IMIDAZO[1,2-B]PYRIDAZINES .15. SYNTHESIS AND ANXIOLYTIC ACTIVITY OF SOME 3-(BENZAMIDOMETHYL AND FLUOROBENZAMIDOMETHYL)-6-(FLUORO, CHLORO AND METHYLTHIO)-2-(4-TOLYL AND 3,4-METHYLENEDIOXYPHENYL)IMIDAZO[1,2-B]PYRIDAZINES

Syntheses are reported for some 3-(benzamido- and fluorobenzamido-meth yl)-6-(-fluoro, chloro and methylthio)-2(4-methyl-, 4-t-butyl-, 4-cycl ohexyl- and ,4-methylenedioxy-phenyl)imidazo-[1,2b]pyridazines from th e relevant 3-unsubstituted imidazo[1,2-b]pyridazines and the N-(hydrox ymethyl)benzamides. In tests of the ability of these compounds to disp lace [H-3]diazepam from rat brain membrane, 3-(3- or dioxyphenyl)-6-me thylthioimidazo[1,2-b]-pyridazine bound most strongly, with IC50 2 nm; but in behavioural tests in rats the most active compounds were 6-chl oro(and 3,4-methylenedioxyphenyl)imidazo[1,2-b]pyridazines which showe d a significant anxiolytic activity at 2.5 mg/kg.