HYDROXYLATION OF ALPHA,BETA-UNSATURATED NITRILES AND ESTERS IN STEROID SYSTEMS

The hydroxylation of .alpha.,.beta.-unsaturated nitriles or .alpha.,.beta.-unsaturated esters in various steroid systems using stoichiometric amounts of osmium tetroxide furnished .alpha.-hydroxy ketones/aldehydes and .alpha.,.beta.-dihydroxy esters in moderate yield. The absence of a C-21 acetoxy group in 17(20)-pregnene-20-carbonitriles or 5,17(20)-pregnadiene-20-carbonitriles precluded using potassium permanganate to introduce the 17.alpha.-hydroxy 20-ketone synthon. However, the stoichiometric osmium tetroxide oxidation of various 17(20)-pregnene-20-carbonitriles furnished the 17.alpha.-hydroxy 20-ketones in moderate yield. .alpha.,.beta.-Unsaturated nitriles derived from 3-ketones and 20-ketones were also hydroxylated to give .alpha.-hydroxy ketones and aldehydes in moderate yield. No regioselectivity for the .DELTA.17,20-double bond in 5,17(20)-pregnadiene-20-carbonitriles was observed using osmium tetroxide. A catalytic osmium tetroxide-potassium chlorate oxidation of 17(20)-pregnene-20-carbonitriles required zinc nitrate to sequester CN- liberated in the course of the hydroxylation. A brief investigation of osmium tetroxide oxidation of 5,17(20)-pregnadienes bearing withdrawing groups at C-20 other than the nitrile disclosed an interesting hydroxylation of a 17(20)-unsaturated ester in the presence of a nonconjugated .DELTA.5-double bond.