TiCl4-promoted direct N-acylation of sulfonamide with carboxylic ester

Several Lewis acids were investigated as promoters in the intermolecular or intramolecular direct N-acylation reaction of sulfonamides using carboxylic ester as an acylating agent. TiCl4 was found to possess the highest activity and enhanced efficiently sulfonamide to form N-acylsulfonamides under optimized conditions. This method provides a novel approach to make N-acylsulfonamides from ester via an easy work-up procedure.