摘要:

SECTION C Organic Chemistry Reactions of A7-Steroids. Part 111.l Conformational Transmission Effects in the Methylation of 5p-Cholest-7-en-3-one By Peter Morand," J. M . Lyall, and H. Stollar, Department of Chemistry, Universityof Ottawa, Ottawa, Canada M et h y I ati o n of 5 p - c h o I es t - 7 -en - 3 - o n e y i e I ds 2 p- met h y I - 5 p- c h o I e st - 7 -en - 3 -one and 2,2 - d i met h y I - 5 p - c h o I es t- 7-en-3-one. The structure of the former was proven by its conversion into the known 2p-methyl-5p-cholestan- %one; the structure of the latter was established from the mass spectrum of its ethylene acetal. Use i s made of Bucourt's rules of dihedral angle changes in describing the conformational transmission effects which may account for methylation a t C-2 rather than a t C-4.THE term ' conformational transmission ' was introduced by Barton when he reported2 the results of studies on the base-catalysed aldol condensation of benzaldehyde with a wide range of variously substituted 3-oxo- triterpenes, steroids, and decalins to give benzylidene derivatives. He found that the rate of condensation varied widely and was markedly influenced by the presence of unsaturated substituents at positions in the molecules remote from the reaction site. In the various steroid series examined it was found that the effect of any one substituent was consistent. For example, a 7,8-double bond always diminished the condensation rate compared with that in the case of the analogous saturated compound, and a 6,7-double bond increased the rate. With the aid of molecular models, Robinson and Whalley3 were able to account in a semiquantitative manner for the way in which conform- ational deformations caused by unsaturated substituents in the steroid molecule are transmitted to ring A.The mechanism 4 9 5 for the base-catalysed methylation of ketones may be represented as in the Scheme. Since the first step is the formation of an enolate anion, as is also the case in formation of a benzylidene derivative we expected that the alkylation of 3-oxo-steroids would be subject to conformational transmission effects similar to those which Barton detected in his benzalde- hyde condensation reactions. This seems to be the case. For example, whereas methylation of 5~-choles- tan-3-one gives the 2-methyl derivative, 5P-cholestan- 3-one gives the 4-methyl derivative.6 The presence of a 7,s-double bond in 5a-cholest-7-en-3-one causes methyl- Part 11, €'.Morand, M. Flett, J. M. Lyall, and s. StavriC, Steroids, 1966, 8, 679. 2 (a) D. H. R. Barton, A. J. Head, and P. J. May, J . Chem. SOC., 1957, 935; (b) D. H. R. BaFton, in ' Kekul6 Symposium on Theoretical Organic Chemistry, Butterworths, London, 1958. p. 127; (G) D. H. R. Barton, F. McCapra, P. J. May, and F. Thudium, J . Chem. SOC., 1960, 1297. 3 M. J . T. Robinson and W. B. Whalley, Tetrahedron, 1963, 19, 3123. 4 E. S. Gonld, 'Mechanism and Structure in Organic Chemistry,' Holt, Reinhart, and Winston, New York, 1959, p. 373. ation7Bs to occur at C-4 whereas the C-2 methyl com- pound is formed from 5x-cholest-6-en-3-one.In contrast to the benzaldehyde condensation reac- tion,2 which results in the exclusive formation of the L 4 J p- 0 II =CH-C- + C H j X ? -CH-C- + X' a SCHEME C-2 benzylidene product, the methylation of 3-0x0- steriods gives the 2-methyl or the 4-methyl product, depending on the structure of the starting ketone. The difference may be explained by the fact that the carbon- carbon bond formation step in the benzaldehyde con- densation reaction is reversible 2c and the reaction can therefore equilibrate towards the more stable C-2 product even in compounds where enolisation is pre- ferentially towards C-4. In this reaction, the rate of formation of 2-benzylidene product reflects the direction of preferred enolisation. In the methylation reaction, the carbon-carbon bond formation step is irreversible and the position of the methyl group in the product reflects the direction of preferential enolisation in the reactant.In an earlier study it was shown1° that, in J. M. Conia, Rec. Cltem. Prop., 1963, 24, 43. Y. Mazur and F. Sondheimer. J . Amer. Chem. SOC., 1958, W. W. Wells and D. H. Neiderhiser, J . Amer. Chem. SOC., * Y. Mazur and F. Sondheimer, J . Anzer. Chewi. SOC., 1958, F. Sondheimer, Y. Kilbansky, Y. 31. Y . Haddad, G. H. R. lo I?. Morand, S. StavriC, and D. Godin, Tetvahedron Letters, 80, 5220. 1957, 79, 6569. 80, 6296. Summers. and W. Klyne, J . Chenz. SOC., 1961, 767. 1966, 49.2118 J. Chem. SOC. (C), 1970 keeping with the foregoing considerations, the f ormyl- ation of 5a-cholest-7-en-3-one occurred exclusively a t C-2 and not at C-4 as had been reported previously.ll In the methylation reaction in the cholestan-3-one series two different structural features apparently have the same effect in directing the site of methylation.The presence of either a 5P-hydrogen atom or a 7,Sdouble bond causes methylation to occur at C-4 whereas in the 5a-saturated compound, methylation occurs at C-2. We have therefore synthesised a compound in which both of these C-4 directing structural features are present, namely 5p-cholest-7-en-3-one (111), and methylated it in order to determine whether these two structural features exert parallel effects in such a system. 5p-Cholest-7-en-S-one (111) was synthesised in two steps from the commercially available cholesta-5,7- dien-313-01 (7-dehydrocholesterol) (I).Oppenauer oxidation of the latter l2 gave the known cholesta-4,7- dien-3-one (11) which was catalytically hydrogenated over palladium-charcoal by the procedure 1 3 9 l4 used for the hydrogenation of cholest-4-en-3-one to 5p-cholestan- %one. The desired 5p-cholest-7-en-3-one (111) was obtained in about 50% yield by chromatography of the crude hydrogenation product on silica gel with a large ratio of adsorbent to product (750 : 1 w/w), but none of the corresponding 5a-isomer l5 was isolated owing to incomplete separation. Evidence for structure (111) was as follows. The molecular weight was confirmed by the appearance of a l1 J. Pudles and K. Bloch, J . Riol. Chem., 1960, 235, 3417. l2 C. F. Cohen, S. J. Louloudes, and M. J. Thompson, Steroids, 13 H.Grasshof, 2. physiol. Chem., 1934, 249, 223. 14 E. W. Warnhoff and P. NaNonggi, J . Org. Chem., 1962, 15 J. Gardine and E. F. McQuillin, Chem. Comur., 1969, 503. 16 L. Fieser and M. Fieser, ' Steroids,' Reinhold, New York, 17 C. Djerassi and W. Clossen, J . Aynzr. Chenz. Soc., 1956, 1967, 9, 591. 27, 1186. 1959, pp. 273, 352. 78, 3761. molecular ion at m/e 384 in the mass spectrum. The i.r. spectrum indicated the presence of a carbonyl group (1715 cm.-l) and a double bond (1665 cm.-l); the presence of the latter was confirmed by a broad n.m.r. peaklo at 6 5.13 p.p.m. An 8,14-double bond, which might have been formed during the hydrogenation,16 would show no olefinic proton absorption in the n.m.r. spectrum since it would be tetrasubstituted. The 5p-stereochemistry of the ketone (111) was confirmed by a negative Cotton effect l7%l8 in the 0.r.d.curve. The procedure of Mazur and Sondheimers was used for the methylation of 5p-cholest-7-en-3-one (111). Two products were isolated by chromatography on alumina, a more mobile one obtained as an oil (V) in 25% yield, and a less mobile crystalline product (VI) obtained in 53% yield (based on starting material consumed). A mass spectrum of the oily product showed a molecular ion a t m/e 412, indicating that it was a dimethyl derivative. The i.r. spectrum had a carbonyl absorption a t 1700 cm.-l, 15 crn.-l to lower frequency than that of the unmethylated compound, which is consistent with the presence of a gem-dimethyl ketonee6 The 7,s-double bond was unaffected by the methylation reaction as shown by a broad signal a t 6 5.18 p.p.m. in the n.m.r.spectrum. The mass spectra of the ethylene acetals of unsub- stituted 3-oxo-steroids show three main peaks, at m/e 99, 112, and 125, and a considerable amount of evidence supports the postulated origin 19s2* of these peaks. The mass spectrum of the ethylene acetal of the dimethylated compound (V) revealed relative abundances of 60 and 31% a t m/e 112 and 125 respectively and of 39% a t m/e 99 which is compatible only with a 2,2-dimethyl structure, In a 2,4-dimethyl compound, peaks resulting from cleavage of the 2,3-bond (B split) would appear at m/e 113, 126, and 139, whereas cleavage of the 3,4-bond (A split) would show a peak at m/e 113. Such peaks are of very low intensity in the mass spectrum of the dimethyl ketone (V).In a 4,4- dimethyl structure, the B split would be suppressed and peaks a t m/e 112 and 125 would not be significant, whereas the A split would be enhanced, resulting in a very strong peak a t m/e 99. This is not the case with the ethylene acetal of (V) and, therefore, the structure must be as formulated. The mass spectrum of the crystalline product obtained from the methylation of the ketone (111) showed a molecular ion a t m/e 398, indicating the presence of a monomethyl derivative. The carbonyl and 7,8-double bond functions were intact, as indicated by the i.r. absorption a t 1710 cm.-l and a broad n.m.r. peak at S 5.11 p.p.m. respectively. In view of the work of l8 C. Djerassi and W. Klyne, J . Chem. SOC., 1962, 4920. l9 (a) H.Audier, J. Bottin, A. Diara, M. Fetizon, P. Foy, M. Golfier, and W. Vettcr, Bull. SOG. chim. Fyance, 1964, 2292; ( b ) H. Budzikiewicz, C. Djerassi, and D. H. Williams, ' Structure Elucidation of Natural Mass Spectrornctry,' Holden-Day, San Francisco, 1964, pp. 26 et seq. 2o 2. Pelah, D. H. Williams, H. Budzikiewicz, and C. Djerassi, J . Aynev. Chem. SOC., 1964, 86, 3722.Org. 2119 Beton and his co-workers 21 it is reasonable to assume that the methyl group is in the equatorial position. A mass spectrum of the ethylene acetal of the mono- methyl product showed small peaks at m/e 99, 112, and 113. The m/e 99 peak may be accounted for as arising from either a 3,4-bond cleavage (A split) in a 4-sub- stituted compound or a 2,3-bond cleavage (B split) in a 2-substituted compound.The peak at m/e 113 may be considered the result of either an A split in a 2- substituted compound or a B split in a 4-substituted compound. The peak a t m/e 112 (11%) could only arise from a B split in a 2-substituted compound. However, the low intensity of this peak does not allow the methyl group to be assigned to the 2-position with certainty. We thus had a compound which did not undergo the usual fragmentations associated with the ethylene acetals of 2- or 4-methyl-3-oxo-steroids. This anomalous fragmentation pattern is most likely due to the presence of the 7,8-double bond. Among the three secondary fragmentations, 01 (5,6-bond), P (6,7-bond), or y (7,8-bond) associated with the B split, the y fragmentation is the most favoured19s20 in the saturated ethylene acetals of steroidal C-3 ketones.It follows that any structural feature (such as a 7,8-double bond) which may prevent the y fragmentation will thereby suppress the B split since the most favoured pathway of the B split will be blocked. Furthermore, a C-2 methyl group suppresses the A split. Thus, in the ethylene acetal of the monomethyl ketone both the A and B splits are suppressed; this accounts for the low intensities observed for the characteristic peaks at m/e 99, 112, and 113 which makes a mass spectral interpretation of the methylation site uncertain.* Since all the usual spectroscopic methods had been used without success (including o.r.d., about which more will be said later), we had to resort to a chemical proof for the structure of the monomethyl product (VI).Catalytic hydrogenation of the monomethyl ketone (VI) according to the procedure of Pudles and Blochll gave a mixture of saturated alcohols which was sub- sequently oxidised to give 2P-methyl-5e-cholestan-3-0ne.~ The mass spectrum of the ethylene acetal of this coinpound, as expected, showed an intense peak at m/e 125 and a weak one at m/e 112, both of which are compatible only with a 2-methyl structure. The octant rule, applied to 5a-3-oxo-steroids 22 predicts that a bulky substituent such as a methyl group in the axial position at C-2 will cause the Cotton effect to become more positive while one a t C-4 will * In the case of the ethylene acetal of the 2,2-dimethyl derivative (V) the A split is not possible1@# 20 and therefore all the characteristic peaks must arise from the B split.The presence of the peak at m/e 125 ( y split) may be explained by assuming that 7.8-double bond is shifted to another position, possibly to 8,14 thereby allowing the y split to occur. The relative abundance resulting from this y split is half that of the fl split, which indicates that the former is not favourable and probably occurs only because the A split is entirely suppressed. 21 J. L. Beton, T. G. Halsall, E. R. H. Jones, and P. C. Phillips, J . Chem. Soc., 1957, 753. make the Cotton effect more negative with respect to that of the unsubstituted ketone. For 5P-steroids the octant rule predictions will be reversed. The 0.r.d. spectrum of 2,2-dimethyl-5p-cholest-7-en-3-one (V) has a molecular amplitude 11" more negative than the value for S@-cholest-7-en-3-one (111) , which is consistent with the octant rule prediction.However, in the case of the monomethyl ketone (VI) the 0.r.d. spectrum has a molecular amplitude which is 10" more positive than that of the starting ketone (111). This is inconsistent with the octant rule, which predicts little change in molecular amplitude due to an equatorial methyl group a t C-2. A similar apparent anomaly exists in the 0.r.d. spectrum of the analogous saturated compound, 2 (3-methyl-5 13-cholestan-3-one ; the reported 23 molecular amplitude is about 15" more positive than the value for 5P-cholestan-3-one. It is unlikely that these incon- sistencies with the octant rule predictions are due to major conformational distortions 93 24~ 25 of the normal chair of ring A, but rather are due to more subtle con- formational changes.The fact that methylation of a 3-oxo-steroid con- taining both a 5P-hydrogen atom and 7,8-double bond results primarily in the formation of 2-methyl derivatives may be explained in terms of Bucourt's rules 2 6 9 2 7 for dihedral angle changes. The presence of the 7,8-double bond in 5 p-cholest-7-en-3-one causes the para dihedral angle 5,6;10,9 to open with respect to that of the saturated compound. Opening of this dihedral angle causes the dihedral angle 4,5;10,1 to open (A), since the rings are cis-fused. Formation of the 2,3-enolate anion (B) would result in an opening of the para dihedral angle 4,5;10,1 which would be compatible with the effect on this angle exerted by the 7,8-double bond, whereas formation of the 3,kenolate anion (C) would close the meta angle 4,5 ; 10,1, which would be incompatible with the effect of the 7,8-double bond on this angle. The fact that there is no C-7 axial hydrogen atom in 5p-cholest-7-en-3-one also means that there is less interaction27 with the C-4 axial hydrogen atom of the enolate anion with a 2,3-double bond.22 C. Djerassi and W. Klyne, J . Chem. SOC., 1962, 4929. 23 C. Djerassi, 0. Halpern, V. Halpern, and R. Riniker, J . R. Villotti, H. J. Ringold, and C. Djerassi, J. Amer. Chem. 25 N. L. Allinger and M. A. DaRooge. J . Amer. Chem. Soc., 2s R. Bucourt, Bull. SOC. chim. France, 1962, 1983; 1963, 27 L. Velluz, J. Valls, and G. Nomine, Angew. Chem. Internat. Amer. Chem. SOC., 1958, 80, 4001.SOC., 1960, 82, 5693. 1962, 84, 4561. 1262; 1964, 2080. Edn., 1965, 4, 181.2120 J. Chem. SOC. (C), 1970 EXPERIMENTAL M.p.s were taken with a Thonias-Hoover Uni-melt apparatus. 1.r. spectra were recorded with Beckman IR-8 or IR-20 instruments for solutions in chloroform unless otherwise indicated. N.m.r. spectra were taken with Varian T-60 or HA-100 spectrometers for solutions in deuterio- chloroform, with tetramethylsilane as internal standard. Mass spectra were determined with a Hitachi-Perkin-Elmer R.M.U. 6D spectrometer at an ionisation potential of 70 ev. 0.r.d. curves were obtained for solutions in dioxan with a Durrum- Jasco model ORD/UV-5 spectropolarimeter. Optical rotations were measured a t room temperature (23') for solutions in chloroform with a Perkin-Elmer 141 photoelectric polarimeter. In recording 0.r.d.data and optical rotations, the concentrations are expressed in g./100 ml. of solution. Microanalyses were determined in the laboratory of Dr. A. Bernhardt, Elbach uber Engels- kirchen, West Germany. U.V. spectra were recorded with a Perkin-Elmer 202 recording spectrophotometer . SilicaR (200-300 mesh) and neutral alumina (Woelm) were used as adsorbents for column chromatography. Silica gel G (Merck) was used as adsorbent for t.1.c. and sulphuric acid was used as spraying agent. Light petroleum boiling in the range 30-60' was used. Reactions were followed by t.1.c. and, in column chromatography, an L.K.B. 3400 automatic fraction collector was used; fractions with similar t.1.c. characteristics were combined, unless otherwise specified.Cholesta-4,7-dien-3-one (11) ,--This compound was pre- pared by Oppenauer oxidation 11 of cholesta-5,7-diene-3P-ol (I) according to the procedure of Cohen and his co-workers la with the following modifications; four times the amount of silica gel was used for chromatography and benzene w2s used as eluant instead of hexane; yield 60%, m.p. 87-89', A,, (hexane) 230 nm. (B 15,200) [lit.,le m.p. 87-89', I,, (hexane) 230 nm. (E 17,400)]. Catalytic Hydrogenation of Cholesta-4,7-dien-3-one (11) .- To a solution of cholesta-4,7-diene-3-one (11) (2.00 g., 5-24 mmoles) in anhydrous ether (100 ml.) was added finely powdered 10% palladium-charcoal (200 mg.). The resulting slurry was hydrogenated for 2.5 hr. a t atmospheric pressure and room temperature with constant agitation.The slurry was then filtered through Celite on a sintered glass funnel and the filtrate was evaporated to dryness leaving colourless oil (2.03 g.) . This was chromatographed on a SilicaR column (1.5 kg.) with light petroleum as eluant. The first materials eluted were solids with m.p.s between 80 and 86" (total 1.0 g.). Recrystallisation from methanol gave 5(3-choZest-7-en-3-one (111) (778 mg.), m.p. 86-87'. Concentration of mother liquors gave an ad- ditional 72 mg., m.p. 85-97' (total yield 42.5y0). Re- crystallisation of one of the early fractions three times from methanol gave an analytical sample, m.p. 87-88"; [a&, +65-4" (c 0.57), v,, (Nujol) 1715 (ketone) and 1665 (double bond) cm.-l, 6 5.13 (s, 7-H) p.p.m., 0.r.d.(c 0.24) (a -54") nz/e 384(100%), 351(55), 313(37), 119(38), and 105(74) (Found: C, 84.4; H, 11.5. C27H440 requires C, 84.3 ; H, 1 1-55y0) (lit.,28 for 5a-cholest-7-en-3-one, map. 146-148', [a], + 24.7"). Subsequent fractions were partially crystalline oils showing one spot on t.1.c. corres- ponding to 5p-cholest-7-en-3-one (111). These were com- bined (850 mg.) and rechromatographed to obtain more of compound (111). [ ~ I w o 4-520') [$I316 -781", [4]2t15 +4620°, [$]a35 +3050" Methylation of 5p-ChoZest-7-en-3-one (111) .-A solution of potassium (137 mg., 3.5 mmoles) in t-butyl alcohol (9.0 ml.) was added to a boiling solution of 5p-cholest-7- en-3-one (111) (889 mg., 2.31 mmoles). The solution was refluxed for 1 min. and an excess (0.8 mi.) of methyl iodide in benzene (4.0 ml.) was added; refluxing was continued for an additional 35 min.Water was added to the cooled mixture and the product was extracted with ether ( x 3). The combined extract was dried (Na2S04) and evaporated to a yellow oil (965 mg.). Chromatography on an alumina (grade 111) column (1.0 kg.) with light petroleum as eluant gave four products: (i) a colourless oil (52 mg.) assumed to be tri- or tetra-methylated species ; (ii) 2,2-dimethyZ- 5P-choZest-7-en-3-one (V) as a colourless oil (162 mg., 17%) which showed one spot on t.1.c. (attempts a t crystallisation were unsuccessful), [a], +20.5" (c 1.12), vmaK 1700 (ketone) cm.-l, 6 5.18 (s, 7-H) p.p.m., 0.r.d. (G 0.36) [$I,,, +4900° (u -65"), in/e 412(37y0), 379(59), 105(100), and 91(65) (a correct analysis was obtained for the crystalline ethylene acetal) ; (iii) 2fhnethyZ-5~-choZest-7-en-3-one (VI) (344 mg., 37:4,), m.p. 131-132" (from hexane), [oilD +42-6" (G 0.83), v,, (Nujol) 1710 (ketone) and 1665sh (double bond) crn.-l, 6 5-11 (lH, s, 7-H) p.p.m., 0.r.d. (G 0.38) [$I,,, +335", m/e 398(100~0), 365(79), 314(95), 136(30), and 105(40) (Found: C, 84.6; H, 11.7. C,,H,,O requires C, 84-35; H, 11.6) ; and (iv) unchanged 5P-cholest-7-en-3-one (111) (270 mg., 30%), m.p. 85-87' (from methanol). 2~-MethyZ-5p-choZestan-3-one (N) .-To a solution of 2p-methyl-5P-cholest-7-en-3-one (VI) (211 mg., 0.53 mmoles) in glacial acetic acid (10 ml.) and ethyl acetate (2-0 ml.) were added 70% aqueous perchloric acid ( I drop) and platinum oxide (100 mg.).lo This mixture was hydro- genated for 48 hr.at atmospheric pressure and room temperature with constant stirring. More catalyst (100 mg.) was then added and hydrogenation was continued for an additional 72 hr. After filtration and evaporation yellow oil (255 mg.) was obtained which was refluxed for 0.5 hr. in methanolic potassium hydroxide (15% ; 20 ml.) The solution was diluted with water and extracted with ether ( x 3). Drying (Na,SO,) and evaporation of the combined extracts gave a yellow oily residue (234 mg.) whose n.m.r. spectrum showcd no olefinic absorption. Chromatography [SilicaR (200 mg.) ; benzene as eluant] gave oily material (34 mg.) which was not characterised, and more polar material (157 mg.), m.p. 60-70" (from methanol-ether). The product was assumed to be a mixture of the saturated epimeric C-3 alcohols.The mixture was oxidised with Jones reagent 29 (15 drops) in acetone (20 ml.) for 0.5 hr. Methanol was then added to destroy excess of reagent and the oxidised product was isolated with ether t o give 2P-methyl-5f!-cholestan-3-one (IV) as a partially crystalline oil (143 mg.). Filtration through charcoal in ethereal solution followed by crystallis- ation from ether-methanol gave material (40 mg.), m.p. 111-112° [a], +26.2" (G 1-1), 0.r.d. (c 0.21) [$I450 +97", +1080' (a -8") (lit.,27 m.p. 111-112' [aID +30'; Concentration of mother 4P-Methyl- 2p-Methyl-5fl-choZest-7-en-3-one Ethylene Acetal.-A 2u W. Buser, Helv. Chim. Ada, 1947, 30, 1379. 29 A. Bowers, T. G. Halsall, E. R. H. Jones, and A. J. Lemin. [$I317 -1040', [$I272 +3350', [$]I,,, +2060° (a -43.9")~ [$I325 f 216') [$I318 +151', [$I280 +lolo", [$I263 +970°, lit.,23 a slightly less than -9.8').liquors gave more product (total yield 41 yo). 5p-cholestan-3-one has m.p. 58-59', [aID + 34'. J . Chem. SOL, 1953, 2555.Org. solution of 2p-methyl-5B-cholest-7-en-3-one (VI) (1 13 nig. , 0.29 mmoles) in benzene (25 ml.) containing an excess of ethylene glycol (0.2 ml.) and of toluene-psulphonic acid (8 mg.) was refluxed for 6.0 hr. in a flask fitted with a Soxhlet extraction apparatus containing a thimble with calcium carbide.30 Water formed during the reaction was thus continuously removed as acetylene gas. The solution was then poured into a mixture of ether and 5% aqueous sodium hydrogen carbonate in a separating funnel. The ether layer was washed with water, dried (Na,SO,), and evaporated to dryness to give the acetal (128 mg.), m.p. 118-1 19" (from ether-methanol containing a trace of pyridine); [a]= f65" (G 1.37), vmxm 1080 (ether) cmrl, 6 3.97 (4H, s, O*CH,*CH,*O) and 5.10 (lH, s, 7-H) p.p.m., m/e 442(66y0), 365(18), 314(100), 113(22), and 87(30) (Found: C, 81-25; H, 10.8. C30H5002 requires C, 81.4; 11.4%). The following acetals were similarly prepared : 2p- 2121 methyL5~-choZestan-3-one .ethylene acetal, m.p. 104-1 05O [aID $27.2" (G 1-03), vmx. 1080 (ether) cm.-l, 6 3.95 (4H, s, O*CH,*CH,*O) p.p.m., m/e 444(26%), 125(100), 113(70), and 99(12) (Found: C, 80.7; H, 11.7. C30H5202 requires C, 81.0; HI ll.8y0) ; and 2,2-dimethyZ-5~-choZest-7-en-3-one ethylene acetal, n1.p. 103-104", [a], $43.4" (G 1.03), vm= 1070 (ether) cm.-l, 6 3.93 (4H, s, OCH,*CH2-O) and 5.10 (lH, s, 7-H) p.p.m., m/e 456(27%), 379(24), 125(31), 112(60), 99(39), and 55(100) (Found: C, 81.45; H, 11.5. C3,H,,0, requires C, 81.5; H, 11*5y0). We thank the National Research Council of Canada for financial support and Professor J. L. Holmes for discussioiis regarding the mass spectra. [0/034 Received, January 9th, 19701 so E. J. Corey and G. A. Gregoriou, J . Amer. Chem. SOL. 1959, 81, 3124.

ISSN:0022-4952    

DOI:10.1039/J39700002117

出版商:RSC    

年代:1970

数据来源: RSC