Strong Organic Bases as Building Blocks of Mesoporous Hybrid Catalysts for C–C Forming Bond Reactions

Díaz Morales Urbano Manuel, Gianotti Enrica, Velty Alexandra Isabelle Lucienne, Corma Canós Avelino

2012

European Journal of Inorganic Chemistry

1,8-Bis(tetramethylguanidino)naphthalene (TMGN), a neutral organic base that combines the properties of guanidine and the properties of proton sponges, was used as a building block to produce organic–inorganic silica-based mesoporous hybrids with strong basic properties. The TMGN-based mesoporous hybrids (TMGN/SiO2) were prepared by a sol– gel route working at a neutral pH and low temperatures, which avoided the use of SDAs. TMGN has been modified in order to have two terminal reactive silyl groups able to perform co-condensation with a conventional organosilane (TMOS) used as a silicon source. This synthesis has allowed us to directly introduce the unmodified, functionalized TMGN as part of the walls of the mesoporous silica by a onepot synthesis. TMGN/SiO2 hybrid materials present excellent catalytic properties for C–C bond forming reactions: Knoevenagel, Henry (nitroaldol), and Claisen–Schmidt condensations. The activity of the hybrid materials is higher than that of the counterpart homogeneous catalyst.