Synthesis of new heterylmethylidene derivatives of isomeric imidazo[4,5-e]thiazolo-fused [1,2,4]triazines

Novel 6-heterylmethylidene-3a,9a-diphenylimidazo[4,5-e]-thiazolo[3,2-b][1,2,4]triazines were synthesized by the three-component condensation of imidazo[4,5-e][1,2,4]triazine-3-thione derivative with bromoacetic acid and hetero-aromatic aldehydes. The following MeONa-induced skeletal rearrangement gave the recyclized isomeric products, viz. 7-heterylmethylidene-3a,9a-diphenylimidazo-[4,5-e]thi azolo[2,3-c][1,2,4]triazines.