NOVEL METHOD FOR STEREOSPECIFIC GENERATION OF NATURAL C-17 STEREOCHEMISTRY AND EITHER C-20 EPIMER IN STEROID SIDE-CHAINS BY PALLADIUM-CATALYZED HYDROGENOLYSIS OF C-17 AND C-20 ALLYLIC CARBONATES

The allylic alcohol, obtained by the reaction of C-17-keto steroid wit h isopropenyllithium, was converted to carbonate. Its hydrogenolysis w ith triethylammonium formate affords C-17 beta-isopropenyl group. Ster oid side chain units were introduced by the reaction of C-20 keto ster oid with (E) and (Z) alkenyl lithiums. The natural epimer at C-20 in s teroid side-chains was generated stereospecifically by the palladium-c atalyzed hydrogenolysis with triethylammonium formate of C-20 (Z) ally lic carbonates, and the unnatural configuration was generated by the C -20 (E) allylic carbonate.