Unsaturated steroids. Part I. Synthesis of 22,23-dihydroergosterol

Abstract

Bromination of 5α-ergost-7-en-3-one furnishes a mixture of the 2- and 4-bromo-derivatives which is readily dehydrobrominated to yield the isomeric 5α-ergosta-1,7- and ergosta-4,7-dien-3-ones. Reduction of the enol acetate of ergosta-4,7-dien-3-one yields 22,23-dihydroergosterol. Some reactions of the 22,23-epoxide of ergosterol are reported; the configurational assignment of the 22-hydroxy-group in 3,22-dihydroxyergosterols has been clarified.