SELECTIVE REDUCTION OF 3,17—DIOXO—STEROIDS TO 17β-HYDROXY-3-OXO-STEROIDS

11β-Hydroxy-androst-4-en-3,17-dione(1a),androst-4,9(11)-dien-3,17-dione-(2a),androst-4-en-3,11,17-trione(3a),11α-methoxy-androst-4-en-3,17-dione(4a)and 11β-metboxy-androst-4-en-3,17-dione(Sa)were selectively reduced tothe corresponding 17β-OH derivatives in one step without the protection of 3-oxo(and 11-oxo,in the case of 3a)group with the yields ranging from 65% to79%.In these reactions,the ditute NaBH_4(or KBH_4)solution in methanol wasadded dropwise to the 3,17-dioxo-steroids solution in methanol-benzene-pyridine,while the reaction mixtures were well stirred at -5～5℃.Acid(such as gtacialacetic acid)was added to quench the reactions.The resulted testosteronederivatives(1b～5b)were purified by flash chromatography.This method appties to the reduction of other 3,17-dioxo-steroids such as△~1-3-one,△~(1.4)-3-one,△~(4.6)-3-one,△~(1.4.6)-3-one containing compounds.