Synthesis and Benzodiazepine Receptor Affinity of Pyrazolo [1,5-a]pyrimidine Derivatives.3. New 6-(3-Thienyl) Series as a1 Selective Ligands

New 3-aryl-6-(3-thienyl)pyrazolo[1,5-a]pyrimidin-7-ones (2a-j) are synthesized and evaluated in vitro on Bz/GABAA receptors and on recombinant benzodiazepine receptors (αxβ2/3γ2; x= 1-3, 5) expressed in HEK293 cells. SAR studies on the new compounds are conducted and molecular modeling is accomplished to better investigate requirements leading to subtype selectivity. Some of the synthesized compounds are tested in vivo to explore their pharmacological effect as a consequence of their high α1β2γ2 subtype selectivity observed in vitro.