Triazines and related products. Part XIII. Decomposition of 4-Arylamino-1,2,3-benzotriazines and their precursors in secondary amines

4-Arylamino-1,2,3-benzotriazines (1) decompose in piperidine and related secondary amines to afford NNN′-trisubstituted 2-aminobenzamidines (4) in excellent yields. 4-o-Aminoanilinobenzotriazine (1f) yields 2-(2-aminophenyl)benzimidazole (9) when heated in ethylene glycol or piperidine. Nucleophilic attack by the amines at C-4 of the triazine ring is implicated in these transformations. 1-o-Cyanophenyl-3-m-cyanophenyltriazene (13a) is unreactive in piperidine whereas the p-cyanophenyltriazene isomer (13b) yields 2-amino-N′-p-cyanophenyl-NN-pentamethylenebenzamidine (4b). 1,3-Bis-o-cyanophenyltriazene (13c) rearranges and decomposes in boiling piperidine, pyrrolidine, morpholine, diethylamine, di-n-propylamine, and piperazine to afford the triazenylquinazolines (19)–(24), respectively.