Hydroxy-steroids. Part VI. Reactions of olefins with silver salts and iodine

Abstract

The Prévost reaction of 5α-cholest-2-ene with iodine and silver benzoate gives the diaxial and diequatorial esters 2β,3α-dibenzoyloxy- and 2α,3β-dibenzoyloxy-5α-cholestane, the former predominating more markedly at 20 than at 80°. With silver 3,5-dinitrobenzoate similar esters are obtained, together with the intermediate iodo-ester 3α-iodo-5α-cholestan-2β-yl 3,5-dinitrobenzoate, which is more stable in this case. The use of silver p-chlorobenzoate leads to the diaxial ester 2β,3α-di-p-chlorobenzoyloxy-5α-cholestane and, surprisingly, the iodo-diester 2β,3β-di-p-chlorobenzoyloxy-1α-iodo-5α-cholestane.

Mild conditions were developed for carrying out the Woodward cis-hydroxylation of olefinic bonds.