Research on Thia-Michael Addition Tandem Reactions Catalyzed by AlCl3@MNPs

Magnetic nanoparticles (MNPs), prepared by co-precipitation method, were coated using hydrolysis of tetraethyl orthosilicate (TEOS) under basic conditions. The core-shell structured supporters were further grafted by AlCl3 to obtain the finally catalyst AlCl3@MNPs, which was fully characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM), indicating the successful immobilization of AlCl3 on the surface of the MNPs through coordination bond, and the magnetic nanoparticles supported aluminum chloride AlCl3@MNPs was used in the thia-Michael addition tandem reactions. The as-prepared catalyst AlCl3@MNPs promoted smoothly the reaction of amines, carbon disulfide and a,ss-unsaturated carbonyl compounds to achieve good to excellent product yields of 59%similar to 99%. Large surface area, excellent dispersion of catalyst in reaction solution and coordinative bond between AlCl3 and hydroxyl cluster in MNPs ensure the highly catalytic efficiency. In addition, AlCl3@MNPs can be readily recovered with external magnetic field and recycled for 10 times without significant loss of catalytic activity, demonstrating its advantage over the precursor AlCl3 and excellent potential in industrial application.