STEREOSELECTIVITY IN THE EPOXIDATION AND CIS-HYDROXYLATION OF 16-METHYLENE-ESTRA-1,3,5(10)-TRIENES

Epoxidation of -methoxy-16-methylene-estra-1,3,5(10)-trien-17-one in t he presence of alkaline hydrogen peroxide gives rise to (16R)- and eth oxy-17-oxoestra-1,3,5(10)-triene-16,2'-oxirane] in similar proportions . Epoxidation of the corresponding 16-methlene 17 beta-alcohol and 16- methylene-17 beta-acetate with m-chloroperbenzoic acid does not displa y any significant directing effects associated with allylic functional ity, whereas Sharpless epoxidation of the 16-methylene 17 beta-alcohol is highly stereoselective, leading exclusively to the (16R) isomer. c is-Hydroxylation of the 16-methylene 17-ketone with osmium tetroxide/4 -methylmorpholine-4-oxide proceeds stereoselectively to give mainly 16 alpha-hydroxy-16 droxymethyl-3-methoxyestra-1,3,5(10)-trien-17-one. T he isomeric addition products derived from these reactions are correla ted by appropriate interconversions, and the assignments are corrobora ted by comparative reactivity of derived products.