Air-Tolerant Direct Thiol Esterification with Carboxylic Acids Using Hydrosilane via Simple Inorganic Base Catalysis

Direct thioesterification of carboxylic acids with thiols using nontoxic activation agents is highly desirable. Herein, an efficient and practical protocol using safe and inexpensive industrial waste polymethylhydrosiloxane as the activation agent and K 3 PO 4 with 18-crown-6 as a catalyst is described. Various functional groups on carboxylic acid and thiol substituents can be tolerated by the present system to afford thioesters in yields of 19–100%.