A series of potent indol-3-yl-tetramethylcyclopropyl ketones have been prepared as CB 2cannabinoid receptor ligands. Two unsubstituted indoles ( 5, 32) were the starting points for an investigation of the effect of indole ring substitutions on CB 2and CB 1binding affinities and activity in a CB 2in vitro functional assay. Indole ring substitutions had varying effects on CB 2and CB 1binding, but were generally detrimental to agonist activity. Substitution on the indole ring did lead to improved CB 2/CB 1binding selectivity in some cases (i.e., 7− 9, 15− 20). All indoles with the morpholino-ethyl side chain ( 32− 43) exhibited weaker binding affinity and less agonist activity relative to that of their tetrahydropyranyl-methyl analogs ( 5− 31). Several agonists were active in the complete Freund’s adjuvant model of chronic inflammatory thermal hyperalgesia ( 32, 15). [ABSTRACT FROM AUTHOR]