A nuclear magnetic resonance study of the conversion of 4β-acetoxy-3β-hydroxy-Δ5-steroids into 3β,6β-diacetoxy-Δ4-steroids
Abstract
2 H,13C, and 14C Labelling studies have shown that the reaction of 4β-acetoxy-3β-hydroxy-Δ5- and 3β-acetoxy-4β-hydroxy-Δ5-steroids with acetic acid to form 3β,6β-diacetoxy-Δ4-steroids involves an intramolecular rearrangement of the C-4 acetate to C-3 proceeding via a 3β,4β-dioxolanylium ion accompanied by SNi attack at C-6β by the incoming acetate.