New way to digitoxigenin from 3β-acetoxy-5-androsten-17-one. Stereoselective free radical substitution of iodide atom by nitrile group as a key step

Abstract

Digitoxigenin (I) was obtained from 17-oxoandrost-5-en-3β-yl acetate (III) using, as a key step, free radical stereoselective substitution of an iodine atom in VI by a nitrile group. Transformation of the nitrile group at C-17 into a pregnane side chain or a butenolide lactone ring took place without isomerization at C-17.