , conduritols (cyclohexenetetrols) ,and cyclohexanetetrols have been synthesised from myo- and epi-inositol ; 3727 L.Mester and A. Major, J . Amer. Chem. SOC., 1955, 77, 4297.20 F. Weygand, H. Grisebach, K.-D. Kirchner, and M. Haselhorst, Chem. Bey., 1985,80 G. Henseke and H.-J. Binte, ibid., p. 1167.81 G. Henseke and H. Dalibor, ibid., p. 521; G. Henseke and M. Bautze, ibid.,p. 62; V. C. Barry and P. W. D. Mitchell, Nature, 1956, 175, 220.82 S. J. Angyal and N. K. Matheson, J . Amer. Chem. SOC., 1955, 77, 4343.aa S. J. Angyal and D. J. McHugh, Chem. and Ind., 1955, 947.s4 B. Lindberg and J. McPherson, Acta Chem. Scund., 1954, 8, 1875; B. Lindberg,s6 V. Plouvier, Compt. rend., 1955, 241, 765, 983.* I L. Anderson and A. M. Landel, J . Amer. Chem.SOC., 1954, 76, 6130.a7 G. E. McCasland and E. C . Horswill, ibid., p. 2373; G. E. McCasland and J. M.L. Mester, ibid., p. 4301.88,487.;bid.. 1955, 9, 1097; H. Bouveng and B. Lindberg, ibid., p. 168.Reeves, ibid., 1955, 77, 1812.REP.-VOL. LII 258 ORGANIC CHEMISTRY.one of the tetrols was also obtained from cyclohexa-1 : 4-diene by the actionof Pr6vost's reagent (silver benzoate and iodine) .380ligosaccharides.-Investigation of the terpenoid glycoside, stevioside,which is about 300 times as sweet as sucrose, has shown that two of thethree glucose units are present as a 1 : 2-linked disa~charide.~~ The remain-ing glucose unit is independently attached to a hindered carboxyl group ofthe aglycone by esterification at Co), and this glucose residue is eliminatedas 1 : 6-anhydro-~-glucose by the action of potassium hydroxide.2 : 3 : 4 : 6-Tetra-0-acetyl-1-0-(2 : 4 : 6-trimethylbenzoyl)-~-~-glucose also gives 1 : 6-anhydro-D-glucose on treatment with alkali.40 These unusual reactionspresumably involve " alkyl "-oxygen fission.A branched trisaccharide, O-or-~-rhamnopyranosyl-( 1-+2)-0-[$~-glucopyranosyl-( 1+3)]-~-galactose, has been obtained from the alkaloida-solanine.6 The related alkaloid, a-chaconine, contains a branched tri-saccharide in which two L-rhamnopyranosyl units are linked to the 2- and4hydroxyl groups of ~-glucose.~l Human milk continues to yield interest-ing oligosaccharides , one of which is 2'-O-a-~-fucopyranosyl-lactose.~~The observation 43 that disaccharide osazones are hydrolysed to mono-saccharide osazones under conditions which leave disaccharides unchanged ,suggests a method for the stepwise degradation of oligosaccharides.Oligosaccharides encountered during work on polysaccharides are dis-cussed in the latter part of this Report.Miscellaneous.-The reaction of 2-0-sulphonyl derivatives of arabinose,xylose, and fucose with alkali proceeds with inversion at C(,) giving ribose,lyxose , and talomethylose, respectively.u* 45 This inversion provides ao-arabinal and2- de ox y- D- r iborepromising route to some otherwise inaccessible sugar derivatives.3-0-Methanesulphonyl-D-glucose (4) reacts with alkali to give 2-deoxy-~-riboseand D-arabinal, C(l) being eliminated as formate ; 45 this interesting reactionhas a formal analogy in the alkaline cleavage of 3-tosyl esters of steroids* G.E. McCasland and E. C. Horswill, J. Amer. Chem. SOL, 1954, 76, 1654.39 H. B. Wood, jun., R. Allerton, H. W. Diehl, and H. G. Fletcher, jun., J. Ovg.Chem., 1955, 20, 875.40 H. B. Wood, jun., and H. G. Fletcher, jun., J. Amer. Chew. SOC., 1956, 78, 708;Eee also F. Micheel and G. Baum, Chem. B e y . , 1955, 88, 2020.4 1 R. Kuhn, I. Low, and H. Trischmann, Chem. Bey., 1955, 88, 1690.42 R. Kuhn, H. H. Baer, and A. Gauhe, ibid., p. 1135.43 P. A. Finan and P. S. O'Colla, Chem. and Ind., 1955, 1387.44 J. K. N. Jones and W. H. Nicholson, J., 1955, 3050.4 5 D. C. C. Smith, Chem. and Ind., 1955, 92ASPINALL AND SCHWARZ : CARBOHYDRATES. 2593 : 5-diols. 2-Deoxy-DL-ribose has been synthesised from but-2-yne-l : 4-dio1,46 and the branched-chain sugars (-j-)-cordycepose (5 ; R = R' = H)and (-J-)-apiose (5; R = H, R' = OH) have been built up from bromoacetaland ethyl ~odiomalonate.~7 Self-condensation of dihydroxyacetone givesdendroketose (5; R = CH,*OH, R' = OH), which can be degraded to apionicacid (5; R = R = OH).48 4 : 4-Di-C-hydroxymethyl-~-threose, an aldoserelated to dendroketose, and 2-C-hydroxymethyl-D-xylose have been pre-pared from D-fructose by use of the cyanohydrin synthesis.49Recent additional evidence shows the importance of neighbouring-groupparticipation in the reactions of acetohalogeno-sugars and aldose acetates,although the relative reactivities of the a- and p-anomers cannot be entirelyascribed to this effect.This work and other studies on reaction mechanismsin carbohydrate chemistry are discussed in the section on TheoreticalChemistry.Reactions involving neighbouring-group participation have led to severalinteresting new orthobenzoic acid derivatives. Hydrolysis of tri-O-benzoyl-P-D-ribofuranosyl bromide gave 2 : 3 : 5-tri-O-benzoyl-p-~-ribose and thecrystalline orthoacid (6; R = H), which rapidly rearranged to 2 : 3 : 5-tri-0-benzoyl-p-mribose in the presence of a trace of base.50 The orthoacid ""q$ "10 Q\/Y H 0 HOHO 0- '-C).CH,Ph= ($9 I5, 8 2 <--ORLh(6) (7) Ph(6; R = H) can also be prepared by hydrogenolysis of the orthoester (6;R = benzyl), which is obtained when the above ribofuranosyl halide reactswith benzyl alcohol in the presence of quinoline.Reaction of tri-O-benzoyl-P-D-ribopyranosyl bromide with benzyl alcohol in the presence of quinoline,followed by debenzoylation, yields the labile orthoester (7) ,51 and underweakly acidic conditions this readily gives the crystalline 1 : 2 : 4-O-ortho-benzoyl-a-D-ribopyranose (8) ; 2 : 3 : 6-O-orthobenzoyl-~-fructofuranose hasbeen obtained in a similar way.52Poly saccharides.The period reviewed has seen the extended application of chromato-graphic methods in the determination of the detailed structure of poly-saccharides ; as a result many new polysaccharides have been investigated,and previously unknown structural features have been revealed in substanceswhose general structures were already known.Progress has been limitedin some investigations by difficulties in isolating individual molecular species46 M. M. Fraser and R. A. Raphael, J., 1955, 4280.47 R. A. Raphael and C. M. Roxburgh, ,/., 1955, 3405.4 8 L. M. Utkin, Doklady Akad. Nauk S.S.S.R., 1949, 67, 301.49 R. J. Woods and A. C. Neish, Canad. J. Chem., 1954, 32, 404.61 H. G. Fletcher, jun., and R. K. Ness, ibid., 1955, 77, 5337.62 B. Helferich and L. Bottenbruch, Chenz. Ber., 1953, 86, 651 ; B. Helferich andR. K. Ness and H. G. Fletcher, jun., J. Amer. Chem. Soc., 1954, 76, 1663.W. Schulte-Hurmann, ibid., 1954, 87, 977260 ORGANIC CHEMISTRY.from the complex mixtures present in natural sources. The greatest singleneed in this field, therefore, is for new and powerful methods for fractionationof polysaccharides, both for separation of structurally distinct molecularspecies and for resolution of closely-related substances of the same generaltype.A chromatographic method for the separation of acid mucopoly-saccharides has been described, which makes use of a " carrier " amine toincrease the solubility of such polysaccharides in the mobile organic phase ; 53not only was the separation of chondroitin-sulphuric acid and hyaluronicacid effected by this technique, but the resolution of hyaluronic acid fractionsof different molecular weight was achieved without apparent degradation.Fractional precipitation with ammonium sulphate has proved of value in theseparation of glucosans and araboxylans present in the water-soluble gumand hemicellulose fractions of cereal 55 An electrophoretic methodfor the analysis of neutral polysaccharides in borate buffer has been re-ported ; 56 separations were effected between amylose and amylopectin,and between yeast mannan and yeast glycogen. Electrophoretic separationof polysaccharides in alkali appears to be limited to the gross separation ofcharged from neutral molecules, e.g., sodium alginate and laminarin.57Paper-ionophoretic separations in the presence of borate buffer have beenachieved between amylose and amylopectin, although the ionophoresis ofamylose was complicated by absorption on the paper.58 Some mucopoly-saccharides can be resolved by paper electrophore~is,~~ whilst paper iono-phoresis in borate buffer has been employed in the separation of someneutral polysaccharides from cereals.60The value of serological cross-reactions, carried out on milligram quanti-ties, in the clarification of structural chemical relationships has been demon-strated in their application to the structure of lung galactan.61 The immuno-logical specificities of galactose-containing polysaccharides of known generalstructure have been determined.'j2 The nitrogen and sulphur contents ofthe polymers obtained by the condensation of periodate-oxidised poly-saccharides with isonicotinhydrazide and thiosemicarbazide give a measureof the proportion of sugar units attacked by p e r i ~ d a t e .~ ~ This methodprovides a useful check on direct measurements of periodate consumptionby polysaccharides, and in addition enables a polysaccharide containing both1 : 3- and 1 : 4-linkages to be distinguished from a mixture of polysaccharides,each containing only one type of linkage. The optical rotations of tri-carbanilates of polyglucosans in pyridine and morpholine have been shownto be dependent on the position and anomeric type of 1inkage.aCellulose and Hemicelluioses.-The use of paper-chromatographic6s G.S. Berenson, S. Roseman, and A. Dorfman, Biochim. Biophys. Acta, 1955,17,75.64 I. A. Preece and K. G. Mackenzie, J . Inst. Brewing, 1952, 58, 353, 457.55 I. A. Preece and R. Hobkirk, ibid., 1963, 59, 386; 1954, 60, 490.6 6 D. H. Northcote, Biochem. J., 1954, 58, 353.5 7 J. R. Colvin, W. H. Cook, and G. A. Adams, Canad. J .Chem., 1952, 30, 603.ti8 A. B. Foster, P. A. Newton-Hearn, and M. Stacey, J., 1956, 30.60 K. G. Rienits, Biochem. J., 1953, 53, 79.80 I. A. Preece and R. Hobkirk, Chem. and Ind., 1955, 257.62 M. Heidelberger, ibid., p. 4308.83 V. C. Barry, J. E. McCormick, and P. W. D. Mitchell, J.. 1954, 3692.64 I. A. WoIff, P. R. Watson, and C. E. Rist, J . Amer. Chem. SOL, 1953, 75, 4897.M. Heidelberger, 2. Dische, W. B. Neely, and M. L. Wolfrom, J . Amer. Chem.SOL, 1955, 77, 3511ASPINALL AND SCHWARZ : CARBOHYDRATES. 261techniques together with methylation end-group assay has enabled oneterminal group in a thousand to be detected in celluloses, which have beenmethylated with rigorous exclusion of oxygen to exclude degradati~n.~~The values obtained for the chain lengths of methylated celluloses by end-group assay were in reasonable agreement with those obtained from physicalmeasurements; it is necessary, therefore, to abandon the loop structureproposed for cellulose by W.N. Haworth.66 Kinetic studies of the acidhydrolysis of cellulose 67 have failed to provide evidence for the presenceof periodic abnormally-sensitive linkages of the type previously proposed. 68In the case of cotton cellulose, such acid-sensitive linkages may be presentin celluloses regenerated from cuprammonium and cupriethylenediaminesolutions.The close association of cellulose and other cell-wall polysaccharidescontinues to be emphasised, but there is still no conclusive evidence for thepresence or absence of formal linkages between these substances.Forexample, sugars other than glucose have been detected in the hydrolysatesfrom jute 69 and wheat-straw 70 a-celluloses. Careful fractionation of white-spruce a-cellulose nitrates 71 has yielded fractions of high and of low molecularweight which contain both glucose and mannose residues. The close associ-ation of glucose and mannose residues in coniferous woods has also beenindicated by the isolation of a disaccharide, composed of glucose andmannose units , from the acetolysis of slash-pine a-cellulose ; 72 hemicellulosescomposed of glucose and mannose residues occur in such woods, and theseresults may arise from the incomplete removal of these components.The cell-wall polysaccharides associated with cellulose are generallyreferred to as hemicelluloses , although this definition lacks precision inrespect of both chemical structure and biological function. In the followingaccount , these polysaccharides are classified according to their basic struc-tural features and are thus differentiated from those polysaccharides whosechemical structures and biological functions are more clearly defined, e.g.,the gums exuded from certain plants and reserve polysaccharides such asstarch and fructosans.The hemicellulose group of polysaccharides has beenreviewed in E. L. Hirst’s Pedler Lecture.73Xy1an.s.-A large number of polysaccharides of this group have receivedattention during the last three years. All the xylans from land plants, sofar examined, contain backbones of p-1 : 4-linked D-xylopyranose residues,but they differ in the number and nature of the other sugar residues present ;even within a single botanical species, it is clear that several different, butclosely related , xylans may be present.The L-arabofuranose residues presentin many of these hemicelluloses are integral parts of the xylan molecules,usually occurring as terminal groups and probably linked directly to themain chains as single-unit side-chains; there is no evidence at present for6 6 D. I. McGilvray, J., 1953, 2577.6 8 W. N. Haworth, Chem. and Ind., 1939, 917.67 A. Sharples, J . Polymer Sci., 1954, 13, 393; 14, 95.68 E. V. Schulz, J . Polymer Sci., 1948, 3, 365; E. Pacsu, ibid., 1947, 2, 565.70 G. A. Adams and C . T. Bishop, ibid., p.28.7 1 T. E. Timell, Pulp and Pafier Mag. Canada, 1955, 56, 104.72 J. G. Leech, T.A.P.P.I., 1952, 35, 249.79 E. L. Hirst, J., 1955, 2974.D. B. Das, M. K. Mitra, and J. F. Wareham, Nature, 1953, 171, 613262 ORGANIC CHEMISTRY.the occurrence, in the hemicellulose group, of arabans similar to those foundin the pectic substances. Methylation studies have shown that wheat-straw,74, 75 ~ o r n - c o b , ~ ~ and wheat-leaf 77 xylans contain L-arabo-furanose residues linked to the main chain through C(,) of the D-xyloseresidue, whilst in the more highly branched araboxylans from wheat endo-sperm ,78 arabinose residues are also linked through C(2) of doubly-branchedxylose residues. Additional evidence that the arabinose residues of wheat-straw xylans are integral parts of the molecule has been obtained by theisolation from enzymic hydrolysis of a series of oligosaccharides containingboth xylose and arabinose ~ n i t s .7 ~ Wheat-leaf 77 and some wheat-straw 749 81 xylans also contain D-glucuronic acid units as a part of theirmolecular structure. In wheat-straw xylans, some of the main chains ofxylose residues are linearJ81 whilst others contain branch points.82Xylans containing D-glucuronic acid (mainly as the 4-methyl ether) , butno arabinose, residues are found in elm,m beech,M and birch 85 woods.Structural investigation of beechwood hemicellulose A has shown thatevery tenth D-xylopyranose residue carries a single 4-O-methyl-~-glucuronicacid residue attached as a side-chain through C(2).The isolation of xylobioseand of 2-0-(4-0-methy~-D-g~ucuronosy~)-D-xy~ose from the partial acidhydrolysis of black spruce and Scots pine shows that xylans of the samegeneral type are also present in coniferous woods.86 Methylation of flax-straw hemicellulose 87 has indicated a structural similarity to the woodrather than to the cereal-straw hemicelluloses, in that the backbone ofxylose residues carries single 4-O-methy~-~-g~ucuronic acid units linked asside-chains, again through Ct2) of the xylose residues ; 2 : 4-di-O-methyl-~-rhamnose was also isolated from the hydrolysis of the methylated poly-saccharide, but its structural significance is not yet clear. Xylans of stillgreater complexity occur in the hemicelluloses of corn cobs (hemicelluloseB) and wheat bran,gl where some L-arabinose residues are present innon-terminal positions. Several oligosaccharides have been isolated fromcorn-cob hemicellulose B on partial acid hydrolysis, and it is clear from theisolation of four aldobiouronic acids 88 that both D-glucuronic acid and 4-0-methyl-D-ghcuronic acid residues are linked to separate D-xylose residuesthrough C(,> and C(*). The isolation of 2-O-a-D-xylopyranosyl-L-arabinose74 G.A. Adams, Canad. J . Chem., 1952, 30, 698; A. Roudier, Compt. rend., 1953,75 I. Ehrenthal, R. Montgomery, and F. Smith, J . Amer. Chem. SOC., 1954, 76, 3509.7g G. 0. Aspinall, E. L. Hirst, R. W. Moody, and E. G. V. Percival, J., 1953, 1631.7 7 G. A. Adams, Canad. J . Chem., 1954, 32, 186.R.Montgomery and F. Smith, J , Amer. Chem. SOC., 1955, 77, 2834, 3325.70 C. T. Bishop and D. R. Whitaker, Chem. and Ind., 1955, 119.C. T. Bishop, Canad. J . Chem., 1953, 31, 134.G. 0. Aspinall and R. S. Mahomed, J., 1954, 1731.82 C . T. Bishop, Canad. J . Chem., 1955, 33, 1073.83 I. Tachi and N. Yamamori, J . Agric. Chem. SOC. Japan, 1951-52,25, 12, 130,262.*4 G. 0. Aspinall, E. L. Hirst, and R. S. Mahomed, J., 1954, 1734.8 5 J. Saarnio, K. WathCn, and C. Gustafsson, Acta Chem. Scand., 1954, 8, 825.8 6 A. R. N. Gorrod and J. K. N. Jones, J., 1954, 2522.237, 840; Assoc. tech. ind. papetidre Bull., 1954, 53.F. Smith and J. D. Geerdes, J . Amer. Chem. SOC., 1955, 77, 3572.R. L. Whistler and L. Hough, ibid., 1953, 75, 4918 ; R. L. Whistler, H.E. Conrad,R. L. Whistler and D. I. McGilvray, ibid., 1955, 77, 1884.G. A. Adams, Canad. J . Chem., 1955, 33, 56.and L. Hough, zbzd., 1954, 76, 1668.O0 Idem, ibid., p. 2212ASPINALL AND SCHWARZ CARBOHYDRATES. 263shows that non-terminal arabinose residues are present in the polysaccharide,but does not indicate whether they are present in the furanose or pyranoseform. It is clear from methylation studies that wheat-bran hemicelluloseis a highly branched polysaccharide containing D-xylose and L-arabinose,each in three or four states of combination, together with uronic acidresid~es.~lGalactans and Galact0arabans.-The galactan from Strychnos nux-vomicaseeds 92 has been shown by methylation and periodate oxidation studies to bean essentially linear p-1 : 4-galactan, similar to that previously isolated fromLupinus albus pectin.93 The arabogalactan from Jeffrey pine 94 contains amuch higher proportion of L-axabinose residues than the E-galactan fromlarch,g5* 96 and in the highly branched molecular structure the majority ofL-arabinose residues occur in the furanose form as terminal groups; there isno evidence that any of the arabinose residues are present in the pyranoseform, as in larch e-galactan.96 The backbone of the pine galactan is probablycomposed of 1 : 6-linked D-galactopyranose units, some of which are branchedthrough C(3).The galactoaraban from Japanese larchJg7 like those fromEuropean 95 and Western 98 larches, contains galactose and arabinose residuesin the ratio of 6 : 1 ; fractionation of the methylated polysaccharide failedto yield components having different physical and chemical properties. Asa result of the application of Barry’s degradation 99 t o the galactogen of thesnail Helix pomatia, a dichotomously branched structure has been advancedto replace the comb-like structure of a backbone of galactose residues withsingle unit branches previously put forward for this polysaccharide on thebasis of methylation results.100 It is now clear from the results of cross-precipitin reactions that the uronic acid-containing moieties associatedwith beef-lung galactan 101 arise from a contaminating polysaccharide.Mannans, Glucomannans, and Galactomannans.-Methylation has shownthat the mannose-containing polysaccharides of Iris ochroleuca and I .sibiricaare composed of equal proportions of 1 : 4-linked D-mannose and D-glucoseresidues together with a small number of D-galactopyranose residues linkedsolely as non-reducing end-groups.1o2 A re-investigation, by chromato-graphic methods, of the sugars obtained on hydrolysis of the methylatedivory-nut mannans A and B indicates that both polysaccharides containmixtures of molecular species, terminated by D-mannopyranose and D-galactopyranose residues, respectively ; lo3 both species are linear, but inaddition to the 1 : 4-linked D-mannose units, some mannose units are presentin one or both types of molecule linked through C(I) and Cts). It is clear fromO2 P. Andrews, L. Hough, and J. K. N. Jones, J., 1954, 806.B3 E.L. Hirst, J. K. N. Jones, and W. 0. Walder, J., 1947, 1225.94 W. H. Wadman, A. B. Anderson, and W. 2. Hassid, J. Amer. Chem. SOC., 1954,96 W. G. Campbell, E. L. Hirst, and J . K. N. Jones, J., 1948, 774.96 J. K. N. Jones, J.. 1953, 1692.O * E. V. White, J. Amer. Chem. SOC., 1941, 63, 2871; 1942, 64, 302, 1507, 2838.loo E. Baldwin and D. J . Bell, J., 1938,1461 ; D. J . Bell and E. Baldwin, J., 1941, 125.lol M. L. Wolfrom, G. Sutherland, and M. Schlamowitz, J. Amer. Chem. Soc., 1952,lo2 P. Andrews, L. Hough, and J . K. N. Jones, J . , 1953, 1186.loS G . 0. Aspinall, E. L. Hirst, E. G. V. Percival, and I. R. Williamson, J., 1953,78, 4097.I. Tachi and N. Yamamori, J. Agric. Chem. SOC., Japan, 1953, 27, 139.P. O’Colla, Proc. Roy. Irish Acad., 1953, 55, B, 165.74, 4883.3184264 ORGANIC CHEMISTRY.structural investigations that the polysaccharide associated with yeastinvertaselM is identical with the mannan, yeast gum, obtained by theautolysis of yeast.lo5 Iles mannan,19 the polysaccharide extracted fromthe tubers of some ArnorPhoPhaElus species, is a mixture of two linear poly-saccharides, an a-1 : &linked polyglucosan resembling amylose and a p-1 : 4-linked glucomannan containing two mannose to every glucose residue.Thegalactomannan from Kentucky coffee bean lo6 has the same general structureas p a r and carob-bean galactomannans, containing a backbone of 1 : 4-linked D-mannopyranose residues with every fourth residue carrying ata D-galactopyranose residue as side-chain.G1ucosans.-Barley gum , the mixture of water-soluble polysaccharidesisolated from barley grain, has been fractionated by precipitation withammonium sulphate to give a lzvorotatory glucosan free from pent0san.aMethylation has shown that this polysaccharide contains unbranched chainsof p-D-glucopyranose residues with approximately equal proportions of1 : 3- and 1 : 4-linkages; lo7 the polysaccharide appears to be structurallyrelated to lichenin.An evidently similar polysaccharide, the so-called oat‘‘ lichenin ” has been shown by periodate oxidation and partial acetolysisto possess 1 : 3- and 1 : 4-linked D-glUCOSe units in the approximate ratio of1 : 2.108 The general character of pustulan, the polysaccharide obtainedfrom the lichen Umbilicaria pustulata, has been indicated by the isolationfrom partial acid hydrolysis of a series of g-1 : 6-linked oligosaccharides; Io9the absence of oligosaccharides containing other linkages suggests that thepolysaccharide is linear.Fructosans.-Chemical evidence now indicates that many fructosans ofboth the inulin and the levan type contain terminal glucose residues linked asin sucrose, thus supporting the view that these polysaccharides are built upin the plant from sucrose by transfructosylation.110- 111 The hydrolysis ofmethylated leafy cocksfoot levan 112 yields 1 : 3 : 4 : 6-tetra-O-methyl-~-fructose (4%), 2 : 3 : 4 : 6-tetra-O-methyl-~-glucose (1.8%), and 1 : 3 : 4-tri-o-methyl-D-fructose (93.3%) , showing the fructosan to be of levan type ;D-glucose residues occur only as non-reducing end-groups, and it is probablethat the majority of fructosan chains are terminated by sucrose-type linkages.The isolation of sucrose 113 from the partial hydrolysis of perennial rye-grasslevan 114 provides definite proof of the existence of this terminal group inthe polysaccharide.Perennial rye-grass also contains short-chain fructosansof chain length 5-10 having the same general structure.l15 OtherworkersY1l6 however, find no glucose residues in perennial rye-grass levanlo4 J. A. Cifonelli and F. Smith, J. Amer. Chem. Soc., 1955, 77, 6682.lo6 W. N. Haworth, E. L. Hirst, and F. A. Isherwood, J., 1937, 784; W. N. Haworth,lo6 E. B. Larson and F. Smith, J. Amer. Chem. Soc., 1955, 77, 429.10’ G.0. Aspinall and R. G. J. Telfer, J., 1954, 3519.108 L. Acker, W. Diemair, and E. Samhammer, 2. Lebansm.-Untersuck., 1955, 100,100 B. Lindberg and J. McPherson, Acta Chem. Scund., 1954, 6, 985.l 1 0 S. A. Barker and E. J. Bourne, Quart. Rev., 1953, 7, 56.111 J. S. D. Bacon, Ann. Reports, 1953, 50, 281.112 G. 0. Aspinall, E. L. Hirst, E. G. V. Percival, and R. G. J . Telfer, J., 1953, 337.*I3 G. 0. Aspinall and R. G. J. Telfer, J., 1955, 1106.R. A. Laidlaw and S. G. Reid, J., 1951, 1830.*16 V. D. Harwood, R. A. Laidlaw, and R. G. J . Telfer, J., 1954, 2364.116 H. H. Schlubach and K. Holzer, Annalen, 1953, 578, 207.R. L. Heath, and S. Peat, J., 1941, 833.180; 102, 225ASPINALL AND SCHWARZ : CARBOHYDRATES. 266and postulate a difructose anhydride type of termination.l17 Studies of thedegradation of fructosans in hot aqueous solution 113 emphasise the need forthe utmost caution in the isolation of these extremely labile polysaccharideslest scission of the fructosan chain results in loss of the glucose-containingmoiety. Methylation studies have shown that the fructosans from Ken-tucky blue,ll* red fescue,llQ and common fox-tail 120 grasses are of the levantype.Studies on the fructosans from the stems and ripening ears of thecommon cereals have been reviewed.121Starch and Glycogen.-The fractionation of starch under conditionswhich minimise the possibility of degradation, particularly of the amylose,continues to attract much attention. The linear component appears to beespecially susceptible to degradation, which may occur in at least two ways.It has been shown viscometrically that potato amylose is degraded inaqueous solution in the presence of oxygen; 122 this oxidative degradation,which is appreciable in neutral solution, occurs much more rapidly in alkali.Amylose is degraded by alkali in the absence of oxygen with the formationof a mixture of D-glucoisosaccharinic acids.123 The fall in viscosity wouldbe much less obvious if degradation proceeds solely by the “peeling”reaction 1% from the reducing end of the chain, than if random oxidationresults in the formation of alkali-sensitive bonds in the middle of the chain.A method for the anaerobic fractionation of starch, which depends on thepreferential solubility of amylose in water, has been r e ~ 0 r t e d .l ~ ~ As a resultof other investigations, it has been suggested that amylose and amylopectinoccur naturally in chemical combination, 126 possibly through a phosphatidecross-link, and that preferential precipitation of the amylose with a com-plexing agent can only occur when the acid-labile linkage has been severed.The claim 12’ that amylopectin can be purified by selective precipitation ofthe amylose with stearic acid has been refuted.128The oxidation of starches by potassium metaperiodate has been studiedin detail, and an accuracy of k0.5 glucose residue is claimed for unit-chainlength determinations.129 The repeating units of many starches have beendetermined by this method, and from parallel determinations of their amylosethe average unit-chain lengths of the amylopectin componentscalculated.A valve microvoltmeter, which increases the accuracy ofdifferential potentiometric titrations,131 has been described and its use instudying the interaction of starches and other branched a-1 : 4-glucosanswith iodine reported.130 This sensitive method not only enables the amylose11’ H. H. Schlubach and K. Holzer, Annulen, 1953, 578, 213.H. H. Schlubach and L. Gassmann, ibid., 1953, 583, 81.llQ H. H. Schlubach and K. Holzer, ibid., p. 88.120 H. H. Schlubach, K. Holzer, and L. Gassmann, ibid., 1954, 587, 107.121 H. H. Schlubach, Experientia, 1953, 9, 230.lZ2 R. T. Bottle, G. A. Gilbert, C. T. Greenwood, and K. N. Saad, Chem. and Ind.,123 J. Kenner and G.N. Richards, ibid., 1954, 1483.124 W. M. Corbett and J. Kenner, J., 1955, 1431.126 H. A. Baum and G. A. Gilbert, Chem. and I.nd., 1954, 490.126 A. W. Bauer and E. Pacsu, Textile Res. J., 1953, 23, 853, 860, 864, 870.12’ K. H. Meyer and G. C. Gibbons, Helv. Chim. Acta, 1950, 33, 210.128 G. A. Gilbert, C. T. Greenwood, and F. J. Hybart, J., 1954, 4454.12Q D. M. W. Anderson, C. T. Greenwood, and E. L. Hirst, J., 1955, 225.lSo D. M. W. Anderson and C. T. Greenwood, J., 1955, 3016.lal G. A. Gilbert and J. V. R. Marriott, Trans. Faraday SOC., 1948, 44, 84.1953, 541266 ORGANIC CHEMISTRY.contents of starches to be accurately determined but also detects significantdifferences in iodine binding power between amylopectins and glycogens.In a detailed chemical and physical ~ t u d y , l ~ ~ the starch from rubberseeds was found to contain 20% of amylose and an amylopectin of averageunit-chain length 23 If 1 glucose units, and in which the majority of branchpoints were through C(6).Starches of abnormally high amylose content andwith amylopectins of increased unit-chain length have been isolated fromwrinkled-seeded peas and from a variety of maize.l= Whilst the starchfrom smooth-seeded peas contained 35% of amylose (Le., more than normal)and an amylopectin of normal unit-chain length (25 units), that fromwrinkled-seeded peas contained 66% of amylose and an amylopectin of chainlength 36.133 The abnormal maize starch contained ca. 50% of amyloseand an amylopectin with a repeating unit of 36 glucose residues; thep-amylolysis limit of 58% for this amylopectin indicated an inner chain of13 units (cf.5-8 units for an average amyl~pectin),l~~ and showed that bothinner and outer chains were longer than usual. Structural studies of thestarch from malted barley have indicated that malting results in the partialdegradation of the outer chains of the amylopectin (26 + 18 units) withrelatively little degradation of the amylose. 136Evidence that the inter-chain linkages in glycogens are only of the1 : 6-type has been provided by the virtual absence of glucose in the hydro-lysates of several periodate-oxidised glycogens,l37 and in the case of baker’syeast glycogen by “ linkage analysis ” in which the oligosaccharides formedon partial acid hydrolysis were shown to contain only a-1 : 4- and a-1 : 6-linkages.Both chemical and enzymic methods have been used in theinvestigation of the structure of baker’s 1389 139 and brewer’s 140 yeast glyco-gens. Similar methods have been used in the examination of an abnormalglycogen, from a case of von Geirke’s disease, which had a unit-chain lengthof only 6 ~ n i t s . 1 ~ ~Algal Po1ysaccharides.-Recent work on the fine structure of laminarinhas necessitated a modification of the view that this polysaccharide is com-posed solely of P-1 : 3-linked D-glucopyranose residues. In addition to themajor product, laminaribiose, gentiobiose, l-0-p-~-glucosyl-~-mannitol,~~~and 1-0-laminaribiosyl-~mannitol143 have been isolated on partial acidhydrolysis of the polysaccharide.It is evident, however, that not alllaminarin molecules are terminated by mannitol residues as some of thepolysaccharide is degraded on treatment with lime water ; lz4 it is probablethat two closely-related molecular species are present. The mercaptolysisof algal polysaccharides has given evidence of 3 : 6-anhydrogalactose residues.13* C. T. Greenwood and J. S. M. Robertson, J., 1954, 3769.A. L. Potter, V. Silveira, R. M. McCready, and H. S. Owens, J . Amer. Ckem. Soc.,134 I. A. Wolff, B. T. Hofreiter, P. R. Watson, W. L. Deatherage, and M. M. Mac-lS6 D. J. Manners, Quart. Rev., 1955, 9, 73.lS6 G. 0. Aspinall, E. L. Hirst, and W. McArthur, J.. 1955, 3075.lS7 D. J. Bell and D. J. Manners, J., 1954, 1891.S. Peat, W.J. Whelan, and T. E. Edwards, J., 1955, 355.13@ D. H. Northcote, Biochem. J., 1953, 53, 348.ld0 D. J. Manners and Khin Maung, J., 1955, 867.u1 D. J. Manners, J., 1954, 3527.142 S. Peat, W. J. Whelan, and H. G . Lawley, Chem. and Ind., 1955, 35.Ira S. Peat, W. J. Whelan, H. G. Lawley, and J . M. Evans, Biochem. J . , 1965, 61, x.1953, 75, 1335.Masters, ibid., 1955, 77, 1654ASPINALL AND SCHWARZ CARBOHYDRATES. 267The mercaptolysis of agar thus yields the diethylmercaptals of D-galactose,DL-galactose, and 3 : 6-anhydro-~-galactose, and of 3 : 6-anhydro-4-0-fb~-galactopyranosyl-L-galactose (agarobiose) . 145 The isolation from agar in69.5% yield of agarobiose dimethylacetal and its methanolysis products 146indicates that the agarobiose residue is the dominant repeating unit of thispolysaccharide.On the other hand, the mercaptolysis of the polysaccharidefrom Chondrus crispus yields the diethylmercaptal of 3 : 6-anhydro-~-gala~tose.1~~ The heterogeneous character of this polysaccharide has beenindicated by a fractionation which gave K-carrageenin, precipitated bypotassium chloride, and A-carrageenin.148 K-Carrageenin contains D-galac-tose, 3 : 6-anhydro-~-galactose, and sulphate groups in approximatelyequimolecular proportions, and the low consumption of periodate by thepolysaccharide suggests that the D-galactose 4-sulphate residues are linkedthrough positions 1 and 3.1g9 1-Carrageenin is composed mainly of D-galactose sulphate residues, only small quantities of the anhydro-sugarbeing present.149 A re-investigation 150 of Floridean starch has failed toproduce evidence for the presence of 1 : 3-linkages; the periodate oxidationof the polysaccharide and an examination of the thiosemicarbazide andisonicotinhydrazide derivatives of the oxidised polysaccharide indicate thatall the glucose residues are attacked by p e r i ~ d a t e .~ ~ The conversion of themain product of partial acetolysis of fucoidin into 2-O-~-fucopyranosyl-~-fucitol confirms the presence of 1 : 2-linked L-fucose residues in this poly-~accharide.1~1 A sulphated polysaccharide from Ulva Zactuca 152 containsmglucose, D-xylose, L-rhamnose, and D-glucuronic acid residues, andpreliminary evidence as to its molecular structure has been obtained frommethylation and periodate oxidation.A complex acidic polysaccharide, containing D-glucose, D-xylose, D-galactose, L-rhamnose, L-arabinose, and glucuronic acid units, has beenextracted from the fresh-water alga, Anabena cylindrica.153 The cellulosefrom the alga Chara 154 has been examined; extraction of the alga withalkali yields a starch-like polysaccharide 155 contaminated by small amountsof a xylose-containing polysaccharide.Plant Gums and Mucilages.-The occurrence of L-arabopyranose inaddition to L-arabofuranose residues in plant gums has been demonstrated inthe cases of cherry,156 peach,156 golden apple,157 lernon,l5* and Acaciakarroo 159 gums. In each case 3-0-~-~-arabopyranosyl-~-arabinose, pre-viously isolated from larch g gal act an,^^ was present amongst the products144 C.Araki and S. Hirase, Bull. Chem. SOC. Japan, 1953, 26, 463.146 C. Araki and S. Hirase, ibid., p. 109.14* D. A. I. Goring and E. G. Young, Canad. J . Chern., 1955, 33, 480.140 D. B. Smith, A. N. O’Neill, and A. S. Perlin, ibid., p. 1352.lSo P. O’Colla, PYOC. Roy. Irish Acad., 1953, 56, B, 321.161 A. N. O’Neill, J . Amer. Chem. SOC., 1954, 76, 5074.152 J. W. E. Brading, M. M. T. Georg-Plant, and D. M. Hardy, J., 1954, 319.163 C. T. Bishop, G. A. Adams, and E. 0. Hughes, Canad. J . Chem., 1954, 32, 999.lS4 El S. Amin. J., 1955, 281.lSs Idem, ibid., p. 282.ls6 P. Andrews, D. H. Ball, and J. K. N. Jones, J., 1953, 4090.157 P. Andrews and J. K. N. Jones, J., 1954, 4134.Is* Idem, I., 1955, 583.16* A. J.Charlson, J. R. Nunn, and A. M. Stephen, J., 1955, 1428.S. Hirase and C. Araki, ibid., 1954, 27, 105.E. Percival, Chem. and Ind., 1954, 1487; A. N. O’Neill, J . Amer. Chew. SOC.,1955, 77, 2837268 ORGANIC CHEMISTRY.of partial acid hydrolysis; although this disaccharide can be formed as anacid reversion product from L-arabinose,lG0 it is probable that in these casesits isolation has structural significance. Under similar conditions, 5-0-p-~-xylopyranosyl-L-arabinose has been isolated from peach 156 and cholla 156gums, and 3-0-cc-~-xy~opyranosyl-~-arabinose from golden-apple gum.157Lemon gum also yields 4-0-(4-0-methyl-~-glucuronosyl)-~-arabinose ongraded hydrolysis.161Successive applications of Barry’s degradation 162 have shown that gumarabic contains a central core of 1 : 3-linked D-galactopyranose residues; asimilar conclusion has been reached from a study of the fragment of thedegraded gum remaining after periodate oxidation and controlled hydrolysisto remove the cleaved aldobiouronic acid side-chains.la Several gums ofthe Acacia genus, namely A .senegalensis (gum arabic),lM A. moZZissima,165A . j5ycnantha,166 A . ~yanophyZla,l~~ and A . k a ~ ~ o o , ~ ~ ~ contain the same con-stituent sugars, although in different proportions; all yield the same aldo-biouronic acid, 6-O-~-D-glucuronosyl-~-ga~actose, on partial hydrolysis.In the case of A . karroo gum, a second aldobiouronic acid, 4-O-a-~-glucurono-syl-D-galactose, was i~olated.16~ The similarity of A . fiycnantha 166 andA .cyanophyZZa. 167 gums to gum arabic is emphasised by the isolationof 3-O-~-galact opyranosyl-D-galact ose 168 and 3-0- a-D-galact opyranosyl-L-arabino~e,l~~ respectively, from the products of partial hydrolysis. Gumghatti 1’0 resembles damson 1 7 1 and cherry 172 gums in respect of its con-stituent sugars, L-arabinose, D-galactose, D-mannose, xylose and D-glucuronicacid, and in yielding the same aldobiouronic acid, 2-O-~-~-glucuronosyl-~-mannose on partial hydrolysis, but the isolation also of 6-0-p-~-glucuronosyl-D-galactose suggests some similarity with the gums of the Acacia group.40-(4-O-Methyl-a-D-glucuronosyl)- and 6-0- (4-O-methyl-p-~-glucuronosyl)-D-galactose have been isolated from gum m ~ r r h , l ~ ~ and 4-O-~-glucuronosyl-D-galaCtOSe and 3-0-~-glucuronosyl-~-galactose from Neem gum 17* andKetha gum,l75 respectively.The partial methanolysis of methylatedsapote gum yields the methyl glycosides of 3-O-methyl-~-xylose, 2 : 3 : 4-tn-O-methyl-D-xylose, 2 : 3 : 4-tri-O-met hyl-L-arabinose, and 3 : 4-di-0-methyl-D-glucuronic acid, together with the methyl glycosides of thepartially methylated aldobiouronic acids, 3-0-methyl-2-0-(2 : 3 : 4-tri-O-methyl-D-glucuronosyl)-D-xylose and 2-O- (3 : 4-di-O-methyl-~-glucuronosyl)-1.0 D. H. Ball, J. K. N. Jones, and W. H. Nicholson, Amer. Chem. SOC. Meeting,Minneapolis, Sept., 1955, Abs. Papers, 7 ~ .161 P. Andrews and J. K. N. Jones, J.. 1954, 1724.T. Dillon, D. F. O’Ceallachain, and P. O’Colla, PYOC. Roy. Irish Acad., 1953,55, B, 331 ; 1954, 57, B, 31.~8 F.Smith and D. Spriestersbach, Amer. Chem. SOC. Meeting, Minneapolis, Sept.,1955, Abs. Papers, 1 5 ~ .Id* S. W. Challinor, W. N. Haworth, and E. L. Hirst, J., 1931, 258.lBS A. M. Stephen, J., 1951, 646.166 E. L. Hirst and A. S. Perlin, J., 1954, 2622.167 A. J. Charlson, J. R. Nunn, and A. M. Stephen, J., 1955, 269.188 J. Jackson and F. Smith, J., 1940, 79.ld0 F. Smith, J., 1939, 744.170 G. 0. Aspinall, E. L. Hirst, and A. Wickstrom, J., 1955, 1160.171 E. L. Hirst and J. K. N. Jones, J., 1938, 1174.17% J. K. N. Jones, J., 1939. 658.17a J. K. N. Jones and J. R. Nunn, J., 1955, 3001.17’ S. Mukherjee and H. C. Srivasta, J. Amm. Chem. SOC., 1955, 77, 422.176 G. P. Mathur and S. Mukherjee, J . Sci. Ind. Res. (India), 1964, 13, B, 462ASPINALL AND SCHWARZ : CARBOHYDRATES.2893-O-methyl-~-xylose.~~~ In contrast to these glucuronic acid-containinggums, Cochlospermum gossypizcm gum 177 contains residues of D-galacturonicacid, in addition to L-rhamnose and D-galactose. The hydrolysis productsfrom the methylated gum, together with the mixture of aldobiouronic acids,2-O-~-gdacturonosyl-~-rhamnose and 4-O-~-galacturonosyl-~-galactose, ob-tained on partial hydrolysis, indicate a highly branched structure.A re-investigation of the mucilage from Plantago arenaria seeds 178 stillleaves doubt concerning the homogeneity of the polysaccharide. Although2-O-a-~-galacturonosyl-~-rhamnose was isolated from the partial hydrolysisof the mucilage, the hydrolysis of the methylated polysaccharide gave acomplex mixture of methyl ethers of D-xylose, L-arabinose, and D-galactose,but no methylated derivatives of D-galacturonic acid or L-rhamnose could beisolated.Partial hydrolysis of okra mucilage 179 yielded PO-or-~-galacto-pyranosyl-D-galactose and 2-O-a-~-ga~acturonosy~-~-rhamnose. An acidicpolysaccharide isolated from the juice of ripe grapes consisted of residues ofD-galactose, D-mannose, L-arabinose , L-rhamnose, and D-galaCtUrOniC acid,and yielded 2-O-a-~-galacturonosyl-~-rhamnose on partial hydrolysis.l**Polysaccharides synthesised by Micro-organisms.-Further structuralexaminations of dextrans have shown that these polysaccharides have back-bones of cc-1 : 6-linked D-glucopyranose residues, but that they differ con-siderably in their degrees of branching and also in the nature of the branchpoints.Thus, Betacoccus arabinosaceous normally synthesises a brancheddextran with a repeating unit of 6-7 glucose residues and with branchingthrough C(3).181 The same organism, when grown in a magnesium-deficientmedium, elaborates a much less highly branched polysaccharide of the samegeneral type with a unit-chain length of 40--50.182 A large number ofdextrans, synthesised by different strains of Leuconostoc mesenteroides, havebeen examined by periodate oxidation,183$ and the proportions of 1 : 6-,1 : 4-, and 1 : 3-linkages determined. The results obtained from the quan-titative analysis of the products (glucose, glycerol, and erythritol) of hydro-lysis of the polyol, isolated from the catalytic reduction of the periodate-oxidised polysaccharides,l were in reasonable agreement with those calculatedfrom the titrimetric determinations of periodate consumed and formic acidreleased during the oxidation.183 Methylation has shown that the levansformed by Pseudomonas +runicola, Wormald and Bacillus subtilis BG2 F1are branched molecules, with repeating units of 9-10 2 : 6-linked @-D-fructo-furanose residues and with 2 : l-linkages at the branch p0ints.18~ A similarlevan, but of shorter average chain length (8-9 units), has been isolatedfrom B.Polymyxa.ls6176 E. V. White, J . Amev. Chem. Soc., 1953, 75, 257, 4692; 1954, 76, 4906.177 E. L. Hirst and S. Dunstan, J.. 1953, 2332.178 R. L. Whistler and H. E.Conrad, J . Amer. Chem. SOL, 1954, 76, 1673, 3544.lSo W. Biichi and H. DeueI, Helv. Chirn. Acta, 1954, 3'7, 1392.181 S. A. Barker, E. J. Bourne, G. T. Bruce, W. B. Neely, and M. Stacey, J., 1954,lS2 S. A. Barker, E. J. Bourne, A. E. James, W. B. Neely, and M. Stacey, J., 1955,lE8 J. W. SIoan, B. H. Alexander, R. L. Lohmar, I. A. Wolff, and C. E. Rist, J . Amer.180 J. C. Rankin and A. Jeanes, ibid., p. 4435.lS6 D. J. Bell and R. Dedonder, J.. 1954, 2866.la6 D. Murphy, Canad. J . Chem., 1952, 80, 872.E. L. Hirst, E. G . V. Percival. and C. B. Wylam, J., 1954, 189.2395.2096.Chem. SOC., 1954, 16, 4429270 ORGANIC CHEMISTRY.Several polysaccharides of the amylopectin-glycogen type have beenisolated from micro-organisms. The polysaccharides synthesised by theholotrichously ciliated protozoa present in the sheep’s rumen and byCyclopostium found in the colon and ca3cum of a horse 188 contain unitchains of 22-23 a-1 : 4-linked D-glucose residues joined by 1 : 6-linkages.The polysaccharides from the protozoa Trichomonas fEtus and T.gaZZinea,l*gand from BaciZZus megatherium lgo contain shorter unit chains of 15, 9, and10-1 1 residues, respectively.Serological cross reactions have been used in the comparison of the acidiccapsular polysaccharide from A zotobacter c3aroococcum 191 and the Type I1Pneumococcus specific polysaccharide lg2 with polysaccharides whose mainstructural features are known. Methylation has shown that the A . chroococ-cum polysaccharide contains D-glucose and D-galactose residues in theratio of 3 : 1, together with a small proportion of D-glucuronic acid residues.From similar experiments, it is clear that the Type I1 Pneumococcus poly-saccharide is highly branched and contains L-rhamnose, D-glucose, andD-glucuronic acid residues in the approximate ratio of 7 : 1 : 3; whilst thedetailed structure is not yet known, the molecule must contain chains of1 : 3-linked L-rhamnopyranose residues. Two serologically active poly-saccharides have been isolated from Bacillus antkracis; 1g3 one of the poly-saccharides is a mannan in which the residues are 1 : .Q-linked, whilst theother contains D-galactose and N-acetyl-D-glucosamine units in the ratioof 2 : 1.L-Fucose is a constituent sugar of three widely different polysaccharides.The capsular polysaccharide from Pseudomonas jkorescens, strain I1 , yieldson hydrolysis D-glucose, D-glucosamine, L-fucose, a crystalline disaccharidecomposed of glucose and fucose, and a crystalline tetrasaccharide composedof a glucose, a glucosamine, and two fucose residues.lM The extracellularpolysaccharide from Mucor racemosus195 is composed of residues of D-galactose, D-mannose, L-fucose, and o-glucuronic acid ; it is probable thatall the fucose residues occur in the furanose form in terminal positions asthey are all attacked by periodate and are all released on autohydrolysis ofthe polysaccharide.An extracellular polysaccharide from A erobacteraerogenes is composed of D-glucose (50y0), L-fucose (lo%), and unidentifieduronic acid residues (29Y0).lg6Mucopo1ysaccharides.-Although much work has been carried out duringrecent years on this group of polysaccharides, knowledge of their detailedchemical structure is still limited.Some aspects of the chemistry of thesesubstances, including their relation to proteins in protein-carbohydratecomplexes, formed a part of the Faraday Society Discussion on ‘ I TheG. Forsyth and E. L. Hirst. J., 1953, 2132.G. Forsyth, E. L. Hirst, and A. E. Oxford, J., 1953, 2030.la@ D. J. Manners and J. F. Ryley, Biochem. J., 1955, 59, 369.lgo C. Barry, R. Cavard, G. Milhaud, and J. P. Aubert, Ann. Insf. Pusteuv, 1953, 84,lD1 G. J. Lawson and M. Stacey, J., 1954, 1925.12@ K. Butler and M. Stacey, J., 1955. 1537.lnS J. E. Cave-Brown-Cave, E.J. S. Fry, H. S . El Khadem, and H. N. Rydon, J.,lg4 R. G. Eadon and R. Dedonder, Compf. vend., 1955, 241, 579.lg5 L. Hough and M. B. Perry, Biochem. J., 1955, 61, viii.lg6 J. F. Wilkinson, W. F. Dudman, and G. 0. Aspinall, Biochem. J., 1955, 59,446.605.1954, 3866BARKER AMINO-ACIDS, YEPTIDES, AND PROTEINS. 27 1Physical Chemistry of Proteins." lg7 The structure of chondrosin, thedisaccharide obtained from cartilage chondroitinsulphuric acid,l9* has beenestablished as 2-amino-2-deoxy-3-0- ( p-D-glucopyranuronosyl)-D-galact oseby degradation and reduction to 2-0-( p-D-glucopyranosy1)-D-lyxitol, whosestructure was proved by periodate oxidation.199 A similar conclusion wasreached from a study of the periodate oxidation of N-acetylchondrosin ethylester.200 Chondroitin,201 a mucopolysaccharide isolated from bovine cornea,has a very low sulphate content and also yields chondrosin on hydrolysis.The disaccharide isolated from the partial acid hydrolysis of hog gastricmucin with blood group A activity has been identified as 2-acetamido-2-deoxy-kO-P-D-galactopyranosyl-D-glucose by periodate oxidation,202s 203and by oxidative degradation (with ninhydrin) and synthesis from,2043-O-p-~-galactopyranosy~-~-arabinose, and also by comparison with thesynthetic disac~haride.~Os Hydrolysis of the periodate-oxidised hog-muchpolysaccharide after bromine oxidation yielded tartronic acid, D-glyceric acid,and D-glucosamine hydrochloride, and so showed that the galactose residuesare linked through Ct2>.206 Periodate oxidations of the polysaccharide andits degradation products suggest that the small proportion of L-fucoseresidues (<lo%) present in the molecule replace some of the D-galactoseresidues in the basic disaccharide repeating unit, probably near the ends ofthe chain~.~O'G.0. A.J. C. P. S.11. AMINO-ACIDS, PEPTIDES, AND PROTEINS.Natural Amino-acids.-A new attempt has been made to discover theultimate origin of natural amino-acids. In a remarkable paper evidencehas been presented that a wide variety of amino-acids is formed when amixture of methane, ammonia, hydrogen, and water are subjected to thecombined action of a silent electrical discharge and a high-frequency spark.In contrast with the results of earlier attempts to reproduce the synthesisof the raw materials of life ab initio, the products in this case were appreciablein quantity and identified with certainty, while proof that microbiologicalprocesses were not involved was adequate.Glycine, a- and f3-alanine,sarcosine, and a-aminobutyric acid were among the thirty or more ninhydrin-active compounds separated.A considerable number of new natural amino-acids has been reported,many of which occur in the free state. Recent surveys have been made oflg7 Discuss. Faraday SOC., 1953, 13, pp. 245-287.200 H. Masamune, 2. Yoshizawa, and M. Maki, Tohuku J. Exp. Med., 1951, 55, 47.201 E. A. Davidson and K. Meyer, J. BioE. Chem., 1954, 211, 605.202 2. Yoshizawa, Tohuku J. Exp. Med., 1950, 52, 111.203 F. Zilliken, P.N. Smith, R. M. Tomarelli, and P. Gyorgy, Arch. Biochem. Biophys.,204 2. Yoshizawa, Tohuku J. Exp. Med., 1950, 62, 145.206 R. Kuhn and W. Kirschenlohr, Chem. Bey., 1954, 87, 1547,t o 4 2. Yoshizawa, Tohuku J. Exp. Med., 1951, 54, 129.207 H. Masamune and 2. Yoshizawa, ibid., 1954, 60, 135,1 S. L, Miller, J, Amey. Chem. Soc., 1955, 77, 2351.E. A. Davidson and K. Meyer, J. Amer. Chem. Soc., 1954. 76, 5686.Idem, ibid., 1955, 77, 4796.1955, 54, 398272 ORGANIC CHEMISTRY.free amino-acids both in plant and animal tissues2 The biochemical signi-ficance of much recent work is outside the scope of this Report which willbe concerned with only a selection of papers published in 1954 and 1955.The methylsulphonium analogue of methionine has been obtained intwo laboratories and appears to be of wide occurrence in green plants.Itis more active than methionine as an antagonist of the toxicity of sulphanil-amide for certain micro-organisms. A substantial proportion of the organicsulphur of cabbage is believed to be present as one of the diastereoisomericforms of L-S-methylcysteine sulphoxide (8-methylsulphinylalanine) .4 Be-sides the occurrence of y-methylproline in young apple fruit, a further newproline derivative has been observed in both the fruit and the twigs of appletrees5 It is believed to be a hydroxymethylproline, but it is not as yetpossible to distinguish between the two possibilities (1) and (2).H 2 N l ; J p N H 2 FOPHO t-J C02"HHo*cHz-LJ C0,HH(1) (2) (3)Roseothricin, besides containing 3 : 6-diaminohexanoic acid,' yields anamino-acid " roseonine " to which the structure (3) has been assigned.8Permanganate oxidation of the material gave guanidine and a small quantityof glycine; one mol.of periodate was consumed quickly, producing form-aldehyde and ammonia, and, after twenty hours, a further mol. of oxidantwas used. This behaviour is similar to that of serine and was regarded assupport for structure (3). It seems to the Reporter, however, that thestructure needs further consideration in view of the fact that the pK,' valueis lower than that of isoserine.A previously unidentified peak in ion-exchange chromatograms of humanurine has been shown to be due to ~-3-methylhistidine,~ which has beenobtained also, together with other met hylhis tidines, by met hylation ofhistidine and is distinguished from l-methylhistidine by chromatographyon Dowex-50 resin and by its infrared spectrum.and of a-aminoy-hydroxy-pimelic acid 11 in hydrolysates of nerve proteins has been claimed, buta-aminobutyric acid, previously obtained therefrom,12 has now been shownto arise by decomposition of threonine hydrochloride and serine hydro-2 N.Grobbelaar, J. K. Pollard, and F. C . Steward, Nature, 1955, 175, 703; A. I.Virtanen, Angew. Chem., 1955, 67, 381; W. H. Stein and S. Moore, J . Baol. Chem.,1954, 211, 915; H. H. Tallan and S. Moore, ibid., p. 927.R. A. McRorie, G. L. Sutherland, M. S. Lewis, A. D. Barton, M. R. Glazener, andW. Shine, J . Amer. Chem.Soc., 1954, 76, 115; F. Challenger and B. J. Hayward,Biochem. J., 1954, 58, iv.R. L. M. Synge and J. C. Wood, ibid., 1955, 60, xv.5 A. C. Hulmeand W. Arthington, Nature, 1954,173, 588; A. C. Hulme, ibid., 1954,174, 1055; G. Urbach, ibid., 1955, 175, 170.13 A. C. Hulme and F. C. Steward, ibid., p. 171.7 K. Nakanishi, T. Ito, M. Ohashi, I. Morimoto, and Y . Himta, BUZZ. Ckem. Soc.Japan, 1954, 27, 639.The presence of a-aminopimelic acidK. Nakanishi, T. Ito, and Y . Hirata, J . Amer. Chem. SOC., 1954, 76, 2845.H. H. Tallan, W. H. Stein, and S. Moore, J . Biol. Chem., 1954, 206, 825.lo A. I. Virtanen and A.-M. Berg, Acta Chem. Scand.. 1954, 8, 1086.l1 A. I. Virtanen, E. Uksila, and E. J. Matikkala, ibid., p. 1091.l2 K. Heyns and W. Walter, 2.physiol. Chem., 1952, 289, 85BARKER : AMINO-ACIDS, PEPTIDES, AND PROTEINS. 273chloride.13 An imino-acid from species of Liliacm has been identified l4as an azetidine derivative (4). The tentative identification of y-methyl-glutamic acid and y-hydroxy-y-methylglutamic acid in PhyZZitis scolo-pendrium l5 and of y-hydroxyglutamic acid in Phlox decussata l6 is to beCH -CH I‘ N”qH’Co2H (4)contrasted with the finding that Dakin’s so-called p-hydroxyglutamic acid l7consists mainly of a mixture of glutamic and aspartic acid.ls It is also ofinterest that y-methyleneglutamine, first reported as a constituent of thepeanut plant,lg and y-methyleneglutamic acid have been recognised in thetulip bulb 2o and in hops.21 The structures of the natural materials havebeen confirmed by synthesis.22Synthetic Amino-acids.-Acylaminomalonic esters, for which an im-proved preparation is a ~ a i l a b l e , ~ ~ have been used in a large number of theC o p e C02MeI ICH-NHsCHO - CH,:CH.CH,-C- NH-CHO --DIC0,Mc C o p e(3C0,McIICOaMeMoSgCHiCH;CH,-C‘NH.CHO - MeS*CH,-CH,*CH .CHgCO,H(6) NH2C0,Et .C 02EtI IC 1.CHiCH.C 0,Et 4- CH*N H Ac - E t 0,C.CH-C H,*C*NHAcI I I I(7) (0)0 A c c 0,E t OAc C0,Et - HO,C* C H*C H2* CH-C02HI IOH NH,(9)syntheses of amino-acids described in the period under review. DL-Homo-methionine has been obtained 24 by the route (5) _t (6) and DL-y-hydroxy-glutamic acid 25 by route (7) + (8) + (9). The latter product was alsolS K. Heyns and W. Walter, 2. physiol.Chem., 1953, 294, 111.l4 A. I. Virtanen and P. Linko, Actu Chem. Scand., 1955,9, 551 ; L. Fowden, Nature,16 A. I. Virtanen and P. K. Hietala, ibid., p . 175.l7 H. D. Dakin, Biochem. J., 1918,12, 290; 1919,13, 398.1s C. E. Dent and D. I. Fowler, ibid., 1954, 56, 54.1* J. Done and L. Fowden, ibid., 1951, 49, xx; 1951, 51, 541.R. M. Zacharius, J. K. Pollard, and F. C. Steward, J . Amer. Chem. Soc., 1954, 76,21 G. Harris, Chem. and Ind., 1954, 244.22 P. C. Wailes, M. C. Whiting, and L. Fowden, Nature, 1954,174, 130; P. C. WailesH. Hellmann and F. Lingens, 2. physiol. Chem., 1964, 297, 283.24 A. Kjaer and S . Wagner, A d a Chem. Scand.. 1955. 9. 721.zs L. Benoiton and L. P. Bouthillier, Canad. J . Chern., 1955, 83, 1473.1955,176, 347; A. I.Virtanen, ibid., p . 984; Angew. Chem., 1955, 67, 619.A. I. Virtanen and A.-M. Berg, Acfu Chem. Scand., 1955, 9, 553.1961.and M. C. Whiting, J., 1956, 3636274 ORGANIC CHEMISTRY.obtained by bromination of a-phthalimidoglutaric anhydride, and its struc-ture was confirmed by the fact that the material obtained by either routewas unaffected by periodate. DL-Lysine has been synthesised by makinguse of the fact that l-bromo-4-chlorobutane (10) reacts 26 with the sodio-derivative (11) to give the acetamidomalonic ester (12), and a furtherC 02E t CO Et I I 2I IAc+JH.CNa + Br*CH,.CH,*CH;CH,CI --C Ac*NH*C*CH;CH;CH2Ci01) C0,Et 00) C02Et Q2)interesting adaptation 2' of this type of synthesis is the formation of glutamicacid through the intermediate (13).Glutamic acid has also been obtainedfrom ethyl a-bromoglut arate .28C02R C02RI IIC 02RII4 CH*CH *C*NHAcC02RIFH, + CHzO + CH'NHAcC02R C 02R C0,R C02R03)L-isoGlutamine has been synthesised 29 by an unambiguous route involv-ing the formation of a lactam (14) from N-toluene-P-sulphonylglutamic acidL-isoGlutamine is also pro- means of phosphorus pentachloride.CONH2I CDNH,C02H I CH*NH2I O{ '7H2 - 7% - y 2-2 CH*HOS ICH. NHlor7"2 y 2TosN-CCH'COCIFH2 -y 2C02H C02H C02H6s) 04)chromatographically pure form by conversion of y-benzyl-N-benzyl-oxycarbonyl L-glutamate into the amide, followed by hydrogenolysis of theprotective gr0ups.~0 It may be noted that removal of water by azeotropicdistillation 31 or by polyphosphoric acid 32 results in improved yields ofbenzyl esters of amino-acids. A modification of the Strecker synthesis hasbeen used for the preparation of DL-a-methylghtamic acid, which acts as aninhibitor of the synthesis and utilisation of glutamine.=Other innovations include the synthesis of homologues of glutamic acid,methionine, and diaminopimelic acid via the hydantoins,34 and the produc-tion of a-amino-acids by interaction of a-keto-aldehydes with ammoniumsalts in the presence of thi01s.~~Stereochemical Relations-An extensive study of the optical rotations26 M.Servigne and E. Szarvasi, Compt. rend., 1954, 2.38, 1595.27 H. Hellmann and F. Lingens, Angew. Chem., 1954, 66, 201.28 G. Pans, R. Gaudry, and L. Berlinguet, Canad. J . Chem., 1955, 53, 1724.2s J.M. Swan and V. Du Vigneaud J . Amer. Chem. SOC., 1954, 76, 3110.30 M. Kraml and L. P. Bouthillier, Canad. J . Chem., 1955, 33, 1630.31 J. D. Cipera and R. V. V. Nicholls, Chem. and Ind., 1955, 16.st B. F. Erlanger and R. M. Hall, J . Amer. Chem. SOC., 1954, 76, 6781.33 A. E. Gal, S. Avakian, and G. J. Martin, ibid., p. 4181.s4 K. Pfister, W. J. Leanza, J. P. Conbere, H. J. Becker, A. R. Matzuk, and E. F.35 T. Wieland, J. Franz, and G. Pfleiderer, Chem. Ber., 1955, 88, 641.Rogers, ibid., 1955, 77, 697BARKER : AMINO-ACIDS, PEPTIDES, AND PROTEINS. 275of amino-acids has been made and it is claimed that reliable conclusions canbe drawn from optical data concerning the structures both of amino-acidscontaining one asymmetric centre, and of diastereoisomeric amino-acid~.~~Diastereoisomers of amino-acids such as hydroxylysine and isoleucine arenow conveniently separated by ion-exchange chr~matography.~~X-Ray studies have shown that (the usual convention being followed) theamino-group of D(-)-isoleucine is cis with respect to the methylIt follows from this that, since L-isoleucine and D-alloisoleucine on treatmentwith ninhydrin give (+)-a-methylbutyraldehyde, and misoleucine andL-alloisoleucine give the laevorotatory aldehyde, the configurations of allfour isomeric isoleucines are kn0wn.~9 It is interesting to note that O-methyl-threonine acts as a competitive inhibitor for the incorporation of radioactiveisoleucine into proteins, a fact which is in agreement with the existence ofrelated configurations at both the asymmetric centres of the amino-a~ids.~~A method which may well be applicable to the determination of theconfigurations of diastereoisomeric amino-acids is exemplified by the con-version of L-alanine into y-aminovaleric a ~ i d .~ 1 L-a-Phthalimidoprop-aldehyde (16), previously obtained from L-alanine, was converted by aDoebner condensation into the pent-2-enoic acid (17) which, after hydrogen-ation and hydrolysis, gave ( +)-y-aminovaleric acid. This aminovalericacid is therefore related structurally to L-alanine..p4t04y cp4 ea, tiJMe-C-CHO Me - C- Cn : C 14. CO~HI IH H0s) Q7)Preparation of Amino-acids from Peptides and Proteins.-Variousmodifications of the methods of acid hydrolysis of peptides and proteinshave been introduced.Dissolution of tissue in 85% formic acid followedby addition of 2~-hydrochloric acid results in liberation of all amino-acids,except tryptophan, within two hours.42 It is agreed that different peptidebonds are split at different rates,43 but there appear to be differences ofopinion as to the mechanism of the hydrolysis.44 The preferential liberationof threonine and serine recorded by Elliott 45 has been observed also in thehydrolysis of wheat gluten under the conditions used by and also38 M. Winitz, S. M. Birnbaum, and J. P. Greenstein, J . Amer. Chem. SOC., 1955, 77,37 K. A. Piez, J . Biol. Chem., 1954, 207, 77; P. B. Hamilton and R. A. Anderson,38 J. Trommel and J. M. Bijvoet, Actu Cryst., 1954, 7, 703.3B W.S. Fones, J . Amer. Chem. SOC., 1954, 76, 1377.40 M. Rabinovitz, M. E. Olsen, and D. M. Greenberg, ibid., 1955, 77, 3109.I1 K. Balenovic and D. Cerar, J., 1955, 1631.42 S. U. Gurnani, U. S. Kumta, and M . B. Sahasrabudhe, Biochim. Biophys. Acfu,43 R. Hirohata, Y . Kanda, M. Nakamura, N. Izumiya, A. Nagamatsu, T. Ono,44 R. J. L. Martin, Nature, 1955, 175, 771.4 5 D. F. Elliott, Biochem. J., 1952, 50, 542.46 L. Wiseblatt, L. Wilson, and W. B. McConnell, Canad. J . Chem., 1955, 33, 1295.716; M. C. Otey, J. P. Greenstein, M. Winitz, and S. M. Birnbaum, ibid., p. 3112.ibid., 1955, 213, 249.1955, 16, 553.S. Fujii, and M. Kimitsuki, Z . physiol. Chem., 1953, 295, 368276 ORGANIC CHEMISTRY.during the hydrolysis of insulin4' by 10-5w-hydrochloric acid at 0'.Hydro-lysis of peptide bonds with acidic resins is being used increasingly. Dowex-50 is preferred>* but it is found that prolonged treatment with water causesappreciable breakdown of this resin , with liberation of sulphuric acid andsome brown material, particularly with high degrees of cross-linking of thepolymer.49 Temperature is an important factor, and the method is un-suitable in certain cases such as the hydrolysis of insulin.50During the alkaline fission of peptide bonds, a secondary reaction mayoccur whereby an N-terminal glycine residue reacts reversibly with analdehyde to give a hydroxyamino-acid or, conversely, a terminal hydroxy-amino-acid may be degraded to an aldehyde and gly~ine.~l A new reactionhas been reported which may prove useful in the degradation of peptidesand proteins.52Most developments in the isolation of amino-acids from protein hydro-lysates concern partition, ion-exchange, or electrophoretic techniques.However, it is useful to note that methionine may be isolated from hydro-lysates of casein and zein in 65% and 85% yield respectively by conversioninto the methylsulphonium derivative which is precipitated as the phospho-tungstate.63 Sublimation is possible with a number of amino-acids and thistechnique should find considerable use in the purification of labelledmaterials.54Partition Chromatography, Ion-exchange Chromatography, and Iono-graphy of Amino-acids.-Various minor modifications in the analysis ofamino-acid mixtures by partition chromatography have been introduced.Amino-acids are located on paper by spraying it with naphthaquinone-sulphonic acid and heating it to 60".The amino-acids appear as spots whichfluoresce strongly in ultraviolet light,55 and it is claimed that the methodis more sensitive than the ninhydrin technique. Modifications in techniquenow largely eliminate errors in the quantitative determination of amino-acids on paper chromatograms by the ninhydrin method,66 and improve-ments in the c,opper method have also been sugge~ted.~'Ion-exchange chromatography is probably more widely applicable to theseparation and isolation of amino-acids; and, of the many studies of theamino-acid composition of proteins which have come to the notice of theReporter during the last two years, over half have employed ion-exchangechromatography. Zeokarb-225 can be used 58 instead of Dowex-60, as inthe original work of Moore and Stein.59 It is recommended that '' waterregain" as defined by Pepper 60 be used instead of the degree of cross-47 G. L.Mills, Biochem. J., 1954, 56, 230.48 J. R. F i t a k e r and F. E. Deatherage, J . Amer. Chem. Soc., 1955, 77, 3360.A. S. Dlxon, Biochem. J., 1955, 59, xii; 60, 165.6o J. C. Paulson and F. E. Deatherage, J . Amer. Chem. SOC., 1954,76, 6198.61 T. Wieland and K. Dose, AIzgew. Chem., 1954, 66, 781.62 K. Heyns and K. Stange, 2. Naturforsch., 1955, lob, 129.6s N. F. Floyd and T. F. Lavine, J . Biol. Chem., 1954, 207, 119.64 D. Gross and G. Grodsky, J .Amev. Chern. Soc., 1955, 77, 1678.66 E. Kofranyi, 2. physiol. Chem., 1955, 299, 129.66 W. Gerok, ibid., p. 112.67 H. Boser, ibid., 1954, 296, 10.6* P. N. Campbell, S. Jacobs, T. S. Work, and T. R. E. Kressman, Chem. axd Id.,60 S. Moore and W. H. Stein, J . Biol. Chem., 1951, 192, 663.6o K. W. Pepper, J . Appl. Chem., 1951, 1, 124.1955, 117BARKER : AMINO-ACIDS, PEPTIDES, AND PROTEINS. 271linking to designate a particular resin since this quantity can readily bemeasured. Minor modifications in technique are advisable for effectiveresolution of basic amino-acids 61 and it is also recommended that acidicamino-acids should be first isolated on a strongly basic resin with a volatileacid as eluant.62Ionographic separation of amino-acids on filter paper results in poorerresolution than with partition chromatography or ion-exchange chromato-graphy, but better results are obtained at high potential gradients.Atechnique has been described 63 using 6000 v, giving a gradient up to130 v per cm.Determination of End-groups and Sequence in Polypeptides and Proteins.-Comparatively little work has been reported during the period underreview concerning improved or new techniques for the determination ofN-terminal residues. It has been pointed out 64 that determination ofN-terminal residues by the fluorodinitrobenzene method and of C-terminalresidues by using carboxypeptidase may lead to contradictory results. Thelarge number of papers dealing with the determination of C-terminal residuesis indicative of the fact that a wholly satisfactory method has yet to befound.The 2-thiohydantoin method still receives considerable attention,66but serine and proline are now added to the list of C-terminal groups whichvitiate the method. Anodic oxidation of C terminal residues according toBoissonnas 66 is found to be unsatisfactory with peptides containing phenyl-alanine or tyrosine since these amino-acids are destroyed irrespective of theirposition in the chain.67 An interesting modification of the previouslyreported 68 reaction of peptides with hydrazine has been d e ~ e l o p e d . ~ ~ Thisallows of simultaneous determination of N-terminal and C-terminal residues.Treatment of the benzyloxycarbonyl-peptide or -protein with hydrazinehydrate converts amino-acid residues in the middle of a peptide chain intoamino-acid hydrazides (18), and the N-terminal residue is converted into thedihydrazide (19), whereas C-terminal amino-acid is liberated as such.Thedihydrazides are converted into what may be either a triazine (20) or anaminohydantoin (21), and the products are separated chromatographically.The method is not satisfactory for the detection of glycine, serine, or cysteineas N-terminal residues, since compounds ot type (20) or (21) are not formed;difficulties also arise with glutamyl-peptides. Insulin has been subjectedto ammonolysis in liquid ammonia at 120" which converts all residues intoamides except the C-terminal residue which is recovered as the free amino-acid.70 C-Terminal groups have also been converted by acetic anhydrideP.B. Hamilton and R. A. Anderson, J. Biol. Chem., 1954, 211, 95.D. Gross, Natuve, 1955, 176, 72.M. Rovery and P. Desnuelle, Bull SOC. Chim. biol., 1954, 36, 95.62 C. H. W. Hks, S. Moore, and W. H. Stein, J. Amer. Chem. SOC., 1954,76, 6063.66 A. L. Levy, Biochim. Biophys. Acta, 1954,15, 589; R. A. Turner and G. Schmerz-ler, ibid., 1954, 13, 553; M. Dautravaux and G. Biserte, Compt. rend., 1965, 240, 1153;S . W. Fox, T. L. Hurst, J. F. Griffith, and 0. Underwood, J . Amer. Chem. Soc., 1955,77,3119.g6 R. A. Boissonnas, Nature, 1953, 171, 304.6 7 A. R. Thompson, Biochim. Biophys. Acta, 1954, 15, 299.*.a S. Akabori, K. Ohno, and K. Narita, BuIl. Chem. SOC. Japan, 1952, 25, 214;6s K. Schlogl and E.Wawersich, Naturmiss., 1954, 41, 38; K. SchIocrl. F. Wesselly,70 R. W. Chambers and F. H. Carpenter, J. Amer. Chem. SOC., 1955, 77, 1527.K. Ohno, -1. Biochem. Japan, 1953, 40, 621.and E. Wawersich, Monatsh., 1954, 85, 957278 ORGANIC CHEMISTRY.and pyridine at 150" into ketones which are liberated on complete hydrolysisof the peptide bonds.71Ph'CH200'C0.NH*FH.CO-ENn. H.CO-),-NH.Cl+C02H IR3'iR, R2H2NNH.CO-NHCH*C0.NHNH, + n H,N*YHCO*NHNH, + W N=CHC02HI 2 1R1 00) R2 08) IRit'+-CO-Y" oT R;CH I -C,O ,N.NH2NH- CO- NH NH-CO0a QOOf the methods of stepwise degradation for the determination of sequence,the route via an amino-alcohol is probably the most promising. It is gener-ally agreed 72 that lithium borohydride is preferable to lithium aluminiumhydride for reduction of the free carboxyl group, and it has been shownthat isomerisation of the p-hydroxy-amide (22) by acid or acid chloride tothe 9-amino-ester (23) is effected in 85-90% yield.73 Reduction of thisester with lithium borohydride gives the amino-alcohol in 8S-90% yieldand a new p-hydroxy-amide (24) which can then be treated with phosphorusoxychloride, so that the series of processes can be repeated.RCO*NHCHR*CO*NH*CHR'*CH2*OH R*CO.NH*CHR'*CO.O~CHXCHR".NH,(22) (23)(24)Biologically Active Peptides.-New methods involving chromatographyon charcoal and zone electrophoresis have been described 74 for the puri-fication of bacitracin A, which is now believed to have the empirical formulaC66H103016N1,S and to contain three isoleucine residues.75, 76 The presenceof alloisoleucine is c~nfirrned,~~ but there is general agreement that theamino-acid sequence of Porath 77 is incorrect and that the sequence (25) morecorrectly represents the structure.78, 79,809 81982 The possibilities cannot beruled out that interaction occurs also between phenylalanine and the terminalisoleucine residue 79 and that the two aspartic acid residues are joined in anunbranched chain.81 It appears probable that, of these two residues, thatRCO*NH*CHR*CH,*OH + HO-CH2*CHR"*NHa71 R.A. Turner and G. Schmerzler, J . Amer. Chem. SOC., 1954, 76, 949.72 W. Grassmann. H. Hormann, and H. Endres, Chem. Bar., 1953, 86, 1477; 1955,88, 102; M. Justisz, D. M. Meyer, and L. Penasse, Bull. SOC.chim. Fvance, 1954, 1087;J. C. Crawhall and D. F. Elliott, Biochem. J., 1955, 61, 264.J. L. Bailey, ibid., 1955, 60, 173.74 J. Porath, Acta Chem. Scand., 1954, 8, 1813.75 L. C. Craig, W. Hausmann, and J. R. Weisiger, J . Amer. Chem. SOC., 1954, 76,7 6 W. Hausmann, J. R. Weisiger, and L. C. Craig, ibid., 1955, 77, 721.77 J. Porath, Nature, 1953, 172, 871.7 8 A. 1. M. Lockhart, G. G. F. Newton, and E. P. Abraham, ibid., 1954, 173, 536.79 A. I. M. Lockhart and E. P. Abraham, Biochem. J., 1954, 58, 633.82 J. R. Weisiger, W. Hausmann, and L. C. Craig, ibid., p. 731.2839.Idem, J . Amer. Chem. SOC., 1954, 76, 2839.W. Hausmann, J R. Weisiger, and L. C . Craig, ibid., 1955, 77, 723BARKER : AMINO-ACIDS, PEPTIDES, AND PROTEINS. 259attached to lysine is L-aspartic acid and is joined to the c-amino-group.83aZZoisoLeucine is believed to be next to the latent cysteine residue, which, assuggested by Newton and Abraham,84 is combined to form a thiazoline ring.This formulation is in agreement with the ultraviolet absorption of theIleu*Cy.Leu*Glu*Ileu.Lys /Phe/Orn*Leu\\+sp-His(25) ASPpeptide and the fact that the yield of the dinitrophenyl derivative of iso-leucine is increased by previous oxidation of the sulphur-containing residuewith performic acid.75Oxytocin and vasopressin continue to receive considerable attentionand, following the full description of the first synthesis of o x y t o ~ i n , ~ ~ a newsynthesis of the hormone has been described 86 which makes use of the samefinal stage as was used by Du Vigneaud's school.The unusual fission withbromine water of a peptide bond in performic acid-oxidised oxytocin, dis-cussed in a previous Report,s7 has been shown not to be connected necessarilywith the bromination of tyrosine, since this can be achieved without cleavageof the peptide bond by using glacial acetic acid or dilute hydrobromic acidas solvent. 88 Nevertheless, prevention of bromination by conversion of thephenolic group of tyrosine into the dinitrophenyl ether renders the peptidebond stable towards bromine water.Full details of the determination of the sequence of amino-acids inarginine-vasopressin have now been published, 89 and, by similar methods tothose used for lysine-vasopressin, a synthetic polypeptide has been obtainedhaving the same relative pressor, antidiuretic, and avian vasopressoractivities as arginine-vas~pressin.~OVarious improvements in the preparation of hypertensin (angiotonin)have been introdu~ed,~~ and it has been demonstrated that treatment ofplasma with renin at 0" is advisable since, under these conditions, hyper-tensinase is inactive, whereas the renin activity remains.The purifiedpeptide shows the presence of only one active pressor principle after onehundred transfers in a counter-current apparatus. It contains the followingamino-acids in the molecular proportions indicated : aspartic acid (2),serine (l), glutamic acid (l), proline (2), glycine (l), alanine (l), valine (l),isolepcine (1), tyrosine (1), phenylalanine (1) , leucine (2), histidine (2), lysine(l), and arginine (2).Fission of the peptide by hydrazine indicates thateither leucine or isoleucine is the C-terminal residue, and examination of theA. I. M. Lockhart and E. P. Abraham, Biochem. J., 1954, 58, xlvii.84 G. G. F. Newton and E. P. Abraham, ibid., 1963, S3, 604.V. Du Vigneaud, C. Ressler, J. M. Swan, C. W. Roberts, and P. G. Katsoyannis,86 R. A. Boissonnas, S. Guttmann, P. A. Jaquenoud, and J. P. Waller, HeZv. Chim.87 Ann. Reports, 1953, 50, 269.J . Amer. Chem. SOC., 1954, 76, 3115.Acta, 1955, 38, 1491.C. Ressler and V. Du Vigneaud, J . Biol. Chem., 1954, 211, 809.E. A. Popenoe and V. Du Vigneaud, ibid., 1954, 206, 353; R. Archer and J.Chauvet, Biochim. Biophys. Acta, 1954, 14, 421.V.DU Vigneaud, D. T. Gish, and P. G. Katsoyannis, J. Amev. Chem. SOC., 1954,76, 4751.s1 L. C. Clark, C. Winkler, F. Gollan, and R. P. Fox, J . Biol. Chem., 1954, 206,717; A. A. Green and F. M. Bumpus, ibid., 1954. 210. 281280 ORGANIC CHEMISTRY.dinitrophenyl derivative shows aspaxtic acid as the only N-terminal group.The last fact supports the claim for the homogeneity of the preparation.02The complete sequence of amino-acids in P-corticotropin has beenThe order of most of the residues is also known for cortico-tropin-AJM and the N-terminal sequence has been confirmed by synthesis ofthe pentapeptide produced by peptic digestion.95 It appears that the onlypossible difference between corticotropin-A and p-corticotropin is in thesequence of seven residues, the positions of which are uncertain in theformer peptide ; also corticotropin-A probably contains no amide groupsP6a-Corticotropin has the same terminal tripeptide sequence as corticotropin-Abut differs from it in arnino-acid content and partition b e h a v i ~ u r .~ ~Synthetic Peptides-An excellent survey of the methods of peptidesynthesis has appearedg8 and only more recent developments will be dis-cussed. A thorough examination of the use of N-substituted amides ofphosphorous and phosphoric acids has been made.99 An unusual rearrange-ment of compounds such as the perchlorate of O-glycylsalicylamide (26) tosalicylglycine amide (27) affords a route for the synthesis of peptides asindicated, 100%*C H;NH,,HClO, -+ ao;NH-CHjC0.NH2 LCO-NY co(2 6) (21)In addition to the use of the benzyl residue for protecting the amino-group during peptide synthesisJlOl the triphenylmethyl residue has beenrecommended102 since it is readily removed with aqueous acetic acid.AO 2 F. M. Bumpus, A. A. Green, and I. H. Page, J . Biol. Chew., 1964, 210, 287.O3 K. S. Howard, R. G. Shepherd, E. A. Eigner, D. S. Davies, and P. H. Bell, J .W. F. White and W. A. Landmann, ibid., p. 771.96 K. Hofmann and A. Johl, ibid., p. 2914.O6 W. F. White and W. A. Landmann, ibid., p. 1711.97 J. I. Harris and C. H. Li, J . Biol. Chem., 1955, 213, 499.98 T. Wieland, Angew. Chem., 1954, 66, 507.OD S . Goldschmidt and F. Obermeier, Annalen, 1954, 588, 24.loo M. Brenner, J. P. Zimmermann, J. Wehrmiiller, P.Quitt, and I. Photaki, Ex-lol L. Velluz, J. Anatol, and G. Amiard, Bull. SOC. chim. France, 1954, 1449; L.l o 2 G. Amiard, R. Heymbs, and L. Velluz, ibid., p. 191.Amer. Chem. SOL, 1955, 77, 3419.perientia, 1955, 11, 397.Velluz, G. Amiard, and R. HeymBs, ibid., 1955, 201BARKER : AMINO-ACIDS, PEPTIDES, AND PROTEINS. 281further method of somewhat limited application is the use of the benzoyl-L-phenylalanyl residue which is removed by the action of chymotrypsin.103It has been found that reduction of the benzyloxyimino-group, first sug-gested by Weaver and Hartung,l@ in ammoniacal solution favours the form-ation of peptides and avoids the production of diketopiperazines.lo5 TheN-trifluoroacetyl residue as a protecting group 106 has found further applic-ation,l07 and an important new route to the synthesis of trifluoroacetamido-acids has been introduced.lo8 This involves transacylation between theamino-acid and ethyl trifluorot hiolacetate :The trifluoroacetylglycine was converted by the phenyl thiol ester methodof Wieland and his co-workers log into a dipeptide, and the protective groupwas readily removed at a pH above 10.No racemisation was observedduring the above processes. It has been reported that P-nitrophenyl estersare more satisfactory for peptide synthesis.110 A new method of forming thepeptide bond has been developed simultaneously in two laboratories, usingdicycZohexylcarbodi-imide.lll The method is not sensitive to moisture, incontrast to those using mixed anhydrides, and the dicyclohexylurea which isformed as a by-product is readily removed.CF,CO*SEt + NR,*CH,*CO,H + EtSH + CF,*CO*NH*CH,CO,HRC0,H + H,N*R + C6H,,*N:C:NC6H11 + R-CO-NH-R' + C,H,,*NH*CO~NH*C,H,,Space does not permit discussion of all the syntheses of polyamino-acidswhich have been described in the past two years.The method using the'' Leuchs anhydride " as monomer has been applied to the synthesis ofpolymers containing various side chains such as poly-(S-allylcysteine) ,112polytryptophan,l13 and poly-P-aminophenyl-~~-danine.~~~ By initiationof the polymerisation with polylysine, cross-linked polymers have been0btained.11~ Termination of the polymerisation of " Leuchs anhydrides "may take place as shown, since it has been found that ureido end-groups arepresent : 116CO*CHRCO*NHX.[COCHR-NH],,,-H + o< I -X.[CO*CHR*NH],* CO*NH-CHR*CO,HA polyglutamic acid has also been obtained by this method using y-benzylL-glutamate as monomer, the benzyl groups being removed with phosphon-lo3 R. W. Holley, J . Amer. Chem. SOC., 1955, 77, 2552.Io4 W. E. Weaver and W. H. Hartung, J . Org. Chem., 1950, 15, 741.lo5 W. H. Hartung, D. N. Kramer, and G. P. Hager, J . Amer. Chenz. Sot., 1954,76,2261.lo6 F. Weygand and E. Csendes, Angew. Chem., 1952, 64, 136.lo' F. Weygand and E. Leising, Chem. Ber., 1954, 87, 248; F. Weygand andlo8 E. Schallenberg and M. Calvin, J . Amer. Chem. Sot., 1955, 77, 2779.loo T. Wieland, W, Schafer, and E. Bokelmann, Annalen, 1951, 573, 99.110 J. A. Farrington, G.W. Kenner, and J. M. Turner, Chem. and Ind., 1955, 601.111 J. C. Sheehan and G. P. Hess, J . Amer. Chem. Sot., 1955, 77, 1067; H. G.112 M. Frankel and A. Zilkha, Nature, 1955, 175, 1045.114 M. Sela and E. Katchalski, ibid., p. 129.115 Idem, Experientia, 1955, 111, 62.116 M. Sela and A. Berger, J . Amer. Chem. SOC., 1955, 77, 1893.M. Reiher, ibid., 1955, 88, 26.Khorana, Chem. and Ind., 1955, 1087.A. Patchornik, M. Sela, and E. Katchalski, J . Amer. Chem. Soc., 1954, 76, 299282 ORGANIC CHEMISTRY.ium iodide.11’ It has been shown that removal of ester groups from methylpoly-a-glutamate with O*S~-sodium hydroxide in the presence of freshlyprecipitated copper hydroxide produces no racemisation. 118 Synthesis ofa y-linked polyglutamic acid 7)ia a dipeptide ester gave a product whichresembled a natural bacterial polyglutamic acid and differed from poly-a-glutamic acid in solubility, in giving a strongly positive ninhydrin reaction,in titration constant, and in infrared spectrum.llg A mixed ay-polyglutamicacid has also been obtained by polymerisation of an ay-dipeptide ester,followed by hydrolysis of ester residues.120 Among other studies of peptideester polymerisation, it is important to notice that di- and tri-peptide esterspolymerise more readily than higher members of the series.121 It was alsoshown that azides polymerise in aqueous solution to give polyamino-acidsof high molecular weight.On the other hand, the azide of triglycine hasbeen converted into a cyclic peptide 122 which it is now agreed 123 is a cyclichexaglycine identical with a product obtained by the *I Leuchs anhydride ”method.l= Other monomers which have been used include N-phenylthio-carbonyl derivatives 125 and acyl chlorides,126 the latter being particularlyuseful for the polymerisation of p-amino-acids. Synthetic polypeptidescontaining more than one type of functional group have been prepared bythe I ‘ Leuchs anhydride ” method,12’ and also by ester condensation.lZ8Finally, an interesting approach to the production of polyamino-acids isexemplified by the formation of a polyphenylalanine by introducing func-tional groups into a styrene p01ymer.l~~Isolation and Purification of Proteins.-It has been found 130 that, bycareful attention to conditions such as pH, some of the older protein pre-cipitants such as metallic tungstates, sulphosalicylic acid, and metaphos-phates can be used with advantage for the fractionation of serum proteins.On the other hand, precipitation of serum proteins by acids is complete onlyon heating.131 A very simple method has been described for carrying outpreliminary experiments as a guide in devising suitable techniques for theresolution of mixtures of proteins : 132 the solution containing the mixtureof proteins is diluted to enable its optical density to be measured in theultraviolet spectrometer ; pH and ionic strength are varied and the increasein optical density due to the development of turbidity is observed ; then thedecrease in soluble protein is indicated by measurement of the optical density11’ E.R. Blout, R. H. Karlson, P. Doty, and B. Hargitay, J . Amer. Chem. SOC.,1954, 76, 4492.11* V. Bruckner, K. KovBcs, J. KovQcs, and A. Kotai, Experientia, 1954, 10, 166.119 S. G. Waley, J., 1955, 517.120 V. Bruckner, M. Szckerke, and J. KOVBCS, Naturmiss., 1955, 42, 179.121 H. N. Rydon and P. W. G. Smith, J., 1955, 2542.lZ2 J. C. Sheehan and W. L. Richardson, J . Anzer. Chem. Soc., 1954, 76, 6329.123 J. C. Sheehan, M. Goodman, and W. L. Richardson, ibid., 1955, 77, 6391.lZ4 D. G. H. Ballad, C. H. Bamford, and F. J . Weymouth, Proc. Roy. Soc., 1955,A , 227, 155; C. H. Bamford and F. J. Weymouth, J . Amer. Chein. SOC., 1955, 77, 6368.126 J. Noguchi and T. Hayakawa, ibid., 1954, 76, 2846.126 M. Frankel, Y. Liwschitz, and 2. Zilkha, ibid., p. 2814.12’ B. G. Overell and V. Petrow, J., 1955, 232; F. Micheel and C. Berding, Chem.12* K. Schlogl and H. Fabitschowitz, Monalsh., 1955, 86, 233.129 Idem, ibid., 1954, 85, 1223.13a E. L. Hess and D. S. Yasnoff, J. Amer. Chem. SOC., 1954, 76, 931.Ber., 1955, 88, 1062.T. Astrup, A. Birch-Andersen, and K. Schilling, Acta Chem. Scand., 1954, 8, 901.K. Simon, Experientia, 1954, 10, 506BARKER AMINO-ACIDS, PEPTIDES, AND PROTEINS. 283of the supernatant liquid after centrifugation. It has been pointed out thatunexpected results may be obtained in the solubility test for homogeneityowing to what appears to be an isomorphic transformation in the solidphase.l= Fractional separation from concentrated aqueous solution has beenused for the purification of clupein, and the purified material had only proline asend-group. In a development of previous work, blood-clotting factors andserum proteins have been purified by chromatography on diatomaceous earths,different commercial specimens of which vary in adsorptive capacity.135The two chains of performic acid-oxidised insulin have been separatedand isolated with a recovery of 95% by counter-current di~tributi0n.l~~Although the phenylalanyl chain was not separated from unoxidised insulin,the recovery is much better than that originally obtained by solvent pre-cipitation. The isolated peptides may also be purified by partition chromato-g r a p h ~ . ~ ~ ' Chromatographic separation of the A and the B chain of reducedinsulin has also been reported.13* By careful choice of a critical pair ofphases, a direct separation of y-globulin and albumin can be obtained.13g Anoutstanding success has been achieved by using partition chromatography,in that y-globulin from immune rabbits has been partially separated intoinert globulin and antibody.140The separation of neutral proteins by chromatography on IRC-50 resinis well established. Closely related carbon monoxide hzemoglobins havebeen separated by this means and it has been shown that the eluted proteinsare unaltered and can be readily crystallised.141 Ion-exchange chromato-graphy of acidic proteins presents some difficulties since IRC-50 adsorbsthese too strongly and basic polystyrene resins such as Dowex-50 are un-suitable because of the physical form of the polymer. However, kieselguhrcoated with a cross-linked polystyrene resin has been used with su~cess.1~~Electrophoresis continues to be used very largely for the separation ofproteins, and the subject has been reviewed by T i ~ e l i u s . l ~ ~Structure of Proteins.-As indicated in a previous Report,87 the twooutstanding problems concerning the structure of insulin involve the positionsof the amide and the disulphide residue. It appears possible, however,from a study of optical rotations, that the structure of insulin itself may bedifferent from those present in the derived A and B peptides.la Thepositions of the amide groups have been determined by estimating therelative ionophoretic mobilities and amide contents of peptides obtainedfrom enzymic digests of A and B fractions of oxidised in~u1in.l~~ The diffi-culty introduced by the occurrence of disulphide-interchange reactions 146133 0. Smithies, Biochem. J., 1954, 58, 31,134 E. Waldschmidt-Leitz and R. Voh, 2. physiol. Chem., 1954, 298, 257.136 J. H. Milstone, J . Gen. Physiol., 1955, 38, 743.138 J. G. Pierce, J . Amer. Chem. SOC., 1955, 77, 184.13' W. Andersen, Actu Chem. Scund., 1954, 8, 359.13* H. Lindley, J . Amer. Chem. SOC., 1955, 77, 4927.139 P. von Tavel, HeZv. Chim. Actu, 1955, 38, 520.140 R. R. Porter, Biochem. J., 1955, 59, 405.141 N. K. Boardman and S. M. Partridge, Biochem. J . , 1955, 59, 543.142 N. K. Boardman, Biochim. BioFhys. Actu, 1955, 18, 290.143 A. Tiselius, Angew. Chem., 1955, 67, 245.144 K. Linderstrnm-Lang and J. A. Schellman, Biochim. Bio9hys. Actu, 1954,15, 156.145 F. Sanger, E. 0. I?. Thompson, and R. Kitai, Biochem. J., 1955, 59, 509.146 F. Sanger, Nature, 1953, 171, 1025; A. P. Ryle and F. Sanger, Biochem. J., 1955,60, 535284 ORGANIC CHEMISTRY.has been overcome by digesting insulin with chymotrypsin and oxidising thepeptides formed, and by this means the disulphide linkages have beenlocated. 14' Disulphide cross-linkages have been studied also in connectionwith other proteins. For instance, it has been shown that the reductionof disulphide groups in wheat gluten is accompanied by loss of elasticity andcohesion.148 However, in wool, the susceptibility of cystine linkages toreduction is governed by their accessibility to the reagent.149 A disulphidedimer of human mercaptalbumen has been produced by oxidation withiodine of the mercury dimer.150 Other types of interchain links are presentin collagen, and a direct correlation has been found between intermolecularcohesion in the protein and its hydroxyproline ~ 0 n t e n t . l ~ ~ It is believedthat linkages occur between hydroxyl and keto-imide g r 0 ~ p s . l ~ ~ There hasbeen considerable disagreement as to the nature of the units in the collagenmolecule, but it is now claimed that they are rigid, rod-shaped particles offairly uniform size.153Several studies have been made concerning the nature of the linkages inconjugated proteins. For instance, pepsin and ovalbumen have beendegraded to peptides to which the original phosphate residue of the proteinis still attached by esterification.l= Similarly, fibrinogen has yielded apeptide containing tyrosine O-sulphate 155 and cytochrome c has beendegraded by peptic digestion to a hzmopeptide, the configuration of whichhas been discussed.158 The present state of knowledge of the configurationof a number of proteins has been reviewed.15'G. R. B.147 A. P. Ryle, F. Sanger, L. F. Smith, and R. Kitai, Biockem. J . 1955, 60, 541.148 R. H. de Deken and M . De Deken-Grenson, Biochim. Biophys. Acta, 1955, 16,149 A. J. Farnworth, Biochem. J., 1955, 60, 626.160 R. Straessle, J . Amer. Chem. SOC., 1954, 76, 3138.161 K. H. Gustavson, Acta Chem. Scand., 1954, 8, 1298.162 Idem, ibid., 1299.lti5 H. Boedtker and P. Doty, J . Amer. Chem. SOC., 1955, 77, 248.M. Flavin, J . Biol. Chem., 2954, 210, 771.ls6 F. R. Bettelheim, J . Amer. Chem. SOC., 1954, 76, 2838.166 A. Ehrenberg and H. Theorell, Nature, 1955, 175, 158.lS7 J. T. Edsall, J . Polymer Sci., 1954, 12, 253.566