Benzodiazepine receptor ligands. 4. Synthesis and pharmacological evaluation of 3-heteroaryl-8-chloropyrazolo[5,1-c][1,2,4]benzotriazine 5-oxides

The synthesis of new 3-heteroaryl-8-chloropyrazolo[5,1-c][1,2,4]benzotriazi ne 5-oxides and their binding activities at the central benzodiazepine rece ptor (BZR) are reported. The derivatives substituted at the 3-position with electron-rich five-membered rings, such as pyrrole 11, 2-thiophene 13c, or 3-thiophene 13d, showed good affinity values for BZR. In in vivo tests the 3-(thien-3-yl)-8-chloropyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide; (13d) showed selective anticonvulsant activity.