Environmentally benign synthesis of pyranopyrazole derivatives by cobalt Schiff-base complexes immobilized on magnetic iron oxide nanoparticles

Abstract

In this work, an efficient and straight procedure has been described for one-pot three-component synthesis of pyranopyrazole derivatives in the presence of a new cobalt Schiff-base complex immobilized on silica-coated Fe3O4 nanoparticles as a reusable catalyst. This new catalyst was characterized by different techniques, such as Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), inductively coupled plasma (ICP) and vibrating sample magnetometry (VSM). The described catalyst was efficiently tested in the synthesis of pyranopyrazoles via three-component condensation of different aromatic aldehydes, malononitrile and 3-methyl-1-phenyl-2-pyrazoline-5-one at room temperature with short reaction times, high yields and TON values up to 388. The considered catalyst can be reused several times without loss of its catalytic activity. Finally, we compared the results for the synthesis of desired products in the presence of our nanocatalyst with previously reported catalysts in the literature.