Investigation into the regioisomeric composition of some fused tetrazoles

Abstract

Treatment of 7-chloro-1-phenylpyrimido[4,5-e][1,3,4]thiadiazines with hydrazine in boiling ethanol gave corresponding7-hydrazinyl derivatives. Diazotization of the latter compounds acheived a mixture of 5<em>H</em>-tetrazolo[1',5':1,2]pyrimido[4,5-<em>e</em>][1,3,4]thiadiazine and 9<em>H</em>-tetrazolo[5',1':2,3]pyrimido[4,5-<em>e</em>][1,3,4]thiadiazines. Ratio of these two group of products determined by ¹HNMR studies and no significant preference was observed for their formation. Efforts for separation of the products were unsuccessful and its reason is discussed.