1,2,4‐Triazines. Synthesis of selected members of the s‐triazolo[3,4‐f]‐ [1,2,4] triazine and tetrazolo[1,5‐f] [1,2,4] triazine ring systems

Abstract A convenient synthesis of 3‐amino‐6‐hydrazino‐5(2 H )[1,2,4]triazinone 4 has been developed and a study of the reactions of 4 with aliphatic acids, orthoesters and miscellaneous active carbonyl reagents has been undertaken. When 4 was refluxed in either neat acid or orthoester in dimethylformamide, a facile ring closure reaction with the N‐1 nitrogen of the 1,2,4‐triazine ring occurs affording a novel series of 3‐aIkyl(aryl)‐8(5 H )‐ s ‐triazolo[3,4‐ f ] [1,2,4]triazinones ( 6–11 ). Ring closure with carbon disulfide and cyanogen bromide is also reported affording 6‐amino‐3(2 H )thio‐8(5 H )‐ s ‐triazolo[3,4‐ f ] [1,2,4]triazinone 12 and 3,6‐diamino‐8(5 H )‐ s ‐triazolo‐[3,4‐ f ] [1,2,4]triazinone 14 , respectively. In addition 4 has been converted into 3‐amino‐6‐azido‐5(2 H )‐1,2,4‐triazinone 15 which was employed in a study of azide‐tetrazole equilibrium affording 6‐amino‐8(5 H )tetrazolo[1,5‐ f ][1,2,4]triazinone 16 . Rates for interconversion at various temperatures were measured and an activation energy for the process determined.