Direct Thioesterification Of Carboxylic Acids With Thiols

The most popular method for preparing thioesters is the reaction of acid chlorides with thiols. Alternatively DCC can be used with an acid and a thiol, but the reagent is used in stoichiometric amounts. It has now been reported (Iimura S et al, Chem Comm, 2002, 94) that a catalytic amount of triflic acid can cause thioesterification in toluene under azeotropic reflux conditions. (This is presumably a limitation if highly volatile thiols are used).