Pyrolysis and Photolysis of 1-Aroylamino-4,5-diaryl-1,2,3-triazoles: Generation and Thermal Transformations of 4,5-Diaryl-1,2,3-triazolyl Radicals

Abstract

The pyrolysis of 1-aroylamino-4,5-diphenyl-1,2,3-triazoles 1 yields, pressumably via the 4,5-diphenyl-1,2,3-triazolyl radical (2a), 2,3-diphenyl-2H-azirine (11a) and 2-aryl-4,5-diphenylimidazoles 14 as the major products. Upon irradiation 1-benzoylamino-4,5-diphenyl-1,2,3-triazole (1a) gives 4,5-diphenyl-1(2)H-1,2,3-triazole (4a) via the 1,2,3-triazolyI radical 2a, together with benzamide (5a) and 1,2-bisbenzoylhydrazine (6a). Products 5a and 6a result from the benzoylamino radical 3a by hydrogen atom abstraction and dimerization respectively.