120466-66-2Relevant articles and documents
Amino alcohol effects on the ruthenium(II)-catalysed asymmetric transfer hydrogenation of ketones in propan-2-ol
Takehara, Jun,Hashiguchi, Shohei,Fujii, Akio,Inoue, Shin-Ichi,Ikariya, Takao,Noyori, Ryoji
, p. 233 - 234 (1996)
A ruthenium(II) complex generated in situ from [{RuCl2(η6-C6Me6)}2], (1S,2S)-2-methylamino-1,2-diphenylethanol and KOH serves as an efficient catalyst for asymmetric transfer hydrogenation of acetophe
Pushing the limits: Cyclodextrin-based intensification of bioreductions
Rapp, Christian,Nidetzky, Bernd,Kratzer, Regina
, p. 57 - 64 (2021)
The asymmetric reduction of ketones is a frequently used synthesis route towards chiral alcohols. Amongst available chemo- and biocatalysts the latter stand out in terms of product enantiopurity. Their application is, however, restricted by low reaction output, often rooted in limited enzyme stability under operational conditions. Here, addition of 2-hydroxypropyl-β-cyclodextrin to bioreductions of o-chloroacetophenone enabled product concentrations of up to 29 % w/v at full conversion and 99.97 % e.e. The catalyst was an E. coli strain co-expressing NADH-dependent Candida tenuis xylose reductase and a yeast formate dehydrogenase for coenzyme recycling. Analysis of the lyophilized biocatalyst showed that E. coli cells were leaky with catalytic activity found as free-floating enzymes and associated with the biomass. The biocatalyst was stabilized and activated in the reaction mixture by 2-hydroxypropyl-β-cyclodextrin. Substitution of the wild-type xylose reductase by a D51A mutant further improved bioreductions. In previous optimization strategies, hexane was added as second phase to protect the labile catalyst from adverse effects of hydrophobic substrate and product. The addition of 2-hydroxypropyl-β-cyclodextrin (11 % w/v) instead of hexane (20 % v/v) increased the yield on biocatalyst 6.3-fold. A literature survey suggests that bioreduction enhancement by addition of cyclodextrins is not restricted to specific enzyme classes, catalyst forms or substrates.
Chiral Ru complex immobilized on mesoporous materials by ionic liquids as heterogeneous catalysts for hydrogenation of aromatic ketones
Lou, Lan-Lan,Dong, Yanling,Yu, Kai,Jiang, Shu,Song, Yang,Cao, Song,Liu, Shuangxi
, p. 20 - 27 (2010)
Four kinds of mesoporous material-supported ionic liquid phase catalysts containing chiral Ru complex were synthesized using mesoporous MCM-41, MCM-48, SBA-15 and amorphous SiO2, respectively. The results of N2 sorption and XRD indicated the successful immobilization of chiral Ru complex inside the channels of the mesoporous materials. These immobilized catalysts were evaluated in the asymmetric hydrogenation of aromatic ketones and the reaction conditions were optimized. Comparable catalytic activities and enantioselectivities to those of nonimmobilized counterpart were obtained. Moreover, all the four catalysts were stable and could be easily recovered for reuse for at least four times without obvious decrease in conversions and ee values. Especially, the SiO2-based catalyst still preserved high activity and enantioselectivity in the fifth run. The comparison experiments indicated that the two kinds of ionic liquids in the heterogeneous catalyst were beneficial to the enhancement of the stability of active species.
Stereoselective Reduction of Prochiral Ketones, Using Aluminum Hydride Reagents Prepared from LiAlH4 and Chiral Diethanolamines
Vries, Erik F.J. de,Brussee, Johannes,Kruse, Chris G.,Gen, Arne van der
, p. 377 - 386 (1994)
The asymmetric reduction of prochiral ketones to chiral secondary alcohols by LiAlH4, modified with optically active diethanolamines, was studied.Asymmetric inductions of up to 94percent were obtained with these reagents.The stereoselectivity of the reaction was found to depend both upon the temperature at which the reduction was performed and upon the conditions under which the chiral aluminum hydride reagent had been prepared.By changing the substituents at the carbon atom α to nitrogen in the chiral auxiliary, either the (R)- and (S)-enantiomer of the secondary alcohol could be obtained in excess.
Synthesis of a fluorous ligand and its application for asymmetric addition of dimethylzinc to aldehydes
Sokeirik, Yasser S.,Mori, Hiroyuki,Omote, Masaaki,Sato, Kazuyuki,Tarai, Atsushi,Kumadaki, Itsumaro,Ando, Akira
, p. 1927 - 1929 (2007)
A new fluorous ligand was synthesized from the acetonide of dimethyl tartarate, which showed excellent asymmetric induction on the addition of dimethylzinc to aldehydes. This ligand will be useful for synthesis of bioactive compounds with a methyl carbinol moiety. It could be recycled without using a fluorous solvent or a fluorous column.
Asymmetric transfer hydrogenation of aromatic ketones catalyzed by SBA-15 supported Ir(I) complex under mild conditions
Shen, Yanbin,Chen, Qiu,Lou, Lan-Lan,Yu, Kai,Ding, Fei,Liu, Shuangxi
, p. 104 - 109 (2010)
A heterogeneous catalyst of Ir(I)-9-amino epi-cinchonine complex immobilized on the surface of mesoporous SBA-15 was firstly synthesized and used in the asymmetric transfer hydrogenation of aromatic ketones. Enhanced enantioselectivity compared with homog
Kinetic resolution of secondary alcohols. Enantioselective acylation mediated by a chiral (dimethylamino)pyridine derivative
Vedejs, Edwin,Chen, Xinhai
, p. 1809 - 1810 (1996)
-
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.
Single-Point Mutant Inverts the Stereoselectivity of a Carbonyl Reductase toward β-Ketoesters with Enhanced Activity
Li, Aipeng,Wang, Ting,Tian, Qing,Yang, Xiaohong,Yin, Dongming,Qin, Yong,Zhang, Lianbing
, p. 6283 - 6294 (2021/03/16)
Enzyme stereoselectivity control is still a major challenge. To gain insight into the molecular basis of enzyme stereo-recognition and expand the source of antiPrelog carbonyl reductase toward β-ketoesters, rational enzyme design aiming at stereoselectivity inversion was performed. The designed variant Q139G switched the enzyme stereoselectivity toward β-ketoesters from Prelog to antiPrelog, providing corresponding alcohols in high enantiomeric purity (89.1–99.1 % ee). More importantly, the well-known trade-off between stereoselectivity and activity was not found. Q139G exhibited higher catalytic activity than the wildtype enzyme, the enhancement of the catalytic efficiency (kcat/Km) varied from 1.1- to 27.1-fold. Interestingly, the mutant Q139G did not lead to reversed stereoselectivity toward aromatic ketones. Analysis of enzyme–substrate complexes showed that the structural flexibility of β-ketoesters and a newly formed cave together facilitated the formation of the antiPrelog-preferred conformation. In contrast, the relatively large and rigid structure of the aromatic ketones prevents them from forming the antiPrelog-preferred conformation.
