Gas-phase thermolysis of condensed-1,2,4-triazines: interesting routes toward heterocyclic ring systems

Gas-phase thermolysis of thieno2,3-e]1,2,4]triazines gave benzonitrile, isothiazole, pyridazine, and thieno2,3-d]thiazole derivatives. Similar transformation of benzo1,2,4]triazine and phenanthro9,10-e]1,2,4]triazine derivatives into their corresponding condensed thiazoles has been achieved by heating at 350 °C with sulfur. A mechanism for these pyrolytic transformations was proposed.