Fe-catalyzed thioesterification of carboxylic esters.

Second nature: Starting from shelf-stable aryl esters and thiols, a variety of carboxylic acid esters were transformed into the corresponding thioesters with no racemization of labile stereocenters. The method was successfully applied in a native chemical-ligation-type peptide formation, which suggests that the thiol may act as a co-catalyst for future 1,2-additions of pronucleophiles to carboxylic esters.