Direct formation of esters and amides from carboxylic acids using diethyl chlorophosphate in pyridine

An efficient method involving pyridine activation of the carboxylate–phosphate anhydride pathway is described resulting in a direct synthesis of esters from carboxylic acids and alcohols, as well as in the formation of useful amide and peptide derivatives. The reaction proceeds with retention of configuration with both chiral secondary alcohols and α-amino acid derivatives. Ester and amide products can be isolated directly in high yield due to the water soluble nature of the side products.