Asymmetric benzoylation of hydrobenzoin by copper(II) bis(oxazoline) anchored onto ordered mesoporous silicas and their carbon replicas
authors Silva, AR; Carneiro, L; Carvalho, AP; Pires, J
nationality International
journal CATALYSIS SCIENCE & TECHNOLOGY
keywords FUNCTIONALIZED ACTIVATED CARBONS; ENANTIOSELECTIVE CATALYSIS; HETEROGENEOUS CATALYSTS; KINETIC RESOLUTION; CHIRAL CATALYSTS; COMPLEXES; LIGANDS; IMMOBILIZATION; EPOXIDATION; ACETYLACETONATE
abstract A copper(II) complex with a commercial chiral bis(oxazoline) was anchored onto ordered mesoporous silica materials and their respective carbon replicas. The amount of transition metal complex loaded onto the mesostructured solids was determined by ICP-AES and the materials were also characterized by elemental analysis, FTIR, TG/DSC and isotherms of N-2 adsorption at -196 degrees C. For the first time the asymmetric benzoylation of a 1,2-diol was performed in the heterogeneous phase by using an anchored commercial bis(oxazoline) ligand. The effect of the type of mesoporous material on the catalytic parameters, as well as on the reutilization of catalysts in several catalytic cycles, was checked. All the composites prepared were active, selective and enantioselective in this asymmetric organic transformation. Using the two ordered mesoporous silicas as supports good selectivities, with comparable yields and TONs to the homogeneous phase reaction, were obtained. Furthermore these two heterogeneous catalysts are more stable upon reuse than the corresponding ordered carbon replica materials. One of the former heterogeneous catalysts, with mesoporous silica as a support, could be further reused for 4 consecutive cycles without significant loss of selectivity, the TON or enantioselectivity.
publisher ROYAL SOC CHEMISTRY
issn 2044-4753
year published 2013
volume 3
issue 9
beginning page 2415
ending page 2424
digital object identifier (doi) 10.1039/c3cy00232b
web of science category Chemistry, Physical
subject category Chemistry
unique article identifier WOS:000322780200032
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