Highly active hybrid mesoporous silica-supported base organocatalysts for C-C bond formation

New base hybrid catalysts, based on silyl-derivatives of molecules carrying amino, diamino, pyrrolidine, pyrazolium and imidazolium functionalities have been successfully achieved through post synthetic grafting onto M41S-type support. Different characterization techniques were implemented to study the characteristics of the materials, such as elemental analysis, solid state MAS NMR and FTIR spectroscopies, X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TGA-DTA) and textural properties through N-2 physisorption analysis. The catalytic activity and recyclability of these compounds as base catalysts was demonstrated for C-C bond forming reactions such as Knoevenagel condensations and Michael additions rationalizing the differences observed as function of the reaction mechanisms. An enamine mechanism was proposed for Knoevenagel condensations and an enolate mechanism for Michael additions.