1517-70-0Relevant articles and documents
A New Class of "Tethered" Ruthenium(II) Catalyst for Asymmetric Transfer Hydrogenation Reactions
Hannedouche, Jerome,Clarkson, Guy J.,Wills, Martin
, p. 986 - 987 (2004)
Ruthenium dimer 4 is converted directly to monomeric asymmetric transfer hydrogenation catalyst 2 under the conditions employed for ketone reduction. Using 0.25 mol % of either 4 or 0.5 mol % of 2 in formic acid/triethylamine, it is possible to achieve ketone reduction in quantitative conversion and with ee's as high as 98%. Complex 2 is a robust "single-reagent" catalyst which offers significant scope for modification toward specific substrates. The synthesis and applications of an analogous complex derived from (1R,2S)-norephedrine are also described. Copyright
Biocatalytic anti-Prelog stereoselective reduction of 4′- methoxyacetophenone to (R)-1-(4-methoxyphenyl)ethanol with immobilized Trigonopsis variabilis AS2.1611 cells using an ionic liquid-containing medium
Lou, Wen-Yong,Wang, Wei,Smith, Thomas J.,Zong, Min-Hua
, p. 1377 - 1384 (2009)
The biocatalytic anti-Prelog enantioselective reduction of 4′-methoxyacetophenone (MOAP) to (R)-1-(4-methoxyphenyl)ethanol {(R)-MOPE} using immobilized Trigonopsis variabilis AS2.1611 cells was, for the first time, successfully conducted in an ionic liqui
New Homochiral Binaphthol-Modified Organolanthanide Reagents for the Enantioselective Addition to Aldehydes
Chibale, Kelly,Greeves, Nicholas,Lyford, Lisa,Pease, J. Elizabeth
, p. 2407 - 2410 (1993)
Optically active secondary alcohols were obtained in high chemical yield and optical purity (up to 85percent ee) from the lanthanide-mediated enantioselective addition of alkyl nucleophiles to aromatic aldehydes.
Facile synthesis of a mesoporous silica-supported catalyst for Ru-catalyzed transfer hydrogenation of ketones
Liu, Guohua,Yao, Mei,Zhang, Fang,Gao, Yan,Li, Hexing
, p. 347 - 349 (2008)
A convenient method for preparation of a mesoporous silica-supported chiral catalyst by postgrafting a homogeneous catalyst on SBA-15 was developed and its application in the asymmetric transfer hydrogenation of aromatic ketones was investigated. The Roya
Immobilization of marine fungi on silica gel, silica xerogel and chitosan for biocatalytic reduction of ketones
Rocha, Lenilson Coutinho,De Souza, Adriano Lopes,Rodrigues Filho, Ubirajara Pereira,Campana Filho, Sergio Paulo,Sette, Lara Duraes,Porto, Andre Luiz Meleiro
, p. 160 - 165 (2012)
The scanning electron microscopy (SEM) analysis showed that whole living hyphal of marine fungi Aspergillus sclerotiorum CBMAI 849 and Penicillium citrinum CBMAI 1186 were immobilized on support matrices of silica gel, silica xerogel and/or chitosan. P. citrinum immobilized on chitosan catalyzed the quantitative reduction of 1-(4-methoxyphenyl)-ethanone (1) to the enantiomer (S)-1-(4-methoxyphenyl)-ethanol (3b), with excellent enantioselectivity (ee > 99%, yield = 95%). Interestingly, ketone 1 was reduced with moderate selectivity and conversion to alcohol 3b (ee = 69%, c 40%) by the free mycelium of P. citrinum. This free mycelium of P. citrinum catalyzed the production of the (R)-alcohol 3a, the antipode of the alcohol produced by the immobilized cells. P. citrinum immobilized on chitosan also catalyzed the bioreduction of 2-chloro-1-phenylethanone (2) to 2-chloro-1-phenylethanol (4a,b), but in this case without optical selectivity. These results showed that biocatalytic reduction of ketones by immobilization hyphal of marine fungi depends on the xenobiotic substrate and the support matrix used.
Stereoselective reduction of ketones by histidine-alkoxysilane complexes: The role of imidazole in nucleophilic substitution at silicon
LaRonde, Frank J.,Brook, Michael A.
, p. 3507 - 3510 (1999)
The reduction of carbonyl compounds with transient, hypervalent silicon hydrides is described. Trialkoxysilanes, upon activation by a catalytic amount of lithium imidazolide or the mono or dilithium salt of histidine, but not by neutral imidazole or histi
Dithiourea ligands in the rhodium-catalyzed hydride-transfer reduction of ketones - A theoretical and experimental approach
Bernard, Maud,Delbecq, Fran?oise,Fache, Fabienne,Sautet, Philippe,Lemaire, Marc
, p. 1589 - 1596 (2001)
Various dithioureas bearing an aromatic ring on their terminal nitrogen atoms have been synthesized. These have been tested in the asymmetric reduction of ketones as catalyzed by a rhodium complex. The influence of electron-withdrawing and electron-donating substituents on the aromatic rings on the reactivity and the enantiomeric excess (ee) has been assessed. The coordination modes of a model thiourea have been studied by Density Functional Theory (DFT) calculations. The electronic effects have also been analyzed and an interpretation of the variation in the enantiomeric excess, based on a supposed change in the coordination mode, is given.
Nickel-Catalyzed Enantioselective Hydroboration of Vinylarenes
Tran, Hai N.,Stanley, Levi M.
supporting information, p. 395 - 399 (2021/12/27)
The enantioselective hydroboration of vinylarenes catalyzed by a chiral, nonracemic nickel catalyst is presented as a facile method for generating chiral benzylic boronate esters. Various vinylarenes react with bis(pinacolato)diboron (B2pin2) in the presence of MeOH as a hydride source to form chiral boronate esters in up to 92% yield with up to 94% ee. The use of anhydrous Me4NF to activate B2pin2 is crucial for ensuring fast transmetalation to achieve high enantioselectivities.
Cinchona-Alkaloid-Derived NNP Ligand for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
Zhang, Lin,Zhang, Ling,Chen, Qian,Li, Linlin,Jiang, Jian,Sun, Hao,Zhao, Chong,Yang, Yuanyong,Li, Chun
supporting information, p. 415 - 419 (2022/01/12)
Most ligands applied for asymmetric hydrogenation are synthesized via multistep reactions with expensive chemical reagents. Herein, a series of novel and easily accessed cinchona-alkaloid-based NNP ligands have been developed in two steps. By combining [Ir(COD)Cl]2, 39 ketones including aromatic, heteroaryl, and alkyl ketones have been hydrogenated, all affording valuable chiral alcohols with 96.0-99.9% ee. A plausible reaction mechanism was discussed by NMR, HRMS, and DFT, and an activating model involving trihydride was verified.
Dynamic Kinetic Resolution of Alcohols by Enantioselective Silylation Enabled by Two Orthogonal Transition-Metal Catalysts
Oestreich, Martin,Seliger, Jan
, p. 247 - 251 (2020/10/29)
A nonenzymatic dynamic kinetic resolution of acyclic and cyclic benzylic alcohols is reported. The approach merges rapid transition-metal-catalyzed alcohol racemization and enantioselective Cu-H-catalyzed dehydrogenative Si-O coupling of alcohols and hydrosilanes. The catalytic processes are orthogonal, and the racemization catalyst does not promote any background reactions such as the racemization of the silyl ether and its unselective formation. Often-used ruthenium half-sandwich complexes are not suitable but a bifunctional ruthenium pincer complex perfectly fulfills this purpose. By this, enantioselective silylation of racemic alcohol mixtures is achieved in high yields and with good levels of enantioselection.
