Silica-Supported Magnetic Nanoparticles Functionalized with Phosphorus Species (Fe₃O₄@SiO₂–O–PCl₂): An Efficient and Recyclable Catalyst for the One-Pot Synthesis of Isatin-Based Imidazoles under Mild and Green Conditions

The synthesis, characterization, and catalytic activity of a novel magnetic nanocatalyst based on phosphorus-functionalized silica-coated iron oxide nanoparticles (Fe₃O₄@SiO₂–O–PCl₂) are described. The prepared nanocatalyst was characterized using FTIR, XRD, VSM, TGA/DTG, FESEM, SEM–EDX, and mapping techniques. Its catalytic performance was evaluated in a one-pot three-component reaction of aromatic aldehydes, isatin, and ammonium acetate to afford a series of substituted ۲-phenyl-۳,۴-dihydroimidazo[۴,۵-b]indoles with yields of up to ۹۰%. The method offers several advantages, including mild reaction conditions, short reaction times (۱ h), high product yields, and excellent catalyst reusability (up to ۵ cycles with only a slight loss of activity). The magnetic nature of the catalyst enables facile recovery using an external magnet, making this protocol economically and environmentally benign.

کلیدواژه ها:

۲‑Phenyl‑۳ ، ۴‑dihydroimidazo[۴ ، ۵‑b]indoles ، Heterocyclic compounds ، Multicomponent reactions