cis-Hydroxylation of steroidal olefins with thallium triacetate

Abstract

Treatment of 5α-cholest-2-ene (1) with thallium triacetate in acetic acid afforded, in good yield, following hydrolysis, the corresponding β-cis-diol. The reaction constitutes a convenient procedure for cis-hydroxylation of disubstituted olefins from the hindered side of the molecule and appears to be assisted by the presence of a homoallylic hydroxy-group. 5α-Cholest-2-en-5-ol and 5-hydroxy-5α-cholest-2-en-6-one are converted under milder conditions than compound (1) and 5α-cholest-2-en-6-one into the corresponding 2β,3β-diols.