amines and carboxylicacids that complement the popular amide coupling can significantly expand accessible chemical space if they yield products distinct from the classic R–NHC(O)–R′ amide arrangement. Here we have developed an amine–acid esterification reaction based on pyridinium salt activation of amine C–N bonds to create products of type R–OC(O)–R′ upon reaction with alkyl and aryl carboxylic acids