Nickel supported on magnetic biochar as a highly efficient and recyclable heterogeneous catalyst for the one-pot synthesis of spirooxindole-dihydropyridines

Magnetic materials show promising applications in heterogeneous catalysis because of their ease of separation and good reusability. The present work reports the design, synthesis, and characterization of a novel magnetic biochar supported nickel catalyst. Fourier infrared spectroscopy (FT-IR), powder X-ray diffraction technology (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM) techniques were used for analyzing the prepared catalyst. The prepared catalyst exhibited excellent catalytic activity for synthesis of spirooxindole-dihydropyridines derivatives by a one-pot three-component reaction of isatin, barbituric acid, and 6-amino uracil or 1H-pyrazol-5-amine. This new methodology demonstrated some important features, including high yields, lower loading of the catalyst, easy work-up, and recyclability of the catalyst for a minimum of six times without an obvious decay of catalytic performance.