Efficient method for thioacetalization of carbonyl compounds in the presence of a catalytic amount of benzyltriphenylphosphonium tribromide (BTPTB) under solvent-free conditions

A variety of carbonyl compounds have been successfully converted to the corresponding thioacetal derivatives in good to excellent yields on reaction of carbonyl compounds with 1,2-ethanedithiole, 1,3-propanedithiol, and ethylthiol in the presence of a catalytic amount of benzyltriphenylphosphonium tribromide (BTPTB) under solvent-free conditions. Some of the major advantages of this method are mild reaction conditions, high efficiency, and the compatibility with other reported methods. In addition, no bromination occurs at the double bond or to the keto position or even in the aromatic ring under these experimental conditions.