53651-69-7Relevant articles and documents
Poly(3-hydroxyoctanoate) depolymerase from Pseudomonas fluorescens GK13: Catalysis of ester-forming reactions in non-aqueous media
Santos, Marta,Gangoiti, Joana,Llama, Maria J.,Serra, Juan L.,Keul, Helmut,Moeller, Martin
experimental part, p. 81 - 86 (2012/06/29)
Several industrial processes based on lipase catalysis have been established. However, since there are still a vast number of catalytic processes that lack a suitable enzyme, the discovery of new biocatalysts is required to fulfil this purpose. The potential of using the medium-chain-length (mcl)-PHA depolymerase from Pseudomonas fluorescens GK13 in anhydrous media to catalyze ester-forming reactions has been investigated and compared with that of Novozyme 435. The mcl-PHA depolymerase catalyzes the ring-opening polymerization of racemic β-butyrolactone (β-BL), l- and d-lactide (LLA, DLA) with high yield resulting in low molecular weight polymers. On the other hand, ε-caprolactone and pentadecalactone, which show high polymerizability using Novozyme 435 as catalyst, were not polymerized by mcl-PHA depolymerase. Besides, the activity of mcl-PHA depolymerase toward transesterification and esterification of ethyl-3-hydroxyoctanoate, lauric acid, (R,S)-β-BL, LLA and DLA has been studied.
Synthesis and characterization of chiral mono N-heterocyclic carbene-substituted rhodium complexes and their catalytic properties in hydrosilylation reactions
Steinbeck, Martin,Frey, Guido D.,Schoeller, Wolfgang W.,Herrmann, Wolfgang A.
scheme or table, p. 3945 - 3954 (2011/12/22)
Different chiral mono-substituted N-heterocyclic carbene complexes of rhodium were prepared, starting from [Rh(COD)Cl]2 (COD = cyclooctadiene) by addition of free N-heterocyclic carbenes (NHC), or an in-situ deprotonation of the corresponding iminium salt. All new complexes were characterized by spectroscopy methods. In addition, the structures of chloro(η4-1,5-cyclooctadiene)(1,3-di-[(1R,2R,3R,5S)-2,6, 6-trimethylbicyclo[3.1.1]hept-3-yl] imidazolin-2-ylidene)rhodium(I) (5a), chloro(η4-1,5-cyclooctadiene)(1,3-di-[(1R,2S,5R) -2-isopropyl-5-menthylcyclohex-1-yl]imidazol-2-ylidene)rhodium(I) (5b) and chloro(η4-1,5-cyclooctadiene)(1,3-di-[(2R,4S,5S) -2-methyl-4-phenyl-1,3-dioxacyclohex-5-yl]imidazolin-2-ylidene)rhodium(I) (5i) were analyzed by DFT-calculations. The enantioselective hydrosilylation of acetophenone, ethylpyruvate and n-propylpyruvate with diphenylsilane and hydrolysis was carried out with chiral C2-symmetrical mono-substituted N-heterocyclic carbene rhodium complexes giving for the first time an enantioselective excess of up to 74% ee in the case of the n-propylpyruvate.
Enantioselective hydrogenation of pyruvates over polymer-stabilized and supported platinum nanoclusters
Zuo, Xiaobin,Liu, Hanfan,Guo, Dawei,Yang, Xiaozhen
, p. 7787 - 7804 (2007/10/03)
The cinchonidine-modified enantioselective hydrogenation of pyruvates has been studied over polyvinylpyrrolidone-stabilized platinum (PVP-Pt) and the corresponding alumina-supported platinum (Al2O3-Pt) clusters. It is shown that the catalysts with particle size less than 2.0 nm demonstrate >90% enantioselectivity in favor of (R)-lactates. The solvent effect is similar to that over the conventional supported platinum catalyst except for tetrahydrofuran. These colloidal and supported clusters are stable with no obvious loss of activity and enantioselectivity even after 18 months standing in air at room temperature. Molecular mechanics calculations of the modifier- reactant interaction on the platinum surface suggest that it is possible to obtain good enantioselectivity on the small clusters.
