Preparation Of 3alpha- And 3beta,17beta-Dihydroxy-17alpha-Ethynl-Estr-5(10)-Ene

Norethynodrel (1, 17β-hydroxy-17α-ethynyl-estr-4-en-3-one) when reduced at -70°C with lithium tri(t-butoxy) hydride yielded predominantly (98%) the equatorial Sec-alcohol II together with 27. of the axial 3β-alcohol III. Reduction of norethynodrel with sodium borohydride resulted in increased yields of the 3β alcohol III, the ratio of the 3α to 3β-alcohols varying from 4:1 to 3:1 depending upon the solvent used. The 3β-aicohol III was obtained in 38% yield following reduction of the ketone I with diisobutylaluminum hydride. The most efficient synthesis of the 3β-alcohol III was by a MeerweinPondorff reduction of ketone I carried out over a very short reaction period (9). In an alternate route the equatorial 3α-alcohol II was converted to the 3β-axial alcohol III via the 3α-mesitylenesulfonyloxy derivatives IVd and the 3β formate V.