TRICYCLIC HETEROAROMATIC SYSTEMS - SYNTHESIS, [H-3]FLUNITRAZEPAM BRAIN MEMBRANE-BINDING INHIBITION, AND STRUCTURE ACTIVITY RELATIONSHIPS OF 2,3-DIHYDRO-2-ARYL-4-R-[1]BENZOPYRANO[4,3-C]PYRAZOLE-3-ONES

We report the synthesis and binding activity to the central benzodiazepine receptors of some 2,3-dihydro-2-aryl-4-R-[1]benzopyrano[4,3-c]pyrazole-3-ones, which are isosteres of the CGS series. Although the compounds of the CGS series are potent ligands of the benzodiazepine receptors, none of the isosteres tested showed any significant inhibiting potency. This may be due to the change in electronic properties brought about by the replacement of the NH of the CGS series with an oxygen atom