sulfonic acid supported on fe2o3/vo2 nanocatalyst: a highly efficient and reusable nanocatalyst for synthesis of spirooxindole derivatives

Fe2o3/vo2/so3h nanocatalyst is reported for simple, and three-component reaction for the synthesis of spirooxindole derivatives by the reaction of isatin, 1,3-cyclohexadiene and malonitrile in solvent-free condition. the method allows easy construction of a library of spirooxindoles in moderate to good yields. the prepared nanocomposite was characterized using fourier transform infrared spectroscopy (ft-ir), scanning electron microscopy (sem), x-ray diffraction (xrd) analysis, and energy dispersive x-ray spectroscopy (edx). the nanocomposite was easily recovered using an external magnet and reused several times without a significant loss of the efficiency.