Synthetic steroids. Part VI. Some reactions of 1α,5-cyclo-5α-cholest-2-ene

Abstract

Peroxidation of 1α,5-cyclo-5α-cholest-2-ene with p-nitroperoxybenzoic acid yields 2α,3α-epoxy-1α,5-cyclo-5α-cholestane which upon lithium aluminium hydride reduction gives 1α,5-cyclo-5α-cholestan-2α-ol. Oxidation of this alcohol gives 1α,5-cyclo-5α-cholestan-2-one which can be reduced to 5α-cholestan-2-one, to 1α,5-cyclo-5α-cholestane and to 1(10→5α)abeo-cholestan-2-one by hydrogen and catalytic platinum, by Huang-Minlon reduction, and by lithium in liquid ammonia, respectively. The same cyclopropyl ketone adds hydrogen bromide to give 5β-bromocholestan-2-one, from which the cyclopropyl grouping may be regenerated by treatment with base.

Hydroboration of 1α,5-cyclo-5α-cholest-2-ene results in a mixture of 1α,5-cyclo-5α-cholestan-2α-ol and 1α,5-cyclo-5α-cholestan-3α-ol, both of which have been oxidised to the corresponding ketones. An independent synthesis of 1α,5-cyclo-5α-cholestane is described starting from 3β-acetoxy-5β-hydroxycholestan-6-one.