Bismuth triflate: A highly efficient catalyst for the synthesis of bio-active coumarin compounds via one-pot multi-component reaction

A series of coumarin-chalcone hybrid compounds and coumarins linked to pyrazoline was synthesized in good yield and short time using a simple and efficient method. This method involved the one-pot reaction of salicylaldehyde, an alpha-ketoester and an aromatic aldehyde (in the case of the coumarin-chalcone derivatives) in addition to hydrazine hydrate (in the case of the pyrazolyl coumarins) in the presence of a catalytic amount of bismuth triflate [Bi(OTf)(3), 5 mol%]. The synthesized compounds showed scavenging activity towards the free radical 2,2-diphenyl-1-picrylhydrazyl. All compounds were characterized using IR, H-1 NMR and C-13 NMR spectroscopy. (C) 2015, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.