IMIDAZO[1,2-B]PYRIDAZINES .12. SYNTHESES AND CENTRAL-NERVOUS-SYSTEM ACTIVITIES OF SOME SUBSTITUTED IMIDAZO[1,2-B]PYRIDAZINES AND RELATED IMIDAZO[1,2-A]PYRIDINES, IMIDAZO[1,2-A]PYRIMIDINES AND IMIDAZO[1,2-A]PYRAZINES

Syntheses are reported for some 6-chloro(alkoxy, alkylthio and phenylthio)-3-benzamidomethyl-(acetamidomethyl and methoxy)-2-arylimidazo[1,2-a]pyridines and some corresponding imidazo[1,2-b]pyridazines, imidazo[1,2-a]pyrimidines and imidazo[1,2-a]pyrazines. IC50 values (or percentage displacement) are reported and discussed for the displacement of [H-3]diazepam from rat brain membrane by each of these compounds. The imidazo[1,2-a]pyridines were generally slightly less potent than the imidazo[1,2-b]pyridazines but considerably more potent than the corresponding imidazo[1,2-a]pyrimidines or imidazo[1,2-a]pyrazines. Substitution of a 2-aryl group by a 2-alkyl group in imidazo[1,2-b]pyridazines led to a significant loss of activity.