Imidazo[1,2-b]Pyridazines. XVI. Synthesis and Central Nervous System Activities of Some 6-(Chloro, Alkylthio, Phenylthio, Benzylthio or Pyridinylmethylthio)-3-(unsubstituted, benzamidomethyl or methoxy)-2-(styryl or benzoyl)imidazo[1,2-b]pyridazines

Abstract

Some 6-( chloro, alkylthio, phenylthio, benzylthio or pyridinylmethylthio )-3-( unsubstituted , benzamidomethyl or methoxy )-2-styrylimidazo[1,2-b] pyridazines and 6-chloro-3-( unsubstituted and benzamidomethyl )-2-benzoylimidazo[1,2-b] pyridazines have been prepared and tested for their ability to displace [³H]diazepam from rat brain plasma membranes. The structures of 6-chloro-2-benzoyl[and 6-fluoro-2-(4′-tolyl)] imidazo [1,2-b] pyridazine have been confirmed by X-ray analyses. The reactions of 6-methylthio(and 6-phenylthio)pyridazin-3-amines with 3-bromo-1-phenylpropane-1,2-dione also have been investigated.

The 6-substituted 3-unsubstituted 2-styryl(and benzoyl ) imidazo [1,2-b] pyridazines did not bind strongly to rat brain benzodiazepine receptors; nor did the 3-benzamidomethyl or 3-methoxy derivatives (cf. the 2-phenyl analogues). However, 3-benzamidomethyl-6-(pyridin-3-ylmethylthio)-2-styrylimidazo[1,2-b] pyridazine was an exception with IC₅₀ 68 nM.