Ceric Ammonium Nitrate Immobilized on Linoleic Acid-Functionalized FeO Nanoparticles as a Magnetically Recyclable Catalyst for C3-Selective Formylation of N-H Indoles.

In this study, a novel magnetically recyclable catalyst was developed by immobilizing ceric ammonium nitrate (CAN) onto linoleic acid-functionalized magnetite nanoparticles (FeO-LA@CAN). The catalyst was thoroughly characterized using FT-IR, XRD, TEM, SEM-EDX, VSM, TGA, and N adsorption-desorption analyses. The catalytic efficiency of FeO-LA@CAN was evaluated in the C3-selective formylation of free (N-H) indole derivatives, exhibiting excellent activity and broad substrate scope. The catalyst was easily recovered from the reaction mixture using an external magnet and demonstrated remarkable reusability for at least ten consecutive cycles without significant loss in performance. This efficient, green, and reusable catalytic system provides a promising alternative to conventional formylation methods and highlights its potential for sustainable synthetic applications.