IMIDAZO[1,2-B]PYRIDAZINES .19. SYNTHESES AND CENTRAL-NERVOUS-SYSTEM ACTIVITIES OF SOME 6-ARYLTHIO(ARYLOXY AND ALKYLTHIO)-3-(ACETAMIDOMETHYL, BENZAMIDORNETHYL, METHOXY AND UNSUBSTITUTED)-2-ARYLIMIDAZO[1,2-B]PYRIDAZINES

Some 6-arylthio(aryloxy and alkylthio)-3-(acetamidomethyl, benzamidome thyl, methoxy and unsubstituted)-2-arylimidazo [1,2-b]pyridazines have been prepared and examined for their ability to displace [H-3]diazepa m from rat brain membranes. The most active compound was 2-(3',4'-meth ylenedioxyphenyl)-6-phenylthioimidazo [1,2-b]pyridazine with IC50 4 . 4 nM. The 3-acylaminomethyl-6-(2- and thoxyphenylthio)-2-phenylimidazo [1,2-b]pyridazines proved less active than their 6-phenylthio analogue s, and larger substituents at the 2- and 6-positions markedly decrease d binding. Significant differences in binding ability have been observ ed between ethyl-2-aryl-6-phenylthioimidazo[1,2-b]pyridazines and the corresponding imidazo[1,2-a] pyridines.