A convenient synthesis of 4-(phenylsulfonylthio)-2-azetidinones

4-(Phenylsulfonylthio)-2-azetidinones have been prepared conveniently by the reaction of 4-(2-benzothiazolyldithio)-2-azetidinones with 2-benzothiazolyl benzenethiosulfonates. A combination of this reaction with the electrolytic cross-coupling of bis(benzothiazolyl) disulfide and ammonium benzenesulfinate can establish a recycling system, in which S-(2-benzothiazolyl) benzenethiosulfonate is regenerated to play a critical role in penicillin–cephalosporin conversions.