Ni2+ supported on hydroxyapatite-core@shell gamma-Fe2O3 nanoparticles as new and green catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free condition

The aim of this research is to study Ni2+ supported on hydroxyapatite-core-shell magnetic gamma-Fe2O3 nanoparticles (gamma-Fe2O3@HAp-Ni2+) as a green and recyclable catalyst for the Biginelli reaction under solvent-free conditions. One-pot multi-component condensation of 1,3-dicarbonyl compounds, urea and aldehydes at 80 degrees C affords the corresponding compounds in high yields and in short reaction times using gamma-Fe2O3@HAp-Ni2+. The catalyst can be readily isolated using an external magnet and no obvious loss of activity was observed when the catalyst was reused in seven consecutive runs. The mean size and the surface morphology of the nanoparticles were characterized by transmission electron microscopy, scanning electron microscope, vibrating sample magnetometry, X-ray powder diffraction and Fourier transform infrared techniques.