Synthetic steroids. Part X. Preparation of (3S)- and (3R)-spiro-[5α-cholestane-3,2′-oxiran] and their corresponding 2α-methyl and 2,2-dimethyl analogues

Abstract

The preparation is reported of the 3R- and 3S-forms of spiro-[5α-cholestane-3,2′-oxiran] and their 2α-methyl and 2,2-dimethyl derivatives. The six epoxides were synthesised by addition of methylene to the relevant 3-ketone with either dimethylsulphoxonium methylide or dimethylsulphonium methylide, or by peroxidation of the corresponding 3-methylene-steroid with either m-chloroperoxybenzoic acid or peroxybenzimidic acid.

The stereochemistry of each epoxide is determined both chemically and spectroscopically and the stereochemistry of the reactions is discussed.