Synthesis and benzodiazepine receptor binding activity of 2, 9-disubstituted quinolino[2', 3'-5, 4](3-pyrazolino)[3, 2-b]purin-4-ones

2, 9-Disubstituted quinolino2', 3'-5, 4](3-pyrazolino)pyrimidin-2-ones and purin-4-ones were synthesized and their benzodiazepine receptor activity was evaluated for their ability to displace (3)H]R015-1788 from its specific binding in bovine brain membranes. Compound 5c caused 83 +/- 8 %inhibition in (3)H]R015-1788 specific benzodiazepine receptor binding followed by compounds 5f, 5h, and 5i while other analogs were inactive at 10 microM concentration.