Phosphorus oxychloride as an efficient coupling reagent for the synthesis of esters, amides and peptides under mild conditions

Abstract

A mild method is described for the conversion of carboxylic acids into esters, amides, as well as peptides without racemization through carboxyl activation by the reagent combination of POCl₃ and DMAP. Long chain alcohols could be converted to the corresponding ester in good yields. ³¹P NMR spectrum was used to detect phosphorus-containing intermediates in ongoing reactions directly, and a possible mechanism has been proposed based on these results.