The Preparation of 3β-Methoxy-5-Methyl-10-Nor-8(9)-Cholestene, an Isomer of Cholesteryl Methyl Ether

Shealy, Y. Fulmer; Dodson, R. M.

doi:10.1021/jo50003a014

Cited by 19 publications

(7 citation statements)

References 6 publications

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“…In order to prepare the isomeric epoxides ( 16) and (21) it was necessary to obtain 5,6a-epoxy-3a-methoxy-5a-cholestane (11) as an intermediate. An attempt to prepare the last-named compound by treatment of 5,6a-epoxy-5a-cholestan-3P-o1 toluene-p sulphonate (7) with methanolic sodium methoxide gave instead 3a,5-epoxy-6P-methoxy-5a-cholestane (8) as the major product, together with a smaller amount of cholesterol aepoxide (9). The structure of the oxetane (8) follows from its n.m.r.…”

Section: Preparation and Lsomerisation Of Some Steroidal Hydroxy Epox...mentioning

confidence: 99%

Preparation and isomerisation of some steroidal hydroxy epoxides

Morrison¹,

Wilkinson²

1989

J. Chem. Soc., Perkin Trans. 1

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Section: Preparation and Lsomerisation Of Some Steroidal Hydroxy Epox...mentioning

confidence: 99%

Preparation and isomerisation of some steroidal hydroxy epoxides

Morrison¹,

Wilkinson²

1989

J. Chem. Soc., Perkin Trans. 1

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“…In particular the is spectrum shows a nonhydrogen-bonded hydroxyl group, favouring the 5c( configuration slnce the hydroxyl group in the 5P isomer would be expected to hydrogen bond with the 3P-methoxyl group. 12 A n unusual feature in the 'H ninr spectrum of 13 is the accidental equivalence of the two olefinlc protons in deuteriochloroform, hexadeuterioacetone, and hexadeuteriobenzene solutions, This was un-'OAlthough the reaction with butyllithium was conducted under nitrogen, air could have been introduced during the transfer to the freeze-thaw degassing cycle.…”

Section: 'This Epinierization Has Also Been Carried Out Recently B Y mentioning

confidence: 99%

“…3~-Methoxy-5n-cholestane-5,6~ioI (8) was prepared by methylation of cholesterol to give cholesteryl methyl ether (19) and treatment of this with hydrogen peroxide and formic acid followed by hydrolysis with base (12).…”

Section: Substratesmentioning

confidence: 99%

“…Quantitative estimation of the ratio by integration of the peak areas from crude thermolysates was not justified in this case; however, beca~~se gc-ms of the mixtures showed that although the peak eluting with retention time corresponding to 2 was Epin~ei.izntiorl of Sa-Hydro.~~-3~i1e~~1o.~y-5r-c/1oIe~s~an-6-one 20. Forillatior~ of 21 and 2Z9 A lo:< vjw solution of potassium hydroxide in anhydrous methanol (100 mL) mas added to 5x-hydroxy-3B-methoxy-5a-cholestan-6-one (20: 334 mg) (12). The mixture was boiled at rellux under dry nitrogen for 48 h, added to ice water (500 mL) and extracted with ether (1 x 50, 2 x 100 n1L).…”

Section: Ailalj~sis For Cis-rrrzd Trans-12-cyclohexat~ediols ( 1 2 )mentioning

confidence: 99%

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Stereochemical equilibration of the lithium derivatives of 1,2-diols

Slemon¹,

Yates²

1979

Can. J. Chem.

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, 304 (1979). The dilithiuin derivatives of the ditertiary 1,2-diols, cis-and rrar~s-1,2-dirnethyl-l,2-~yclo-hexanediol, fail to undergo base-induced stereochemical equilibration under conditions that lead to such equilibration uith the dilithiurn derivatives of the disecondary 1,2-diols, cis-and rrnns-l,2-cyclohexanediol. This casts doubt on the proposal that the latter equilibration proceeds by c a r b o n~a r b o n bond cleavage of the dialkoxide to give a diketyl intermediate. It is highly probable that it involves oxidation-reduction as established by Doering in the case of monohydric alcohols. Examination of steroidal secondary-tertiary 1,'-diols under similar conditions shows that such systems can epimerize at both carbinol centres; this is interpreted in terms of sequential oxidation, rr-ketol rearrangement, and reduction. CLARKE E. SLE\IOI\' et PETER YATES. Can. J. Chem. 57, 304 (1979) Les derives dilithies des diols-1,2 ditertiaires, cis-et trans-dimethyl-1, cyclohexanediols-1,2 ne subissent pas d'equilibrations stereochimiques induites par les bases dans des conditions qui permettent de telles equilibrations avec les derives dilithies des diols-1,' disecondaires, cis-et truns-cyclohexanediols-1,2. Ces resultats jettent un doute sur la proposition a l'effet que la del-niere equilibration se produit par I'intermediaire de la rupture de la liaison carbonecarbone du dialcoolate conduisant a un intermediaire dicetyle. II est tres probable que cette reaction implique une oxqdo-reduction du type propose par Doering dans le cas des monoalcools. Un examen de diols-1,2 steroidaux secondaire-tertiaire dans des conditions semblables n~ontre que de tels systemes s'epirnerisent au niveau des deux centres carbinoliques; on interprete ces resultats en termes d'une oxydation sequentielle, d'une transposition u-cetolique et d'une reduction.[Traduit par le journal] Intoductionshows a variable induction period depending upon ~h~ mechallism by ,.,,hich secondary alkali metal the extent of exclusion of oxidizing impurities. alkoxides epimerire has been thorounhly examined Moreover, it has been observed that heating alkox-(1, 2). ~h~ results are accounted-for by a reac-ides racemizes asymmetric centres u to the carbinol tion sequence (Scheme 1) wherein the substrate is carboll if bear a h~drogell Such data conform with the proposed lnechailisms in which the arrested. Alternatively, by the addition of a mixture of fluorenone and fluorenol, one a facile hydride slowly oxidized by solvellt illlpurities or atmos-acceptor and the other a facile hydride donor, such pheric oxygen to form a quantity of the stereocl~einically hindered substrates as u-and Pcorresponding carbonyl compoulld, slnall alnounts fenchol, which were inert under other conditions, of this hydride acceptor are sufficient to prime a could be e~imerized. chain of hydride transfers between substrate moleIn 1970 Schlosser Weis (3) reported the Gules that eventually in complete stereo-stereochemical equilibration of the dilithium derivachemical equilibration.tive...

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“…Thermodynamic parameters for the equilibration of the conformationalenantiomorphs (37) and (38) these conditions to give 3S,6S-diacetoxy-5-methyl-19-nor-5S- [2][3][4][5][6] cholest-9-ene (2) {fig. 1)…”

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confidence: 99%