Triazines and related products. Part XVI. Synthesis of triazolotriazines by cyclisation of 3-hydrazino-1,2,4-triazines and 3-hydrazino-1,2,4-triazoles

Abstract

Cyclisation of 3-hydrazino-5,6-diphenyl-1,2,4-triazine with cyanogen bromide afforded 3-amino-6,7-diphenyl-1,2,4-triazolo[4,3-b][1,2,4]triazine, whereas interaction of 3-amino-5-hydrazino-1,2,4-triazole and benzil yielded the isomeric 2-amino-6,7-diphenyl-1,2,4-triazolo[5,1-c][1,2,4]triazine: both amines were deaminated with amyl nitrite in boiling tetrahydrofuran without rearrangement of the heterocyclic skeleton. 6,7-Diphenyl-1,2,4-triazolo[5,1-c][1,2,4]triazine, also formed from 3-hydrazino-1,2,4-triazole and benzil in alcoholic sodium acetate, formed a covalent hydrate which could be detected spectroscopically in solution, and a covalent methanolate and ethanolate which could be isolated. The alcoholates reverted to the aromatic system on being heated, or in hot acetic acid or pyridine.