Aliphatic amides of 7-methoxy-2-oxo-8-pentyloxy-1,2-dihydroquinoline-3-carboxylic acid 6 were synthesized and evaluated for their CB2 and CB1 receptor activities by a [35S]GTPgammaS membrane-binding assay. Compounds 7-18 produced CB2 inverse agonist activities with a variety of potencies (IC50: 1 nm-1 microm). By contrast, no considerable antagonism of CB1 receptor was observed by 1-10 microm concentrations indicating that synthesized compounds were CB2 receptor selective.