Synthesis of 16.ALPHA.-hydroxyandrost-4-ene-3,17,19-trione and 3.BETA.,16.ALPHA.-dihydroxyandrost-5-ene-17,19-dione: Potential intermediates of estriol biosynthesis.

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Abstract
16.alpha.-Hydroxyandrost-4-ene-3,17,19-trione (10) was synthesized from the 16.alpha.-hydroxy-6.beta.,19-epoxy-17-one 3 via protection of the 16.alpha.-hydroxy function as its tert-butyldimethylsilyl ether or acetate. Reductive cleavage of the epoxy ring of the silyl ether 4 or the acetate 5 with zinc dust gave the 19-alcohol 6 or 7, which was treated with pyridinium dichromate or Jones reagent, respectively, and then hydrolyzed with diluted sulfuric acid, yielding the desired steroid 10. 3.beta.,16.alpha.-Dihydroxyandrost-5-ene-17,19-dione (14) was also synthesized from 5.alpha.-bromo-3.beta.,16.alpha.-diacetoxy-6.beta.,19-epoxyandrostan-17-one (11) through the intermediates 12 and 13 with the 3.beta.- and 16.alpha.-hydroxy functions protected as their acetates in a reaction sequence similar to that above.