Synthesis and properties of 1H-1,2,4-benzotriazepines

The synthesis of some N,N-disubstituted benzhydrazidoyl chlorides and their reaction with cyano compounds in the presence of a Lewis acid are described. Whereas N-methyl-N-phenylbenzhydrazidoyl chloride (1a) gave 1H-1,2,4-triazoles, N,N-diphenylbenzhydrazidoyl chloride (1b) afforded 1H-1,2,4-benzotriazepines (3b) and N,N-(2,2′-biphenylen)benzhydrazidoyl chloride (10) yielded the corresponding 1H-1,2,4-benzotriazepine (12) or a hydrolysis product (13). Properties of compounds 3b, specially their near-quantative acid hydrolysis to 1-phenylindazoles, are reported.