Synthesis of 1H-1,2,4-triazolo[5,1-a]isoindoles by intramolecular condensation of 4-substituted 1,2,4-triazol-1-ium 4-substituted benzoyl 2,4,6-trinitrophenylmethylides

The reaction of the 4-substituted 1,2,4-triazol-1-ium 4-substituted benzoyl 2,4,6-trinitrophenylmethylides (5) with piperidine gave the 1H-1,2,4-triaz olo[5,1-a]isoindoles (7) by a cyclization and then elimination of nitrous a cid.