Cycloaddition route to 14,17-ethano- and 14-alkyl-19-norsteroids

Abstract

Cycloaddition of phenyl vinyl sulphone to 14,16-dien-17-yl acetates derived from estrone proceeds regio- and stereo-selectively to give intermediates for conversion into 14,17α-ethenoestra-1,3,5(10)-triene-3,17β-diol derivatives and related ring D bridged 19-norsteroids. Oxidative cleavage of the 14α,17α-etheno bridge leads to 14α,17α-diformyl-17β-acetates and to 14α-formyl-17-ketones. Aspects of the chemistry of the 14α-formyl compounds are discussed, and methods are described for their conversion into 14α-methyl- and 14-hydroxymethyl-19-norsteroids.