Functionalized Magnetic Mesoporous Silica Nanoparticle-Supported Palladium Catalysts for Carbonylative Sonogashira Coupling Reactions of Aryl Iodides

Magnetic mesoporous silica nanoparticles (MMSN) were prepared and used as a support for palladium catalysts. MMSN with a surface area of 1909 m² g^-1 were synthesized by a nanoemulsification process involving the dispersion of hydrophobic magnetite nanoparticles in chloroform in the presence of cetyltrimethylammonium bromide, followed by the addition of tetraethoxysilane and its polycondensation by a sol-gel route. The MMSN were modified with phosphine and N-heterocyclic carbene-based ligands, which provided coordination sites for conjugation with a palladium catalyst. These modified particles were fully characterized and employed as catalyst nanosupports. The palladium catalyst was immobilized on the surface and within the pores of MMSN and applied in copper-free carbonylative Sonogashira coupling reactions of aryl iodides with terminal alkynes.