in potent CB2 antagonists (27 or 28, IC50 = 16–28 nM). Replacement of the amidoalkyls from 3-position to the 2-position of the indole ring dramatically increased the agonist selectivity on the CB2 over CB1 receptor. Particularly, compound 57 displayed a potent agonist activity on the CB2 receptor (EC50 = 114–142 nM) without observable agonist or antagonist activity on the CB1 receptor. Furthermore,