Triazines and related products. Part 28. Conversion of 3-aryl-1-(2-cyanophenyl)triazenes into 3-arylquinazolin-4(3H)-ones with formamide

Abstract

The thermolysis of 4-anilino-1,2,3-benzotriazines and their precursor 3-aryl-1-(2-cyanophenyl)-triazenes in hot formamide to give 3-arylquinazolin-4(3H)-ones in high yield is described. The reaction cannot be extended to the preparation of 2-alkyl-3-arylquinazolinones. In hot acetamide–diglyme 4-(4-nitroanilino)-1,2,3-benzotriazine (5c) gives a high yield of the 3-substituted 4-(4-nitrophenylimino)-3,4-dihydro-1,2,3-benzotriazine (11c).