1,6-Dihydro-2H-indeno[5,4-b]furan Derivatives: Design, Synthesis, and Pharmacological Characterization of a Novel Class of Highly Potent MT2-Selective Agonists

A novel series of 1,6-dihydro-2H-indeno[5,4-b]furan derivatives were designed and synthesized as MT2-selective ligands. This scaffold was identified as a potent mimic of the 5-methoxy indole core of melatonin, and introduction of a cyclohexylmethyl group at the 7-position of this scaffold afforded an MT2-selective ligand 15 (Ki = 0.012 nM) with high MT1/MT2 selectivity (799). Compound 15 was identified as a potent full agonist for the MT2 subtype and exhibited reentrainment effects to a new light/dark cycle in ICR mice at 3−30 mg/kg. This result demonstrated the involvement of the MT2 receptors in chronobiotic activity.