Synthesis and structure-activity relationship of 1H-indole-3-carboxylic acid pyridine-3-ylamides: a novel series of 5-HT2C receptor antagonists.

A novel series of 1H-indole-3-carboxylic acid pyridine-3-ylamides were synthesized and identified to show high affinity and selectivity for 5-HT(2C) receptor. Among them, 1H-indole-3-carboxylic acid[6-(2-chloro-pyridin-3-yloxy)-pyridin-3-yl]-amide (15k) exhibits the highest affinity (IC(50)=0.5 nM) with an excellent selectivity (>2000 times) over other serotonin (5-HT(1A), 5-HT(2A), and 5-HT(6)) and dopamine (D(2)-D(4)) receptors.