Urinary steroids. Part VIII. An exploration of routes to pregnane-20α,21-diol derivatives

Abstract

Reduction of 3β,21-dihydroxypregn-5-en-20-one 21-acetate with sodium–n-propanol gave a mixture containing the 3β,20α- and 3β,20β- diols as well as the 3β,20α,21- and 3β,20β,21 -triols. Attempts to prepare 20α,21-diols by nucleophilic substitution at C-20 in a 21-acetoxy-20β-tosyloxy-compound (IXe) gave largely D-homoandrostane derivatives. The 20α,21-epoxypregnane (XII) obtained by mild alkaline hydrolysis of the 21 -acetoxy-20β-tosylate (IXe) was converted into the 20α,21 -diol either by vigorous alkaline hydrolysis, or by boron trifluoride-catalysed opening of the epoxide with dimethyl sulphoxide or NN-dimethylacetamide, followed by hydrolysis.