Palladium containing nanostructured silica functionalized with pyridine sites: a versatile heterogeneous catalyst for Heck, Sonogashira, and cyanation reactions

Nanostructured hybrid silica bearing pyridine binding sites was prepared in a template assisted hydrolysis–polycondensation of tetraethylorthosilicate (TEOS) and the ionic precursor N,N-dimethyl-pyridin-4-yl-(3-triethoxysilyl-propyl)-ammonium iodide using N-dodecyl-N′-methyl-imidazolium bromide as structure directing agent. After treatment with palladium acetate, the material appeared as a versatile heterogeneous catalyst for Heck, Sonogashira, and cyanation reactions. In Heck and Sonogashira cross-coupling reactions, unchanged catalytic activity was observed in at least five reaction cycles.