Imidazo[1,2-b]Pyridazines. V. Syntheses and Central Nervous Activities of Some 3-Alkoxy-6-benzylthio(substituted benzylthio and Other phenylalkylthio)-2-phenyl(and substituted phenyl)imidazo[1,2-b]pyridazines

Syntheses are reported for a number of 3-alkoxy-6-benzylthio(substituted benzylthio and other phenylalkylthio )-2-phenyl(and substituted phenyl)imidazo[l,2-b]pyridazines. These compounds were then examined for their ability to displace 3H-diazepam from rat brain membranes. In preliminary tests, in the presence of 100 �m γ- aminobutyric acid (GABA) and under standard assay conditions (see Experimental), 6-benzylthio-3-methoxy-2-phenylimidazo[l,2- b]pyridazine gave an lC50 value of 25nM (IC50 for unlabelled diazepam is 4.3 nM ); its 6-(m- aminophenyl ), 6-(p- aminophenyl ) and 6-(m- nitrophenyl ) analogues gave values of 15, 9 and 8 nM respectively.