Synthesis of benzoxanthene‐triones and tetrahydrochromenoxanthene tetraones via three‐ or pseudo–five‐component reactions using Fe3O4@SiO2/PEtOx as a novel, magnetically recyclable, and eco‐friendly nanocatalyst

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.