Eco-Friendly Synthesis of Highly Substituted Pyridines Using Magnetically Recoverable Fe₃O₄@Cu@Cu₂O Core-Shell Nanocatalysts

This research introduces a highly efficient, one-pot pseudo-three-component synthesis of multisubstituted pyridine derivatives using a novel magnetically recoverable Fe₃O₄@Cu@Cu₂O core-shell nanocatalyst. The catalyst, fabricated via co-precipitation and solvothermal techniques, was thoroughly characterized by XRD, FTIR, SEM, and VSM analyses, confirming its structural integrity, spherical morphology with an average size of ۴۵ nm, and superparamagnetic behavior with a saturation magnetization of ۲۸.۵ emu/g. It exhibited outstanding catalytic performance in the cyclocondensation of arylaldehydes, malononitrile, and various alcohols under ambient conditions, affording ۲-amino-۶-alkoxy-۴-arylpyridine-۳,۵-dicarbonitriles (۲) in excellent yields (۸۹–۹۶%) with remarkable functional group tolerance. A plausible domino mechanism involving Knoevenagel condensation, Michael addition, and oxidative aromatization, synergistically promoted by the Lewis acid, basic, and redox-active sites of the Cu/Cu₂O shell, was proposed. Notably, the catalyst's strong magnetic responsiveness enabled rapid separation within ۳۰ seconds and multiple reusability over eight cycles without significant loss of activity. This sustainable protocol highlights the significant potential of engineered core-shell nanomaterials in advancing green, heterogeneous catalytic systems for the efficient construction of pharmaceutically relevant heterocyclic scaffolds.

کلیدواژه ها:

Fe₃O₄@Cu@Cu₂O ، Magnetic separation ، Pyridine ، Green chemistry ، Multicomponent reactions