1-Oxo-steroids. Part 2. Model studies for the synthesis of the withanolides

Abstract

Several cholestane derivatives possessing rings A and B with the same substitution pattern as in the naturally occurring steroidal lactones of the withanolide group have been synthesised: 4β-hydroxycholesta-2,5-dien-1-one (10), 5,6β-epoxy-4β-hydroxy-5β-cholest-2-en-1-one (12), cholesta-2,5-dien-1-one (19), and 5,6β-epoxy-5β-cholest-2-en-1-one (21). Several other compounds in which rings A and B have a substitution pattern not yet encountered among the natural withanolides have also been prepared: 5,6α-epoxy-4β-hydroxy-5α-cholest-2-en-1-one (11), 5,6α-epoxy-5α-cholest-2-en-1-one (20), and 4α-acetoxy-5-hydroxy-5β-cholest-2-en-1-one (28).