Triazoles and especially fused triazoles are also an important class of heterocyclic compounds with antifungal, anticonvulsant, herbicidal and antidepressant activities [1]. Pyridazinothiadiazines are also of interest as potential inhibitors of cyclic nucleotide phosphodiesterase[2], dyestuff [3], and precursors of herbicides [4]. In continuation of our interest in chemistry of fused heterocycles of pharmacological importance and exploration of their synthetic pathways, we decided to synthesize the new heterocyclic systems of pyridazino[4,3-e][1,2,4]triazolo[3,4-b][1,3,4]thiadiazine. In this study, the prepared 4-bromo-3,6-dichloropyridazine was reacted with in acetonitrile which was subsequently treated with secondary amines and cyclized in the presence of sodium amide.

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