Triazines and related products, Part 22. Synthesis and reactions of imidazo[5,1-c][1,2,4]triazines

Abstract

5-Diazomidazole-4-carboxamide couples with reactive methylenic substrates to afford a series of imidazolyl-hydrazones which cyclise in acid or alkali to imidazo[5,1-c][1,2,4]triazines. Hydrazones with cyano-substituents cyclise in acid to yield 7-aminoimidazotriazines whereas hydrazones with acetyl groups undergo acidic dehydration to form bicycles with a 7-methylene substituent. In basic conditions, hydrazones with a reactive ester group cyclisa to imidazotriazin-7(4H)-ones with loss of an alcohol moiety. Ethyl 7-amino-3-carbamoylimidazo[5,1-c][1,2,4]-triazine-6-carboxylate hydrolyses in boiling 2N-hydrochloric acid, forms an N-acetyl derivative, and reacts with secondary heteroalicyclic amines to form amides.