Imidazo[1,2-b]pyridazines .19. Syntheses and central nervous system activities of some 6-arylthio(aryloxy and alkylthio)-3-(acetamidomethyl, benzamidomethyl, methoxy and unsubstituted)-2-arylimidazo[1,2-b]pyridazines

Some 6-arylthio(aryloxy and alkylthio)-3-(acetamidomethyl, benzamidomethyl, methoxy and unsubstituted)-2-arylimidazo [1,2-b]pyridazines have been prepared and examined for their ability to displace [H-3]diazepam from rat brain membranes. The most active compound was 3-acetamidomethyl-2-(3',4'-methylenedioxyphenyl)-6-phenylthioimidazo [1,2-b]pyridazine with IC50 4 . 4 nM. The 3-acylaminomethyl-6-(2- and 3-methoxyphenylthio)-2-phenylimidazo[1,2-b]pyridazines proved less active than their 6-phenylthio analogues, and larger substituents at the 2- and 6-positions markedly decreased binding. Significant differences in binding ability have been observed between 3-acylaminomethyl-2-aryl-6-phenylthioimidazo[1,2-b]pyridazines and the corresponding imidazo[1,2-a] pyridines.