t-Butyl bromide–dimethyl sulphoxide reactions. Pummerer-like reaction with carboxylic acids and N-protected amino-acids

Abstract

t-Butyl bromide-activated dimethyl sulphoxide reacted with carboxylic acids and differently N-protected aminoacids in the presence of a base (NaHCO₃ or Et₃N). High to quantitative yields of methylthiomethyl (MTM) esters were obtained in all cases without interference by other functional groups or racemization. The mechanism of the reaction is discussed on the basis of the products formed, of spectral data, and of other miscellaneous experiments.