Fe3O4-Supported Macroacyclic Schiff-Base Copper Complex: A valuable Heterogeneous Nanocatalyst for One-Pot Synthesis of New Pyrano[2,3- b]pyridine-3-carboxamide Derivatives

Over the following few decades, environmental problems and green chemistry have becomeincreasingly important issues and much effort has been directed towards the development ofsustainably enhanced and environmentally benign synthetic procedures for organic chemistry[1]. In this context, a growing field of research in green chemistry has been devoted to the developmentof a wide variety of recyclable, eco-friendly, selective, easily accessible, and economicallyviable catalysts, and their application in chemical transformations and industrialfields [2, 3]. A novel macroacyclic Cu(II) Schiff-base complex immobilized on core-shellmagnetic Fe3O4 nanoparticles [Fe3O4@SiO2-4N-Cu(II)] was successfully designed and synthesized.The structural features of these nanoparticles were studied and confirmed by usingvarious techniques including FT-IR, SEM, TEM, EDS, VSM, XRD, WDX and ICP. Thesesynthesized nanoparticles have been used as an efficient heterogeneous nanocatalytic systemfor the one-pot multicomponent synthesis of new pyrano[2,3-b]pyridine-3-carboxamide derivatives(Fig. 1). Notably, the catalyst could be easily separated from the reaction mixture byusing an external magnet and reused for several successive reaction runs with no significantloss of activity or copper leaching. The present protocol benefits from a hitherto unreportedMNPs-immobilized macroacyclic Cu(II) Schiff-base complex as an efficient nanocatalyst forthe synthesis of newly reported derivatives of pyrano[2,3-b]pyridine-3-carboxamide.