Mechanistic studies of a Pummerer-type reaction in acyclic and rigid cyclic sulfoxides induced by ketene tert-butyldimethylsilyl methyl acetal

Abstract

The Pummerer-type reaction of acyclic and rigid cyclic sulfoxides with ketene tert-butyldimethylsilyl methyl acetal 2 in the presence of a catalytic amount of zinc iodide in acetonitrile has been shown to proceed with highly stereoselective deprotonation of the α-methylene proton. A plausible reaction mechanism involving an anti elimination process is proposed based on an isotope labelling experiment using syn- and anti-[α-²H₁]benzyl methyl and [α-²H₁]benzyl tert-butyl sulfoxides.