Synthesis of the bi‐heterocyclic parent ring system 1,2,4‐triazolo[4,3‐b][1,2,4,5]tetrazine and some 3,6‐disubstituted derivatives

The synthesis of the previously unknown parent ring system was developed. Treatment of 3‐hydrazino‐1,2,4,5‐tetrazine ( 4 ) with diethoxymethyl acetate gave the parent ring system. Similar treatment of 3‐(3,5‐dimethylpyrazol‐1‐yl)‐6‐hydrazino‐1,2,4,5‐tetrazine ( 2 ) with one carbon cyclizing reagents gave 3,6‐di‐substituted derivatives of the 1,2,4‐triazolo‐1,2,4,5‐tetrazine ring system.