Green multicomponent synthesis of four different classes of six-membered N-containing and O-containing heterocycles catalyzed by an efficient chitosan-based magnetic bionanocomposite

摘要

In this work, an efficient chitosan-based magnetic bionanocomposite was synthesized via a two-step method and characterized by Fourier-transform infrared (FT-IR) spectroscopy, thermo gravimetric analysis (TGA), energy-dispersive X-ray (EDX) analysis and scanning electron microscopy (SEM) images. Then, it was used as a heterogeneous catalyst for the one-pot multicomponent syntheses of a variety of heterocyclic compounds including 2-amino-4H-pyrans, 2-amino-4H-chromens and polyhydroquinoline derivatives in ethanol at room temperature. The catalyst was simply separated from the reaction mixture by an external magnet and reused several times. The products were isolated from the reaction mixtures, without any need of column chromatography, in high-to-excellent yields. A reusable and easily recoverable catalyst, use of a green solvent, room temperature and mild reaction conditions are some advantages of the present work.