Formation of oestratrienes from 5,6-epoxyandrostan-7-ols

Abstract

The preparation of the four isomeric 17β-acetoxy-5,6-epoxyandrostan-7-ols is described. On treatment with hydrobromic acid in glacial acetic acid, they yield 17β-acetoxy-4-methyloestra-1,3,5(10)-triene rather than an anthrasteroid. The formation of 17β-acetoxy-1,4-dimethyloestra-1,3,5(10)-triene from 17β-acetoxy-5β,6β-epoxy-3α-methylandrostan-7β-ol indicates that the reaction involves a skeletal rearrangement rather than a methyl group migration.