DYNAMIC KINETIC RESOLUTION AND ASYMMETRIC TRANSFORMATIONS BY ENZYME-METAL COMBINTIONS

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Recyclable gold nanoparticle catalyst for the aerobic alcohol oxidation and C-C bond forming reaction between primary alcohols and ketones under ambient conditions

A recyclable gold catalyst is synthesized from readily available reagents by immobilizing gold nanoparticles in aluminum oxyhydroxide support through a simple sol-gel method. The catalyst showed the high activity even at room temperature in the aerobic oxidation of various alcohols and in the coupling reaction between primary alcohols and ketones. (C) 2008 Elsevier Ltd. All rights reservedclose626

Ruthenium-Catalyzed, One-Pot Alcohol Oxidation-Wittig Reaction Producing alpha,beta-Unsaturated Esters"

By a one-pot process, alpha,beta-unsaturated esters were synthesized in high yield through the Ru-catalyzed oxidation of primary alcohols and the coupling of the resulting aldehydes and stabilized Wittig reagents. The ruthenium catalyst is composed of ruthenium nanoparticles embedded in aluminum oxyhydroxide and can be recovered simply by filtration or decantation. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009close212

Ruthenium Bisammine Complex and Its Reaction with Aryl Azides

A ruthenium bisammine complex was formed in the reaction of ruthenium 1,4-dibenzyltetraazadiene complex with primary amines at room temperature, which was a versatile precursor for the synthesis of various Ru(II) complexes through ligand exchange reactions. In the reaction with azidobenzene, ruthenium 1,4-diphenyltetraaza-1,3-diene complex was formed, while ruthenium imido complexes were given in the reaction with bulky aryl azides such as 2-azido-1,3-dimethylbenzene and 2-azido-1,3-diisopropylbenzene. The ruthenium imido complexes showed high catalytic activity in the reaction of alkyl azides with primary amines to afford N-substituted imines.11sciescopu

Ionic-surfactant-coated subtilisin: activity, enantioselectivity, and application to dynamic kinetic resolution of secondary alcohols

In this work, we explored the utility of ionic-surfactant-coated Bacillus licheniformis subtilisin (ISCBLS) as the catalyst for the dynamic kinetic resolution of secondary alcohols. ISCBLS was prepared by freeze-drying Bacillus licheniformis subtilisin with both ionic surfactant 1 and dextrin. ISCBCL displayed 9300-fold enhanced activity relative to its native counterpart in the transesterificaion of N-acetyl phenylalanine ethyl ester with 1-propanol in hexane and 12 800-fold enhanced activity in the transesterification of trifluoroethyl butyrate with 1-phenylethanol in THF. The enantioselectivity of ISCBLS was examined with 50 secondary alcohols as the substrates for kinetic resolution in the presence of trifluoroethyl butyrate. ISCBLS displayed synthetically useful enantioselectivity for most of the secondary alcohols tested. The enantioselectivity of ISCBLS was in particular good to high for m-or p-substituted 1-phenylethanols. The DKRs of these secondary alcohols by the combination of ISCBLS and a ruthenium-based racemization catalyst provided the products of (S)-configuration with good results (80-94% yield, 90-99% ee). It is concluded that ISCBLS is of great use as the enantiocomplementary counterpart of (R)-selective lipase for the dynamic kinetic resolution of secondary alcohols.11sciescopu

Rhodium and iridium nanoparticles entrapped in aluminum oxyhydroxide nanofibers: Catalysts for hydrogenations of arenes and ketones at room temperature with hydrogen balloon

The recyclable metal nanoparticle catalysts, rhodium in aluminum oxyhydroxide [Rh/AlO(OH)] and iridium in aluminum oxyhydroxide [Ir/AlO(OH)], were simply prepared from readily available reagents. The catalysts showed high activities in the hydrogenation of various arenes and ketones under mild conditions. Selective hydrogenation was possible for bicyclic and tricyclic arenes in high yields. The catalysts were active at room temperature even with a hydrogen balloon. Also, the catalysts showed high turnover frequency (TOF) values under solventless conditions at 75 degrees C under 4 atm hydrogen pressure: ca. 1700 h(-1) in the hydrogenation of benzene. Furthermore, Rh/AlO(OH) can be reused for at least 10 times without activity loss. The catalysts were characterized by the transmission electron microscopy (TEM), powder X-ray diffraction (XRD), inductively coupled plasma (ICP), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption and hydrogen chemisorption experiments. The sizes of rhodium and iridium particles were estimated to be 3-4 nm and 2-3 nm, respectively. Aluminum oxyhydroxide nanofibers of these catalysts have surface areas of 500-600 m(2)g(-1)close50575

Magnetically separable Pd catalyst for highly selective epoxide hydrogenolysis under mild conditions

A magnetically separable palladium catalyst was synthesized simply through a sol-gel process incorporating palladium nanoparticles and superparamagnetic iron oxide nanoparticles in aluminum oxyhydroxide matrix, which is highly active and selective for epoxide hydrogenolysis at room temperature under 1 atm H-2. The catalyst was recycled for 25 times without loss of the activityclose323

Palladium nanoparticles entrapped in aluminum hydroxide: Dual catalyst for alkene hydrogenation and aerobic alcohol oxidation

A new aluminum hydroxide-supported palladium catalyst (1) made by a one-pot synthesis through nanoparticle generation and gelation shows a dual catalytic activity for olefinic hydrogenation and aerobic alcohol oxidationclose1231

Facile synthesis of (eta5-Ph4C4COH)(CO)2RuCl and Catalytic Oxidation of Alcohols with Chloroform

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