Conversion of 3-aryl-5-phenyl-2(3H)-furanones into 3(2H)-isothiazolone derivatives

Upon heating 3-aryl-5-phenyl-2(3H)-furanones (1a-c) with benzylamine at 100 degreesC in the absence of solvents, ring opening occurred with the formation of the corresponding N-benzy-lamides (3a-c). When the latter compounds (3a-c) were allowed to react with thionyl chloride at room temperature, the corresponding isothiazolones (4a-c) were obtained. Treatment of the isothiazolones (4a-c) with sodium hydroxide in benzene at room temperature affected debenzoylation to give the corresponding 2-benzyl-4-aryl-3(2H)-isothiazolones (5a-c).