Condensation of 1,2-diamino-4-phenylimidazole and N-arylmaleimides with the formation of new tetrahydroimidazo[1,5-b]pyridazines

We studied the condensation of 1,2-diamino-4-phenylimidazole with N -arylmaleimides and established that this reaction occurred upon brief refluxing of reactants in isopropanol in the presence of a catalytic amount of acetic acid and produced substituted 7-amino- N -aryl-2-oxo-5-phenyl-1,2,3,4-tetrahydroimidazo[1,5- b ]pyridazine-4-carboxamides. Performing this reaction at room temperature led to the acyclic intermediates N -aryl-3-(1,2-diamino-4-phenylimidazol-5-yl)pyrrolidine-2,5-diones.