6,7-Dihydro-2-benzothiophen-4(5H)-ones:  A Novel Class of GABA-A α5 Receptor Inverse Agonists

Nonselective inverse agonists at the benzodiazepine binding site on the GABA-A chloride ion channel enhance cognitive performance in animals but cannot be used in the treatment of cognitive disorders because of anxiogenic and convulsant side effects. We have identified a novel series of GABA-A alpha5 receptor ligands during our search for alpha5 receptor inverse agonists as potential cognition enhancers. In particular, 6,6-dimethyl-3-(2-hydroxyethyl)thio-1-(thiazol-2-yl)-6,7-dihydro- 2-benzothiophen-4(5H-)-one (26) has been identified as a functionally selective GABA-A alpha5 inverse agonist.