Poly(vinylpyridine)-Grafted Silica Containing Palladium or Nickel Nanoparticles as Heterogeneous Catalysts for the Sonogashira Coupling Reaction

Efficient catalytic systems based on palladium and nickel nanoparticles supported on poly(4‐vinylpyridine) (P4VPy)‐grafted silica were prepared. After preparation of P4VPy‐grafted silica, complexation with PdCl2 and NiCl2 was carried out to obtain the heterogeneous catalytic systems. Scanning and transmission electron microscopy (SEM and TEM) showed that palladium and nickel particles on the nanoscale were dispersed throughout the surface. Under copper‐, amine‐, and phosphine‐free conditions, the palladium catalyst exhibited excellent activity in the Sonogashira cross‐coupling reaction. An amine‐ and phosphine‐free nickel‐catalyzed Sonogashira reaction in the presence of CuI as a cocatalyst was also performed successfully. In both systems phenylacetylene reacted with aryl iodides, bromides, and chlorides in high yield and over short reaction times. Offering support: Catalytic systems based on palladium and nickel nanoparticles supported on poly(4‐vinylpyridine) (P4VPy)‐grafted silica for efficient use in Sonogashira reactions have been prepared (see figure). These heterogeneous catalysts exhibit excellent activity under amine‐ and phosphine‐free conditions. The Ni catalyst can be an inexpensive alternative to Pd catalysts.