Imidazo[1,2-b]pyridazines. XIV. Syntheses and Central Nervous System Activities of Some 6-(Methoxy-, dimethoxy-, methylenedioxy-, chloro- and fluoro-)-3-alkoxy-2-phenyl(and substituted phenyl)imidazo[1,2-b]pyridazines

Syntheses are reported for 28 new 3-alkoxy-6-(3′-methoxy-,3′,4′-dimethoxy, 3′,4′-methylene-dioxy-, 2′- and 4′-chloro- and 4′-fluoro-benzylamino)-2-phenyl(and substituted phenyl) imidazo -[1,2-b] pyridazines from the corresponding 6-substituted pyridazin-3-amine 2-oxides with α- bromoacetophenones, followed by alkylation of the intermediate 3-hydroxyimidazo[1,2-b] pyridazines. In tests of the ability of these compounds to displace [3H]diazepam from rat brain membrane, 3-(2′-ethoxyethoxy)-6(3′-methoxybenzylamino)-2-phenyl- and 6(3′,4′-methylenedioxybenzylamino )-2-(3″,4″-methylenedioxyphenyl)-3-methoxy-imidazo[1,2-b] pyridazine bound most strongly, with IC50 values of 1nM.