Fe3O4@SiO2-SnCl4: An Efficient Catalyst for the Synthesis of Xanthene Derivatives under Ultrasonic Irradiation

Grafting of SnCl4 on the Fe3O4@SiO2 nanoparticles afforded Fe3O4@SiO2-SnCl4 as a novel inorganic heterogenous catalyst, which was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM), Field Emission Scanning Electron Microscopy (FE-SEM), and transmission electron microscopy (TEM). In this research, we report a convenient and efficient direct protocol for the preparation of xanthene derivatives via condensation of -naphthol, dimedone, or mixture of -naphthol and dimedone with various aromatic aldehydes in the presence of the catalytic amount of Fe3O4@SiO2-SnCl4 under ultrasonic irradiation. This procedure has a lot of advantages such as: very easy reaction conditions, absence of any tedious workup, or purification, and much milder method. The corresponding products have been obtained in excellent yields, high purity, and short reaction times.