New melatonin (MT1/MT2) ligands: Design and synthesis of (8,9-dihydro-7H-furo[3,2-f]chromen-1-yl) derivatives

Abstract Herein we describe the synthesis of novel tricyclic analogues issued from the rigidification of the methoxy group of the benzofuranic analogue of melatonin as MT 1 and MT 2 ligands. Most of the synthesized compounds displayed high binding affinities at MT 1 and MT 2 receptors subtypes. Compound 6b (MT 1 , K i  = 0.07 nM; MT 2 , K i  = 0.08 nM) exhibited with the vinyl 6c and allyl 6d the most interesting derivatives of this series. Functional activity of these compounds showed full agonist activity with EC 50 in the nanomolar range. Compounds 6a (EC 50  = 0.8 nM and E max  = 98%) and 6b (EC 50  = 0.2 nM and E max  = 121%) exhibited good pharmacological profiles.