Synthesis and pharmacological screening of pyrazolo[3,4-c]pyridazine derivatives

Ethyl 3-chloro-6-(4-chlorophenyl)-pyridazine-4-carboxylate [VII] was cyclized with some nucleophilic reagents (hydrazine hydrate or N-monosubstituted hydrazines) to the new derivatives of pyrazolo[3,4-c]pyridazine [IXa-d]. The structures of the novel compounds were confirmed by elemental and spectral analyses. The effect of several synthesized derivatives on the central nervous system was studied.