Beyond Amide Bond Formation: TCFH as a Reagent for Esterification.

In this Communication, an investigation of the combination of N , N , N ', N '-tetramethylchloroformamidinium hexafluorophosphate (TCFH) and N -methylimidazole (NMI) for the synthesis of esters and thioesters is described. This work revealed the unique challenges of the reactions of less nucleophilic alcohols and more reactive thiols with the N -acyl imidazolium intermediate and led to the identification of general enabling conditions that provide high yields and selectivity for a range of alcohols and thiols.