1:3-Rearrangement of steroidal allylic acetoxy groups during epoxidation
Abstract
Epoxidation of both 4β-acetoxyandrost-5-en-17-one and 6β-acetoxyandrost-4-en-17-one by m-chloroperbenzoic acid affords a similar mixture of 4β-acetoxy-5α,6α-epoxy- and 6β-acetoxy-4α,5α-epoxyandrostan-17-one. This is interpreted in terms of a symmetrical ‘acetoxylinium’(1,3-dioxan-2-ylium) ion and a degree of charge separation in the transition state for epoxidation.