[1,2,3]Triazoloazine/(Diazomethyl)azine Valence Tautomers from 5-Azinyltetrazoles

[1,2,3]Triazoloazines are formed by thermolysis of 5-azinyltetrazoles in the gasphase or in solution. Thus, 5-(2-pyridyl)tetrazole (7) and 5-(2-pyrazinyl)tetrazole (11) yield [1,2,3]triazolo[1,5-a]pyridine (9) and [1,2,3]triazolo[1,5-a]pyrazine (13), respectively, at 400°/10−3 - 10−5 Torr. 5-(2-Phenyl-4-quinazolinyl)tetrazole (15) gives 5-phenyl[1,2,3]triazolo[1,5-c]quinazoline (17) in 75% yield by heating under reflux in mesitylene solution. 2-(Diazomethyl)pyridine (8), a valence tautomer of 9, can be trapped by fumaronitrile, leading to 3-(2-pyridyl)-1, 2-cyclopropanedicarbonitrile (19). The [1,2,3]triazoloazines undergo base catalysed H/D-exchange in D2O solution.