- C1-Symmetric PNP Ligands for Manganese-Catalyzed Enantioselective Hydrogenation of Ketones: Reaction Scope and Enantioinduction Model
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A family of ferrocene-based chiral PNP ligands is reported. These tridentate ligands were successfully applied in Mn-catalyzed asymmetric hydrogenation of ketones, giving high enantioselectivities (92%~99% ee for aryl alkyl ketones) as well as high efficiencies (TON up to 2000). In addition, dialkyl ketones could also be hydrogenated smoothly. Manganese intermediates that might be involved in the catalytic cycle were analyzed. DFT calculation was carried out to help understand the chiral induction model. The Mn/PNP catalyst could discriminate two groups with different steric properties by deformation of the phosphine moiety in the flexible 5-membered ring.
- Zeng, Liyao,Yang, Huaxin,Zhao, Menglong,Wen, Jialin,Tucker, James H. R.,Zhang, Xumu
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- Iron achieves noble metal reactivity and selectivity: Highly reactive and enantioselective iron complexes as catalysts in the hydrosilylation of ketones
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Chiral iron alkyl and iron alkoxide complexes bearing boxmi pincers as stereodirecting ligands have been employed as catalysts for enantioselective hydrosilylation reactions with unprecedented activity and selectivity (TOF = 240 h-1 at -40 °C, ee up to 99% for alkyl aryl ketones), which match the performance of previously established noble-metal-based catalysts. This shows the potential of earth-abundant metals such as iron for replacing platinum-metals without any drawbacks for the reaction design.
- Bleith, Tim,Wadepohl, Hubert,Gade, Lutz H.
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- Practical and efficient procedure for the in situ preparation of B-alkoxyoxazaborolidines. Enantioselective reduction of prochiral ketones
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A new method for the in situ elaboration of B-alkoxyoxazaborolidines is presented. Their use in the enantioselective reduction of prochiral aromatic ketones provides excellent chemical and optical yields of chiral alcohols.
- Ponzo, Viviana L.,Kaufman, Teodoro S.
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- An efficient Ir(III) catalyst for the asymmetric transfer hydrogenation of ketones in neat water
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The chiral M-CsDPEN [M = Ru, Rh, Ir; CsDPEN = (R,R,R)- or (S,S,S)-N-camphorsulfonyl-1,2-diphenylethylenediamine] catalysts have been shown to be efficient for the asymmetric transfer hydrogenation (ATH) of aryl ketones by formate in neat water. Of particular note is the Ir-(R,R,R)-CsDPEN catalyst, which catalyzes the ATH of a wide range of ketones and delivers almost full conversions within a few hours at a S/C ratio of 1000 at 40 °C in most cases, with enantioselectivities up to 98% ee. Georg Thieme Verlag Stuttgart.
- Li, Xiaohong,Blacker, John,Houson, Ian,Wu, Xiaofeng,Xiao, Jianliang
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- Asymmetric hydrosilylation of ketones catalyzed by magnetically recoverable and reusable copper ferrite nanoparticles
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(Chemical Equation Presented) Herein we present magnetically recoverable and reusable copper ferrite nanoparticles for asymmetric hydrosilylation of several ketones. Up to 99% enantiometric excess was obtained at room temperature using polymethylhydrosiloxane as the stoichiometric reducing agent. The copper ferrite nanoparticles were magnetically separated, and the efficiency of the catalyst remains almost unaltered up to three cycles.
- Kantam, M. Lakshmi,Yadav, Jagjit,Laha, Soumi,Srinivas, Pottabathula,Sreedhar, Bojja,Figueras
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- Imidazolium ion tethered TsDPENs as efficient water-soluble ligands for rhodium catalyzed asymmetric transfer hydrogenation of aromatic ketones
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An imidazolium ion tethered TsDPEN has been synthesized readily and used as a water-soluble ligand for [Cp*RhCl2]2 catalyzed asymmetric transfer hydrogenation (ATH) of aromatic ketones in water. This process provided the secondary alcohols in moderate to excellent conversions (up to 100%) with high enantioselectivities (up to 98% ee) under mild reaction conditions without adding any surfactants. The catalytic system is highly effective with the substrate to catalyst (S/C) ratio of 500 and low hydride donor loading of 1.5 equiv. of HCO2Na. The procedure presented is simple and makes this method suitable for practical use.
- Kang, Guowei,Lin, Silong,Shiwakoti, Atul,Ni, Bukuo
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- Optimisation, scope and advantages of the synthesis of chiral phenylethanols using whole seeds of Bauhinia variegata L. (Fabaceae) as a new and stereoselective bio-reducer of carbonyl compounds
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With the aim of finding new methods for environmentally friendly synthesis of chiral phenylethanols, a screening was carried out to identify seeds that could be used as a biocatalyst capable of reducing stereoselectively prochiral ketones. As a result, seeds of Bauhinia variegata L. (Fabaceae) were identified as being an efficient and stereoselective biological reducer of acetophenone to produce (S)-1-phenylethanol (conversion of 98% and 99 e.e.%). Then, to optimise the reductive process, the effects of some variables such as temperature, load of substrate, pH, co-solvent, and reuse and storability of the seeds as a function of time were established. Utilising the optimal reaction conditions, nineteen substituted acetophenones were reduced to their corresponding chiral alcohols with a conversion ranging from 30% to 98% and enantiomeric excess of between 65% and >99%, and in addition, useful key intermediates were also obtained by the synthesis of drugs. The scope and advantages of this new biocatalytic synthetic method are also discussed.Research highlights A screening was carried out to identify seeds that could be used as a biocatalyst Seeds of Bauhinia variegata have been identified as an efficient biocatalyst to reduce carbonyl compounds. Acetophenone and substituted acetophenones were reduced with high stereoselectivity. Some key intermediates were synthetised using this methodology. Seeds can be stored for twenty-four months without loss of activity.
- Aimar, Mario L.,Bordón, Daniela L.,Cantero, Juan J.,Decarlini, María F.,Demmel, Gabriela I.,Rossi, Laura I.,Ruiz, Gustavo M.,Vázquez, Ana M.
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- New air-stable iron catalyst for efficient dynamic kinetic resolution of secondary benzylic and aliphatic alcohols
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We herein report a catalyst system for the dynamic kinetic resolution of secondary alcohols by combining the enzymatic resolution with an iron-catalyzed racemization. A new air-stable tricarbonyl (cyclopentadienone)iron complex is identified as the active racemization catalyst for this transformation without any additive. Various substrates including benzylic, heteroaromatic, aliphatic alcohols can be used and afford the corresponding esters in good yields and with excellent enantioselectivities.
- Yang, Qiong,Zhang, Na,Liu, Mingke,Zhou, Shaolin
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- Asymmetric palladium-catalyzed hydrosilylation of styrenes using efficient chiral spiro phosphoramidite ligands
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Asymmetric hydrosilylation of styrene derivatives with trichlorosilane in the presence of palladium complexes of chiral spiro phosphoramidites provided 1-aryl-1-silylalkanes as single regioisomers in high yields, which have been oxidized with hydrogen peroxide to give the corresponding chiral alcohols in up to 99.1% ee.
- Guo, Xun-Xiang,Xie, Jian-Hua,Hou, Guo-Hua,Shi, Wen-Jian,Wang, Li-Xin,Zhou, Qi-Lin
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- Catalytic Asymmetric Addition of Organolithium Reagents to Aldehydes
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Herein we report an efficient catalytic system for the titanium-promoted enantioselective addition of organolithium reagents to aldehydes, based on chiral Ar-BINMOL ligands. Unprecedented yields and enantioselectivities are achieved in the alkylation reactions of aliphatic aldehydes. Remarkably, methyllithium can be added to a wide variety of aromatic and aliphatic aldehydes, providing versatile chiral methyl carbinol units in a simple one-pot procedure under mild conditions and in very short reaction times.
- Veguillas, Marcos,Solà, Ricard,Shaw, Luke,Maciá, Beatriz
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- Enantioselective reduction of prochiral ketones employing sprouted Pisum sativa as biocatalyst
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Sprouted green peas have been used for the first time as biocatalysts for enantioselective reduction of prochiral ketones. The reactions are highly enantioselective to furnish chiral alcohols in good yields. The sprouted peas as biocatalysts are a cheap and easy way for generating some interesting chiral alcohols. This process is efficient and convenient to produce chiral secondary alcohols in water. Georg Thieme Verlag Stuttgart.
- Yadav, Jhillu S.,Subba Reddy, Basi V.,Sreelakshmi, Chittamuru,Rao, Adari Bhaskar
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- Novel (+)-3-carene derivatives and their application in asymmetric synthesis
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A simple synthetic procedure for the preparation of mono-N-tosylated-1,2-diamines derived from (+)-3-carene is described. (+)-3-Carene is transformed into the corresponding N-tosylaziridine derivative using chloramine-T trihydrate. Subsequent ring opening with sodium azide followed by reduction of the azide function gives the optically pure mono-N-tosylated-1,2-diamine. This ligand is effective in asymmetric transfer hydrogenations of aromatic ketones. It can also be transformed into other chiral ligands by alkylation of the amino group for application in the addition of diethylzinc to benzaldehydes.
- Roszkowski, Piotr,Malecki, Pawel,Maurin, Jan K.,Czarnocki, Zbigniew
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- Chiral amplification based on enantioselective dual-phase distribution of a scalemic bisoxazolidine catalyst
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A readily available bisoxazolidine ligand was found to catalyze the asymmetric alkylation of aldehydes with Et2Zn and less reactive Me2Zn, providing high yields and ee's in both reactions. The bisoxazolidine-catalyzed alkylations and alkynylation of benzaldehyde show a positive nonlinear effect that cannot be accounted for by Kagan's MLn model. The chiral amplification originates from selective phase distribution favoring enrichment of the major enantiomer of the scalemic catalyst in solution.
- Liu, Shuanglong,Wolf, Christian
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- Electronic effects of para-substitution on acetophenones in the reaction of rat liver 3α-hydroxysteroid dehydrogenase
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Stereoselective reductive metabolism of various p-substituted acetophenone derivatives was studied using isolated rat liver 3α-hydroxysteroid dehydrogenase (3α-HSD). Kinetic experiments were performed and analyzed by measuring the products by HPLC using a
- Uwai, Koji,Konno, Noboru,Yasuta, Yuka,Takeshita, Mitsuhiro
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- Asymmetric reduction of ketones by the acetone powder of Geotrichum candidum
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Aromatic ketones, β-keto esters, and simple aliphatic ketones were reduced with excellent selectivity to the corresponding (S)-alcohols by using the acetone powder of Geotrichum candidum. This method is superior in reactivity and stereoselectivity to reduction by the whole-cell. The experimental conditions for the reduction system such as ratio of the biocatalyst to the substrate, kinds of coenzymes, alcohol for coenzyme regeneration, and buffer, pH, and reaction temperature were investigated, and stability and preservability of the biocatalyst were also examined. This method is very convenient for the synthesis of optically pure alcohols on a gram scale.
- Nakamura,Matsuda
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- New silica monolith bonded chiral (R)-γ butyrolactone for enantioselective micro high-performance liquid chromatography
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A single low-molecular mass chiral selector namely (R)-acryloyloxy-β- β-dimethyl-γ-butyrolactone has been bonded to a modified silica-based monolith to form a new brush-type chiral stationary phase for micro-high performance liquid chromatography (HPLC) separation.
- Ghanem, Ashraf,Ikegami, Tohru,Tanaka, Nobuo
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- New Chiral Ruthenium(II) Catalysts Containing 2,6-Bis(4′ -(R)-phenyloxazolin-2′-yl)pyridine (Ph-pybox) Ligands for Highly Enantioselective Transfer Hydrogenation of Ketones
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Treatment of complex trans-[RuCl2(η2-C 2H4){K3-N,N,N-NNN-(R,R)-Ph-pybox}] [(R,R)-Ph-pybox = 2,6-bis{4′-(R)-phenyloxazolin-2′-yl}pyridine] with phosphines or phosphites in dichloromethane at 50°C leads to the formation of novel ruthenium(II)-pybox complexes trans-[RuCl 2(L){K3-N,N,N-(R,R)-Ph-pybox}] [L = PPh3 (1a), PPh2Me (2a), PPh2(C3H5) (3a), PPh2(C4H7) (4a), PMe3 (5a), PiPr3 (6a), P(OMe)3 (7a) and P(OPh)3 (8a)]. Likewise, reaction of trans-[RuCl2(η2-C 2H4) {K3-N,N,N-(R,R)-Ph-pybox}] with PPh 3 or PiPr3 in refluxing methanol leads to the complexes cis-[RuCl2(L)(K3-N,N,N-(R,R)-Ph-pybox] [L = PPh 3 (1b), PiPr3 (6b)]. No trans-cis isomerisation of complexes 1a-8a has been observed. Complexes 1a-8a, 1b, 6b together with the analogous trans-[RuCl2{P(O-Me)3}{K 3-N,N,N-(S,S)-iPr-pybox}] (10a) and the previously reported trans- and cis-[RuCl2(PPh3){K3-N,N,N-(S,S)-iPr-pybox}] (9a and 9b, respectively) are active catalysts for the transfer hydrogenation of acetophenone in 2-propanol in the presence of NaOH (ketone/cat/NaOH 500:1:6). cis-Ph-pybox derivatives are the most active catalysts. In particular, cis complexes 1b and 6b led to almost quantitative conversions in less than 5 min with a high enantioselectivity (up to 95%). A variety of aromatic ketones have also been reduced to the corresponding secondary alcohols with very high TOF and ee up to 94%. The overall catalytic performance seems to be a subtle combination of the steric and/or electronic properties both the phosphines and the ketones. A high TOF (27300 h-1) and excellent ee (94%) have been found for the reduction of 3-bromoacetophenone with catalyst 6b. Reductions of alkyl ketones also proceed with high and rapid conversions but low enantioselectivities are achieved.
- Cuervo, Dario,Gamasa, M. Pilar,Gimeno, Jose
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- A simple protocol for the one pot synthesis of chiral secondary benzylic alcohols by catalytic enantioselective reduction of aromatic ketones
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A simple and efficient protocol for the one-pot catalytic enantioselective reduction of prochiral aromatic ketones mediated by in situ prepared catalysis derived from (S)-(-)-diphenyl-pyrrolidin-2-yl-methanol, is reported.
- Ponzo, Viviana L.,Kaufman, Teodoro S.
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- Asymmetric transfer hydrogenation of ketones catalyzed by thermoregulated ionic liquid-regulating ruthenium complexes
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A sulfonated chiral diamine ligand anion-based functionalized ionic liquid has been synthesized. Then the new ionic liquid-regulating ruthenium complexes were prepared successfully and employed as efficient catalysts for the asymmetric transfer hydrogenat
- Liu, Xuerui,Chen, Chen,Xiu, Yuhe,Chen, Angjun,Guo, Li,Zhang, Ran,Chen, Jizhong,Hou, Zhenshan
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- Synthesis, characterization, and organocatalytic application of chiral ionic liquids derived from (S,R)-noscapine
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(S,R)-Noscapine, a phthalideisoquinoline alkaloid has been used as precursor for the synthesis of chiral ionic liquids (CILs). Noscapine based CILs have been synthesized from reaction between (S,R)-noscapine and methyl iodide in acetonitrile at room temperature. The synthesized CILs have been characterized by 1H NMR, 13C NMR, EI-MS, and polarimetry techniques. These CILs have been used as organocatalysts in the enantioselective reduction of prochiral ketones to produce optically active secondary alcohols. The optically active secondary alcohols have been obtained with excellent yields and low to moderate enantiomeric excess (ee); also the complete enantiomeric excess (100% ee) has been achieved in some cases.
- Kaur, Nirmaljeet,Chopra, Harish Kumar
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- Chiral-Mn(salen)-complex-catalyzed kinetic resolution of secondary alcohols in water
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A mild, green method for enantioselective kinetic resolution of secondary alcohols has been developed using Mn(salen) complexes as catalysts in water. Up to 97.8% ee was attained. PTC = phase-transfer catalyst.
- Sun, Wei,Wang, Hongwang,Xia, Chungu,Li, Jingwei,Zhao, Peiqing
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- A Simple Biosystem for the High-Yielding Cascade Conversion of Racemic Alcohols to Enantiopure Amines
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The amination of racemic alcohols to produce enantiopure amines is an important green chemistry reaction for pharmaceutical manufacturing, requiring simple and efficient solutions. Herein, we report the development of a cascade biotransformation to aminate racemic alcohols. This cascade utilizes an ambidextrous alcohol dehydrogenase (ADH) to oxidize a racemic alcohol, an enantioselective transaminase (TA) to convert the ketone intermediate to chiral amine, and isopropylamine to recycle PMP and NAD+ cofactors via the reversed cascade reactions. The concept was proven by using an ambidextrous CpSADH-W286A engineered from (S)-enantioselective CpSADH as the first example of evolving ambidextrous ADHs, an enantioselective BmTA, and isopropylamine. A biosystem containing isopropylamine and E. coli (CpSADH-W286A/BmTA) expressing the two enzymes was developed for the amination of racemic alcohols to produce eight useful and high-value (S)-amines in 72–99 % yield and 98–99 % ee, providing with a simple and practical solution to this type of reaction.
- Li, Zhi,Tian, Kaiyuan
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- Chiral bicyclic NHC/Ir complexes for catalytic asymmetric transfer hydrogenation of ketones
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A diverse series of chiral bicyclic NHC/Ir complexes were prepared via a previously developed divergent synthesis of chiral imidazolium salts. Among the complexes, 8dz was found to be an excellent catalyst precursor for the Ir-catalyzed asymmetric transfer hydrogenation of ketones. The reaction of ketones with 8dz proceeded smoothly to give corresponding alcohols with high enantioselectivities (up to 98%) and productivities (TON up to 4500).
- Yoshida, Kazuhiro,Kamimura, Takumi,Kuwabara, Hiroshi,Yanagisawa, Akira
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- Control of enantioselectivity in the enzymatic reduction of halogenated acetophenone analogs by substituent positions and sizes
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We utilized acetophenone reductase from Geotrichum candidum NBRC 4597 (GcAPRD), wild type and Trp288Ala mutant, to reduce halogenated acetophenone analogs to their corresponding (S)- and (R)-alcohols beneficial as pharmaceutical intermediates. Reduction by wild type resulted in excellent (S)-enantioselectivity for all of the substrates tested. Meanwhile, reduction by Trp288Ala resulted in high (R)-enantioselectivity for the reduction of 4′ substituted acetophenone and 2′-trifluoromethylacetophenone. In addition to that, we were able to control the enantioselectivity of Trp288Ala by the positions and sizes of the halogen substituents.
- Koesoema, Afifa Ayu,Standley, Daron M.,Ohshima, Shusuke,Tamura, Mayumi,Matsuda, Tomoko
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- Catalytic enantioselective acyl transfer: the case for 4-PPY with a C-3 carboxamide peptide auxiliary based on synthesis and modelling studies
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A series of 4-pyrrolidinopyridine (4-PPY) C-3 carboxamides containing peptide-based side chains have been synthesised and evaluated in the kinetic resolution of a small library of chiral benzylic secondary alcohols. A key design element was the incorporation of a tryptophan residue in the peptide side chain for promoting π-stacking between peptide side chain and the pyridinium ring of the N-acyl intermediate, in which modelling was used as a structure-based guiding tool. Together, a catalyst containing a LeuTrp-N-Boc side chain (catalyst 8) was identified that achieved s-values up to and in slight excess of 10. A transition-state model based on the modelling is proposed to explain the origin of enantioselectivity. This study establishes the usefulness of modelling as a structure-based guiding tool for enantioselectivity optimization as well as the potential for developing scalable peptide-based DMAP-type catalysts for large-scale resolution work.
- Cozett, Rudy E.,Venter, Gerhard A.,Gokada, Maheswara Rao,Hunter, Roger
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- Enantioselective acylation of alcohols catalyzed by lipase QL from Alcaligenes sp.: A predictive active site model for lipase QL to identify the faster reacting enantiomer of an alcohol in this acylation
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Lipase QL-catalyzed acylation of secondary alcohols using isopropenyl acetate as the acylating agent in diisopropyl ether gave preferentially the corresponding acetate with an R configuration. On the basis of the results, a predictive active site model for lipase QL is proposed for identifying which enantiomer of a secondary alcohol reacts faster in this reaction.
- Naemura,Murata,Tanaka,Yano,Hirose,Tobe
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- Copper-dipyridylphosphine-polymethylhydrosiloxane: A practical and effective system for the asymmetric catalytic hydrosilylation of ketones
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In the presence of the inexpensive and non-toxic stoichiometric reductant polymethylhydrosiloxane (PMHS), the chiral copper(II)-dipyridylphosphine catalyst displayed high efficiency in the stereoselective hydrosilylation of a wide scope of aryl alkyl and heteroaromatic ketones under an air atmosphere and mild conditions in good to excellent ees (up to 97%). With certain amounts of sodium tert-butoxide and tert-butyl alcohol as additives, the reaction on a 21-g substrate scale can be conveniently completed within a few hours even at a substrate-to-ligand (S/L) ratio of 50,000. Copyright
- Zhang, Xi-Chang,Wu, Fei-Fei,Li, Shijun,Zhou, Ji-Ning,Wu, Jing,Li, Ning,Fang, Wenjun,Lam, Kim Hung,Chan, Albert S. C.
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- Green synthesis of chiral aromatic alcohols with Lactobacillus kefiri P2 as a novel biocatalyst
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Biocatalytic reduction is a very important field of research in synthetic organic chemistry. Herein, three different Lactic Acid Bacteria (LAB) strains were evaluated for their bioreduction potential using acetophenone as a model substrate. Among these strains, Lactobacillus kefiri P2 strain was determined as the best asymmetric reduction biocatalyst. Reaction optimization parameters such as reaction time, temperature, agitation speed and pH were systematically optimized using Lactobacillus kefiri P2 strain and model substrate acetophenone. Under these optimized reaction conditions, secondary chiral alcohols were obtained by bioreduction of various prochiral ketones with results up to 99% enantiomeric excess. In addition, the steric and electronic effects of substituents on enantioselectivity and conversion were evaluated. It has been shown that Lactobacillus kefiri P2 biocatalyst was an effective catalyst for asymmetric reduction. This method provides an environmentally friendly method for the synthesis of optically pure alcohols and an alternative approach to chemical catalysts.
- Bayda?, Yasemin,Dertli, Enes,?ahin, Engin
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- Asymmetric reduction of aromatic ketones by the baker's yeast in organic solvent systems
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The reduction of aromatic ketones to optically active alcohols, mediated by dried baker's yeast, proceeded in moderate conversion and good enantioselectivity (82 ~ 91% e.e.) in a number of organic solvents, including petroleum ether, toluene, chloroform, and tetrahydrofuran. A small amount of water (0.4 mL: g yeast) was required for the reaction to proceed. The water:yeast ratio and the solvent polarity were found to significantly influence the reactivity of the system.
- Liu,Zhu,Sun,Xu
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- Chromoselective Photocatalysis Enables Stereocomplementary Biocatalytic Pathways**
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Controlling the selectivity of a chemical reaction with external stimuli is common in thermal processes, but rare in visible-light photocatalysis. Here we show that the redox potential of a carbon nitride photocatalyst (CN-OA-m) can be tuned by changing the irradiation wavelength to generate electron holes with different oxidation potentials. This tuning was the key to realizing photo-chemo-enzymatic cascades that give either the (S)- or the (R)-enantiomer of phenylethanol. In combination with an unspecific peroxygenase from Agrocybe aegerita, green light irradiation of CN-OA-m led to the enantioselective hydroxylation of ethylbenzene to (R)-1-phenylethanol (99 % ee). In contrast, blue light irradiation triggered the photocatalytic oxidation of ethylbenzene to acetophenone, which in turn was enantioselectively reduced with an alcohol dehydrogenase from Rhodococcus ruber to form (S)-1-phenylethanol (93 % ee).
- Schmermund, Luca,Reischauer, Susanne,Bierbaumer, Sarah,Winkler, Christoph K.,Diaz-Rodriguez, Alba,Edwards, Lee J.,Kara, Selin,Mielke, Tamara,Cartwright, Jared,Grogan, Gideon,Pieber, Bartholom?us,Kroutil, Wolfgang
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- Flower-like mesoporous silica: A bifunctionalized catalyst for rhodium-catalyzed asymmetric transfer hydrogenation of aromatic ketones in aqueous medium
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Functionalized flower-like mesoporous silica with a chiral organorhodium functionality incorporated within its silica framework is prepared through an assembly of chiral 4-((trimethoxysilyl)ethyl)phenylsulfonyl-1,2- diphenylethylenediamine and tetraethoxysilane under a cooperative dual-template approach followed by complexation with organorhodium complexes. Structural characterization discloses its mesostructure and well-defined single-site chiral organorhodium functionality, while electron microscopy analyses reveal the uniformly distributed three-dimensional spherical flowers constructed by the stacking of leaf-shaped nanoflakes. In particular, as a bifunctionalized heterogeneous catalyst, it shows excellent catalytic activity and high enantioselectivity in the asymmetric transfer hydrogenation of aromatic ketones in aqueous medium (more than 99% conversion and up to 97% ee). The superior catalytic performance is attributed to the synergistic effect of the salient cetyltrimethylammonium bromide phase-transfer function and confined chiral organorhodium catalytic nature. Furthermore, this heterogeneous catalyst could be recovered easily and reused repeatedly (ten times) without affecting its ee value, showing a practical application in asymmetric synthesis.
- Gao, Fei,Jin, Ronghua,Zhang, Dacheng,Liang, Quanxi,Ye, Qunqun,Liu, Guohua
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- Highly Enantioselective Production of Chiral Secondary Alcohols with Candida zeylanoides as a New Whole Cell Biocatalyst
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The increasing demand for biocatalysts in synthesizing enantiomerically pure chiral alcohols results from the outstanding characteristics of biocatalysts in reaction, economic, and ecological issues. Herein, fifteen yeast strains belonging to three food originated yeast species Candida zeylanoides, Pichia fermentans, and Saccharomyces uvarum were tested for their capability for asymmetric reduction of acetophenone to 1-phenylethanol as biocatalysts. Of these strains, C.?zeylanoides P1 showed an effective asymmetric reduction ability. Under optimized conditions, substituted acetophenones were converted to corresponding optically active secondary alcohols in up to 99% enantiomeric excess and at high yields. The preparative scale asymmetric bioreduction of 4-nitroacetophenone (1m) by C.?zeylanoides P1 gave (S)-1-(4-nitrophenyl)ethanol (2m) with 89% yield and >?99% enantiomeric excess. Compound 2m has been obtained in an enantiomerically pure and inexpensive form. Additionally, these results indicate that C.?zeylanoides P1 is a promising biocatalyst for the synthesis of chiral alcohols in industry.
- ?ahin, Engin,Dertli, Enes
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- Relative reactivity of substituted acetophenones in enantioselective biocatalytic reduction catalyzed by plant cells of Daucus carota and Petroselinum crispum
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We have examined enantioselective bioreduction of acetophenone and its substituted derivatives into corresponding S-alcohols catalyzed by Daucus carota and Petroselinum crispum plant cells in water and isooctane. We found that the nature of the substituen
- Chanysheva,Vorobyova,Zorin
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- A ruthenium catalyst with simple triphenylphosphane for the enantioselective hydrogenation of aromatic ketones
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An efficient Ru catalyst constructed from simple and commercially available triphenylphosphane and enantiopure (1S,1′S)-1,1′-biisoindoline (BIDN) was applied to the asymmetric hydrogenation of aromatic ketones. A range of simple aromatic ketones could be hydrogenated with good to excellent enantioselectivities (up to 95% ee). An appropriate enantioselective transition state was proposed to explain the high enantioselectivity obtained with this catalytic system. This study represents the first example to establish a practical Noyori-type catalyst with a simple achiral monophosphane for highly enantioselective hydrogenation. Keep it simple: An efficient Ru catalyst constructed from simple and commercially available triphenylphosphane and enantiopure (1S,1′S)-1,1′-biisoindoline (BIDN) was applied to the asymmetric hydrogenation of aromatic ketones. A range of simple aromatic ketones could be hydrogenated with good to excellent enantioselectivities (up to 95% ee).
- Zhou, Han,Huang, Hanmin
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- Water-soluble arene ruthenium complexes containing a trans-1,2- diaminocyclohexane ligand as enantioselective transfer hydrogenation catalysts in aqueous solution
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The cationic chloro complexes [(arene)Ru(H2N∩NH 2)Cl]+ (1: arene = C6H6; 2: arene = p-MeC6H4iPr; 3: arene = C6Me6) have been synthesised from the correspond
- Canivet, Jerome,Labat, Gael,Stoeckli-Evans, Helen,Suess-Fink, Georg
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- Biocompatible metal-assisted C-C cross-coupling combined with biocatalytic chiral reductions in a concurrent tandem cascade
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In this study, we present a concurrent chemo/biocatalytic one pot reaction cascade by combining a metal (Pd/Cu) assisted Liebeskind-Srogl (L-S) coupling with an enantioselective enzymatic reduction for the production of chiral amines and alcohols. The latter transformation was realized by applying enantiocomplementary alcohol dehydrogenases from Lactobacillus kefir (R-selective) and Rhodococcus ruber (S-selective). Compatibility issues were solved by investigating first the L-S-coupling protocol in water at room temperature. Subsequently, we investigated two different biphasic systems and applied a biomimicking approach to separate enzyme-deactivating components. By using a lipophilic membrane in a smart reactor design, we were able to perform concurrent catalytic cascades with overall concentrations up to 100 mM substrate and to produce 1-phenylethylamine and several chiral alcohols in high yields (up to 81% over 2 steps) and enantiomeric purity ((+) and (?)-enantiomers both with 99% ee).
- Schaaf, Patricia,Bayer, Thomas,Koley, Moumita,Schnürch, Michael,Bornscheuer, Uwe T.,Rudroff, Florian,Mihovilovic, Marko D.
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- In situ measurement of the enantiomeric excess of alcohols and amines under asymmetric reduction reaction by 1H NMR
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(Figure Presented) 1H NMR, in situ, determines the enantiomeric excess of reduced chiral alcohols or amines without adding any auxiliary and workup. The percent ee data determined by this method agree well with those given by HPLC. This approach may be potentially applicable to many asymmetric reductions.
- Ye, Xiaoxia,Lei, Xinxiang,Chen, Zhenfei,Zhang, Lixue,Zhang, Anjiang
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- Reduction of various ketones by red algae
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The reduction of acetophenone derivatives, (+)- and (-)-camphorquinones and steroidal ketones using red algae (Cyanidioschyzon merolae 10D and Cyanidium caldarium) was investigated. It was found that fluoro, chloro and bromo acetophenone derivatives 1a-i were reduced with good enantioselectivity. On the contrary, reduction of methyl and methoxy acetophenone 1j-o showed low enantioselectivity. The reduction followed Prelog's rule, giving the (S)-alcohols in all cases. Moreover, (+)- camphorquinone 5a was reduced to give (-)-3S- exo-hydroxycamphor 5d as the major product with high stereoselectivity in high yield. In addition, it was found that reduction of 5α-androstane-3,17-dione 8a gave the 3α-OH isomer (3α-OH/3β-OH = 76/24) with high stereoselectivity. Overall it was found that C. merolae and C. caldarium were able to reduce various substrates.
- Utsukihara, Takamitsu,Misumi, Osami,Kato, Nakahide,Kuroiwa, Tsuneyoshi,Horiuchi, C. Akira
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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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- An efficient catalyst system for the asymmetric transfer hydrogenation of ketones: Remarkably broad substrate scope
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A BINOL-derived diphosphonite having a xanthene backbone is an excellent bidentate ligand in Ru-catalyzed 2-propanol-based transfer hydrogenation of aryl/alkyl and alkyl/alkyl ketones (ee = 76-99%). Even notoriously difficult ketones such as isopropyl methyl ketone are reduced with extraordinarily high enantioselectivity (ee = 99%). Copyright
- Reetz, Manfred T.,Li, Xiaoguang
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- Asymmetric bioreduction of p-haloacetophenones by Mucor
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A number of p-haloacetophenones were asymmetrically bioreduced to their corresponding (S)-alcohols by Mucor sp. CG10 with good conversion and excellent enantioselectivity. The results showed that the electronic effects of the halogen substituent (X-group) affected the conversion of the substrates and the enantioselectivity of the reaction. The trend observed was as the X-group at the para-position became more electron donating from F, to Cl, Br and I, the conversion of substrates decreased, while the enantioselectivity increased.
- Zhang, Zuohui,Liu, Xiongmin,Ma, Li,Zhuo, Meifang,Shen, Fang
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- Enantioselective reduction of bromo- and methoxy-acetophenone derivatives using carrot and celeriac enzymatic system
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The enantioselective reductions of the carbonyl group of bromo- and methoxy-acetophenones have been conducted using comminuted carrot (Daucus carota L.) and celeriac (Apium graveolens L., var. rapaceum) roots. (S)-(-)-1-(3-Methoxyphenyl)ethanol (100% yield, ee=100%) has been obtained by reduction of meta-methoxyacetophenone using carrot.
- Maczka, Wanda K.,Mironowicz, Agnieszka
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- Water-soluble chiral monosulfonamide-cyclohexane-1,2-diamine-RhCp* complex and its application in the asymmetric transfer hydrogenation (ATH) of ketones
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Monosulfonamide ligands with heteroatom/heterocyclic systems were derived from trans-(1R,2R)-cyclohexane-1,2-diamine and complexed with [Ru(benzene)Cl2]2, [Cp*RhCl2]2 in situ and used in the ATH of ar
- Cortez, Norma A.,Aguirre, Gerardo,Parra-Hake, Miguel,Somanathan, Ratnasamy
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- Reversible, short α-peptide assembly for controlled capture and selective release of enantiomers
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Although significant progress has been achieved with short peptide nanostructures, the construction of switchable membrane assemblies remains a great challenge. Here we report short α-peptide assemblies that undergo thermo-reversible switching between assembly and disassembly states, triggered by the conformational change of laterally grafted short peptides from a folded α-helix to a random coil conformation. The α-helical peptide based on two oligoether dendron side groups forms flat disks, while the peptide helix based on three dendron side groups forms hollow vesicles. The vesicular membrane can spontaneously capture a racemic mixture through the self-formation of vesicular containers upon heating and enantioselectively release the chiral guest molecule through preferential diffusion across the vesicular walls.
- Chen, Xi,He, Ying,Kim, Yongju,Lee, Myongsoo
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- Reduction of 4-Substituted Acetophenones by Yeast
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The velocity of reduction of 4-substituted acetophenones by baker's yeast is decreased by electron donating substituents.The steric course, howewer, is little influenced and (S)-1-arylethanols 2 are generally formed with over 90percent enantiomeric excess. - Keywords: Stereoselective reduction; (S)-1-Phenylethanol; Yeast
- Eichberger, Guenter,Faber, Kurt,Griengl, Herfried
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- Mesoporous SBA-15-supported chiral catalysts: preparation, characterization and asymmetric catalysis
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Two mesoporous silica-supported chiral Rh and Ru catalysts 5 and 6 with ordered two-dimensional hexagonal mesostructures were prepared by directly postgrafting organometallic complexes RhCl[(R)-MonoPhos(CH2)3Si(OMe)3][(R,R
- Liu, Guohua,Liu, Mouming,Sun, Yunqiang,Wang, Jianyao,Sun, Chuanshou,Li, Hexing
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- Highly enantiomeric reduction of acetophenone and its derivatives by locally isolated Rhodotorula glutinis
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Ninety isolates of microorganisms belonging to different taxonomical groups (30 bacteria, 20 yeast, and 40 fungi) were previously isolated from various samples. These isolates were screened as reducing agents for acetophenone 1a to phenylethanol 2a. It was found that the isolate EBK-10 was the most effective biocatalyst for the enantioselective bioreduction of acetophenone. This isolate was identified as Rhodotorula glutinis by the VITEK 2 Compact system. The various parameters (pH 6.5, temperature 32°C, and agitation 200 rpm) of the bioreduction reaction was optimized, which resulted in conversions up to 100% with >99% enantiomeric excesses (ee) of the S-configuration. The preparative scale bioreduction of acetophenone 1a by R. glutinis EBK-10 gave (S)-1-phenylethanol 2a in 79% yield, complete conversion, and >99% ee. In addition, R. glutinis EBK-10 successfully reduced various substituted acetophenones.
- Zilbeyaz, Kani,Kurbanoglu, Esabi B.
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- Aerobic oxidative kinetic resolution of racemic alcohols with bidentate ligand-binding Ru(salen) complex as catalyst
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Chiral Ru(salen)(nitrosyl) complex 1 is a useful catalyst for asymmetric aerobic oxidation of alcohols under photo-irradiation. In?this study, it was found that addition of β-hydroxy ketone or 1,3-diketone had a significant influence on its asymmetric catalysis. For example, the addition of 1,3-bis(p-bromophenyl)propane-1,3-dione 9 improved the relative reaction ratio in kinetic resolution of simple racemic secondary alcohols up to 30, while the addition gave an adverse effect on desymmetrization of an acyclic meso-1,3-diol. This additive effect was considered to be attributable to the chelate formation of the β-hydroxy ketone or 1,3-diketone with a Ru(salen) complex.
- Nakamura, Yukie,Egami, Hiromichi,Matsumoto, Kazuhiro,Uchida, Tatsuya,Katsuki, Tsutomu
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- Chitosan as a chiral ligand and organocatalyst: Preparation conditions-property-catalytic performance relationships
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Chitosan is an abundant and renewable chirality source of natural origin. The effect of the preparation conditions by alkaline hydrolysis of chitin on the properties of chitosan was studied. The materials obtained were used as ligands in the ruthenium-catalysed asymmetric transfer hydrogenation of aromatic prochiral ketones and oxidative kinetic resolution of benzylic alcohols as well as organocatalysts in the Michael addition of isobutyraldehyde to N-substituted maleimides. The degrees of deacetylation of the prepared materials were determined by 1H NMR, FT-IR and UV-vis spectroscopy, the molecular weights by viscosity measurements, their crystallinity by WAXRD, and their morphology by SEM and TEM investigations. The materials were also characterized by Raman spectroscopy. The biopolymers which have molecular weights in a narrow (200-230 kDa) range and appropriate (80-95%) degrees of deacetylation were the most efficient ligands in the enantioselective transfer hydrogenation, whereas in the oxidative kinetic resolution the activity of the complexes and the stereoselectivity increased with the degree of deacetylation. The chirality of the chitosan was sufficient to obtain enantioselection in the Michael addition of isobutyraldehyde to maleimides in the aqueous phase. Interestingly, the biopolymer afforded the opposite enantiomer in excess compared to the monomer, d-glucosamine. In this reaction, good correlation between the degree of deacetylation and the catalytic activity was found. These results are novel steps in the application of this natural, biocompatible and biodegradable polymer in developing environmentally benign methods for the production of optically pure fine chemicals.
- Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
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p. 7652 - 7666
(2021/12/13)
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- C3 The symmetry contains a chiral ligand H3L of an amide bond. Preparation method and application
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The invention discloses C. 3 Chiral ligand H with symmetric amide bond3 L Relates to the technical field of material chemistry and chiral chemistry. The invention further provides the chiral ligand H. 3 L Preparation method and application thereof. The present invention has the advantage that the chiral ligand H of the present invention is a chiral ligand. 3 The L has a higher C. 3 The symmetric and flexible amide group enables coordination of the lanthanide metal ions with high coordination number and high oxygen affinity to be assembled into a novel structure-structure lanthanide metal chiral porous coordination cage. Moreover, the abundant chiral amide groups and amino acid residues on the ligand framework can be directly introduced into the synthesized lanthanide metal chiral porous coordination cage, thereby being beneficial to generating multiple chiral recognition sites and unique chiral microenvironments which mimic the biological enzyme binding pocket and further realize the purpose of high enantioselectivity separation of a series of chiral small molecule compounds.
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Paragraph 0092-0099
(2021/09/08)
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- Amino Acid-Functionalized Metal-Organic Frameworks for Asymmetric Base–Metal Catalysis
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We report a strategy to develop heterogeneous single-site enantioselective catalysts based on naturally occurring amino acids and earth-abundant metals for eco-friendly asymmetric catalysis. The grafting of amino acids within the pores of a metal-organic framework (MOF), followed by post-synthetic metalation with iron precursor, affords highly active and enantioselective (>99 % ee for 10 examples) catalysts for hydrosilylation and hydroboration of carbonyl compounds. Impressively, the MOF-Fe catalyst displayed high turnover numbers of up to 10 000 and was recycled and reused more than 15 times without diminishing the enantioselectivity. MOF-Fe displayed much higher activity and enantioselectivity than its homogeneous control catalyst, likely due to the formation of robust single-site catalyst in the MOF through site-isolation.
- Newar, Rajashree,Akhtar, Naved,Antil, Neha,Kumar, Ajay,Shukla, Sakshi,Begum, Wahida,Manna, Kuntal
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supporting information
p. 10964 - 10970
(2021/03/29)
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- Chiral Iron(II)-Catalysts within Valinol-Grafted Metal-Organic Frameworks for Enantioselective Reduction of Ketones
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The development of highly efficient and enantioselective heterogeneous catalysts based on earth-abundant elements and inexpensive chiral ligands is essential for environment-friendly and economical production of optically active compounds. We report a strategy of synthesizing chiral amino alcohol-functionalized metal-organic frameworks (MOFs) to afford highly enantioselective single-site base-metal catalysts for asymmetric organic transformations. The chiral MOFs (vol-UiO) were prepared by grafting of chiral amino alcohol such as l-valinol within the pores of aldehyde-functionalized UiO-MOFs via formation of imine linkages. The metalation of vol-UiO with FeCl2 in THF gives amino alcohol coordinated octahedral FeII species of vol-FeCl(THF)3 within the MOFs as determined by X-ray absorption spectroscopy. Upon activation with LiCH2SiMe3, vol-UiO-Fe catalyzed hydrosilylation and hydroboration of a range of aliphatic and aromatic carbonyls to afford the corresponding chiral alcohols with enantiomeric excesses up to 99%. Vol-UiO-Fe catalysts have high turnover numbers of up to 15 ?000 and could be reused at least 10 times without any loss of activity and enantioselectivity. The spectroscopic, kinetic, and computational studies suggest iron-hydride as the catalytic species, which undergoes enantioselective 1,2-insertion of carbonyl to give an iron-alkoxide intermediate. The subsequent σ-bond metathesis between Fe-O bond and Si-H bond of silane produces chiral silyl ether. This work highlights the importance of MOFs as the tunable molecular material for designing chiral solid catalysts based on inexpensive natural feedstocks such as chiral amino acids and base-metals for asymmetric organic transformations.
- Akhtar, Naved,Antil, Neha,Begum, Wahida,Chauhan, Manav,Kumar, Ajay,Manna, Kuntal,Newar, Rajashree
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p. 10450 - 10459
(2021/08/31)
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- Exploration of highly electron-rich manganese complexes in enantioselective oxidation catalysis; A focus on enantioselective benzylic oxidation
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The direct enantioselective hydroxylation of benzylic C-H bonds to form chiral benzylic alcohols represents a challenging transformation. Herein, we report on the exploration of new biologically inspired manganese and iron complexes bearing highly electron-rich aminopyridine ligands containing 4-pyrrolidinopyridine moieties ((S,S)-1, (R,R)-1, 2 and 5) in combination with chiral bis-pyrrolidine and N,N-cyclohexanediamine backbones in enantioselective oxidation catalysis with aqueous H2O2. The current manganese complexes outperform the analogous manganese complexes containing 4-dimethylaminopyridine moieties (3 and 4) in benzylic oxidation reactions in terms of alcohol yield while keeping similar ee values (~60% ee), which is attributed to the higher basicity of the 4-pyrrolidinopyridine group. A detailed investigation of different carboxylic acid additives in enantioselective benzylic oxidation provides new insights into how to rationally enhance enantioselectivities by means of proper tuning of the environment around the catalytic active site, and has resulted in the selection of Boc-l-Tert-leucine as the preferred additive. Using these optimized conditions, manganese complex 2 was shown to be effective in the enantioselective benzylic oxidation of a series of arylalkane substrates with up to 50% alcohol yield and 62% product ee. A final set of experiments also highlights the use of the new 4-pyrrolidinopyridine-based complexes in the asymmetric epoxidation of olefins (up to 98% epoxide yield and >99% ee).
- Klein Gebbink, Robertus J. M.,Li, Fanshi,Lutz, Martin,Masferrer-Rius, Eduard
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p. 7751 - 7763
(2021/12/13)
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- Copper-catalyzed asymmetric reductions of aryl/heteroaryl ketones under mild aqueous micellar conditions
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Enantioselective syntheses of nonracemic secondary alcohols have been achieved in an aqueous micellar medium via copper-catalyzed (Cu(OAc)2·H2O/(R)-3,4,5-MeO-MeO-BIPHEP) reduction of aryl/heteroaryl ketones. This methodology serves as a green protocol to access enantio-enriched alcohols under mild conditions (0-22 °C) using a base metal catalyst, together with an inexpensive, innocuous, and convenient stoichiometric hydride source (PMHS). The secondary alcohol products are formed in good to excellent yields with ee values greater than 90%.
- Etemadi-Davan, Elham,Fialho, David M.,Gadakh, Amol,Langner, Olivia C.,Lipshutz, Bruce H.,Sambasivam, Ganesh,Takale, Balaram S.
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supporting information
p. 3282 - 3286
(2021/05/29)
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- One-Pot Chemoenzymatic Conversion of Alkynes to Chiral Amines
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A one-pot chemoenzymatic sequential cascade for the synthesis of chiral amines from alkynes was developed. In this integrated approach, just ppm amounts of gold catalysts enabled the conversion of alkynes to ketones (>99%) after which a transaminase was used to catalyze the production of biologically valuable chiral amines in a good yield (up to 99%) and enantiomeric excess (>99%). A preparative scale synthesis of (S)-methylbenzylamine and (S)-4-methoxy-methylbenzylamine from its alkyne form gave a yield of 59 and 92%, respectively, withee> 99%.
- Mathew, Sam,Renn, Dominik,Rueping, Magnus,Sagadevan, Arunachalam
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p. 12565 - 12569
(2021/10/21)
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- Mechanochemical, Water-Assisted Asymmetric Transfer Hydrogenation of Ketones Using Ruthenium Catalyst
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Asymmetric catalytic reactions are among the most convenient and environmentally benign methods to obtain optically pure compounds. The aim of this study was to develop a green system for the asymmetric transfer hydrogenation of ketones, applying chiral Ru catalyst in aqueous media and mechanochemical energy transmission. Using a ball mill we have optimized the milling parameters in the transfer hydrogenation of acetophenone followed by reduction of various substituted derivatives. The scope of the method was extended to carbo- and heterocyclic ketones. The scale-up of the developed system was successful, the optically enriched alcohols could be obtained in high yields. The developed mechanochemical system provides TOFs up to 168 h?1. Our present study is the first in which mechanochemically activated enantioselective transfer hydrogenations were carried out, thus, may be a useful guide for the practical synthesis of optically pure chiral secondary alcohols.
- Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
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- Dynamic Kinetic Resolution of Alcohols by Enantioselective Silylation Enabled by Two Orthogonal Transition-Metal Catalysts
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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.
- Oestreich, Martin,Seliger, Jan
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p. 247 - 251
(2020/10/29)
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- Phase Separation-Promoted Redox Deracemization of Secondary Alcohols over a Supported Dual Catalysts System
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Unification of oxidation and reduction in a one-pot deracemization process has great significance in the preparation of enantioenriched organic molecules. However, the intrinsic mutual deactivation of oxidative and reductive catalysts and the extrinsic incompatible reaction conditions are unavoidable challenges in a single operation. To address these two issues, we develop a supported dual catalysts system to overcome these conflicts from incompatibility to compatibility, resulting in an efficient one-pot redox deracemization of secondary alcohols. During this transformation, the TEMPO species onto the outer surface of silica nanoparticles catalyze the oxidation of racemic alcohols to ketones, and the chiral Rh/diamine species in the nanochannels of the thermoresponsive polymer-coated hollow-shell mesoporous silica enable the asymmetric transfer hydrogenation (ATH) of ketones to chiral alcohols. To demonstrate the general feasibility, a series of orthogonal oxidation/ATH cascade reactions are compared to prove the compatible benefits in the elimination of their deactivations and the balance of the cascade directionality. As presented in this study, this redox deracemization process provides various chiral alcohols with enhanced yields and enantioselectivities relative to those from unsupported dual catalysts systems. Furthermore, the dual catalysts can be recycled continuously, making them an attractive feature in the application.
- Zhao, Zhitong,Wang, Chengyi,Chen, Qipeng,Wang, Yu,Xiao, Rui,Tan, Chunxia,Liu, Guohua
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p. 4055 - 4063
(2021/08/12)
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- Homochiral Dodecanuclear Lanthanide "cage in Cage" for Enantioselective Separation
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It is extremely difficult to anticipate the structure and the stereochemistry of a complex, particularly when the ligand is flexible and the metal node adopts diverse coordination numbers. When trivalent lanthanides (LnIII) and enantiopure amino acid ligands are utilized as building blocks, self-assembly sometimes yields rare chiral polynuclear structures. In this study, an enantiopure carboxyl-functionalized amino acid-based ligand with C3 symmetry reacts with lanthanum cations to give a homochiral porous coordination cage, (Δ/λ)12-PCC-57. The dodecanuclear lanthanide cage has an unprecedented octahedral "cage-in-cage"framework. During the self-assembly, the chirality is transferred from the enantiopure ligand and fixed by the binuclear lanthanide cluster to give 12 metal centers that have either Δor λ homochiral stereochemistry. The cage exhibits excellent enantioselective separation of racemic alcohols, 2,3-dihydroquinazolinones, and multiple commercially available drugs. This finding exhibits a rare example of a multinuclear lanthanide complex with a dual-walled topology and homochirality. The highly ordered self-assembly and self-sorting of flexible amino acids and lanthanides shed light on the chiral transformation between different complicated artificial systems that mimic natural enzymes.
- Zhu, Chengfeng,Tang, Haitong,Yang, Keke,Fang, Yu,Wang, Kun-Yu,Xiao, Zhifeng,Wu, Xiang,Li, Yougui,Powell, Joshua A.,Zhou, Hong-Cai
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supporting information
p. 12560 - 12566
(2021/08/23)
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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 0095-0102; 0105-0109
(2021/06/26)
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- Synthesis, characterization and catalytic performance in enantioselective reactions by mesoporous silica materials functionalized with chiral thiourea-amine ligand
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Chiral heterogeneous catalysts have been synthesized by grafting of silyl derivatives of (1R, 2R)- or (1S, 2S)-1,2-diphenylethane-1,2-diamine on SBA-15 mesoporous support. The mesoporous material SBA-15 and so-prepared chiral heterogeneous catalysts were characterized by a combination of different techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) surface area. Results showed that (1R, 2R)- and (1S, 2S)-1,2-diphenylethane-1,2-diamine were successively immobilized on SBA-15 mesoporous support. Chiral heterogeneous catalysts and their homogenous counterparts were tested in enantioselective transfer hydrogenation of aromatic ketones and enantioselective Michael addition of acetylacetone to β-nitroolefin derivatives. The catalysts demonstrated notably high catalytic conversions (up to 99%) with moderate enantiomeric excess (up to 30% ee) for the heterogeneous enantioselective transfer hydrogenation. The catalytic performances for enantioselective Michael reaction showed excellent activities (up to 99%) with poor enantioselectivities. Particularly, the chiral heterogeneous catalysts could be readily recycled for Michael reaction and reused in three consecutive catalytic experiments with no loss of catalytic efficacies.
- G?k, Ya?ar,G?k, Halil Zeki
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p. 853 - 874
(2020/11/10)
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- SECONDARY ARYL ALCOHOL AND METHOD OF SYNTHESIZING THEREOF
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The present invention relates to secondary aryl alcohol and a method for synthesizing the same and, specifically, to synthesizing secondary aryl alcohol having high optical selectivity through a hydrosilylation reaction using ketone containing an aryl group. In the method for synthesizing secondary aryl alcohol according to an embodiment of the present invention, secondary aryl alcohol is synthesized by making ketone react with hydrosilane under a chiral boron Lewis acid catalyst.COPYRIGHT KIPO 2020
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Paragraph 0032; 0062-0069
(2020/05/13)
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- Asymmetric Catalytic Meerwein-Ponndorf-Verley Reduction of Ketones with Aluminum(III)-VANOL Catalysts
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We report herein an efficient aluminum-catalyzed asymmetric MPV reduction of ketones with broad substrate scope and excellent yields and enantiomeric inductions. A variety of aromatic (both electron-poor and electron-rich) and aliphatic ketones were converted to chiral alcohols in good yields with high enantioselectivities (26 examples, 70-98percent yield and 82-99percent ee). This method operates under mild conditions (-10 °C) and low catalyst loading (1-5 mol percent). Furthermore, this process is catalyzed by the earth-abundant main-group element aluminum and employs 2-propanol as the hydride source.
- Guan, Yong,Mohammadlou, Aliakbar,Staples, Richard,Sullivan, Ryan P.,Wulff, William D.,Yin, Xiaopeng,Zheng, Li
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p. 7188 - 7194
(2020/07/21)
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- Iridium-Catalyzed Enantioselective Transfer Hydrogenation of Ketones Controlled by Alcohol Hydrogen-Bonding and sp3-C?H Noncovalent Interactions
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Iridium-catalyzed enantioselective transfer hydrogenation of ketones with formic acid was developed using a prolinol-phosphine chiral ligand. Cooperative action of the iridium atom and the ligand through alcohol-alkoxide interconversion is crucial to facilitate the transfer hydrogenation. Various ketones including alkyl aryl ketones, ketoesters, and an aryl heteroaryl ketone were competent substrates. An attractive feature of this catalysis is efficient discrimination between the alkyl and aryl substituents of the ketones, promoting hydrogenation with the identical sense of enantioselection regardless of steric demand of the alkyl substituent and thus resulting in a rare case of highly enantioselective transfer hydrogenation of tert-alkyl aryl ketones. Quantum chemical calculations revealed that the sp3-C?H/π interaction between an sp3-C?H bond of the prolinol-phosphine ligand and the aryl substituent of the ketone is crucial for the enantioselection in combination with O?H???O/sp3-C?H???O two-point hydrogen-bonding between the chiral ligand and carbonyl group. (Figure presented.).
- Murayama, Hiroaki,Heike, Yoshito,Higashida, Kosuke,Shimizu, Yohei,Yodsin, Nuttapon,Wongnongwa, Yutthana,Jungsuttiwong, Siriporn,Mori, Seiji,Sawamura, Masaya
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supporting information
p. 4655 - 4661
(2020/07/13)
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- Enantiocomplementary C–H Bond Hydroxylation Combining Photo-Catalysis and Whole-Cell Biocatalysis in a One-Pot Cascade Process
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Enantiocomplementary hydroxylation of alkyl aromatics through a one-pot photo-biocatalytic cascade reaction is described. The photoredox process is implemented in aqueous phase with O2 as oxidant and the subsequent (R)- or (S)-selective bioreduction is performed by whole cell system without the addition of the expensive cofactor (NADPH). This mild, operationally simple protocol transforms a wide variety of readily available aromatic compounds into valuable chiral alcohols with high yield (up to 90 %) and stereoselectivity (up to 99 %), thereby displaying important potentials in organic synthesis.
- Peng, Yongzhen,Li, Danyang,Fan, Jiajie,Xu, Weihua,Xu, Jian,Yu, Huilei,Lin, Xianfu,Wu, Qi
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supporting information
p. 821 - 825
(2020/02/20)
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- Cationic NHC-Phosphine Iridium Complexes: Highly Active Catalysts for Base-Free Hydrogenation of Ketones
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Novel bidentate N-heterocyclic carbene-phosphine iridium complexes have been synthesized and evaluated in the hydrogenation of ketones. Reported catalytic systems require base additives and, if excluded, need elevated temperature or high pressure of hydrogen gas to achieve satisfactory reactivity. The developed catalysts showed extremely high reactivity and good enantioselectivity under base-free and mild conditions. In the presence of 1 mol % catalyst under 1 bar hydrogen pressure at room temperature, hydrogenation was complete in 30 minutes giving up to 96 % ee. Again, this high reactivity was achieved in additive-free conditions. Mechanistic experiments demonstrated that balloon pressure of hydrogen was sufficient to form the activate species by reducing and eliminating the 1,5-cyclooctadiene ligand. The pre-activated catalyst was able to hydrogenate acetophenone with 89 % conversion in 5 min.
- Quan, Xu,Kerdphon, Sutthichat,Peters, Bram B. C.,Rujirawanich, Janjira,Krajangsri, Suppachai,Jongcharoenkamol, Jira,Andersson, Pher G.
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supporting information
p. 13311 - 13316
(2020/09/22)
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- One-pot Chemoenzymatic Deracemisation of Secondary Alcohols Employing Variants of Galactose Oxidase and Transfer Hydrogenation
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Enantiomerically enriched chiral secondary alcohols serve as valuable building blocks for drug intermediates and fine chemicals. In this study the deracemisation of secondary alcohols to generate enantiomeric pure chiral alcohols has been achieved by combining enantio-selective enzymatic oxidation of a secondary alcohol, by a variant of GOase (GOase M3-5), with either non-selective ketone reduction via transfer hydrogenation (TH) or enantio-selective asymmetric transfer hydrogenation (ATH). Both the enzymatic oxidation system and the transition-metal mediated reduction system were optimised to ensure compatibility with each other resulting in a homogeneous reaction system. 1-(4-nitrophenyl)ethanol was generated with 99 % conversion and 98 % ee by the deracemisation method, and it has been extended to a series of other secondary alcohols with comparable results.
- Yuan, Bo,Debecker, Damien P.,Wu, Xiaofeng,Xiao, Jianliang,Fei, Qiang,Turner, Nicholas J.
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p. 6191 - 6195
(2020/10/15)
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- Observation of hyperpositive non-linear effect in catalytic asymmetric organozinc additions to aldehydes
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Asymmetric amplification is a phenomenon that is believed to play a key role in the emergence of homochirality in life. In asymmetric catalysis, theoretical and experimental models have been investigated to provide an understanding of how chiral amplification is possible, in particular based on non-linear effects. Interestingly, it has been proposed a quarter century ago that chiral catalysts, when not enantiopure might even be more enantioselective than their enantiopure counterparts. We show here that such hyperpositive non-linear effect in asymmetric catalysis is indeed possible. An in-depth study into the underlying mechanism was carried out, and the scheme we derive differs from the previous proposed models.
- Geiger, Yannick,Achard, Thierry,Maisse-Fran?ois, Aline,Bellemin-Laponnaz, Stéphane
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supporting information
p. 1250 - 1256
(2020/07/25)
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- RETRACTED ARTICLE: The Manganese(I)-Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege
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The bis(carbonyl) manganese(I) complex [Mn(CO)2(1)]Br (2) with a chiral (NH)2P2 macrocyclic ligand (1) catalyzes the asymmetric transfer hydrogenation of polar double bonds with 2-propanol as the hydrogen source. Ketones (43 substrates) are reduced to alcohols in high yields (up to >99 %) and with excellent enantioselectivities (90–99 % ee). A stereochemical model based on attractive CH–π interactions is proposed.
- Passera, Alessandro,Mezzetti, Antonio
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supporting information
p. 187 - 191
(2019/12/11)
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- Copper(I) Diphosphine Bifluoride Complexes as Efficient Preactivated Catalysts for Nucleophilic Addition on Unsaturated Functional Groups
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Herein we report the synthesis of a family of copper(I) diphosphine bifluoride complexes, their characterization, and their use as efficient preactivated catalysts for nucleophilic copper addition of pronucleophiles on unsaturations. Their use as mechanistic probes is also highlighted by the identification of two copper deuterides.
- Rasson, Corentin,Riant, Olivier
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supporting information
p. 835 - 840
(2020/02/13)
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- Efficient asymmetric synthesis of chiral alcohols using high 2-propanol tolerance alcohol dehydrogenase: Sm ADH2 via an environmentally friendly TBCR system
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Alcohol dehydrogenases (ADHs) together with the economical substrate-coupled cofactor regeneration system play a pivotal role in the asymmetric synthesis of chiral alcohols; however, severe challenges concerning the poor tolerance of enzymes to 2-propanol and the adverse effects of the by-product, acetone, limit its applications, causing this strategy to lapse. Herein, a novel ADH gene smadh2 was identified from Stenotrophomonas maltophilia by traditional genome mining technology. The gene was cloned into Escherichia coli cells and then expressed to yield SmADH2. SmADH2 has a broad substrate spectrum and exhibits excellent tolerance and superb activity to 2-propanol even at 10.5 M (80%, v/v) concentration. Moreover, a new thermostatic bubble column reactor (TBCR) system is successfully designed to alleviate the inhibition of the by-product acetone by gas flow and continuously supplement 2-propanol. The organic waste can be simultaneously recovered for the purpose of green synthesis. In the sustainable system, structurally diverse chiral alcohols are synthesised at a high substrate loading (>150 g L-1) without adding external coenzymes. Among these, about 780 g L-1 (6 M) ethyl acetoacetate is completely converted into ethyl (R)-3-hydroxybutyrate in only 2.5 h with 99.9% ee and 7488 g L-1 d-1 space-time yield. Molecular dynamics simulation results shed light on the high catalytic activity toward the substrate. Therefore, the high 2-propanol tolerance SmADH2 with the TBCR system proves to be a potent biocatalytic strategy for the synthesis of chiral alcohols on an industrial scale.
- Yang, Zeyu,Fu, Hengwei,Ye, Wenjie,Xie, Youyu,Liu, Qinghai,Wang, Hualei,Wei, Dongzhi
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- N2Phos - an easily made, highly effective ligand designed for ppm level Pd-catalyzed Suzuki-Miyaura cross couplings in water
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A new biaryl phosphine-containing ligand from an active palladium catalyst for ppm level Suzuki-Miyaura couplings, enabled by an aqueous micellar reaction medium. A wide array of functionalized substrates including aryl/heteroaryl bromides are amenable, as are, notably, chlorides. The catalytic system is both general and highly effective at low palladium loadings (1000-2500 ppm or 0.10-0.25 mol%). Density functional theory calculations suggest that greater steric congestion in N2Phos induces increased steric crowding around the Pd center, helping to destabilize the 2?:?1 ligand-Pd(0) complex more for N2Phos than for EvanPhos (and less bulky ligands), and thereby favoring formation of the 1?:?1 ligand-Pdocomplex that is more reactive in oxidative addition to aryl chlorides.
- Akporji, Nnamdi,Andersen, Joel,Aue, Donald H.,Cortes-Clerget, Margery,Gallou, Fabrice,Landstrom, Evan,Lipshutz, Bruce H.,Thakore, Ruchita R.
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p. 5205 - 5212
(2020/06/03)
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- Efficient Asymmetric Synthesis of Ethyl (S)-4-Chloro-3-hydroxybutyrate Using Alcohol Dehydrogenase SmADH31 with High Tolerance of Substrate and Product in a Monophasic Aqueous System
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Bioreductions catalyzed by alcohol dehydrogenases (ADHs) play an important role in the synthesis of chiral alcohols. However, the synthesis of ethyl (S)-4-chloro-3-hydroxybutyrate [(S)-CHBE], an important drug intermediate, has significant challenges concerning high substrate or product inhibition toward ADHs, which complicates its production. Herein, we evaluated a novel ADH, SmADH31, obtained from the Stenotrophomonas maltophilia genome, which can tolerate extremely high concentrations (6 M) of both substrate and product. The coexpression of SmADH31 and glucose dehydrogenase from Bacillus subtilis in Escherichia coli meant that as much as 660 g L-1 (4.0 M) ethyl 4-chloroacetoacetate was completely converted into (S)-CHBE in a monophasic aqueous system with a >99.9% ee value and a high space-time yield (2664 g L-1 d-1). Molecular dynamics simulation shed light on the high activity and stereoselectivity of SmADH31. Moreover, five other optically pure chiral alcohols were synthesized at high concentrations (100-462 g L-1) as a result of the broad substrate spectrum of SmADH31. All these compounds act as important drug intermediates, demonstrating the industrial potential of SmADH31-mediated bioreductions.
- Chen, Rong,Liu, Qinghai,Wang, Hualei,Wei, Dongzhi,Xie, Youyu,Yang, Zeyu,Ye, Wenjie
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p. 1068 - 1076
(2020/07/06)
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- One-pot kinetic resolution-Mitsunobu reaction to access optically pure compounds, using silver salts in the substitution protocol
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A practical method is developed to access chiral arylalkyl carbinols with a high yield from racemic alcohols. A one-pot enzyme mediated Kinetic Resolution followed by Mitsunobu esterification of the unreacted enantiomer of alcohol with metal acetate results in a nearly complete formation of chiral acetate. Substitution with AgOAc was found to be the most efficient, and the use of sub stoichiometric amounts of AgNO3 and excess of NaOAc affords comparable results; the protocol was further extended to introduce azide as a nucleophile.
- Raval, Hiten B.,Bedekar, Ashutosh V.
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p. 21238 - 21243
(2020/12/31)
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- Engineering a homochiral metal-organic framework based on an amino acid for enantioselective separation
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A chiral metal-organic framework possessing an open amphiphilic channel is constructed from a dicarboxylate ligand derived from an amino acid and is shown to be an efficient and recyclable chiral solid adsorbent, which is capable of separating racemic secondary alcohols, epoxides, and ibuprofen with very high enantioselectivity.
- Tang, Haitong,Yang, Keke,Wang, Kun-Yu,Meng, Qi,Wu, Fan,Fang, Yu,Wu, Xiang,Li, Yougui,Zhang, WenCheng,Luo, Yunfei,Zhu, Chengfeng,Zhou, Hong-Cai
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p. 9016 - 9019
(2020/08/17)
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- An Enantioconvergent Benzylic Hydroxylation Using a Chiral Aryl Iodide in a Dual Activation Mode
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The application of a triazole-substituted chiral iodoarene in a direct enantioselective hydroxylation of alkyl arenes is reported. This method allows the rapid synthesis of chiral benzyl alcohols in high yields and stereocontrol, despite its nontemplated nature. In a cascade activation consisting of an initial irradiation-induced radical C-H-bromination and a consecutive enantioconvergent hydroxylation, the iodoarene catalyst has a dual role. It initiates the radical bromination in its oxidized state through an in-situ-formed bromoiodane and in the second, Cu-catalyzed step, it acts as a chiral ligand. This work demonstrates the ability of a chiral aryl iodide catalyst acting both as an oxidant and as a chiral ligand in a highly enantioselective C-H-activating transformation. Furthermore, this concept presents an enantioconvergent hydroxylation with high selectivity using a synthetic catalyst.
- Abazid, Ayham H.,Clamor, Nils,Nachtsheim, Boris J.
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p. 8042 - 8048
(2020/09/21)
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- Imine containing C2-Symmetric chiral half sandwich η6-p-cymene-Ru(II)- phosphinite complexes: Investigation of their catalytic activity in the asymmetric transfer hydrogenation of ketones
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New chiral C2-symmetric bis(phosphinite) ligands containing imine group were synthesized from 1-({[(1R,2R)-2-{[(2-hydroxynaphthalen-1-yl)methylidene] amino}cyclohexyl]- imino}methyl)- naphthalen-2-ol and two equivalents of Ph2PCl, (i-Pr)2PCl or (Cy)2PCl, in high yields. Binuclear C2-symmetric half sandwich η6-p-cymene-Ru(II) complexes of the chiral phosphinite ligands were synthesized by treating of [Ru(η6-p-cymene)(μ-Cl)Cl]2 with the phosphinites in 1:1 M ratio in CH2Cl2. Their catalytic activities in asymmetric transfer hydrogenation (ATH) were investigated for the reaction of acetophenone derivatives with isopropyl alcohol. The corresponding optically active secondary alcohols were obtained in excellent levels of conversion (96–99%) and moderate enantioselectivity (up to 60% ee). Among three complexes investigated, complex 4 was the most efficient one.
- Saleh, Najmuldain Abdullah,Pa?a, Salih,Kayan, Cezmi,Meri?, Nermin,Sünkür, Murat,Aral, Tar?k,Aydemir, Murat,Baysal, Ak?n,Durap, Feyyaz
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- Co-immobilization of metal and enzyme into hydrophobic nanopores for highly improved chemoenzymatic asymmetric synthesis
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Chemoenzymatic catalysts with hydrophobic nanopores were fabricated by co-immobilizing metal nanoparticles and enzymes into the dendritic organosilica nanoparticles. They demonstrated highly improved catalytic performance in chemoenzymatic asymmetric synthesis of chiral amines and alcohols. The hydrophobic microenvironment proved to be critical to enhanced stability, activity and cascade efficiency. This journal is
- Gao, Liya,Wang, Zihan,Liu, Yunting,Liu, Pengbo,Gao, Shiqi,Gao, Jing,Jiang, Yanjun
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supporting information
p. 13547 - 13550
(2020/11/17)
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- CO2-expanded liquids as solvents to enhance activity of Pseudozyma antarctica lipase B towards ortho-substituted 1-phenylethanols
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Pseudozyma (Candida) antarctica lipase B (CAL-B, Novozym 435) is one of the most widely used and outstanding biocatalysts. However, CAL-B-catalyzed transesterification of ortho-substituted 1-phenylethanol analogs suffers low conversion. In this research, the reactions were accelerated by using CO2-expanded liquids, liquids expanded by dissolving pressurized CO2, such as CO2-expanded hexane or CO2-expanded MeTHF.
- Hoang, Hai Nam,Koesoema, Afifa Ayu,Matsuda, Tomoko,Otsu, Moeko,Suzuki, Yuichi,Tamura, Mayumi
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supporting information
(2020/09/18)
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- Diphenylamine-amine-oxazoline ligand, synthesis method as well as metal complex and application thereof
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The invention provides a diphenylamine-amine-oxazoline ligand which is a compound of formula (1) or an antipode or racemate of the compound of formula (1), wherein R1 and R2 are respectively and separately one of C1 to C10 hydrocarbon group, benzyl group, phenyl group or substituted phenyl group and heteroaryl group; and R3 is H or methyl. The invention also discloses a synthesis method as well asa metal complex and application thereof, which aims at providing a catalyst capable of realizing high synthesis yield by virtue of a simple synthesis route, and ensuring that the catalyst has very high catalytic activity in asymmetric hydrogenation and hydrogen transfer reactions of olefins and ketones.
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Paragraph 0122-0128; 0139; 0140
(2019/04/17)
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- Deracemization of sec-alcohols through sequential application of C. Albicans and Ketoreductases
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A biocatalytic cascade process was developed using immobilized cells of the wild type yeast Candida albicans CCT 0776 in calcium alginate beads and a commercially available ketoreductase. The aim was to promote deracemization by stereoinversion of (±)-1-arylethanols in high substrate concentration (above 100 mmol L-1) to prepare the (R)-enantiomers of the alcohols (90-99percent), with a high enantiomeric excess (83-99percent) after 2 to 19 h. The (R)-1-(3-methoxyphenyl)ethanol, with 70percent yield and 91percent ee, obtained after 5 h was used to prepare (S)-1-(3-methoxyphenyl)-ethylamine with 60percent yield and 91percent ee after two steps, a key intermediate in the synthesis of (S)-rivastigmine.
- Nasário, Fábio D.,Moran, Paulo J.S.,Rodrigues, José Augusto R.
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p. 772 - 779
(2019/08/26)
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- Enantioselective Reduction of α,β-Unsaturated Ketones and Aryl Ketones by Perakine Reductase
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This report describes the enantioselective reduction of structurally diverse α,β-unsaturated ketones and aryl ketones by perakine reductase (PR) from Rauvolfia. This enzymatic reduction produces α-chiral allylic and aryl alcohols with excellent enantioselectivity and most of the products in satisfactory yields. Furthermore, the work demonstrates 1 mmol scale reactions for product delivery without any detrimental effect on yield and enantioselectivity. The catalytic mechanism, determined by 3D-structure-based modeling of PR and ligand complexes, is also described.
- Cai, Sheng,Shao, Nana,Chen, Yuanyuan,Li, Anbang,Pan, Jie,Zhu, Huajian,Zou, Hongbin,Zeng, Su,Sun, Lianli,Zhao, Jinhao
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supporting information
p. 4411 - 4414
(2019/05/22)
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- Thermoregulated ionic liquid-coordinating ruthenium complexes for asymmetric hydrogenation of aromatic ketones
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This work presented the synthesis and characterization of new ionic liquid-coordinating ruthenium complexes. The resulting ruthenium complexes exhibited not only excellent thermoregulated phase-separation behavior but also highly catalytic activity and enantioselectivity for the asymmetric hydrogenation with molecular hydrogen. The thermoregulated ionic liquid catalyst was highly resistant to leaching and was recycled consecutively for six times without significant loss of catalytic activity and enantioselectivity. The presence of Ru–H species revealed that NH and a Ru–H unit, involved in the hydride transfer process, were of great importance in the present catalytic system.
- Tang, Guoping,Chen, Manyu,Fang, Jian,Xu, Zichen,Gong, Honghui,Peng, Qingpo,Hou, Zhenshan
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- Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of Ketones
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A highly enantioselective Piers-type hydrosilylation of simple ketones was successfully realized using a chiral frustrated Lewis pair of tri-tert-butylphosphine and chiral diene-derived borane as catalyst. A wide range of optically active secondary alcohols were furnished in 80%—99% yields with 81%—97% ee's under mild reaction conditions.
- Liu, Xiaoqin,Wang, Qiaotian,Han, Caifang,Feng, Xiangqing,Du, Haifeng
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p. 663 - 666
(2019/05/21)
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- Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
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Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
- Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
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supporting information
p. 16490 - 16494
(2019/11/03)
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- Synthetic Versatility of Lipases: Application for Si-O Bond Formation and Cleavage
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Several commercially available lipases were examined in a study on O-Si bond formation and cleavage applying silicon-based protecting groups and alcohols or the corresponding silyl ethers. With regard to deprotection, from silyl ether to the corresponding alcohol, only the solvent and the lipase were necessary. The influence of the protecting group, the lipase source, and the substituent was investigated to optimize the results. The TMS moiety could be removed in 24 hours of reaction at room temperature in aqueous systems (conv. up to 99%, depending on the substrate and lipase). The reverse reactions, that is, with the protection of the alcohols, were carried out in hexane using different silyl chlorides. The TMS, TES, and TBS moieties were successfully inserted in the primary and secondary alcohols without the need for dry conditions or an inert atmosphere, presenting conversions of up to 99%, depending on the substrate.
- Brondani, Patrícia Bulegon,Mittersteiner, Mateus,Voigt, Morgana Aline,Klinkowski, Bruna Heloisa,Riva Scharf, Dilamara,De Jesus, Paulo Cesar
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supporting information
p. 477 - 485
(2019/01/10)
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- Iridium-catalyzed asymmetric hydrogenation method for the preparation of chiral alcohols
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The present invention provides one kind of iridium-catalyzed asymmetric hydrogenation method for the preparation of chiral alcohols, the method specifically is: in the glove box filled with nitrogen, the [Ir (COD) Cl]2 With a chiral P, N, N ligand soluble in methanol, stir at room temperature 1 hour, [...] catalyst. Adding substrate alkone and alkali additive, is placed on the high-pressure in the reactor, for a certain reaction under the pressure of the hydrogenation reaction. Slowly release hydrogen, silica gel to remove the solvent and separate the product after the alcohol. The invention states iridium catalyzed alkone asymmetric hydrogenation for the preparation of chiral reaction has mild condition, easy to operate, and the product of the enantioselectivity and the like.
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Paragraph 0095-0100; 0103; 0104
(2019/06/07)
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- A chiral nitrogen nitrogen phosphine tridentate ligand based on a ferrocene skeleton and an application thereof
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The invention belongs to the technical field of asymmetric catalysis and specifically relates to a chiral nitrogen nitrogen phosphine tridentate ligand based on a ferrocene skeleton and an applicationthereof. A coordination compound is obtained by the disclosed chiral nitrogen nitrogen phosphine tridentate ligand base on the ferrocene skeleton complexed with a transition metal precursor, the complex is used as a precious metal catalyst, and is successfully applied to high efficiency asymmetric hydrogenation of aromatic ketone. Compared with other tridentate ligands, the ligand is simple to synthetize, is stable to water and air, and easy to prepare on a large scale, shows high activity and high enantioselectivity on carbon and oxygen double bond, and has greater implementation value and social and economic benefits.
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Paragraph 0089-0096
(2018/12/02)
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- A comparative study on asymmetric reduction of ketones using the growing and resting cells of marine-derived fungi
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Whole-cell biocatalysts offer a highly enantioselective, minimally polluting route to optically active alcohols. Currently, most of the whole-cell catalytic performance involves resting cells rather than growing cell biotransformation, which is one-step process that benefits from the simultaneous growth and biotransformation, eliminating the need for catalysts preparation. In this paper, asymmetric reduction of 14 aromatic ketones to the corresponding enantiomerically pure alcohols was successfully conducted using the growing and resting cells of marine-derived fungi under optimized conditions. Good yields and excellent enantioselectivities were achieved with both methods. Although substrate inhibition might be a limiting factor for growing cell biotransformation, the selected strain can still completely convert 10-mM substrates into the desired products. The resting cell biotransformation showed a capacity to be recycled nine times without a significant decrease in the activity. This is the first study to perform asymmetric reduction of ketones by one-step growing cell biotransformation.
- Liu, Hui,Chen, Bi-Shuang,Ribeiro de Souza, Fayene Zeferino,Liu, Lan
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- Development of Ferrocene-Based Diamine-Phosphine-Sulfonamide Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
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A series of air-stable, easily accessible tridentate ferrocene-based diamine-phosphine sulfonamide (f-diaphos) ligands were successfully developed for iridium-catalyzed asymmetric hydrogenation of ketones. The f-diaphos ligands exhibited excellent enantioselectivity and superb reactivity in Ir-catalyzed asymmetric hydrogenation of ketones (for arylalkyl ketones, (S)-selectivity, up to 99.4% ee, and 100 000 TON; for diaryl ketones, (R)-selectivity, up to 98.2% ee, and 10 000 TON). This protocol could be easily conducted on gram scale, thereby providing a chance to various drugs.
- Ling, Fei,Nian, Sanfei,Chen, Jiachen,Luo, Wenjun,Wang, Ze,Lv, Yaping,Zhong, Weihui
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p. 10749 - 10761
(2018/09/06)
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- Transformation of Alkynes into Chiral Alcohols via TfOH-Catalyzed Hydration and Ru-Catalyzed Tandem Asymmetric Hydrogenation
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A novel full atom-economic process for the transformation of alkynes into chiral alcohols by TfOH-catalyzed hydration coupled with Ru-catalyzed tandem asymmetric hydrogenation in TFE under simple conditions has been developed. A range of chiral alcohols was obtained with broad functional group tolerance, good yields, and excellent stereoselectivities.
- Liu, Sensheng,Liu, Huan,Zhou, Haifeng,Liu, Qixing,Lv, Jinliang
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supporting information
p. 1110 - 1113
(2018/02/23)
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