Synthesis and SAR studies of 2-oxoquinoline derivatives as CB2 receptor inverse agonists

The highly CB2 selective cannabinoid receptor inverse agonist, 7-methoxy-2-oxo-8-pentyloxy-1,2-dihydroquinoline-3-carboxylic acid N-benzo[1,3]dioxol-5-ylmethyl)amide (JTE-907; 9b), served as the lead compound for investigating the structure-activity relationships of its analogues and in the search for more potent and effective CB2 receptor inverse agonists. A series of aromatic amides of 7-methoxy-2-oxo-8-pentyloxy-1,2-dihydroquinoline-3-carboxylic acid 6 was synthesized, and the CB2 receptor activities of the compounds were determined by a [S-35]GTP(gamma)S-binding assay using membranes of CHO cells stably transfected with the human CB2 receptor. As a result, all the compounds were defined as full CB2 receptor inverse agonists, and additionally, except for two 3,4-dihydroxyphenylalkylamides, they were found to be equally potent as SR144528.