Efficient synthesis of novel dipyridoimidazoles and pyrido[1′,2′;1,2]imidazo[4,5-d]pyridazine derivatives

Novel dipyrido[1,2-a;3′,4′-d]imidazoles , dipyrido[1,2-a;4′,3′-d]imidazoles and pyrido[1′,2′;1,2]imidazo[4,5-d]pyridazine derivatives were synthesized by two pathways: thermal electrocyclic reaction of 3-alkenylimidazopyridine-2-oximes and direct condensation of ethyl glycinate (or hydrazine) with 2,3-dicarbonylimidazo[1,2-a]pyridines .