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

Abstract [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 D 2 O solution.