Preparation Of Supported Chiral Ruthenium Catalyst And Its Catalytic Activity

As the increasing of environmental pollution and people environmental protection consciousness enhancement, green chemistry arises at the historic monment. The immobilized catalyst is an important research category of green chemistry, which not only solved the problem of homogeneous catalyst’s recycling, but also overcome the issue of environmental pollution.Among the supports of the immobilized catalysts, mesoporous silica nanospheres(MSNs) have been widely concerned in academic world, because they have large surface area, controllable pore size, high thermodynamic and mechanical stability. At the same time, silane with different chemical groups can be introduced to the MSNs by means of copolymerization or post-synthesis.These modification could endow MSNs with specific physicochemical property, such as hydrophobicity, hydrophilicity and so on. These specific properties may improve the catalytic rate and enanioselectivity of immobilized catalysts to some extent.(1):Organoruthenium-functionalized hydrophobic mesoporous silica nanospheres are prepared through the con-condensation of hexadecyl trimethyl ammonium bromide, tetraethyl-orthosilicate, diphenyldichlorosilicane and 4-(trimethoxysilyl)ethyl) phenylsulfonyl-1,2-diphenylethylene-diamin followed by complexation with an organoruthenium complex. It displays high enantioselectivity in the asymmerrtic reductions of α?Ketoimides and α?benzyloxy-β-Ketophosphonates. It is worth mentioned that the asymmetric reaction of α?Ketoimides catalyzed by heterogeneneous catalyst has the reaction rate higher than that attained with its homogeneous counterpart.(2):Organoruthenium-functionalized mesoporous silica nanospheres are prepared through the the con-condensation of hexadecyl trimethyl ammonium bromide、tetraethyl-orthosilicate and chiral 4-(trimethoxysilyl)ethyl)phenylsufoyl-1,2-diphenyphenylsufoyl-1,2-diphenylethylene-diamin followed by complexation with an organoruthenium complex. It displays high catalytic activity and enantioselectivity in the asymmerrtic reductions of isobenzofuran-1(3H)-ones. Futhermore, this heterogeneous catalyst can be conveniently recovered and reused for many times, showing particularly attractive in the practice of organic synthesis.