Study on the reaction of oxathiazolone and dithiazolone with trivalent phosphorus compounds

Abstract

5-Aryl-1,3,4-oxathiazol-2-one was prepared from the reaction of benzamide with chlorocarbonylsulfenyl chloride. The reactions of the various oxathiazolones with triethyl phosphite resulted in the formation of the corresponding benzonitrile and ethyl phosphorothioate in 66-94\% yields. 5-(Nitrophenyl)-1,3,4-oxathiazol-2-one was reacted also with trimethyl phosphite, triethyl phosphine, and triphenyl phosphine to give 4-nitrobenzonitrile. But it gave no reaction with triphenyl phosphite. 5-Aryl-1,2,4-dithiazol-3-one was prepared from the reaction of thiobenzamide with chlorocarbonylsulfenyl chloride. The thiobenzamide was prepared from the reaction of benzamide with phosphorus pentasulfide in pyridine. The reaction of 5-(4-bromophenyl)-1,2,4-dithiazol-3-one with triphenyl phosphine resulted in the formation of 4-bromothiobenzoyl isocyanate and triphenyl phosphine thioxide. The fragmentation of thioacyl isocyanate to nitrile and the 1,4-cycloaddition of the thioacyl isocyanate with benzalaniline were investigated. In each case of the reactions, desulfurization by trivalent phosphorus compound was observed, and the plausible mechanism of the desulfurization, intramolecular rearrangement after insertion of the phosphorus atom into the ring was suggested. 1,4-Cycloaddition of the thioacyl isocyanate with imine gave a new compound, thiadiazinone and its structure was characterized by IR and $^1$H NMR spectrometry.