Reaction of diazomethane with 5-hydroxy-4-phenylabonzofurazan as a synthetic route to derivatives of a new heterocycle—pyrazolo [3,4-f]-1,2,3-benzotriazole

Diazomethane adds to 5-hydroxy-4-phenylazobenzofurazan 1 giving a compound 3 which rearranges in alkaline solution to the 8-monoxime of 2-phenyl-5(6)H-pyrazolo 3,4-f]-1,2,3-benzotriazole-4,8-dione 4, the structure of which has been demonstrated by chemical and spectroscopic methods. The probable structure of adduct 3 is discussed on the basis of the chemical reactivity of the compound. The orientation of the cycloaddition and the dipolarophilic behaviour of the 6,7 double bond of the benzofurazan are interpreted on the basis of the quinone hydrazone struture of 1.