Stereoselectivity in Reduction of Steroidal 7-Ketones(Organic,Chemical)

概要

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Several 7-ketones of lanostane, 4,4-dimethylcholestanc and cholestanc derivatives were subjected to catalytic hydrogenation on platinum, reduction with complex hydrides and reduction with sodium in tert-butanol, and the product ratios (7α-ol/7β-ol) were determined by gas chromatography or high-performance liquid chromatography. Catalytic hydrogenation of 3β-hydroxylanostan-7-onc and 3β-hydroxy-4,4-dimethylcholestan-7-one yielded the 7β-alcohols as the major products, whereas their 3-acetates gave principally the 7α-alcohols. Reduction of various 7-ketones with sodium in teri-butanol gave mainly the 7β-equatorial alcohols, while the epimeric 7α-ols were the major products on reduction with lithium tri-sec-butylborohydride. The stereoselectivity of reduction with sodium borohydride and lithium aluminum hydride was highly dependent on the neighboring double bond and 4,4-dimethyl and/or 14α-methyl substituent(s).
社団法人日本薬学会の論文
1987-05-25