Stereochemical course of the reduction of 5α-cholest-8(14)-en-7-one by metal–ammonia; a ready synthesis of 14β-steroids

Abstract

5α-Cholest-8(14)-en-15-one (III) has been isolated as a by-product of an improved synthesis of 5α-cholest-8(14)-en-7-one (II); the previously undescribed n.m.r. and mass spectra of the former compound are discussed since they are of theoretical interest and diagnostic importance. Whereas reduction of steroidal Δ⁸⁽¹⁴⁾15-ketones by metal–ammonia has been known for some time to produce saturated ketones of natural stereochemistry, the corresponding reaction of the isomeric Δ⁸⁽¹⁴⁾-7-ketone system has now been shown unexpectedly to generate a ketone of unnatural configuration, and so constitutes a novel and simple synthesis of 14β-steroids.