摘要:

Studies on the acid-, base-, and enzyme-catalyzed isomerizations of several variously C-17 substituted Δ5-3-ketosteroids have indicated micellar aggregation of relatively non polar substrates in the dilute aqueous methanol assay solvent to be an important consideration when evaluating specificity data. Further evidence that the isomerase is sensitive to the presence of 17α-substituents in its substrates has been obtained and the probability that tyrosine is the acid catalytic group at the active center is discussed.

ISSN:0008-4042    

DOI:10.1139/v68-241

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Synthetic work leading to the preparation of todomatuic acids (2a), juvabiones (2b), andar-(±)-juvabione (8d) and the successful conversion ofar-(+)-turmerone (9) toar-(+)-juvabione (3b) is presented. The synthetic compounds2band3bexhibit juvenile hormone activity.

ISSN:0008-4042    

DOI:10.1139/v68-242

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Benzil has been irradiated in cyclohexane solution. The principal products are: benzoic acid; benzal-dehyde; phenyl cyclohexyl ketone; benzoin; benzoin benzoate; a compound tentatively identified as desyl benzoyloxydesyl ether; another compound not yet identified; and approximately one-third of the reacted benzil that was not accounted for. A small amount of unsaturation is also found. As long as there is enough benzil present (presumably to absorb all of the light) the benzil disappearance is linear with time. All products appear at the shortest times checked and so cannot be secondary products. If one neglects the benzoic acid approximately 19% of the benzoyl groups that react do so in the form of benzoyl radicals. No evidence for phenyl radical formation was found. The upper limit for the quantum yield of benzil disappearance at 366 mμ is 0.25. The benzoic acid does not arise directly during the photolysis but only when the solution is exposed to oxygen during the work-up. Preliminary experiments in cumene solution have shown that the amount of benzil lost for the same length of irradiation increases by a factor of about 1.5. In 2-propanol solution the increase is by a factor of 2.5. When 2-propanol is the solvent, a new product appears which is most probably the dimer of the ketyl radical which is formed when an excited benzil abstracts a hydrogen atom. This product is very unstable.

ISSN:0008-4042    

DOI:10.1139/v68-243

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The signal assignments for the protons of the epoxide ring in several 3,4-epoxy-2-alkoxytetrahydropyrans have been made by spin decoupling. Because of the close resemblance of these tetrahydropyrans to 2,3-anhydroglycopyranosides, these results have been used to make chemical shift assignments for the H-2 and H-3 protons of the latter compounds. For the compounds examined, the H-2 proton signal occurs at higher field compared to the position of the H-3 proton signal.

ISSN:0008-4042    

DOI:10.1139/v68-244

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A study has been made of the fragmentation upon electron impact of monomethylquinolines, di-methylquinolines, monoethylquinolines, and monopropylquinolines. Deuterium labelled analogues of some of the alkylquinolines have been prepared and their fragmentation studied to gain insight into the mechanism of fragmentation. The fragmentation of the alkylquinolines is closely analogous to that of alkylbenzenes. Rearrangement of the molecular ion appears to precede the fragmentation process in many of the compounds studied. The fragmentation of 2- and 8-ethyl- andn-propylquinolines are influenced by the proximity of their alkyl side chains to the nitrogen atom.

ISSN:0008-4042    

DOI:10.1139/v68-245

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The mass spectra of 1,2,3,4-tetrahydroquinoline and 5,6,7,8-tetrahydroquinoline have been recorded. The spectra of the 1-d1, 2,2-d2, 3,3-d2, and 4,4-d2analogues of 1,2,3,4-tetrahydroquinoline, and the spectra of the 5-d1, 6,6-d2, and 8,8-d2analogues of 5,6,7,8-tetrahydroquinoline have aided in the interpretation of the fragmentation mechanisms. The spectra of both isomers are characterized by fragment ions at M–1, M–15, and M–16 while the 5,6,7,8-isomer has an additional peak at M–28. The spectra of 2-, 3-, 4-, and 6-methyl-1,2,3,4-tetrahydroquinolines have also been examined. Substitution of a hydrogen by a methyl group in the 2- and 4-positions results in an intense M–15 peak, and substitution in the 3-position results in a peak at M–29. The main features of these spectra can be predicted from the proposed fragmentation pathways of the parent tetrahydroquinoline.

ISSN:0008-4042    

DOI:10.1139/v68-246

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

epi-Progoitrin, the major thioglucoside ofCrambeabyssinicaseed, is cleaved by ferrous salts to yield (S)-1-cyano-2-hydroxy-3-butene and (S)-3-hydroxypent-4-enethionamide. The products are the same whether obtained from the purified thioglucoside or from the seed meal. Identical behavior was observed for seed meal ofBrassicanapus, which gave corresponding derivatives of the opposite configuration. Optical rotatory dispersion and proton magnetic resonance studies suggest the existence of solvent-dependent differences in rotamer composition for the 3-hydroxypent-4-enethionamides.

ISSN:0008-4042    

DOI:10.1139/v68-247

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The form and crystal structure of the fibers attached to the diatomThalassiosirafluviatiliswere studied by the electron microscope andx-ray diffraction.These fibers, which were shown previously to be pure, highly crystalline β-(1 → 4) linked poly-N-acetyl-D-glucosamine (chitan), are strap-like in cross section, 1000–2000 Å in width at their widest point close to the base, from which they taper uniformly to a very small tip at their outer extremity. Three connected filaments or microfibrils form the fiber at its widest point.The unit cell of chitan is monoclinic with the space groupP21. The parameters of the unit cell area = 4.80,b = 10.32,c = 9.83 Å, and β = 112°. The density of the chitan fibers is 1.495 g/cm3. There is only one polymeric chain per unit cell with a two-fold screw axis and therefore the chains are parallel to each other. A three-dimensional structure is proposed for chitan which is reasonable from stereochemical considerations and which is in good agreement with all observedx-ray diffraction data.

ISSN:0008-4042    

DOI:10.1139/v68-248

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Esters and hydrocarbons, containing 14 and 15 carbon atoms, are converted to the hydroxy fatty acid portions of glycosides byTorulopsisapicolain yields of 10–20%. When C-15 compounds are fermented, almost half of the hydroxy acids which are produced are 16-hydroxy C-17 acids. The carbon chain of the substrate is first lengthened by two carbon atoms and then hydroxylated. Direct hydroxylation also occurs, to a lesser extent, giving both 14-hydroxy- and 15-hydroxypentadecanoic acids. Similar results are obtained when C-14 compounds are used. Lengthening of the chain followed by hydroxylation gives rise to hydroxy C-16 acids and direct hydroxylation produces 13-hydroxy- and 14-hydroxytetradecanoic acids. Primary and secondary C-14 and C-15 alcohols were also isolated from the products of hydrocarbon fermentation (2.5–5 % yield). Methyl palmitoleate is converted to hydroxy fatty acids in yields of 40–70%, the major component of which is 16-hydroxy-cis-9-hexadecenoic acid.

ISSN:0008-4042    

DOI:10.1139/v68-249

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The deamination of 16-acetyl-17-aminoandrosta-5,16-dien-3β-ol(2a) with nitrous acid afforded two products. Their structures have been established as3aand3b.

ISSN:0008-4042    

DOI:10.1139/v68-250

出版商:NRC Research Press    

年代:1968

数据来源: NRC