- Biocatalytic aminolysis of ethyl (S)-mandelate by lipase from Candida antarctica
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Enzymes play many roles in the advancement of biotechnology, discovery of new therapeutic agents and industrial processes. In this perspective, aminolysis reactions using lipase from Candida antarctica (CAL-B) were performed from ethyl (S)-mandelate and several aliphatic amines (45 °C, hexane, 3–6 h). By means of optimized conditions, amides with excellent isolated yields (60–97%) were synthetized. The biotechnological potential of CAL-B as a promising approach for the synthesis of organic compounds in a more sustainable, rapid, efficient and green chemistry perspective was verified on these results.
- Lima, Rafaely N.,Porto, André L.M.
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- Preparation of γ-Al2O3/α-Al2O3 ceramic foams as catalyst carriers via the replica technique
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This work describes an effective method for the preparation of open-cell ceramic foams for their further use as catalyst supports. The polyurethane sponge replica technique was applied using a ceramic suspension based on a mixture of α-alumina, magnesia a
- Shumilov, Vladimir,Kirilin, Alexey,Tokarev, Anton,Boden, Stephan,Schubert, Markus,Hampel, Uwe,Hupa, Leena,Salmi, Tapio,Murzin, Dmitry Yu.
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- Biocatalysed reductions of α-ketoesters employing CyreneTM as cosolvent
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The search for novel reaction media with environmental friendly properties is an area of great interest in enzyme catalysis. Water is the medium of biocatalysed processes, but due to its properties, sometimes the presence of organic (co)solvents is required. CyreneTM represents one of the newest approaches to this medium engineering. This polar solvent has been employed for the first time in biocatalysed reductions employing purified alcohol dehydrogenases. A set of α-ketoesters has been reduced to the corresponding chiral α-hydroxyesters with high conversions and optical purities, being possible to obtain good results at Cyrene contents of 30% v/v and working at substrate concentrations of 1.0 M in presence of 2.5% v/v of this solvent. At this concentration, the presence of Cyrene has a beneficial effect in the bioreduction conversion.
- de Gonzalo, Gonzalo
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- Structural insights into the desymmetrization of bulky 1,2-dicarbonyls through enzymatic monoreduction
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Benzil reductases are dehydrogenases preferentially active on aromatic 1,2-diketones, but the reasons for this peculiar substrate recognition have not yet been clarified. The benzil reductase (KRED1-Pglu) from the non-conventional yeast Pichia glucozyma showed excellent activity and stereoselectivity in the monoreduction of space-demanding aromatic 1,2-dicarbonyls, making this enzyme attractive as biocatalyst in organic chemistry. Structural insights into the stereoselective monoreduction of 1,2-diketones catalyzed by KRED1-Pglu were investigated starting from its 1.77 ? resolution crystal structure, followed by QM and classical calculations; this study allowed for the identification and characterization of the KRED1-Pglu reactive site. Once identified the recognition elements involved in the stereoselective desymmetrization of bulky 1,2-dicarbonyls mediated by KRED1-Pglu, a mechanism was proposed together with an in silico prediction of substrates reactivity.
- Rabuffetti, Marco,Cannazza, Pietro,Contente, Martina Letizia,Pinto, Andrea,Romano, Diego,Hoyos, Pilar,Alcantara, Andres R.,Eberini, Ivano,Laurenzi, Tommaso,Gourlay, Louise,Di Pisa, Flavio,Molinari, Francesco
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supporting information
(2021/01/25)
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- Exploiting Cofactor Versatility to Convert a FAD-Dependent Baeyer–Villiger Monooxygenase into a Ketoreductase
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Cyclohexanone monooxygenases (CHMOs) show very high catalytic specificity for natural Baeyer–Villiger (BV) reactions and promiscuous reduction reactions have not been reported to date. Wild-type CHMO from Acinetobacter sp. NCIMB 9871 was found to possess an innate, promiscuous ability to reduce an aromatic α-keto ester, but with poor yield and stereoselectivity. Structure-guided, site-directed mutagenesis drastically improved the catalytic carbonyl-reduction activity (yield up to 99 %) and stereoselectivity (ee up to 99 %), thereby converting this CHMO into a ketoreductase, which can reduce a range of differently substituted aromatic α-keto esters. The improved, promiscuous reduction activity of the mutant enzyme in comparison to the wild-type enzyme results from a decrease in the distance between the carbonyl moiety of the substrate and the hydrogen atom on N5 of the reduced flavin adenine dinucleotide (FAD) cofactor, as confirmed using docking and molecular dynamics simulations.
- Xu, Jian,Peng, Yongzhen,Wang, Zhiguo,Hu, Yujing,Fan, Jiajie,Zheng, He,Lin, Xianfu,Wu, Qi
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p. 14499 - 14503
(2019/09/17)
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- Ferroceno quinoline compound with planar chirality and synthesis method thereof
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The invention provides a ferroceno quinoline compound with planar chirality as shown in description, R1-R8 are H or C1-C10 alkyl, the C1-C10 alkyl comprises one or multiple substituents of the methoxyand halogen. The invention further provides a synthesis
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Paragraph 0058-0060
(2019/06/07)
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- Enantioselective hydrogenation of α-ketoesters catalyzed by cinchona alkaloid stabilized Rh nanoparticles in ionic liquid
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The heterogeneous enantioselective hydrogenation of α-ketoesters catalyzed by rhodium nanoparticles (Rh NPs) in ionic liquid was studied with the stabilization and modification of cinchona alkaloids. TEM characterization showed that well-dispersed Rh NPs of about 1.96?nm were obtained in ionic liquid. The results showed that cinchona alkaloids not only had good enantiodifferentiating ability but also accelerated the catalytic reaction. Under the optimum reaction conditions, the enantiomeric excess in ethyl benzoylformate hydrogenation could reach as high as 60.9%.
- Jiang, He-yan,Xu, Jie,Sun, Bin
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p. 818 - 823
(2019/08/07)
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- Asymmetric Transfer Hydrogenation in Thermomorphic Microemulsions Based on Ionic Liquids
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A thermomorphic ionic-liquid-based microemulsion system was successfully applied for the Ru-catalyzed asymmetric transfer hydrogenation of ketones. On the basis of the temperature-dependent multiphase behavior of the targeted microemulsion, simple product separation as well as catalyst recycling could be realized. The use of water-soluble ligands improved the immobilization of the catalyst in the microemulsion phase and significantly decreased the catalyst leaching into the organic layer upon extraction of the product. Eventually, the optimized microemulsion system could be applied to a wide range of aromatic ketones that were reduced with good isolated yields (up to 98%) and enantioselectivities (up to 97%), while aliphatic ketones were less successful.
- Hejazifar, Mahtab,Pálv?lgyi, ádám Márk,Bitai, Jacqueline,Lanaridi, Olga,Bica-Schr?der, Katharina
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p. 1841 - 1851
(2019/10/11)
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- Chiral-at-Iron Catalyst: Expanding the Chemical Space for Asymmetric Earth-Abundant Metal Catalysis
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A new class of chiral iron catalysts is introduced that contains exclusively achiral ligands with the overall chirality being the result of a stereogenic iron center. Specifically, iron(II) is cis-coordinated to two N-(2-pyridyl)-substituted N-heterocycli
- Hong, Yubiao,Jarrige, Lucie,Harms, Klaus,Meggers, Eric
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supporting information
p. 4569 - 4572
(2019/03/19)
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- Fine tuning the enantioselectivity and substrate specificity of alcohol dehydrogenase from Kluyveromyces polysporus by single residue at 237
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Here, S237 was identified to be important in fine tuning the substrate specificity and enantioselectivity of alcohol dehydrogenase from Kluyveromyces polysporus (KpADH). In the reduction of a diaryl ketone, (4-chlorophenyl)-(pyridin-2-yl)-methanone (1a), the highest and lowest enantioselectivity of 96.1% and 27.0% e.e. (R) were obtained with S237A and S237C. Kinetic parameters analysis revealed that S237G, S237A, S237H and S237D displayed improved kcat/Km toward 1a. Various prochiral ketones, including acetophenone, 4-chloroacetophenone and ethyl 2-oxo-4-phenylbutyrate could be asymmetrically reduced by S237C, S237G and S237E with > 99% e.e. This study provides guidance for the application of KpADH in the preparation of chiral secondary alcohols.
- Wang, Yue,Dai, Wei,Liu, Yongmei,Zhang, Zhongwei,Zhou, Jieyu,Xu, Guochao,Ni, Ye
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- Hydrogenation of Ketones on Dispersed Chiral-Modified Palladium Nanoparticles
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Hydrogenation of acetophenone and esters of ketoacids with molecular hydrogen in the presence of the Pd(acac)2-cinchonidine–H2 catalytic system has been studied. The dependence of the molar ratio of (–)-cinchonidine/Pd on size and shape of palladium nanoparticles, formed in the system, also on reaction rate and enantioselectivity has been established. The nature of the regularities observed for the Pd(acac)2-cinchonidine–H2 catalytic system was discussed.
- Nindakova,Strakhov,Kolesnikov
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p. 199 - 207
(2018/03/26)
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- A carbonyl reductase from: Candida parapsilosis ATCC 7330: Substrate selectivity and enantiospecificity
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Candida parapsilosis ATCC 7330, a rich source of highly stereospecific oxidoreductases, catalyzes oxidation-reduction of a plethora of compounds yielding industrially important intermediates. An (S)-specific carbonyl reductase (SRED) purified and characterized from this yeast is reported here. (R)-Specific carbonyl reductase (CpCR) was reported by us earlier. SRED asymmetrically reduces ketones with excellent enantiospecificity (ee > 99%) and α-ketoesters with higher catalytic activity but moderate enantiospecificity (ee 70%) in the presence of NADPH. Minimal activity is shown towards the reduction of aldehydes. While the reduction of α-ketoesters with SRED can occur with either NADPH or NADH, for ketone reduction SRED requires NADPH specifically. SRED with a subunit molecular weight of 30 kDa shows optimal activity at pH 5.0 and 25 °C, and its activity is affected by Cu2+. Taken together, SRED and CpCR offer substrates which on asymmetric reduction give products of opposite absolute configurations.
- Sudhakara, Sneha,Chadha, Anju
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supporting information
p. 4165 - 4171
(2017/07/10)
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- Identification of a Robust Carbonyl Reductase for Diastereoselectively Building syn-3,5-Dihydroxy Hexanoate: A Bulky Side Chain of Atorvastatin
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t-Butyl-6-cyano-(3R,5R)-dihydroxyhexanoate is an advanced chiral precursor for the synthesis of the side chain pharmacophore of cholesterol-lowering drug atorvastatin. Herein, a robust carbonyl reductase (LbCR) was newly identified from Lactobacillus brevis, which displays high activity and excellent diastereoselectivity toward bulky t-butyl 6-cyano-(5R)-hydroxy-3-oxo-hexanoate (7). The engineered Escherichia coli cells harboring LbCR and glucose dehydrogenase (for cofactor regeneration) were employed as biocatalysts for the asymmetric reduction of substrate 7. As a result, as much as 300 g L-1 of water-insoluble substrate was completely converted to the corresponding chiral diol with >99.5% de in a space-time yield of 351 g L-1 d-1, indicating a great potential of LbCR for practical synthesis of the very bulky and bi-chiral 3,5-dihydroxy carboxylate side chain of best-selling statin drugs.
- Gong, Xu-Min,Zheng, Gao-Wei,Liu, You-Yan,Xu, Jian-He
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supporting information
p. 1349 - 1354
(2017/09/23)
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- Asymmetric transfer hydrogenation of aryl ketoesters with a chiral double-chain surfactant-type catalyst in water
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A chiral double-chain surfactant-type ligand was designed and synthesized. The rhodium catalyst formed from the ligand can self-assemble into chiral vesicular aggregates in water, which was applied to the ATH of a broad range of aromatic ketoesters in neat water and gave up to 99% yield and 99% ee. In addition, this double-chain surfactant-type catalyst could also be applied to the dynamic kinetic resolution (DKR) of bicyclic β-ketoesters in water.
- Li, Jiahong,Lin, Zechao,Huang, Qingfei,Wang, Qiwei,Tang, Lei,Zhu, Jin,Deng, Jingen
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supporting information
p. 5367 - 5370
(2017/11/22)
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- Synthetically useful variants of industrial lipases from: Burkholderia cepacia and Pseudomonas fluorescens
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Industrial enzymes lipase PS (LPS) and lipase AK (LAK), which originate from Burkholderia cepacia and Pseudomonas fluorescens, respectively, are synthetically useful biocatalysts. To strengthen their catalytic performances, we introduced two mutations into hot spots of the active sites (residues 287 and 290). The LPS-L287F/I290A double mutant showed high catalytic activity and enantioselectivity for poor substrates for which the wild-type enzyme showed very low activity. The LAK-V287F/I290A double mutant was also an excellent biocatalyst with expanded substrate scope, which was comparable to the LPS-L287F/I290A double mutant. Thermodynamic parameters were determined to address the origin of the high enantioselectivity of the double mutant. The ΔΔH? term, but not the ΔΔS? term, was predominant, which suggests that the enantioselectivity is driven by a differential energy associated with intermolecular interactions around Phe287 and Ala290. A remarkable solvent effect was observed, giving a bell-shaped profile between the E values and the log&P or ? values of solvents with the highest E value in i-Pr2O. This suggests that an organic solvent with appropriate hydrophobicity and polarity provides the double mutant with some flexibility that is essential for excellent catalytic performance.
- Yoshida, Kazunori,Ono, Masakazu,Yamamoto, Takahiro,Utsumi, Takashi,Koikeda, Satoshi,Ema, Tadashi
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supporting information
p. 8713 - 8719
(2017/11/03)
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- Stereoselective reduction of aromatic ketones by a new ketoreductase from Pichia glucozyma
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A new NADPH-dependent benzil reductase (KRED1-Pglu) was identified from the genome of the non-conventional yeast Pichia glucozyma CBS 5766 and overexpressed in E. coli. The new protein was characterised and reaction parameters were optimised for the enantioselective reduction of benzil to (S)-benzoin. A thorough study of the substrate range of KRED1-Pglu was conducted; in contrast to most other known ketoreductases, KRED1-Pglu prefers space-demanding substrates, which are often converted with high stereoselectivity. A molecular modelling study was carried out for understanding the structural determinants involved in the stereorecognition experimentally observed and unpredictable on the basis of steric properties of the substrates. As a result, a new useful catalyst was identified, enabling the enantioselective preparation of different aromatic alcohols and hydroxyketones.
- Contente, Martina Letizia,Serra, Immacolata,Brambilla, Marta,Eberini, Ivano,Gianazza, Elisabetta,De Vitis, Valerio,Molinari, Francesco,Zambelli, Paolo,Romano, Diego
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p. 193 - 201
(2016/01/09)
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- Synthesis of Planar Chiral Shvo Catalysts for Asymmetric Transfer Hydrogenation
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A new type of planar chiral Shvo catalysts, where the chirality is based solely on different substitution flanking the C£O function, was prepared and used for transfer hydrogenation of imines and ketones. The reduction of ketimines represented by N-(1-phe
- Dou, Xiaowei,Hayashi, Tamio
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supporting information
p. 1054 - 1058
(2016/04/19)
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- Copper encapsulated alkaloids composite: An effective heterogeneous catalyst for electrocatalytic asymmetric hydrogenation
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A novel heterogeneous catalyst, alkaloid@Cu was prepared by the entrapment of commercially purchased alkaloids within non-noble metallic copper nanoparticles. This composite was compacted into a coin and directly used as cathode for electrocatalytic asymmetric hydrogenation of aromatic ketones. Using water as hydrogen source, optically active alcohols with 71% ee value and 93% yield were obtained under very mild conditions.
- Yang, Heng-Pan,Fen, Qiu,Wang, Huan,Lu, Jia-Xing
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- Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of 1,2-Dicarbonyl Compounds
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A highly enantioselective hydrosilylation of 1,2-dicarbonyl compounds was successfully realized for the first time utilizing the combination of tricyclohexylphosphine and chiral alkenylborane derived in situ from diyne as a frustrated Lewis pair catalyst. A variety of optically active α-hydroxy ketones and esters were obtained in 52-98% yields with 86-99% ee's.
- Ren, Xiaoyu,Du, Haifeng
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supporting information
p. 810 - 813
(2016/02/09)
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- Alkaloid-induced asymmetric hydrogenation on a Cu nanoparticle cathode by electrochemical conditions
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Copper nanoparticles were prepared in an aqueous solution, compacted into a coin, and used as a cathode for asymmetric hydrogenation by the electrochemical method for the first time. A good ee value and excellent yield were obtained under mild conditions. Electrochemical conditions were crucial for alkaloid adsorption on metallic Cu, which is a key process of asymmetric induction. Furthermore, the ee value was linear with an adsorption amount.
- Yang, Heng-Pan,Wang, Huan,Lu, Jia-Xing
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- Chiral Surfactant-Type Catalyst: Enantioselective Reduction of Long-Chain Aliphatic Ketoesters in Water
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A series of amphiphilic ligands were designed and synthesized. The rhodium complexes with the ligands were applied to the asymmetric transfer hydrogenation of broad range of long-chained aliphatic ketoesters in neat water. Quantitative conversion and excellent enantioselectivity (up to 99% ee) was observed for α-, β-, γ-, δ- and ε-ketoesters as well as for α- and β-acyloxyketone using chiral surfactant-type catalyst 2. The CH/π interaction and the strong hydrophobic interaction of long aliphatic chains between the catalyst and the substrate in the metallomicelle core played a key role in the catalytic transition state. Synergistic effects between the metal-catalyzed site and the hydrophobic microenvironment of the core in the micelle contributed to high stereoselectivity. (Chemical Equation Presented).
- Lin, Zechao,Li, Jiahong,Huang, Qingfei,Huang, Qiuya,Wang, Qiwei,Tang, Lei,Gong, Deying,Yang, Jun,Zhu, Jin,Deng, Jingen
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p. 4419 - 4429
(2015/05/13)
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- Synthesis of a P-stereogenic PNPtBu,Ph ruthenium pincer complex and its application in asymmetric reduction of ketones
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A novel P-stereogenic PNPtBu,Ph ruthenium complex has been synthesized and characterized enabling the asymmetric hydrogenation of a wide range of aromatic ketones with excellent catalytic activities (up to 98% conversion) and good levels of enantiodiscrimination (up to 95% ee). P-stereogenic PNPtBu,Ph Ru complex was for the first time synthesized and characterized and has proven to be an efficient catalyst for the asymmetric reduction of a wide range of ketones
- Arenas, Ismael,Boutureira, Omar,Matheu, M. Isabel,Díaz, Yolanda,Castillón, Sergio
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supporting information
p. 3666 - 3669
(2015/06/16)
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- On-Column Reaction Set-Up for High-Throughput Screenings and Mechanistic Investigations
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A screening platform, which offers a high-throughput approach as well as an easy investigation of kinetic isotope effects, applicable to a wide range of reactions is presented. To illustrate the high potential of this approach, the asymmetric transfer hydrogenation of methyl benzoylformate with copper(II) bis(oxazoline) and Hantzsch ester was examined. Accordingly, the enantioselectivities of the reaction performed on-column in a microcapillary were comparable to standard reaction conditions, however, we were able achieve catalysis and analysis in a single step in less than 30 min. The throughput can be increased by simultaneous investigation of different substrates without increasing the overall analysis time. Use of di-deuterated Hantzsch ester allowed us to investigate the kinetic isotope effect of the transfer hydrogenation reaction only requiring a minute amount of the deuterated transfer hydrogenation reagent. Hence we were able to get further insights into the mechanism of the asymmetric transfer hydrogenation using Hantzsch ester as hydrogen source. The here presented technique is broadly applicable to study isotope effects on a very small scale, which is a rapid and an inexpensive alternative compared to conventional experiments.
- Stockinger, Skrollan,Troendlin, Johannes,Rominger, Frank,Trapp, Oliver
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p. 3513 - 3520
(2016/01/25)
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- Chiral N,N′-dioxide-FeCl3 complex-catalyzed asymmetric intramolecular Cannizzaro reaction
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An environmentally benign catalyst, the N,N′-dioxide-FeCl3 complex, has been developed for the asymmetric intramolecular Cannizzaro reaction. Aryl and alkyl glyoxal monohydrates were applied to obtain α-hydroxy acid esters with excellent results. Deuterium-label and control experiments shed light on the reaction mechanism.
- Wu, Wangbin,Liu, Xiaohua,Zhang, Yuheng,Ji, Jie,Huang, Tianyu,Lin, Lili,Feng, Xiaoming
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supporting information
p. 11646 - 11649
(2015/07/15)
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- Kinetics and catalyst deactivation in the enantioselective hydrogenation of ethyl benzoylformate over Pt/Al2O3
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The enantioselective hydrogenation of ethyl benzoylformate (EBF) to (R)-ethyl mandelate(-)-cinchonidine (CD)-modified Pt/Al2O 3 catalyst in toluene in a semi-batch reactor was studied as a function of modifier concentration, reaction temperature, stirring rate and catalyst particle size. The kinetic results showed higher enantioselectivity and lower initial rates tending asymptotically to a constant value as the amount of modifier increased. The maximum enantiomeric excess (ee) and the initial hydrogenation rate or turnover frequency obtained under optimized conditions with an initial concentration of 5.6 mmol L-1 EBF at 25°C5% (w/w) Pt/Al2O3 were 85% (modifier-to-surface Pt of 1.28) and 109 h-1 (modifier-to-surface Pt of 0.16), respectively. Additionally, catalyst deactivation due to the presence of impurities in the feed was prominent in some cases; therefore activated carbon was used as a cleaning agent of the raw material to remove impurities prior to catalyst addition.
- Martin, Gerson,Maeki-Arvela, Paeivi,Murzin, Dmitry Yu.,Salmi, Tapio
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p. 170 - 178
(2014/01/06)
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- Enantio- and chemoselective Br?nsted-acid/Mg(nBu) 2 catalysed reduction of α-keto esters with catecholborane
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The first enantio- and chemoselective Br?nsted-acid catalysed reduction of α-keto esters with catecholborane has been developed. The α-hydroxy esters were obtained under mild reaction conditions in virtually quantitative yields and excellent enantioselectivities. With slight modifications both enantiomers can be obtained without any loss of selectivity. This journal is the Partner Organisations 2014.
- Enders, Dieter,St?ckel, Bianca A.,Rembiak, Andreas
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supporting information
p. 4489 - 4491
(2014/04/17)
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- Entrapment of alkaloids within silver: From enantioselective hydrogenation to chiral recognition
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An alkaloid@Ag composite was prepared for the first time and used as a cathode for the enantioselective hydrogenation. Excellent yield and a remarkable enantiomeric excess value were obtained under mild conditions. Moreover, alkaloid@Ag after extraction w
- Yang, Hengpan,Chi, Dinghui,Sun, Qilong,Sun, Wenwen,Wang, Huan,Lu, Jiaxing
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supporting information
p. 8868 - 8870
(2014/08/05)
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- A new class of tunable dendritic diphosphine ligands: Synthesis and applications in the Ru-catalyzed asymmetric hydrogenation of functionalized ketones
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A series of tunable G0-G3 dendritic 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) ligands was prepared by attaching polyaryl ether dendrons onto the four phenyl rings on the P atoms. Their ruthenium complexes were employed in the asymmetric hydrogenation of β-ketoesters, α-ketoesters, and α-ketoamides to reveal the effects of dendron size on the catalytic properties. The second- and third-generation catalysts exhibited excellent enantioselectivities, which are remarkably higher than those obtained from the small molecular catalysts and the first-generation catalyst. Molecular modeling indicates that the incorporation of bulky dendritic wedges can influence the steric environments around the metal center. In addition, the ruthenium catalyst bearing a second-generation dendritic ligand could be recycled and reused seven times without any obvious decrease in enantioselectivity.
- Ma, Baode,Miao, Tingting,Sun, Yihua,He, Yanmei,Liu, Ji,Feng, Yu,Chen, Hui,Fan, Qing-Hua
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supporting information
p. 9969 - 9978
(2014/08/18)
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- Steric vs. electronic effects in the Lactobacillus brevis ADH-catalyzed bioreduction of ketones
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Lactobacillus brevis ADH (LBADH) is an alcohol dehydrogenase that is commonly employed to reduce alkyl or aryl ketones usually bearing a methyl, an ethyl or a chloromethyl as a small ketone substituent to the corresponding (R)-alcohols. Herein we have tested a series of 24 acetophenone derivatives differing in their size and electronic properties for their reduction employing LBADH. After plotting the relative activity against the measured substrate volumes we observed that apart from the substrate size other effects must be responsible for the activity obtained. Compared to acetophenone (100% relative activity), other small substrates such as propiophenone, α,α, α-trifluoroacetophenone, α-hydroxyacetophenone, and benzoylacetonitrile had relative activities lower than 30%, while medium-sized ketones such as α-bromo-, α,α-dichloro-, and α,α-dibromoacetophenone presented relative activities between 70% and 550%. Moreover, the comparison between the enzymatic activity and the obtained final conversions using an excess or just 2.5 equiv. of the hydrogen donor 2-propanol, denoted again deviations between them. These data supported that these hydrogen transfer (HT) transformations are mainly thermodynamically controlled. For instance, bulky α-halogenated derivatives could be quantitatively reduced by LBADH even employing 2.5 equiv. of 2-propanol independently of their kinetic values. Finally, we found good correlations between the IR absorption band of the carbonyl groups and the degrees of conversion obtained in these HT processes, making this simple method a convenient tool to predict the success of these transformations. The Royal Society of Chemistry.
- Rodriguez, Cristina,Borzecka, Wioleta,Sattler, Johann H.,Kroutil, Wolfgang,Lavandera, Ivan,Gotor, Vicente
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supporting information
p. 673 - 681
(2014/01/06)
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- Kinetic resolution of mandelate esters via stereoselective acylation catalyzed by lipase PS-30
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By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic mandelate esters has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 197.5. Substituent effect is briefly discussed.
- Chen, Peiran,Yang, Wenhong
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supporting information
p. 2290 - 2294
(2014/04/17)
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- Synthesis of ethynylbenzene-substituted glycol as a versatile probe for labeling oligonucleotides
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Positron emission tomography (PET) is a highly sensitive quantitative imaging technique for studying molecular pathways and interactions in vivo. This imaging technique plays a key role in drug discovery, pharmacokinetics, pharmacodynamics, and assessing in vivo distribution. In this study, we designed an ethynylbenzene-substituted glycol (ME) as a versatile probe for PET labeling of oligonucleotides through a click reaction.
- Ren, Qin,Tsunaba, Kana,Kitamura, Yoshiaki,Nakashima, Remi,Shibada, Aya,Ikeda, Masato,Kitade, Yukio
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supporting information
p. 1519 - 1522
(2014/03/21)
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- Asymmetric catalytic arylation of ethyl glyoxylate using organoboron reagents and Rh(i)-phosphane and phosphane-phosphite catalysts
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Herein we report the first application of Rh(i)-phosphane and phosphane-phosphite catalysts in the enantioselective catalytic arylation of ethyl glyoxylate with organoboron reagents, providing access to ethyl mandelate derivatives in high yield (up to 99%) and moderate to very good enantioselectivities (up to 75% ee). Commercial phosphane ligands, such as (R)-MonoPhos and (R)-Phanephos were tested, as well as non-commercial (R,R)-TADDOL-derived phosphane-phosphite ligands. Those ligands containing bulky substituents in the ortho-and para-positions of the chiral phosphite moiety were found to be the most selective.
- Marques, Carolina Silva,Dindaroglu, Mehmet,Schmalz, Hans-Guenther,Burke, Anthony J.
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p. 6035 - 6041
(2014/01/23)
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- CHIRAL SPIRO-PYRIDYLAMIDOPHOSPHINE LIGAND COMPOUND, SYNTHESIS METHOD THEREFOR AND APPLICATION THEREOF
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The present invention relates to a chiral spiro-pyridylamidophosphine ligand compound, synthesis method therefor and application thereof. The chiral spiro-pyridylamidophosphine compound is a compound having a structure of Formula (I), a racemate or optical isomer thereof, or a catalytically acceptable salt thereof, and is mainly characterized by having a chiral spiro-dihydro-indene skeleton in its structure. The chiral spiro-pyridylamidophosphine compound may be synthesized with optical active 7-diaryl/alkylphosphino-7'-amino-1,1'-spiro-dihydro-indene or substituted 7-diaryl/alkylphosphino-7'-amino-1,1'-spiro-dihydro-indene having a spiro-skeleton as chiral starting material. The chiral spiro-pyridylamidophosphine compound may be used as a chiral ligand in asymmetric hydrogenation of a carbonyl compound catalyzed by iridium, in which the reaction activity is very high, the amount of the catalyst may be 0.0001 mol%, and the enantioselectivity of the reaction is up to 99.9%ee.
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Paragraph 0059; 0060
(2013/10/08)
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- Solvent effects in the enantioselective hydrogenation of ethyl benzoylformate
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Solvent effects in the enantioselective hydrogenation of ethyl benzoylformate (EBF) to (R)-ethyl mandelate(-)-cinchonidine (CD)-modified Pt/Al2O3 catalyst were studied in a semi-batch reactor. Solvents of different nature were used:
- Martin, Gerson,Maeki-Arvela, Paeivi,Murzin, Dmitry Yu.,Salmi, Tapio
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p. 1051 - 1060
(2013/11/19)
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- A homochiral porous metal-organic framework for enantioselective adsorption of mandelates and photocyclizaton of tropolone ethers
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A chiral porous metal-organic framework of an axially C2- symmetric 1,1′-biphenol ligand is constructed and can be used as a solid-state host to enanioselectively adsorb mandelates with up to 93.1% ee and to entrap achiral tropolone ethers and
- Peng, Yongwu,Gong, Tengfei,Cui, Yong
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supporting information
p. 8253 - 8255
(2013/09/12)
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- Enantioselective catalytic synthesis of ethyl mandelate derivatives using Rh(I)-NHC catalysts and organoboron reagents
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Herein we describe for the first time the enantioselective catalytic arylation of ethyl glyoxalate using phenylboron reagents and chiral rhodium(I)-NHC catalysts. KOtBu was the base of choice, along with tert-amyl alcohol as the solvent. A novel chiral bis-imidazolium salt was synthesized and evaluated for the first time in this catalytic transformation. Although moderate enantioselectivities (up to 34% ee) were obtained for the phenylation reaction, despite the excellent yields, very low enantioselectivities were obtained using other arylboronic acids with a variety of chiral rhodium(I)-NHC catalysts.
- Marques, Carolina S.,Burke, Anthony J.
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p. 628 - 632
(2013/07/19)
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- Asymmetric addition of arylboronic acids to glyoxylate catalyzed by a ruthenium/Me-BIPAM complex
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The enantioselective synthesis of α-hydroxy esters by ruthenium-catalyzed 1,2-addition of arylboronic acids to tert-butyl glyoxylate is described. The use of RuCl2(PPh3)3 with (R,R)-Me-BIPAM gave optically active mandelic acids of up to 99% ee. Addition of a fluoride salt such as potassium fluoride (KF) or caesium fluoride (CsF) was effective for achieving high enantioselectivities. The Royal Society of Chemistry 2012.
- Yamamoto, Yasunori,Shirai, Tomohiko,Miyaura, Norio
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scheme or table
p. 2803 - 2805
(2012/04/23)
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- Catalytic enantioselective protonation of α-oxygenated ester enolates prepared through phospha-brook rearrangement
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(Chemical Equation Presented) Phosphonates go chiral: The organocatalytic enantioselective reaction of α-ketoesters with phosphites using cinchona alkaloids and Na2CO3 has afforded α-phosphonyloxy esters with high enantioselectivities (see scheme). This process allows the formation of both enantiomers of the product. A catalyst loading of as low as 2 mol% does not result in a significant decrease of the enantioselectivity.
- Hayashi, Masashi,Nakamura, Shuichi
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supporting information; scheme or table
p. 2249 - 2252
(2011/04/16)
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- Enantioselective hydrogenation of α-ketoesters over alkaloid-modified platinum nanowires
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A green process for enantioselective hydrogenation of α-ketoesters over cinchona alkaloid-modified platinum (Pt) nanowires has been developed. Pt nanowires with a diameter of ~1 nm were successfully synthesized, and used for the asymmetric hydrogenation of α-ketoesters in the presence of cinchona alkaloids under a low pressure at room temperature in water. Quantitative yields and excellent enantioselectivity of up to 78% were achieved. The catalyst along with the modifier was recycled multiple times without any significant loss in activity or selectivity. To our knowledge, such a catalyst system is unprecedented for asymmetric hydrogenation of α-ketoesters. The Royal Society of Chemistry.
- Erathodiyil, Nandanan,Gu, Hongwei,Shao, Huilin,Jiang, Jiang,Ying, Jackie Y.
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experimental part
p. 3070 - 3074
(2011/12/16)
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- Novel anti-Prelog stereospecific carbonyl reductases from Candida parapsilosis for asymmetric reduction of prochiral ketones
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The application of biocatalysis to the synthesis of chiral molecules is one of the greenest technologies for the replacement of chemical routes due to its environmentally benign reaction conditions and unparalleled chemo-, regio- and stereoselectivities. We have been interested in searching for carbonyl reductase enzymes and assessing their substrate specificity and stereoselectivity. We now report a gene cluster identified in Candida parapsilosis that consists of four open reading frames including three putative stereospecific carbonyl reductases (scr1, scr2, and scr3) and an alcohol dehydrogenase (cpadh). These newly identified three stereospecific carbonyl reductases (SCRs) showed high catalytic activities for producing (S)-1-phenyl-1,2-ethanediol from 2-hydroxyacetophenone with NADPH as the coenzyme. Together with CPADH, all four enzymes from this cluster are carbonyl reductases with novel anti-Prelog stereoselectivity. SCR1 and SCR3 exhibited distinct specificities to acetophenone derivatives and chloro-substituted 2-hydroxyacetophenones, and especially very high activities towards ethyl 4-chloro-3-oxobutyrate, a β-ketoester with important pharmaceutical potential. Our study also showed that genomic mining is a powerful tool for the discovery of new enzymes.
- Nie, Yao,Xiao, Rong,Xu, Yan,Montelione, Gaetano T.
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experimental part
p. 4070 - 4078
(2011/07/08)
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- Asymmetric aerobic oxidation of α-hydroxy acid derivatives catalyzed by reusable, polystyrene-supported chiral N-salicylidene oxidovanadium tert-leucinates
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The direct immobilization of two different C-5-propargyl ether-modified, chiral N-salicylidene vanadyl(V) tert-leucinates onto 4-azidomethyl-substituted polystyrene by click chemistry was examined. Among the eight different solvents investigated, the resulting polystyrene-supported catalysts promote the asymmetric, aerobic oxidation of α-hydroxy (thio)esters and amides with enantioselectivities of up to 99% ee (selectivity factor up to 41) in chloroform. These polystyrene-supported catalysts can be readily recovered by filtration and reused for at least four consecutive runs without discernible loss of reactivity and enantioselectivity.
- Salunke, Santosh B.,Babu, N.Seshu,Chen, Chien-Tien
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supporting information; experimental part
p. 1234 - 1240
(2011/06/26)
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- Catalytic asymmetric bromine-lithium exchange: A new tool to build axial chirality
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We present here the first catalytic desymmetrization of the 2,2′,6,6′-tetrabromobiphenyl 1 and analogues, by a bromine-lithium exchange catalyzed by either diamines or diether derivatives (0.5 equiv.), yielding axially chiral compounds in high yield (up to 89%) and high enantioselectivity (up to 82%).
- Perron, Quentin,Alexakis, Alexandre
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supporting information; experimental part
p. 2611 - 2620
(2011/01/05)
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- High-performance liquid chromatography separation of enantiomers of mandelic acid and its analogs on a chiral stationary phase
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The enantiomers of mandelic acid and its analogs have been chromatographically separated on a chiral stationary phase (CSP) derived from 4-(3,5-dinitrobenzamido) tetrahydrophenanthrene. The rationale of separations of these compounds is discussed with respect to the method development for determining enantiomeric purity and possibility of obtaining enantiomerically pure materials by high-pressure liquid chromatography. The relationship of analyte structure to the extent of enantiomeric separation has been examined and separation factors (a) are presented for various groups of structurally related compounds. Chiral recognition models have been suggested to account for the observed separations. These models provide mechanistic insights into the chiral recognition process.
- Aneja, Ritu,Luthra, Pratibha Mehta,Ahuja, Satinder
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experimental part
p. 479 - 485
(2010/08/20)
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- Enantioselective ketoester reductions in water: A comparison between microorganism-and ruthenium-catalyzed reactions
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In the search for green chemistry methods for the enantioselective reduction of ketoesters Saccharomyces cerevisiae-and ruthenium-catalyzed reactions in water have been investigated. The highest enantiomeric excesses for the reduction of α-and β-ketoesters have been obtained by S. cerevisiae. Chiral ruthenium catalysts are active for the reduction of all ketoesters with low to moderate enantioselectivities depending on the nature of the substrate and ligand. Interestingly, for several substrates both enantiomers of the hydroxyesters have been obtained according either to the catalytic method or to the structure of the ligand.
- Zeror, Saoussen,Collin, Jacqueline,Fiaud, Jean-Claude,Zouioueche, Louisa Aribi
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experimental part
p. 1211 - 1215
(2010/10/20)
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- Stereomodulating effect of remote groups on the NADH-mimetic reduction of alkyl aroylformates with 1,4-dihydronicotinamide-β-lactam amides
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Conformationally restricted NADH peptidomimetics 4a-e, characterized by the presence of a (1,4-dihydronicotinamide)-(β-lactam) moiety, have been synthesized and used to study the Mg2+ cation-promoted asymmetric reduction of alkyl aroylformates
- Aizpurua, Jesus M.,Palomo, Claudio,Fratila, Raluca M.,Ferrón, Pablo,Miranda, José I.
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experimental part
p. 3187 - 3194
(2010/06/12)
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- Synthesis of novel new 2-(2-(4-((3,4-dihydro-4-oxo-3-aryl quinazolin-2-yl)methyl)piperazin-1-yl)acetoyloxy)-2-phenyl acetic acid esters
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Stereoselective diazotization of (S)-2-amino-2-phenyl acetic acid (L-phenyl glycine) (4) with NaNO2 in 6% H2SO4 in a mixture of acetone and water gave optically pure (S)-2-hydroxy-2-phenyl acetic acid (L-mandelic acid) (5). Esterification, gave (S)-2-hydroxy-2-phenyl acetic acid esters (6). The latter was treated with chloroacetyl chloride in the presence of triethylamine (TEA) in dichloromethane (DCM) to yield (S)-2-chloroacetyloxy phenyl acetic acid ester (2). In another sequence, the reaction of 2-(chloromethyl)-3-arylquinazolin- 4(3H)-one (9) treated with N-Boc piperazine, followed by deprotection of the Boc group, to obtain 3-aryl-2-((piperazin-1-yl)methyl) quinazolin-4(3H)-one (3). Reaction of 2 with 3 in the presence of K2CO3 and KI gave the title compound, 2-(2-(4-((3,4-dihydro-4-oxo-3-arylquinazolin-2-yl)methyl)piperazin-1-yl) acetoyloxy)-2-phenyl acetic acid esters (1). The structures of all the new compounds obtained in the present work are supported by spectral and analytical data. Copyright Taylor & Francis Group, LLC.
- Acharyulu, Palle V. R.,Dubey,Reddy, P. V. V. Prasada,Suresh, Thatipally
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experimental part
p. 3217 - 3231
(2011/03/17)
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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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supporting information; experimental part
p. 4608 - 4611
(2009/09/08)
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- A rapid and green approach to chiral α-hydroxy esters: asymmetric transfer hydrogenation (ATH) of α-keto esters in water by use of surfactants
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A series of α-hydroxy esters were rapidly prepared (1.5 h) from α-keto esters via asymmetric transfer hydrogenation (ATH) in water by the use of surfactants for the first time. This green method, catalyzed by a water-soluble and recyclable Ru(II) complex, gave moderate to high enantioselectivities (up to 99.7% ee) with DTAB as an additive and HCOONa as the hydrogen source.
- Yin, Lu,Jia, Xian,Li, Xingshu,Chan, Albert S.C.
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experimental part
p. 2033 - 2037
(2010/01/16)
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- Application of copper(II)-dipyridylphosphine catalyst in the asymmetric hydrosilylation of simple ketones in air
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Copper (II)-dipyridylphosphine catalyst was used in the asymmetric hydrosilylation of simple ketones under ambient conditions in competitive levels of enantioinduction and activity. The experiment also described the utility of the combination of copper(II) salt/(S)-1/PhSiH3 in the enantioselective hydrosilylation of heteroaromatic ketones and several other ketonic substrates leading to some valuable pharmaceutical and agricultural chemical intermediates. A number of the resulting chiral alcohols represented valuable intermediates for some physiologically active compounds, with remarkable temperature effects on the asymmetric induction were observed in some cases of heteroaromatic ketones. The results show that the present catalyst system features widespread substrate scope, high air stability, fast rate of reaction, good-to-excellent enantioselectivity, and mild conditions thereby affording a practical protocol to a vast selection of optically enriched alcohols.
- Zhang, Xi-Chang,Wu, Yan,Yu, Feng,Wu, Fei-Fei,Wu, Jing,Chan, Albert S. C.
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supporting information; experimental part
p. 5888 - 5891
(2010/03/03)
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- Enantioselective synthesis of ethyl (S)-2-hydroxy-4-phenylbutyrate by recombinant diketoreductase
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Recombinant diketoreductase showed excellent stereoselectivity in the double reduction of β,δ-diketo esters. To investigate the substrate specificity and to broaden the applications of this new biocatalyst, a number of ketone substrates were used to evaluate the substrate spectrum and enantioselectivity of this enzyme in the present study. Among the ketone substrates tested, only this enzyme displayed high efficiency and excellent enantioselectivity in the reduction of ethyl 2-oxo-4-phenylbutyrate to ethyl (S)-2-hydroxy-4-phenylbutyrate. After optimizing the reaction conditions, the bio-reduction of ethyl 2-oxo-4-phenylbutyrate at a substrate concentration of 0.8 M (164.8 g/L) was achieved by the recombinant diketoreductase in an aqueous-toluene biphasic system coupled with formate dehydrogenase for the regeneration of cofactor, resulting in an overall hydroxyl product yield of 88.7% (99.5% ee). This new enzymatic transformation may offer a practical method for the preparation of this important chiral building block.
- Wu, Xuri,Wang, Yuchen,Ju, Jianming,Chen, Chen,Liu, Nan,Chen, Yijun
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experimental part
p. 2504 - 2509
(2010/03/31)
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