Synthesis of benzo[b]xanthene-triones and tetrahydrochromeno[2,3-b]xanthene tetraones via three- or pseudo-five-component reactions using Fe3O4@SiO2/PEtOx as a novel, magnetically recyclable, and eco-friendly nanocatalyst

摘要

In this study, poly(2-ethyl-2-oxazoline) (PEtOx) immobilized on Fe3O4 nanoparticles (Fe3O4@SiO2/PEtOx) has been constructed as a new, heterogeneous, efficient, and recyclable nanocatalyst. The prepared nanocatalyst was characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) analysis, and vibrating-sample magnetometer (VSM) techniques. Nanocatalyst was employed to synthesize benzo[b]xanthene-triones and tetrahydrochromeno[2,3-b]xanthene tetraones via one-pot three- or pseudo-five-component reaction between 2-hydroxy-1,4-naphthoquinone or 2,5-dihydroxy-1,4-benzoquinone, aldehyde, and dimedone or 1,3-cyclohexanedione under reflux condition in ethanol. The catalyst could be easily separated and recycled several times without considerable loss of activity. Clean methodology, easy work-up, mild reaction condition, short reaction time with good-to-excellent yields, and simple preparation of the catalyst are some advantages of the presented work.