- Asymmetric reduction of 3-aryl-3-keto esters using Rhizopus species
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Ethyl 3-aryl-3-oxopropanoates (aryl: phenyl, 2-fluorophenyl, 3-nitrophenyl, and 4-nitrophenyl) were reduced enantioselectively to the corresponding (S)-alcohols by the fungus Rhizopus arrhizus and other Rhizopus sp. The best results were generally obtaine
- Salvi, Neeta A.,Chattopadhyay, Subrata
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- Asymmetric synthesis XXV: Enantioselective synthesis of ethyl β-hydroxy-β-phenyl propanoate via an asymmetric Reformatsky reaction
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Both stoichiometric and catalytic amounts of N,N-dialkyl derivatives of D or L-1,2-diphenyl aminoalcohols were used as chiral ligands in the enantioselective Reformatsky reaction of benzaldehyde with ethyl bromoacetate at reflux in the presence of Zn-Cu c
- Mi,Wang,Chen,Jiang,Chan,Yang
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- Asymmetric synthesis XXVI: Catalytic enantioselective syntheses of β-hydroxy esters via double chiral induction in asymmetric Reformatsky reactions
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Catalytic asymmetric Reformatsky reactions of benzaldehyde with optically active menthyl bromoacetates in the presence of Zn-Cu couple were performed using 0.25 equiv. of (1R,2S) or (1S,2R)-N,N-dimethyl-2-amino-1,2-diphenyl ethanol as chiral ligand to obt
- Mi, Aiqiao,Wang, Zhaoyang,Zhang, Junmei,Jiang, Yaozhong
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- Trifluoromethylated amino alcohols as chiral ligands for highly enantioselective Reformatsky reaction
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The enantioselective Reformatsky reaction of PhCHO was achieved by the use of trifluoromethylated amino alcohols as chiral ligands to afford the corresponding optically active β-hydroxy ester with up to 90% ee.
- Fujiwara, Yasuyuki,Katagiri, Toshimasa,Uneyama, Kenji
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- Enantioselective synthesis of a key intermediate aldehyde toward the polyene macrolide filipin III, based on a chiral oxazaborolidinone-promoted asymmetric aldol reaction
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A versatile preparation of an enantiopure aldehyde useful for the asymmetric total synthesis of filipin III was developed using a chiral oxazaborolidinone-promoted asymmetric aldol reaction with a dithiolane silyl nucleophile. The sign and magnitude of th
- Kiyooka, Syun-Ichi,Hena, Mostofa A.,Goto, Fumitaka
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- Ruthenium catalyzed asymmetric transfer hydrogenation of β-ketoesters
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Chemoselective transfer hydrogenation of β-ketoesters to the corresponding alcohols is achieved in the presence of catalytic combinations of [RuCl2(η6-arene)]2 and ephedrine or diamino type chiral ligands with activities u
- Everaere, Kathelyne,Carpentier, Jean-Francois,Mortreux, Andre,Bulliard, Michel
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- Immobilized microorganisms in the reduction of ethyl benzoylacetate
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The enantioselective reduction of ethyl benzoylacetate (EBA) into ethyl (S)-3-hydroxy-3-phenylpropanoate (S-HPPE) by nine yeast strains and three filamentous fungi strains is described. The conversion obtained was in the range 0-89% and the enantiomeric excess was 100% in many cases. Conversion levels were higher when the reduction was performed with microorganisms immobilized in calcium alginate and enantioselectivity remained excellent. Some reaction's conditions of bioreduction by immobilized cells of Rhodotorula rubra were studied using a 25-2 fractional factorial design.
- Ramos, Aline de Souza,Ribeiro, Joyce Benzaquem,Vazquez, Leonardo,Fiaux, Sorele Batista,Leite, Selma Gomes Ferreira,Ramos, Maria da Concei??o Klaus V.,Neto, Francisco Radler de Aquino,Antunes
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- Tridentate nitrogen phosphine ligand containing arylamine NH as well as preparation method and application thereof
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The invention discloses a tridentate nitrogen phosphine ligand containing arylamine NH as well as a preparation method and application thereof, and belongs to the technical field of organic synthesis. The tridentate nitrogen phosphine ligand disclosed by the invention is the first case of tridentate nitrogen phosphine ligand containing not only a quinoline amine structure but also chiral ferrocene at present, a noble metal complex of the type of ligand shows good selectivity and extremely high catalytic activity in an asymmetric hydrogenation reaction, meanwhile, a cheap metal complex of the ligand can also show good selectivity and catalytic activity in the asymmetric hydrogenation reaction, and is very easy to modify in the aspects of electronic effect and space structure, so that the ligand has huge potential application value. A catalyst formed by the ligand and a transition metal complex can be used for catalyzing various reactions, can be used for synthesizing various drugs, and has important industrial application value.
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Paragraph 0103-0104; 0110-0114
(2021/06/26)
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- Structure-guided evolution of a ketoreductase for efficient and stereoselective bioreduction of bulky α-amino β-keto esters
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Ketoreductases have shown considerable potential as biocatalysts in the asymmetric synthesis of chiral alcohols. However, compared to the widely studied ketoreductases for chiral alcohols, limited knowledge is available about ketoreductases for efficient
- Chen, Liuqing,Chen, Shaoxin,Feng, Meiqing,Ni, Guowei,Tang, Jiawei,Wang, Hongyi,Yu, Jun,Yuan, Shuguang,Zhang, Fuli,Zhang, Luwen
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p. 6755 - 6769
(2021/10/25)
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- Enantioselective Reformatsky Reaction of Ketones Catalyzed by Chiral Indolinylmethanol
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A reliable and practical Reformatsky reaction of ethyl iodide acetate with ketones for the synthesis of chiral β-hydroxyl carbonyl compounds in good yields and excellent enantioselectivities is presented. A readily available dihydroindole derivative was u
- Luo, Renshi,Chen, Miao-Miao,Ouyang, Lu,Chan, Albert S. C.,Lu, Gui
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supporting information
p. 4805 - 4811
(2020/07/14)
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- Chiral amino-pyridine-phosphine tridentate ligand, manganese complex, and preparation method and application thereof
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The invention discloses a chiral amino-pyridine-phosphine tridentate ligand, a manganese complex, and a preparation method and application thereof. The chiral amino-pyridine-phosphine tridentate ligand is shown as a formula II, and the manganese complex of the chiral amino-pyridine-phosphine tridentate ligand can be used for efficiently catalyzing and hydrogenating ketone compounds to prepare chiral alcohol compounds in a high enantioselectivity mode. The chiral amino-pyridine-phosphine tridentate ligand and the manganese complex are simple in synthesis process, good in stability, high in catalytic activity and mild in reaction conditions.
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Paragraph 0597-0600; 0603
(2020/07/13)
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- Atropselective Dibrominations of a 1,1′-Disubstituted 2,2′-Biindolyl with Diverging Point-to-Axial Asymmetric Inductions. Deriving 2,2′-Biindolyl-3,3′-diphosphane Ligands for Asymmetric Catalysis
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On the 1H NMR timescale, 2,2′-biindolyls with (R)-configured (1-alkoxyprop)-2-yl, (1-hydroxyprop)-2-yl, or (1-siloxyprop)-2-yl substituents at C-1 and C-1′ are atropisomerically stable at 30 °C. A 2,2′-biindolyl (R,R)-17 a of that kind and achiral (!) brominating reagents gave the atropisomerically stable 3,3′-dibromobiindolyls (M)- and/or (P)-18 a at best atropselectively—because of point-to-axial asymmetric inductions—and atropdivergently, exhibiting up to 95 % (M)- and as much (P)-atropselectivity. This route to atropisomerically pure biaryls is novel and should extend to other substrates and/or different functionalizations. The dibromobiindolyls (M)- and (P)-18 a furnished the biindolyldiphosphanes (M)- and (P)-14 without atropisomerization. These syntheses did not require the resolution of a racemic mixture, which distinguishes them from virtually all biaryldiphosphane syntheses known to date. (M)- and (P)-14 acted as ligands in catalytic asymmetric allylations and hydrogenations. Remarkably, the β-ketoester rac-25 c was hydrogenated trans-selectively with 98 % ee; this included a dynamic kinetic resolution.
- Baumann, Thomas,Brückner, Reinhard
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supporting information
p. 4714 - 4719
(2019/03/26)
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- Molecular Insights into the Ligand-Reactant Interactions of Pt Nanoparticles Functionalized with α-Amino Acids as Asymmetric Catalysts for β-Keto Esters
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The asymmetric hydrogenation of ?-keto esters over α-amino acid-functionalized Pt nanoparticles was explored in order to expand our understanding of ligand-reactant interactions underlying the chiral induction. A comprehensive investigation aimed at the quantification of the nonlinear effects demonstrated that for most of the ligands and reactants enantiodifferentiation is determined by 1 : 1 ligand-reactant interaction. However, attachment of phenyl substituents to the ligands or reactants likely involves the formation of more intricate intermediate complexes. We have shown that the asymmetric bias is sensitive to even small changes in the geometry of the ligand. Additionally, we have found that alkali metal cations, which balance the negative charge of the ligand's carboxyl group and originate from the metal hydroxide used for ligand functionalization, play a key role in the process of chiral induction. As the nature of the cation can be varied by simply changing the metal hydroxide used during functionalization, this finding opens an additional possibility to control the stereoselectivity by tuning the ligand-reactant interaction.
- ?ulce, Anda,Mitschke, Nico,Azov, Vladimir,Kunz, Sebastian
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p. 2732 - 2742
(2019/05/15)
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- Method for preparing chiral beta-hydroxycarboxylate compound
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The invention provides a method for preparing a chiral beta-hydroxycarboxylate compound, comprising the following steps: dissolving [Ir(COD)Cl]2, a ligand and an alkaline additive in a solvent, stirring at room temperature, carrying out in-situ synthesis of a catalyst, dissolving a substrate beta-hydroxycarboxylate compound in a solvent, adding the prepared catalyst, and introducing hydrogen to carry out an asymmetric catalytic hydrogenation reaction on the substrate beta-hydroxycarboxylate compound. The reaction conditions are as follows: pressure is 10-100 atmospheres, the reaction temperature is 0-200 DEG C, and the reaction time is 12-48 hours. The reaction activity and selectivity are high, and the hydrogenation reaction conditions are mild. The method is suitable for various beta-hydroxycarboxylate compounds; the substrate application range is wide; and the reaction process causes little environmental pollution.
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Paragraph 0034-0060; 0082-0098
(2019/08/20)
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- On the basis of the phenethylamine skeleton chiral P, N, N ligand compound and its manufacturing method and application (by machine translation)
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The present invention provides a chiral P based on the skeleton of the phenethylamine, N, N ligand compound and its manufacturing method and application, surfactant-ethylamine skeleton chiral P, N, N ligand compound of preparation method is as follows: under the protection of nitrogen, the chiral phenylethylamine - [...] compound with 2 - chloromethyl oxazole oxazoline compounds soluble in the reaction solvent, adding alkali, reflux reaction, filtering, desolvation, column chromatography to obtain the required chiral P, N, N ligand compound. In particular to the β - ketoacid ester compound in asymmetric catalytic hydrogenation reaction. The invention of the phenethylamine skeleton chiral P, N, β - keto ester N ligand can be applied to the asymmetric catalytic hydrogenation reaction, can be high yield and high enantio-selectively for the preparation of chiral β - hydroxy ester. (by machine translation)
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Paragraph 0105; 0115; 0116; 0153-0158; 0160
(2019/06/13)
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- Chiral Bicyclic NHC/Cu Complexes for Catalytic Asymmetric Borylation of α,β-Unsaturated Esters
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The potential of using chiral bicyclic NHC ligands that exhibit modularity was investigated in the Cu-catalyzed asymmetric borylation reaction of α,β-unsaturated esters. After screening for ligands and optimization of the reaction conditions, the corresponding products were afforded with good enantioselectivities (up to 85% ee).
- Miwa, Yuya,Kamimura, Takumi,Sato, Kiyoaki,Shishido, Daichi,Yoshida, Kazuhiro
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p. 14291 - 14296
(2019/11/03)
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- Efficient P-Chiral Biaryl Bisphosphorus Ligands for Palladium-Catalyzed Asymmetric Hydrogenation
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A series of structurally novel P-chiral biaryl bisphosphorus ligands L1-L5 (BABIBOPs) are developed, providing high efficiency for the first time in palladium-catalyzed asymmetric hydrogenation of β-aryl and β-alkyl substituted β-keto esters. With the Pd-L3 (iPr-BABIBOP) catalyst, a series of chiral β-hydroxyl carboxylic esters are formed in excellent enantioselectivities (up to>99% ee) and yields at catalyst loading as low as 0.01 mol%.
- Jiang, Wenhao,Zhao, Qing,Tang, Wenjun
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supporting information
p. 153 - 156
(2018/01/05)
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- Chemoselectivity Control in the Asymmetric Hydrogenation of γ- and δ-Keto Esters into Hydroxy Esters or Diols
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The asymmetric hydrogenation of aromatic γ- and δ-keto esters into optically active hydroxy esters or diols under the catalysis of a novel DIPSkewphos/3-AMIQ–RuII complex was studied. Under the optimized conditions (8 atm H2, Ru complex/t-C4H9OK=1:3.5, 25 °C) the γ- and δ-hydroxy esters (including γ-lactones) were obtained quantitatively with 97–99 % ee. When the reaction was conducted under somewhat harsh conditions (20 atm H2, [t-C4H9OK]=50 mm, 40 °C), the 1,4- and 1,5-diols were obtained predominantly with 95–99 % ee. The reactivity of the ester group was notably dependent on the length of the carbon spacer between the two carbonyl moieties of the substrate. The reaction of β- and ?-keto esters selectively afforded the hydroxy esters regardless of the reaction conditions. This catalyst system was applied to the enantioselective and regioselective (for one of the two ester groups) hydrogenation of a γ-?-diketo diester into a trihydroxy ester.
- Arai, Noriyoshi,Namba, Takanori,Kawaguchi, Kei,Matsumoto, Yuki,Ohkuma, Takeshi
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supporting information
p. 1386 - 1389
(2018/01/01)
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- Method for preparing chiral beta-hydroxy ester by Ir-catalyzed asymmetric hydrogenation
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The invention provides a method for preparing a chiral beta-hydroxy ester compound by Ir-catalyzed asymmetric hydrogenation. The method for preparing the chiral beta-hydroxy ester compound comprises the steps as follows: in a glove box filled with nitrogen, [Ir(COD)Cl]2 and a chiral P, N, N ligand are dissolved in anhydrous methanol, stirring is performed at room temperature for 1 hour, and a Ir catalyst is generated; substrate beta-ketoester and a base additive are added, the mixture is placed in an autoclave and hydrogenated under certain reaction pressure; hydrogen gas is slowly released, separation with a silica gel column is performed after a solvent is removed, and product beta-hydroxy ester is obtained. The reaction for preparing chiral beta-hydroxy ester by Ir-catalyzed asymmetrichydrogenation of beta-ketoester has the advantages that conditions are mild, operation is easy, enantioselectivity of the product is high and the like.
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Paragraph 0091; 0093; 0094
(2018/06/26)
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- Ruthenium(II) complexes bearing (NNN) ligand: Catalytic evaluation of different solvent-mediated coordination modes
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A new (NNN) tridentate ligand was prepared, and its ability to coordinate ruthenium(II) was evaluated. The presence of different functional groups on the ligand allows bi-or tri-coordinated complexes to be obtained depending on complexation conditions. Th
- Pellegrino, Sara,Facchetti, Giorgio,Gandolfi, Raffella,Fusè, Marco,Erba, Emanuela,Rimoldi, Isabella
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- 2-(1S)-Camphanoyloxy-2′-phosphanylbiphenyl Ligands – Synthesis, Structure, and Preliminary Tests in Transition-Metal Catalysis
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Diastereoisomer separation of the (1S)-camphanic acid 2-isopropylphenylphosphanyl-phenyl ester 1 exemplifies the potential of (1S)-camphanoyl chloride for enantiomer separation of hydroxyl-functional asymmetric phosphanes. Esterification of lithium 2′-phosphanylbiphenyl-2-olates, generated from the respective 2-OH or 2-OSiMe3 precursors 2aOH and 2b–fSi, furnished the 2-(1S)-camphanoyloxy-biphenylphosphanes 3a–c as 1:1 mixtures of diastereomers with low barriers for interconversion by rotation around the C–C axis (ΔG# = 70–73 kJ mol–1 for 3a and 3c by 31P VT NMR spectroscopy). The P-asymmetric compounds 3d–f form 1:1 mixtures of stereoisomers. There is a tendency to cocrystallization of two preferred diastereoisomers, as shown by the crystal structure analyses of 3dD and 3fD, and in solution, there is a tendency toward partial isomerization to the sterically less-favored atropisomers. The [RhCl(cod)(3dD)] complex 4dD, however, seems stable in solution. Excess 2dLi reacted with (1S)-camphanoyl chloride preferentially to form the (SP,Rax,1S) isomer, which was separated by crystallization as enantiopure 3dE, characterized by single-crystal XRD. Preliminary screening tests of this ligand in Rh-catalyzed asymmetric hydrogenations of N-(1-phenylvinyl)acetamide allowed high conversion and up to 59 % ee. Hydrosilylation of acetophenone proceeded with 78 % conversion and 48 % ee; Suzuki–Miyaura couplings of 1-bromo-2-naphthol with PhB(OH)2, in the presence of 3b/[Pd(OAc)2], gave yields up to 98 %.
- Wawrzyniak, Piotr,Kindermann, Markus K.,Thede, Gabriele,Thede, Richard,Jones, Peter G.,Enthaler, Stephan,Junge, Kathrin,Beller, Matthias,Heinicke, Joachim W.
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p. 2762 - 2773
(2017/06/06)
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- Microbiological bio-reduction of prochiral carbonyl compounds by antimycotic agent Boni Protect
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The selective properties of the fungus Aureobasidium pullulans, in the antifungal agent Boni Protect, were investigated in the fermentative bioreduction of selected carbonyl compounds. Catalyzed by oxidoreductases contained in the microorganism Aureobasidium pullulans highly enantioselective biotransformation of prochiral ketones provides the secondary alcohols when the reaction is done in the presence of specific additives. Aureobasidium pullulans has also proved to be an effective bioreagent in the reduction of α- and β-keto esters. Optically pure hydroxy esters were obtained under fermentation conditions without the use of additives.
- Ko?odziejska, Renata,Studzińska, Renata,Kwit, Marcin,Jelecki, Maciej,Tafelska-Kaczmarek, Agnieszka
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- Ir-catalyzed asymmetric hydrogenation of β-keto esters with chiral ferrocenyl P,N,N-ligands
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The Ir-catalyzed asymmetric hydrogenation of β-keto esters with chiral ferrocenyl P,N,N-ligands has been developed. Under the optimized conditions, a wide range of β-keto esters were hydrogenated to afford the corresponding β-hydroxy esters in good to excellent enantioselectivities (up to 95% ee).
- Chen, Xiu-Shuai,Hou, Chuan-Jin,Qin, Chao,Liu, Hongzhu,Liu, Yan-Jun,Huang, De-Zhi,Hu, Xiang-Ping
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p. 12871 - 12875
(2017/03/11)
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- Identification of a Robust Carbonyl Reductase for Diastereoselectively Building syn-3,5-Dihydroxy Hexanoate: A Bulky Side Chain of Atorvastatin
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t-Butyl-6-cyano-(3R,5R)-dihydroxyhexanoate is an advanced chiral precursor for the synthesis of the side chain pharmacophore of cholesterol-lowering drug atorvastatin. Herein, a robust carbonyl reductase (LbCR) was newly identified from Lactobacillus brevis, which displays high activity and excellent diastereoselectivity toward bulky t-butyl 6-cyano-(5R)-hydroxy-3-oxo-hexanoate (7). The engineered Escherichia coli cells harboring LbCR and glucose dehydrogenase (for cofactor regeneration) were employed as biocatalysts for the asymmetric reduction of substrate 7. As a result, as much as 300 g L-1 of water-insoluble substrate was completely converted to the corresponding chiral diol with >99.5% de in a space-time yield of 351 g L-1 d-1, indicating a great potential of LbCR for practical synthesis of the very bulky and bi-chiral 3,5-dihydroxy carboxylate side chain of best-selling statin drugs.
- Gong, Xu-Min,Zheng, Gao-Wei,Liu, You-Yan,Xu, Jian-He
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supporting information
p. 1349 - 1354
(2017/09/23)
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- Readily Accessible Unsymmetrical Unsaturated 2,6-Diisopropylphenyl N-Heterocyclic Carbene Ligands. Applications in Enantioselective Catalysis
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A new multicomponent procedure was applied to the synthesis of (a)chiral bulky unsymmetrical unsaturated 2,6-diisopropylphenyl N-heterocyclic carbene (NHC) precursors with excellent selectivity (up to 95%) and good yields. This approach offers access to new chiral NHC ligands, which have found successful applications in both copper-catalyzed asymmetric allylic alkylation and copper-catalyzed asymmetric borylation.
- Tarrieu, Robert,Dumas, Adrien,Thongpaen, Jompol,Vives, Thomas,Roisnel, Thierry,Dorcet, Vincent,Crévisy, Christophe,Baslé, Olivier,Mauduit, Marc
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p. 1880 - 1887
(2017/02/26)
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- γ-Sultam-cored N,N-ligands in the ruthenium(II)-catalyzed asymmetric transfer hydrogenation of aryl ketones
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The synthesis of new enantiopure syn- and anti-3-(α-aminobenzyl)-benzo-γ-sultam ligands 6 and their application in the ruthenium(ii)-catalyzed asymmetric transfer hydrogenation (ATH) of ketones using formic acid/triethylamine is described. In particular, benzo-fused cyclic ketones afforded excellent enantioselectivities in reasonable time employing a low loading of the syn ligand-containing catalyst. A never-before-seen dynamic kinetic resolution (DKR) during reduction of a γ-keto carboxylic ester (S7) derivative of 1-indanone is realized leading as well to excellent induction.
- Rast, Slavko,Modec, Barbara,Stephan, Michel,Mohar, Barbara
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p. 2112 - 2120
(2016/02/18)
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- Triptycene-Based Chiral and meso-N-Heterocyclic Carbene Ligands and Metal Complexes
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Based on 1-amino-4-hydroxy-triptycene, new saturated and unsaturated triptycene-NHC (N-heterocyclic carbene) ligands were synthesized from glyoxal-derived diimines. The respective carbenes were converted into metal complexes [(NHC)MX] (M=Cu, Ag, Au; X=Cl, Br) and [(NHC)MCl(cod)] (M=Rh, Ir; cod=1,5-cyclooctadiene) in good yields. The new azolium salts and metal complexes suffer from limited solubility in common organic solvents. Consequently, the introduction of solubilizing groups (such as 2-ethylhexyl or 1-hexyl by O-alkylation) is essential to render the complexes soluble. The triptycene unit infers special steric properties onto the metal complexes that enable the steric shielding of selected areas close to the metal center. Next, chiral and meso-triptycene based N-heterocyclic carbene ligands were prepared. The key step in the synthesis of the chiral ligand is the Buchwald–Hartwig amination of 1-bromo-4-butoxy-triptycene with (1S,2S)-1,2-diphenyl-1,2-diaminoethane, followed by cyclization to the azolinium salt with HC(OEt)3. The analogous reaction with meso-1,2-diphenyl-1,2-diaminoethane provides the respective meso-azolinium salt. Both the chiral and meso-azolinium salts were converted into metal complexes including [(NHC)AuCl], [(NHC)RhCl(cod)], [(NHC)IrCl(cod)], and [(NHC)PdCl(allyl)]. An in situ prepared chiral copper complex was tested in the enantioselective borylation of α,β-unsaturated esters and found to give an excellent enantiomeric ratio (er close to 90:10).
- Savka, Roman,Bergmann, Marvin,Kanai, Yuki,Foro, Sabine,Plenio, Herbert
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p. 9667 - 9675
(2016/07/14)
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- (R)-(+)-N-Methylbenzoguanidine ((R)-NMBG) catalyzed acylative kinetic resolution of racemic 3-hydroxy-3-aryl-propanoates
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(R)-(+)-N-methylbenzoguanidine ((R)-NMBG) functioned as an efficient acyl transfer catalyst for the acylative kinetic resolution of racemic β-hydroxy esters using cyclohexane carboxylic anhydride under mild reaction conditions. A tert-butyl ester moiety is necessary to achieve a high selectivity. The effects of the substituents on the aromatic rings of the substrates were systematically investigated, and diverse substrates participated in the reaction with good s-values (>20) irrespective of the type of substituents and their patterns, except for o-methoxy group.
- Yamada, Akira,Nakata, Kenya
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supporting information
p. 4697 - 4701
(2016/10/03)
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- Paracyclophane-based carbene-copper catalyst tuned by transannular electronic effects for asymmetric boration
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A series of planar chiral carbene-copper complexes based on the [2.2]paracyclophane backbone with a pseudo-ortho substitution pattern have been synthesized and applied to asymmetric β-boration of α,β-unsaturated esters. As a result, transannular electronic effects of the substituent of the chiral catalyst have significant influence on the catalytic performance. A variety of chiral β-hydroxyl esters were obtained in excellent enantioselectivities (up to 97% ee) and yields (up to 99%).
- Chen, Jianqiang,Duan, Wenzeng,Chen, Zhen,Ma, Manyuan,Song, Chun,Ma, Yudao
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p. 75144 - 75151
(2016/08/24)
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- Simple 1,3-diamines and their application as ligands in ruthenium(II) catalysts for asymmetric transfer hydrogenation of aryl ketones
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In this research work simple unsymmetrical 1,3-diamines were studied. The synthesis of the diamines started from non-commercial available compounds. S-5a and S,S-5c were obtained by biocatalysis with non conventional yeast, Rhodotorula rubra MIM 147, with
- Facchetti, Giorgio,Gandolfi, Raffaella,Fusè, Marco,Zerla, Daniele,Cesarotti, Edoardo,Pellizzoni, Michela,Rimoldi, Isabella
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p. 3792 - 3800
(2015/05/20)
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- Evaluation of a new protocol for enzymatic dynamic kinetic resolution of 3-hydroxy-3-(aryl)propanoic acids
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The application of tandem metal-enzyme dynamic kinetic resolution (DKR) is a powerful tool for the manufacture of high-value chemical commodities. A new protocol of kinetic resolution based on irreversible enzymatic esterification of carboxylic acids with orthoesters was introduced to obtain optically active β-hydroxy esters. This procedure was combined with metal catalyzed racemization of the target substrate providing both (R) and (S) enantiomers of ethyl 3-hydroxy-3-(4-nitrophenyl)propanoate with a high yield of 89% at 40°C. A substantial influence of the enzyme type, organic co-solvent, and metal catalyst on the conversion and enantioselectivity of the enzymatic dynamic kinetic resolution was noted.
- Koszelewski, Dominik,Zysk, Malgorzata,Brodzka, Anna,Zadlo, Anna,Paprocki, Daniel,Ostaszewski, Ryszard
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supporting information
p. 11014 - 11020
(2015/11/24)
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- Enantioselective 1,1-arylborylation of alkenes: Merging chiral anion phase transfer with pd catalysis
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A palladium-catalyzed three-component coupling of α-olefins, aryldiazonium salts, and bis(pinacolato)diboron affords direct access to chiral benzylic boronic esters. This process is rendered highly enantioselective using an unprecedented example of cooperative chiral anion phase transfer and transition-metal catalysis.
- Nelson, Hosea M.,Williams, Brett D.,Miró, Javier,Toste, F. Dean
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supporting information
p. 3213 - 3216
(2015/03/30)
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- Application of bidentate oxazoline-carbene ligands with planar and central chirality in asymmetric β-Boration of α,β-unsaturated esters
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A series of new oxazoline-substituted imidazolium salts based on [2.2]paracyclophane were synthesized and characterized. The new bidentate oxazoline-carbene precursor with planar and central chirality had significant advantage than the bicyclic 1,2,4-triazolium salt derived from [2.2]paracyclophane as a monodentate carbene ligand in Cu(I)-catalyzed asymmetric β-boration of α,β-unsaturated esters, giving the desired products in high enantioselectivities and yields.
- Niu, Zonghong,Chen, Jianqiang,Chen, Zhen,Ma, Manyuan,Song, Chun,Ma, Yudao
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p. 602 - 608
(2016/09/09)
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- Development of an Immobilized Ketoreductase for Enzymatic (R)-1-(3,5-Bis(trifluoromethyl)phenyl)ethanol Production
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The development of an immobilized ketoreductase via covalent binding on resin EC-HFA has demonstrated that it is highly active and stable in organic solvents and can be recycled and reused many times in both batch mode and flow reactor mode. (R)-1-(3,5-Bi
- Li, Hongmei,Moncecchi, Johannah,Truppo, Matthew D.
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p. 695 - 700
(2015/07/27)
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- A Cu(II)-based strategy for catalytic enantioselective β-borylation of α,β-unsaturated acceptors
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Cu(I)-based chemistry has flourished over the last decade because of the reliable use of species such as soft acids. However, the unique nature of Cu(ii) catalysts allows the well-documented Cu(I)-based chemistry to be extended. Prominent advantages of th
- Zhu, Lei,Kitanosono, Taku,Xu, Pengyu,Kobayashi, Shu
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supporting information
p. 11685 - 11688
(2015/07/15)
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- Chiral amide from (1S, 2R)-(+)-norephedrine and furoic acid: An efficient catalyst for asymmetric Reformatsky reaction
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Chiral amide derived from (1S, 2R)-(+)-norephedrine and 2-furoic acid was found to catalyse the asymmetric Reformatsky reaction between prochiral aldehydes and α-bromo ethylacetate with diethylzinc as zinc source. The corresponding chiral β-hydroxy esters were formed in 99% yield with over 80% enantiomeric excess. The presence of air was found to be essential for the effective C-C bond formation. The mechanism for the catalytic reaction was proposed. Indian Academy of Sciences.
- Ananthi, Nallamuthu,Velmathi, Sivan
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p. 151 - 158
(2014/04/03)
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- Chiral amide from (1S, 2R)-(+)-norephedrine and furoic acid: An efficient catalyst for asymmetric Reformatsky reaction
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Chiral amide derived from (1S, 2R)-(+)-norephedrine and 2-furoic acid was found to catalyse the asymmetric Reformatsky reaction between prochiral aldehydes and α-bromo ethylacetate with diethylzinc as zinc source. The corresponding chiral β-hydroxy esters were formed in 99% yield with over 80% enantiomeric excess. The presence of air was found to be essential for the effective C-C bond formation. The mechanism for the catalytic reaction was proposed. [Figure not available: see fulltext.]
- Ananthi, Nallamuthu,Velmathi, Sivan
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p. 151 - 158
(2016/02/18)
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- Asymmetric reformatsky reaction of aldehydes catalyzed by novel β -amino alcohols and zinc complexes
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A series of β-amino alcohols derived from (1R, 2S)-2-amino-1,2- diphenylethanol and substituted salicylaldehydes as novel chiral tridentate ligands has been applied to an asymmetric Reformatsky reaction of aldehydes with ethyl iodoacetate in the presence
- Li, Yan,He, Bin
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supporting information
p. 1938 - 1943
(2014/07/07)
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- Biotransformation of aromatic ketones and ketoesters with the non-conventional yeast Pichia glucozyma
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The non-conventional yeast Pichia glucozyma CBS 5766 has been used for the biotransformation of different aromatic ketones and ketoesters. The growth and biotransformation conditions were optimised for the reduction of acetophenone and under optimised conditions, propiophenone, butyrophenone and valerophenone were reduced to the corresponding (S)-alcohols with high yields and enantioselectivity. Ketoreductase(s) of Pichia glucozyma showed high catalytic activities also towards aromatic β- and γ-ketoesters, being often competitive with esterase(s). These concurrent activities allowed for the preparation of hydroxyesters, hydroxyacids and lactones often in a very selective manner.
- Contente, Martina Letizia,Molinari, Francesco,Zambelli, Paolo,De Vitis, Valerio,Gandolfi, Raffaella,Pinto, Andrea,Romano, Diego
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supporting information
p. 7051 - 7053
(2015/02/02)
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- Genomic mining-based identification of novel stereospecific aldo-keto reductases toolbox from Candida parapsilosis for highly enantioselective reduction of carbonyl compounds
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Biocatalytic reduction of prochiral ketones offers significant potential in synthesis of optically active alcohols. However, so far the application of aldo-keto reductases (AKRs) in asymmetric reduction has been hampered due to limited availability of AKRs with high enantioselectivity and catalytic efficiency. Based on the genome sequence of Candida parapsilosis, a versatile bioresource for asymmetric reduction, eight open reading frames encoding putative AKRs were discovered and expressed, and the resulted enzymes (CPARs), comprising an AKR toolbox, were evaluated toward various carbonyl substrates. The CPARs were active to the selected substrates, especially 2-hydroxyacetophenone and ethyl 4-chloro-3-oxobutyrate. Additionally, most of them were obviously enantioselective to the substrates and gave alcohol products with optical purity up to 99%e.e. Of the enzymes, CPAR4 was outstanding with excellent enantioselectivity and broad substrate spectrum. All these positive features demonstrate that genomic mining is powerful in searching for novel and efficient biocatalysts of desired reactions for pharmaceuticals and fine chemicals synthesis.
- Guo, Rongyun,Nie, Yao,Mu, Xiao Qing,Xu, Yan,Xiao, Rong
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- 8-Amino-5,6,7,8-tetrahydroquinolines as ligands in iridium(III) catalysts for the reduction of aryl ketones by asymmetric transfer hydrogenation (ATH)
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Aqua iridium(III) complexes with 8-amino-5,6,7,8-tetrahydroquinolines CAMPY L1 and its derivatives as chiral ligands proved to be very efficient catalysts for the reduction of a wide range of prochiral aryl ketones, revealing a variety of behaviours in te
- Zerla, Daniele,Facchetti, Giorgio,Fusè, Marco,Pellizzoni, Michela,Castellano, Carlo,Cesarotti, Edoardo,Gandolfi, Raffaella,Rimoldi, Isabella
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p. 1031 - 1037
(2014/08/18)
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- Enantioselective Hydrosilylation of Ketones Catalyzed by a Readily Accessible N-Heterocyclic Carbene-Ir Complex at Room Temperature
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A series of functionalized azolium compounds were synthesized from chiral α-amino acid derivatives such as β-amino alcohols. of hydroxy-amide-functionalized azolium salts thus obtained with Ag2O afforded N-heterocyclic carbene-Ag (NHC-Ag) complexes. Subsequent treatment of the resulting silver compound with [IrCl(cod)]2 yielded monodentate IrCl(cod)(NHC), which was stable in air. The NHC-Ir complex facilitated efficient asymmetric hydrosilylation of ketones using (EtO)2MeSiH under ambient conditions. A chiral ligand containing an isobutyl stereodirecting group was found to be the best ligand for the functionalized NHC-Ir complexes that were examined. A linear relationship was found between the catalyst ee and the product ee. The hydroxy functional group on the NHC ligand side-arm not only induced stereocontrol but also enhanced the reaction rate.
- Shinohara, Kanako,Kawabata, Shun,Nakamura, Hanako,Manabe, Yoshiki,Sakaguchi, Satoshi
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supporting information
p. 5532 - 5539
(2014/10/16)
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- Iron catalyzed asymmetric hydrogenation of ketones
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Chiral molecules, such as alcohols, are vital for the manufacturing of fine chemicals, pharmaceuticals, agrochemicals, fragrances, and novel materials. These molecules need to be produced in high yield and high optical purity and preferentially catalytically. Among all the asymmetric catalytic reactions, asymmetric hydrogenation with H2 (AH) is the most widely used in the industry. With few exceptions, these AH processes use catalysts based on the three critical metals, rhodium, ruthenium, and iridium. Herein we describe a simple, industrially viable iron catalyst that allows for the AH of ketones, a process currently dominated by ruthenium and rhodium catalysts. By combining a chiral, 22-membered macrocyclic ligand with the cheap, readily available Fe 3(CO)12, a wide variety of ketones have been hydrogenated under 50 bar H2 at 45-65 C, affording highly valuable chiral alcohols with enantioselectivities approaching or surpassing those obtained with the noble metal catalysts. In contrast to AH by most noble metal catalysts, the iron-catalyzed hydrogenation appears to be heterogeneous.
- Li, Yanyun,Yu, Shenluan,Wu, Xiaofeng,Xiao, Jianliang,Shen, Weiyi,Dong, Zhenrong,Gao, Jingxing
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supporting information
p. 4031 - 4039
(2014/04/03)
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- Insight into the role of fluorinated dendrimers in ruthenium(II) catalyst for asymmetric transfer hydrogenation: The stabilizing effects from experimental and DFT approach
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A series of fluorinated dendritic chiral ligands have been designed and synthesized. These fluorinated dendrimers are capable of forming a well-defined semi-rigid structure, which was revealed to play a vital role in the ruthenium(II) bifunctional catalys
- Wang, Wei-Wei,Li, Zhi-Ming,Su, Ling,Wang, Quan-Rui,Wu, Ying-Li
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- Imidazolium-based organoiridium-functionalized periodic mesoporous organosilica boosts enantioselective reduction of α-cyanoacetophenones, α-nitroacetophenones, and β-ketoesters
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An imidazolium-based, organoiridium-functionalized periodic mesoporous organosilica is developed through complexation of chiral pentafluorophenylsulfonyl-1,2-diphenylethylenediamine and organoiridiumfunctionalized periodic mesoporous organosilica. Structural analyses and characterizations of catalyst reveal well-defined single-site iridium active species within its organosilicate network. Electron microscopy confirms a highly ordered dimensional-hexagonal mesostructure. This bifunctional heterogeneous catalyst displays excellent catalytic performance in the enantioselective reduction of α-cyano and α-nitroacetophenones. As expected, incorporation of imidazolium-functionality within hydrophobic periodic mesoporous organosilica promotes catalytic activity and enantioselectivity. In addition, this heterogeneous catalyst can be recovered and reused for at least eight times without loss of its catalytic activity. Furthermore, the approach described here can also construct another organoiridium-functionalized periodic mesoporous organosilica through postcoordination of chiral methylsulfonyl-1,2-diphenylethylenediamine, which provides excellent catalytic activity and enantioselectivity in the enantioselective reduction of β-ketoesters. The method presented here offers a potential way for immobilizing various chiral ligands to construct chiral organometal-functionalized periodic mesoporous organosilicas.
- Deng, Boxin,Xiao, Wei,Li, Cuibao,Zhou, Feng,Xia, Xuelin,Cheng, Tanyu,Liu, Guohua
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- Imidazolium-based organoiridium-functionalized periodic mesoporous organosilica boosts enantioselective reduction of α-cyanoacetophenones, α-nitroacetophenones, and β-ketoesters
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An imidazolium-based, organoiridium-functionalized periodic mesoporous organosilica is developed through complexation of chiral pentafluorophenylsulfonyl-1,2-diphenylethylenediamine and organoiridium-functionalized periodic mesoporous organosilica. Structural analyses and characterizations of catalyst reveal well-defined single-site iridium active species within its organosilicate network. Electron microscopy confirms a highly ordered dimensional-hexagonal mesostructure. This bifunctional heterogeneous catalyst displays excellent catalytic performance in the enantioselective reduction of α-cyano and α-nitroacetophenones. As expected, incorporation of imidazolium-functionality within hydrophobic periodic mesoporous organosilica promotes catalytic activity and enantioselectivity. In addition, this heterogeneous catalyst can be recovered and reused for at least eight times without loss of its catalytic activity. Furthermore, the approach described here can also construct another organoiridium-functionalized periodic mesoporous organosilica through postcoordination of chiral methylsulfonyl-1,2-diphenylethylenediamine, which provides excellent catalytic activity and enantioselectivity in the enantioselective reduction of β-ketoesters. The method presented here offers a potential way for immobilizing various chiral ligands to construct chiral organometal-functionalized periodic mesoporous organosilicas.
- Deng, Boxin,Xiao, Wei,Li, Cuibao,Zhou, Feng,Xia, Xuelin,Cheng, Tanyu,Liu, Guohua
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- Access to optically pure β-hydroxy esters via non-enzymatic kinetic resolution by a planar-chiral DMAP catalyst
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The development of new approaches to obtain optically pure β-hydroxy esters is an important area in synthetic organic chemistry since they are precursors of other high value compounds. Herein, the kinetic resolution of racemic β-hydroxy esters using a planar-chiral DMAP derivative catalyst is presented. Following this procedure, a range of aromatic β-hydroxy esters was obtained in excellent selectivities (up to s = 107) and high enantiomeric excess (up to 99% ee). Furthermore, the utility of the present method was demonstrated in the synthesis of (S)-3-hydroxy-N-methyl-3-phenylpropanamide, a key intermediate for bioactive molecules such as fluoxetine, tomoxetine or nisoxetine, in its enantiomerically pure form.
- Daz-lvarez, Alba E.,Mesas-Snchez, Laura,Dinr, Peter
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p. 14273 - 14291
(2014/12/11)
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- Heterogeneous versus homogeneous copper(II) catalysis in enantioselective conjugate-addition reactions of boron in water
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We have developed CuII-catalyzed enantioselective conjugate-addition reactions of boron to α,β-unsaturated carbonyl compounds and α,β,γ,δ-unsaturated carbonyl compounds in water. In contrast to the previously reported CuI catalysis that required organic solvents, chiral CuII catalysis was found to proceed efficiently in water. Three catalyst systems have been exploited: cat. 1: Cu(OH)2 with chiral ligand L1; cat. 2: Cu(OH)2 and acetic acid with ligand L1; and cat. 3: Cu(OAc)2 with ligand L1. Whereas cat. 1 is a heterogeneous system, cat. 2 and cat. 3 are homogeneous systems. We tested 27 α,β-unsaturated carbonyl compounds and an α,β-unsaturated nitrile compound, including acyclic and cyclic α,β-unsaturated ketones, acyclic and cyclic β,β- disubstituted enones, acyclic and cyclic α,β-unsaturated esters (including their β,β-disubstituted forms), and acyclic α,β-unsaturated amides (including their β,β-disubstituted forms). We found that cat. 2 and cat. 3 showed high yields and enantioselectivities for almost all substrates. Notably, no catalysts that can tolerate all of these substrates with high yields and high enantioselectivities have been reported for the conjugate addition of boron. Heterogeneous cat. 1 also gave high yields and enantioselectivities with some substrates and also gave the highest TOF (43 200 h-1) for an asymmetric conjugate-addition reaction of boron. In addition, the catalyst systems were also applicable to the conjugate addition of boron to α,β,γ, δ-unsaturated carbonyl compounds, although such reactions have previously been very limited in the literature, even in organic solvents. 1,4-Addition products were obtained in high yields and enantioselectivities in the reactions of acyclic α,β,γ,δ-unsaturated carbonyl compounds with diboron 2 by using cat. 1, cat. 2, or cat. 3. On the other hand, in the reactions of cyclic α,β,γ,δ-unsaturated carbonyl compounds with compound 2, whereas 1,4-addition products were exclusively obtained by using cat. 2 or cat. 3, 1,6-addition products were exclusively produced by using cat. 1. Similar unique reactivities and selectivities were also shown in the reactions of cyclic trienones. Finally, the reaction mechanisms of these unique conjugate-addition reactions in water were investigated and we propose stereochemical models that are supported by X-ray crystallography and MS (ESI) analysis. Although the role of water has not been completely revealed, water is expected to be effective in the activation of a borylcopper(II) intermediate and a protonation event subsequent to the nucleophilic addition step, thereby leading to overwhelmingly high catalytic turnover. Copyright
- Kitanosono, Taku,Xu, Pengyu,Kobayashi, Shu
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supporting information
p. 179 - 188
(2014/01/06)
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- Studies toward stereoselective bionanocatalysis on gold nanoparticles
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As yet, different enzymes were immobilized on gold nanoparticles both through adsorption and covalent binding. However, there is only one evaluation if such immobilization influenced enzyme enantioselectivity, which is an essential parameter in biocatalys
- Jedrzejewska, Hanna,Ostaszewski, Ryszard
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- Asymmetric β-boration of α,β-unsaturated carbonyl compounds with chiral Rh[bis(oxazolinyl)phenyl] catalysts
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Chiral rhodium[bis(oxazolinyl)phenyl] complexes exhibited high catalytic activity for the β-boration of α,β-unsaturated esters, ketones, and amides with bis(pinacolato)diboron in the presence of sodium tert-butoxide to attain high enantioselectivity of up to 97%. The substrate scope and catalytic mechanism were discussed.
- Toribatake, Kenji,Zhou, Li,Tsuruta, Ayae,Nishiyama, Hisao
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p. 3551 - 3560
(2013/05/08)
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- A flexible enantioselective synthesis of (+)-centrolobine and 5-epi-diospongin-A using asymmetric transfer hydrogenation/tandem Grubbs cross-metathesis/oxy-Michael reaction as key steps
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An efficient enantioselective synthesis of (+)-centrolobine and 5-epi-diospongin-A was achieved by the use of asymmetric transfer hydrogenation (ATH)/tandem Grubbs cross-metathesis/oxy-Michael reaction. Furthermore, this strategy allows for diastereodiver
- Kumaraswamy, Gullapalli,Rambabu, Dasa
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p. 196 - 201
(2013/04/10)
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- Chemoenzymatic synthesis of both enantiomers of 3-hydroxy- and 3-amino-3-phenylpropanoic acid
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Ethyl (S)-3-hydroxy-3-phenylpropionate (S)-2 was obtained by the asymmetric reduction of ethyl 3-phenyl-3-oxopropionate 1 with the yeast Saccharomyces cerevisiae (ATCC 9080). The kinetic resolution of racemic ethyl 2-acetoxy-3-phenyl-propionate rac-3 with the same microorganism, gave after hydrolysis ethyl (R)- and (S)-3-hydroxy-3-phenylpropionates (R)-2 and (S)-2 which were converted by a straightforward series of reactions to the enantiomers of 3-amino-3-phenyl-propionic acids (S)-6 and (R)-6. The asymmetric reduction and hydrolytic kinetic resolution were also tested with several other whole cell systems under a variety of conditions.
- Varga, Annamaria,Zaharia, Valentin,Nogradi, Mihaly,Poppe, Laszlo
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p. 1389 - 1394
(2013/12/04)
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- Highly recoverable organoruthenium-functionalized mesoporous silica boosts aqueous asymmetric transfer hydrogenation reaction
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Exploring functionalized mesoporous silica to achieve enhanced catalytic activity and enantioselectivity in heterogeneous asymmetric catalysis presents a significant challenge that is critical for understanding the function of support and controlling chiral complexation behavior. In this contribution, by cooperative assembly of chiral 4-(trimethoxysilyl)ethyl)phenylsulfonyl-1,2- diphenylethylene-diamine and tetraethoxysilane followed by complexation with organoruthenium complex, we report a unique three-dimensional chiral organoruthenium-functionalized chrysanthemum-like mesoporous silica (CMS). As demonstrated in the studies, taking advantage of the active site-isolated chiral organoruthenium catalytic nature, this heterogeneous catalyst ArRuTsDPEN-CMS (Ar = hexamethylbenzene, TsDPEN = 4-methylphenylsulfonyl-1,2-diphenylethylene- diamine) displays enhanced catalytic activity and enantioselectivity in aqueous asymmetric transfer hydrogenation with extensive substrates. Furthermore, this heterogeneous catalyst can be conveniently recovered and reused at least 10 times without loss of its catalytic efficiency. These features render this catalyst particularly attractive in practice of organic synthesis in an environmentally friendly manner. Also, this outcome from the study clearly shows that the strategy described here offers a general approach to immobilization of chiral ligand-derived silane onto a functionalized mesoporous material with significant improving catalytic activity.
- Liu, Rui,Cheng, Tanyu,Kong, Lingyu,Chen, Chen,Liu, Guohua,Li, Hexing
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- Chiral imidazo[1,5-a]tetrahydroquinoline N-heterocyclic carbenes and their copper complexes for asymmetric catalysis
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Abstract Novel chiral imidazo[1,5-a]tetrahydroquinoline N-heterocyclic carbenes derived from β-pinene have been developed. The preliminary studies with both the in situ generated and preformed copper-carbene complexes have shown these chiral NHCs are efficient and selective ligands in the Cu-catalyzed asymmetric conjugate borylation of α,β-unsaturated esters.
- Zhang, Jin-Long,Chen, Liang-An,Xu, Rui-Bin,Wang, Chuan-Fei,Ruan, Yuan-Ping,Wang, Ai-E,Huang, Pei-Qiang
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p. 492 - 498
(2013/07/19)
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- PH-independent transfer hydrogenation in water: Catalytic, enantioselective reduction of β-keto esters
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A pH-independent asymmetric transfer hydrogenation of β-keto esters in water with formic acid/sodium formate is described. The reaction is conducted open to air and gives access to β-hydroxy esters in excellent yields and selectivities.
- Ariger, Martin A.,Carreira, Erick M.
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supporting information
p. 4522 - 4524
(2012/10/29)
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- Chiral iridium catalysts bearing spiro pyridine-aminophosphine ligands enable highly efficient asymmetric hydrogenation of β-aryl β-ketoesters
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Tons of TONs: Chiral iridium catalysts bearing ligand 1 are highly efficient for the asymmetric hydrogenation of β-substituted β-ketoesters. The product β-hydroxyesters are delivered in high yield with excellent enantioselectivities and high turnover numbers (TONs). cod= 1,5-cyclooctadiene.
- Xie, Jian-Hua,Liu, Xiao-Yan,Yang, Xiao-Hui,Xie, Jian-Bo,Wang, Li-Xin,Zhou, Qi-Lin
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supporting information; experimental part
p. 201 - 203
(2012/03/10)
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- A bifunctionalized organic-inorganic hybrid silica: Synergistic effect enhances enantioselectivity
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An imidazolium-based bifunctional heterogeneous catalyst exhibits excellent catalytic efficiency in asymmetric transfer hydrogenation of aromatic ketones in aqueous medium. The superior catalytic performance and the enhanced enantioselectivity is attributed to the synergistic effect of salient imidazolium phase-transfer function and the confined nature of the chiral organoiridium catalyst.
- Xiao, Wei,Jin, Ronghua,Cheng, Tanyu,Xia, Daquan,Yao, Hui,Gao, Fei,Deng, Boxin,Liu, Guohua
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supporting information
p. 11898 - 11900
(2013/01/16)
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