Graphene oxide based solid acid as an efficient and reusable nano-catalyst for the green synthesis of diindolyl-oxindole derivatives in aqueous media

摘要

Graphene oxide nanosheets were synthesized from natural graphite powder. The prepared catalyst was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, thermogravimetric analysis and ultraviolet–visible spectroscopy. This heterogeneous catalyst was used for the Friedel–Crafts 3-indolylation reaction of isatin with indole derivatives in water as a green media in good to excellent yields. This method has advantages including the use of water as a green solvent, short reaction time, easy workup and excellent yields.