Direct Ortho C–H Arylation of Benzamides/Benzoic Acids with Aryl Iodide Catalyzed by a Pyridine-2-carboimine Pd Complex Immobilized on Amine-Functionalized Magnetic Nanoparticles

A magnetically reusable pyridine-2-carboimine Pd complex immobilized on amine-functionalized magnetic nanoparticles (Fe3O4-DA-2Py-Pd) has been successfully synthesized for its dual function in the direct ortho-C–H arylation of benzamides/benzoic acids with aryl iodide and is demonstrated for the first time. Powder XRD studies reveal single-phased crystalline behavior of the catalyst, and FTIR studies reveal the successful surface functionalization of Fe3O4 with dopamine and the consequent formation of the Schiff base, which is further confirmed by FE-SEM-EDAX analysis. Elemental composition and elemental mapping of the catalyst from EDAX study show the presence of all the elements (Pd, Fe, N, C, and O) and their uniform distribution across the surface of Fe3O4. The XPS analysis confirms the existence of Pd2+ in the catalyst, which is essential for the catalytic activity. The polycrystalline nature and presence of Pd in the catalyst is further confirmed by HRTEM studies. The magnetic parameters measured by VSM confirms the magnetic retrievability of the catalyst. The stability of the catalyst is confirmed by TGA studies. The substrate scope of the catalyst was validated by considering substituted benzamides, benzoic acids, and substituted aryl iodides where it gave 61 to 82% yields of the targeted product in ortho arylation of benzamide and gave 70–88% of the product in the case of ortho-arylation of benzoic acid. The catalyst can be magnetically recovered and reused several times without significant loss in catalytic activity. ICP-OES analysis of the recovered catalyst shows less Pd leaching. The catalyst shows good structural stability, as confirmed by XRD and FTIR analyses of the recovered catalyst.