A green and chemoselective synthesis of coumarins via Pechmann condensation using recoverable heterogeneous catalyst (Au@pSiO2)

Nano Au@porous SiO2 as a heterogeneous catalyst was prepared and characterized by Fourier transform infrared, X-ray powder diffraction, transmission electron microscopy, thermogravimetric analysis and inductively coupled plasma-atomic emission spectroscopy techniques and then used as an efficient catalyst in the condensation of various phenols with ethyl acetoacetate for the preparation of coumarin derivatives through the Pechmann reaction. The combined merits of chemoselective and solvent free reaction conditions and the recyclability of the nanostructured catalyst make the condensation a safe operation, with low pollution, rapid access to products and simple workup.