Supported molybdenum on graphene oxide/Fe3O4: An efficient, magnetically separable catalyst for one-pot construction of spiro-oxindole dihydropyridines in deep eutectic solvent under microwave irradiation

Magnetically separable graphene oxide supported molybdenum (Fe3O4/GO-Mo) nanoparticles were prepared and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometry (VSM) techniques. The synthesized heterogeneous material was found to exhibit high catalytic activity in one-pot, three-component reaction of isatins, malononitrile and anilinolactones using choline chloride (ChCl)/urea as a green solvent under microwave irradiation. It provided an efficient method for the synthesis of spirooxindole dihydropyridines in high to excellent yields. The catalytic system can be successfully reused eight times with a small decrease of its catalytic performance. (C) 2016 Elsevier B.V. All rights reserved.