New entry to the imidazo[4,5-c]pyrazole system through photochemically induced sequential transformations of substituted pyrrolo[2,3-d]-1,2,3-triazoles: X-ray crystal structure of a substituted 1,3a,6,6a-tetrahydroimidazo[4, 5-c] pyrazole

Abstract

Upon UV irradiation, substituted pyrrolo[2,3-d]-1,2,3-triazoles were transformed by a new route to imidazo[4,5-c] pyrazoles. The mechanism of the reaction is discussed in terms of a likely 1,2,3,5-tetrazocine intermediate. An X-ray crystal structure of dimethyl 1,6-di(p-bromophenyl)-3,5-diphenyl-1,3a,6,6a-tetrahydroimidazo[4,5-c] pyrazole-3a,6a-dicarboxylate 4b is reported.