cas 56816-01-4, Ethyl (S)-3-hydroxybutyrate

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THE PRODUCT OF BAKER'S YEAST REDUCTION OF ETHYL 2-CHLORO-3-OXOBUTANOATE AS A PRECURSOR OF THE 1-ETHOXYCARBONYL 2(S)-HYDROXYPROPYL RADICAL
Baker's yeast treatment of ethyl 2-chloro-3-oxobutanoate 1, diethyl 2-acetylmalonate 2 and ethyl 2-cyano-3-oxobutanoate 3 was effected in order to obtain enantiomerically enriched compounds.In contrast to the reaction of 2 and 3, efficient diastereo- and enantioselective reduction of 1 provided ethyl 2(R)-chloro-3(S)-hydroxybutanoate.This product was used as precursor of the 1-ethoxycarbonyl-2(S)-hydroxypropyl radical and the diastereoselectivity of the addition of this intermediate to alkenes was studied.
Hamdani, Mourad,Jeso, Bernard De,Deleuze, Herve,Saux, Annie,Maillard, Bernard
p. 1233 - 1236
(1993)
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Carbanion-Accelerated Claisen Rearrangements. 4. Asymmetric Induction via 1,3,2-Oxazaphosphorinanes
The anions derived from allyl vinyl ethers 1 and 2 undergo rapid and highly selective Claisen rearrangements.The degree of asymmetric induction has been found to be uniformly high (ca.90:10) for various substituent patterns but depends markedly on the presence of lithium cations.The absolute sense of asymmetric induction has been established using chiral, nonracemic 1,3,2-oxazaphosphorinane 2.Two proposals for the transition structures of the phosphorus-stabilized anions are discussed.
Denmark, Scott E.,Marlin, John E.
p. 5742 - 5745
(1987)
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Simple syntheses of (+)-orthosporin and (-)-semivioxanthin methyl ether+
Simple syntheses of (+)-orthosporin(1) and (-)-semivioxanthin methyl ether (11) are described from (S)-ethyl-3-hydroxybutyrate (5) and orsellinic acid derivatives 3 and 4 respectively.
Deshpande,Rai, Beena,Khan
p. 7159 - 7162
(1996)
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Hydrogenation of ethyl acetoacetate catalyzed by hydrosoluble BINAP derivatives
A new Ru hydrosoluble BINAP derivative has been synthesized. This water-soluble catalyst was revealed to be enantioselective up to 94% and recyclable (at least three times) for the asymmetric hydrogenation of ethyl acetoacetate in a biphasic system.
Lamouille, Thierry,Saluzzo, Christine,Ter Halle, Rob,Le Guyader, Fredéric,Lemaire, Marc
p. 663 - 664
(2001)
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A SIMPLE SYNTHESIS OF (S)-(+)-SULCATOL, THE PHEROMONE OF GNATHOTRICHUS RETUSUS, EMPLOYING BAKER'S YEAST FOR ASYMMETRIC REDUCTION
Ethyl (S)-3-hydroxybutanoate of 87percent optical purity was obtained by the yeast reduction of ethyl acetoacetate and was converted into 85-87percent optically pure (S)-(+)-sulcatol (6-methyl-5-hepten-2-ol) by a 5-step sequence in 73percent overall yield.
Mori, Kenji
p. 1341 - 1342
(1981)
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Polymer-supported catalysts: enantioselective hydrogenation and hydrogen transfer reduction.
Different types of heterogenized catalysts were involved in asymmetric reactions. Hydrogen transfer reduction was performed with amino alcohols derived from poly((S)-(GMA-co-EGDMA or DVB)) and hydrogenation with BINAP grafted onto PEG or copolymerized with isocyanates as ligands. Attempts of catalysts recycling are reported.
Saluzzo, Christine,Lamouille, Thierry,Herault, Damien,Lemaire, Marc
p. 1841 - 1844
(2002)
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The Use of Organic Solvent Systems in the Yeast Mediated Reduction of Ethyl Acetoacetate
The reduction of ethyl acetoacetate to ethyl (S)-3-hydroxybutyrate, mediated by freeze-dried yeast, proceeds in good yield (53-58percent) and with high enantioselectivity (>96percentee) in a number of organic solvents; petroleum ether, diethyl ether, toluene, and carbon tetrachloride.A small amount of water (0.8 ml (g-yeast)-1) is required for the reaction to proceed.The water/yeast/substrate ratio and the solvent polarity have been found to significantly influence the reactivity of the system.The enantiomeric excess was determined by gas chromatography employing a chiral column.
Jayasinghe, Leonard Y.,Kodituwakku, Devika,Smallridge, Andrew J.,Trewhella, Maurie A.
p. 2528 - 2531
(1994)
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Single-Point Mutant Inverts the Stereoselectivity of a Carbonyl Reductase toward β-Ketoesters with Enhanced Activity
Enzyme stereoselectivity control is still a major challenge. To gain insight into the molecular basis of enzyme stereo-recognition and expand the source of antiPrelog carbonyl reductase toward β-ketoesters, rational enzyme design aiming at stereoselectivity inversion was performed. The designed variant Q139G switched the enzyme stereoselectivity toward β-ketoesters from Prelog to antiPrelog, providing corresponding alcohols in high enantiomeric purity (89.1–99.1 % ee). More importantly, the well-known trade-off between stereoselectivity and activity was not found. Q139G exhibited higher catalytic activity than the wildtype enzyme, the enhancement of the catalytic efficiency (kcat/Km) varied from 1.1- to 27.1-fold. Interestingly, the mutant Q139G did not lead to reversed stereoselectivity toward aromatic ketones. Analysis of enzyme–substrate complexes showed that the structural flexibility of β-ketoesters and a newly formed cave together facilitated the formation of the antiPrelog-preferred conformation. In contrast, the relatively large and rigid structure of the aromatic ketones prevents them from forming the antiPrelog-preferred conformation.
Li, Aipeng,Wang, Ting,Tian, Qing,Yang, Xiaohong,Yin, Dongming,Qin, Yong,Zhang, Lianbing
p. 6283 - 6294
(2021/03/16)

Effect of organic solvents on asymmetric reduction of β-keto esters using cyanobacterium Synechocystis sp. PCC 6803
The asymmetric reduction of tert-butyl 3-oxobutanoate by cyanobacterium Synechocystis sp. PCC 6803 under illumination with red LED light at 25 °C for 24 h afforded the corresponding (R)-β-hydroxy ester in 79% enantiomeric excess (ee) (81% yield), while the addition of toluene (1% (v/v)) to the system gave the corresponding (S)-β-hydroxy ester in >99% ee (87% yield). Organic solvents such as chloroform, benzene, ethylbenzene, cyclohexane, and methylcyclohexane showed similar effects and afforded the corresponding (S)-β-hydroxy ester in >99% ee. However, polar organic solvents, such as DMSO, THF, and ethanol, as well as dodecane—a hydrophobic solvent with a straight long-chain—did not exhibit such effects.
Tanaka, Shusei,Kojima, Hideo,Takeda, Satomi,Yamanaka, Rio,Takemura, Tetsuo
supporting information

(2021/07/25)

Diverse synthesis of the C ring fragment of bryostatins via Zn/Cu-promoted conjugate addition of α-hydroxy iodide with enone
A convergent approach to 1,5-hydroxy ketones, the general precursors for constructing the C ring of bryostatins, has been developed via a Zn/Cu-promoted conjugate addition of α-hydroxy iodides with enones. The reaction leads to direct formation of the C21-C22 bond and tolerates diverse functionalities at the C17-, C18- and C24-positions. The approach also enables a more concise synthesis of the known C ring intermediate (10 longest linear steps and 14 total steps), in contrast to its previous synthesis (17 longest linear steps and 22 total steps) in our total synthesis of bryostatin 8.
Chu, Zhiwen,Tong, Ruiqi,Yang, Yufan,Song, Xuanyi,Hu, Tian bao,Fan, Yu,Zhao, Chen,Gao, Lu,Song, Zhenlei
supporting information
p. 1 - 4
(2020/12/21)

SYNTHESIS OF 3-HYDROXYBUTYRYL 3-HYDROXYBUTYRATE AND RELATED COMPOUNDS
In various embodiments methods of preparing hydroxybutyryl 3-hydroxybutyrate and related compounds are provided along with methods of use thereof.
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Paragraph 0308; 0331-0333

(2021/04/02)

Asymmetric visible-light photobiocatalytic reduction of β-keto esters utilizing the cofactor recycling system in Synechocystis sp. PCC 6803
The asymmetric reduction of β-keto esters employing a wild-type strain of cyanobacterium Synechocystis sp. PCC 6803 under illumination of red LED light at 25 °C for 24 h was evaluated. As a result, the corresponding (R)-β-hydroxy esters were obtained as major products. The R-selectivity was shown to increase for bulkier substrates. Moreover, it was also found that the R-selectivity increased with decreasing substrate concentrations. This can be explained by the assumption that the Km value of the R-selective reductase is smaller than that of the S-selective enzyme involved in the reaction. Additionally, it was demonstrated that the R-selective reductase required the light-dependent production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) for effective reaction; however, the S-selective variant did not. Overall, cyanobacterium was employed as a sustainable photobiocatalyst proliferating under illumination of light, while utilizing inorganic salts and atmospheric carbon dioxide (CO2). Employing the whole-cell system allowed for the preparation of industrially-important chiral compounds, such as optically active β-hydroxy esters.
Tanaka, Shusei,Kojima, Hideo,Takeda, Satomi,Yamanaka, Rio,Takemura, Tetsuo
supporting information

(2020/05/08)

Homochiral Metal-Organic Cage for Gas Chromatographic Separations
Metal-organic cages (MOCs) as a new type of porous material with well-defined cavities were extensively pursued because of their relative ease of synthesis and their potential applications in host-guest chemistry, molecular recognition, separation, catalysis, gas storage, and drug delivery. Here, we first reported that a homochiral MOC [Zn3L2] is explored to fabricate [Zn3L2] coated capillary column for high-resolution gas chromatographic separation of a wide range of analytes, including n-alkanes, polycyclic aromatic hydrocarbons, and positional isomers, especially for racemates. Various kinds of racemates such as alcohols, diols, epoxides, ethers, halohydrocarbons, and esters were separated with good enantioselectivity and reproducibility on the [Zn3L2] coated capillary column. The fabricated [Zn3L2] coated capillary column exhibited significant chiral recognition complementary to that of a commercial β-DEX 120 column and our recently reported homochiral porous organic cage CC3-R coated column. The results show that the homochiral MOCs will be very attractive as a new type of chiral selector in separation science.
Xie, Sheng-Ming,Fu, Nan,Li, Li,Yuan, Bao-Yan,Zhang, Jun-Hui,Li, Yan-Xia,Yuan, Li-Ming
p. 9182 - 9188
(2018/07/21)

Efficient P-Chiral Biaryl Bisphosphorus Ligands for Palladium-Catalyzed Asymmetric Hydrogenation
A series of structurally novel P-chiral biaryl bisphosphorus ligands L1-L5 (BABIBOPs) are developed, providing high efficiency for the first time in palladium-catalyzed asymmetric hydrogenation of β-aryl and β-alkyl substituted β-keto esters. With the Pd-L3 (iPr-BABIBOP) catalyst, a series of chiral β-hydroxyl carboxylic esters are formed in excellent enantioselectivities (up to>99% ee) and yields at catalyst loading as low as 0.01 mol%.
Jiang, Wenhao,Zhao, Qing,Tang, Wenjun
supporting information
p. 153 - 156
(2018/01/05)

Biaryl diphosphine ligand as well as preparation method and application thereof
The invention discloses a biaryl diphosphine ligand as well as a preparation method and an application thereof. A biaryl diphosphine ligand compound represented as the formula I in the description ora biaryl diphosphine ligand enantiomer is provided, wherein R is alkyl of C1-C10 or naphthenic base of C3-C30 independently; Ra is hydrogen, alkyl of C1-C10, alkoxy of C1-C4, naphthenic base of C3-C30, halogen, R substituted or unsubstituted phenyl, R substituted or unsubstituted aryl of C10-C30 and R substituted or unsubstituted ceteroary of C4-C15 independently; all R, R and R are halogen, alkyl of C1-C4 or alkoxy of C1-C4 independently. With the adoption of the biaryl diphosphine ligand compound I, a series of chiral beta-hydroxy carboxylates with high optical purity can be effectively prepared through catalyzed synthesis, and the compound is high in economic practicability.
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Paragraph 0329; 0330; 0331; 0332; 0333

(2018/05/16)

Efficient synthesis of the ketone body ester (R)-3-hydroxybutyryl-(R)-3-hydroxybutyrate and its (S,S) enantiomer
The ketone body ester (R)-3-hydroxybutyryl-(R)-3-hydroxybutyrate and its (S,S) enantiomer were prepared in a short, operationally simple synthetic sequence from racemic β-butyrolactone. Enantioselective hydrolysis of β-butyrolactone with immobilized Candida antarctica lipase-B (CAL-B) results in (R)-β-butyrolactone and (S)-β-hydroxybutyric acid, which are easily converted to (R) or (S)-ethyl-3-hydroxybutyrate and reduced to (R) or (S)-1,3 butanediol. Either enantiomer of ethyl-3-hydroxybutyrate and 1,3 butanediol are then coupled, again using CAL-B, to produce the ketone body ester product. This is an efficient, scalable, atom-economic, chromatography-free, and low cost synthetic method to produce the ketone body esters.
Budin, Noah,Higgins, Erin,DiBernardo, Anthony,Raab, Cassidy,Li, Chun,Ulrich, Scott
p. 560 - 564
(2018/07/25)

Functional characterization of salt-tolerant microbial esterase WDEst17 and its use in the generation of optically pure ethyl (R)-3-hydroxybutyrate
The two enantiomers of ethyl 3-hydroxybutyrate are important intermediates for the synthesis of a great variety of valuable chiral drugs. The preparation of chiral drug intermediates through kinetic resolution reactions catalyzed by esterases/lipases has been demonstrated to be an efficient and environmentally friendly method. We previously functionally characterized microbial esterase PHE21 and used PHE21 as a biocatalyst to generate optically pure ethyl (S)-3-hydroxybutyrate. Herein, we also functionally characterized one novel salt-tolerant microbial esterase WDEst17 from the genome of Dactylosporangium aurantiacum subsp. Hamdenensis NRRL 18085. Esterase WDEst17 was further developed as an efficient biocatalyst to generate (R)-3-hydroxybutyrate, an important chiral drug intermediate, with the enantiomeric excess being 99% and the conversion rate being 65.05%, respectively, after process optimization. Notably, the enantio-selectivity of esterase WDEst17 was opposite than that of esterase PHE21. The identification of esterases WDEst17 and PHE21 through genome mining of microorganisms provides useful biocatalysts for the preparation of valuable chiral drug intermediates.
Wang, Yilong,Xu, Yongkai,Zhang, Yun,Sun, Aijun,Hu, Yunfeng
p. 769 - 776
(2018/03/29)

Cobalt carbonyl ionic liquids based on the 1,1,3,3-tetra-alkylguanidine cation: Novel, highly efficient, and reusable catalysts for the carbonylation of epoxides
A series of novel cobalt carbonyl ionic liquids based on 1,1,3,3-tetra-alkyl-guanidine, such as [1,1-dimethyl-3,3-diethylguanidinium][Co(CO)4] (3a), [1,1-dimethyl-3,3-dibutylguanidinium][Co(CO)4] (3b), [1,1-dimethyl-3,3-tetramethyleneguanidinium][Co(CO)4] (3c), and [1,1-dimethyl-3,3-pentamethyleneguanidinium] [Co(CO)4] (3d), were synthesized in good yields and were also characterized using infrared spectroscopy, ultraviolet-visible spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, 13C NMR spectroscopy, high–resolution mass spectrometry, differential scanning calorimetry, and thermogravimetric analysis. The four compounds exhibited high thermal and chemical stability. In addition, the catalytic performance of these compounds was investigated in the carbonylation of epoxides, with 3a exhibiting the best catalytic activity without the aid of a base as the additive. The catalyst could be reused at least six times without significant decreases of the selectivity or conversion rate. Moreover, the catalyst system exhibited good tolerance with terminal epoxides bearing alkyl, alkenyl, aryl, alkoxy, and chloromethyl functional groups.
Zhang, Wei,Han, Feng,Tong, Jin,Xia, Chungu,Liu, Jianhua
p. 805 - 812
(2017/05/29)

Synthesis of an advanced intermediate enroute to thiomarinol antibiotics
A stereoselective synthesis of the C1-C14 fragment of thiomarinols is disclosed. The key steps include the stereoselective preparation of an allylic sulfide via a chloro sulfide by 1,2-asymmetric induction, ring-closing metathesis reaction, Kirmse-Doyle reaction for the preparation of a γ,δ-unsaturated ester, Nozaki-Hiyama-Kishi coupling and Julia-Kocienski olefination reaction. Substrate controlled asymmetric induction has been advantageously employed for the creation of stereogenic centers. Noyori transfer hydrogenation and asymmetric hydrogenation reactions have been utilized for the creation of carbinol stereocenters.
Raghavan, Sadagopan,Ravi, Anil
p. 2814 - 2823
(2017/04/14)

Identification of a Robust Carbonyl Reductase for Diastereoselectively Building syn-3,5-Dihydroxy Hexanoate: A Bulky Side Chain of Atorvastatin
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
supporting information
p. 1349 - 1354
(2017/09/23)

Preparation of structurally diverse chiral alcohols by engineering ketoreductase CgKR1
Ketoreductases are tools for the synthesis of chiral alcohols in industry. However, the low activity of natural enzymes often restricts their use in industrial applications. On the basis of computational analysis and previous reports, two residues (F92 and F94) probably affecting the activity of ketoreductase CgKR1 were identified. By tuning these two residues, the CgKR1-F92C/F94W variant was obtained that exhibited higher activity toward all 28 structurally diverse substrates examined than the wild-type enzyme. Among them, 13 substrates have a specific activity over 50 U mg-1 (54-775 U mg-1). Using CgKR1-F92C/F94W as a catalyst, five substrates at high loading (>100 g-1 L-1) were reduced completely in gramscale preparative reactions. This approach provides accesses to pharmaceutically relevant chiral alcohols with high enantioselectivity (up to 99.0% ee) and high space-time yield (up to 583 g-1 L-1 day-1). Molecular dynamics simulations highlighted the crucial role of residues 92 and 94 in activity improvement. Our findings provide useful guidance for engineering other ketoreductases, especially those possessing a similar active pocket to that in CgKR1.
Zheng, Gaowei,Liu, Yuan-Yang,Chen, Qi,Huang, Lei,Yu, Hui-Lei,Lou, Wen-Yong,Li, Chun-Xiu,Bai, Yun-Peng,Li, Ai-Tao,Xu, Jian-He
p. 7174 - 7181
(2017/11/06)

Synthesis of the fungus metabolite cladosin C
Cladosin C is one of the few known enaminotetramic acids, isolated from extracts of the deep sea fungus Cladosporium sphaerospermum. It was synthesised in ten steps and 14% overall yield by a late-stage amination of the corresponding 3-acyltetramic acid. This was obtained by a Dieckmann condensation of an N-β-ketoacylaminoester derived from dehydrovalinate and the thioester-terminated side chain containing the stereogenic centre which stemmed from poly-(R)-3-hydroxybutyrate.
Linder, David,Schobert, Rainer
p. 7672 - 7677
(2017/09/27)

Application of homochiral alkylated organic cages as chiral stationary phases for molecular separations by capillary gas chromatography
Molecular organic cage compounds have attracted considerable attention due to their potential applications in gas storage, catalysis, chemical sensing, molecular separations, etc. In this study, a homochiral pentyl cage compound was synthesized from a condensation reaction of (S,S)-1,2-pentyl-1,2-diaminoethane and 1,3,5-triformylbenzene. The imine-linked pentyl cage diluted with a polysiloxane (OV-1701) was explored as a novel stationary phase for high-resolution gas chromatographic separation of organic compounds. Some positional isomers were baseline separated on the pentyl cage-coated capillary column. In particular, various types of enantiomers including chiral alcohols, esters, ethers and epoxides can be resolved without derivatization on the pentyl cage-coated capillary column. The reproducibility of the pentyl cage-coated capillary column for separation was investigated using nitrochlorobenzene and styrene oxide as analytes. The results indicate that the column has good stability and separation reproducibility after being repeatedly used. This work demonstrates that molecular organic cage compounds could become a novel class of chiral separation media in the near future.
Xie, Shengming,Zhang, Junhui,Fu, Nan,Wang, Bangjin,Hu, Cong,Yuan, Liming
(2016/12/03)

Ru coordinated with BINAP in knitting aryl network polymers for heterogeneous asymmetric hydrogenation of methyl acetoacetate
A facile method for the preparation of heterogeneous asymmetric hydrogenation catalysts was presented. BINAP was knitted with aryl compounds using formaldehyde dimethyl acetal (FDA) as a cross-linker by Friedel-Crafts reaction without any pre-modification. The prepared catalysts showed different catalytic activities, and excellent recyclablilty results could be achieved in asymmetric hydrogenation.
Wang, Tao,Lyu, Yuan,Chen, Xingkun,Li, Cunyao,Jiang, Miao,Song, Xiangen,Ding, Yunjie
p. 28447 - 28450
(2016/04/08)

The effect of particle size and ligand configuration on the asymmetric catalytic properties of proline-functionalized Pt-nanoparticles
The effect of particle size on the asymmetric catalytic properties of supported ligand-functionalized nanoparticles (NPs) was investigated for the first time and found to alter significantly the activity but surprisingly not the stereoselectivity. These results suggest that the stereoselectivity of these complex systems is primarily determined by the ligand-reactant interaction, whereas the activity is determined by the particle size.
Schrader, Imke,Neumann, Sarah,Himstedt, Rieke,Zana, Alessandro,Warneke, Jonas,Kunz, Sebastian
supporting information
p. 16221 - 16224
(2015/11/16)

Chiral spiro-pyridylamidophosphine ligand compound, synthesis method therefor and application thereof
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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Page/Page column 17; 18-20

(2015/03/03)

Efficient synthesis of an ε-hydroxy ester in a space-time yield of 1580 g L-1 d-1 by a newly identified reductase RhCR
A new NADH-dependent carbonyl reductase RhCR capable of efficiently reducing the ε-ketoester ethyl 8-chloro-6-oxooctanoate (ECOO) to give ethyl (S)-8-chloro-6-hydroxyoctanoate [(S)-ECHO], an important chiral precursor for the synthesis of (R)-α-lipoic acid, was identified from Rhodococcus sp. ECU1014. Using recombinant Escherichia coli cells expressing RhCR and glucose dehydrogenase used for the regeneration of cofactor, 440 g L-1 (2 M) of ECOO were stoichiometrically converted to (S)-ECHO in a space-time yield of 1580 g L-1 d-1 without the external addition of any expensive cofactor.
Chen, Rui-Jie,Zheng, Gao-Wei,Ni, Yan,Zeng, Bu-Bing,Xu, Jian-He
p. 1501 - 1504
(2015/02/02)

New asymmetric synthesis of a pheromone component of the shield bug Cantao Parentum
A novel procedure has been developed for the synthesis of (2S,4R,6R,8S)-2,4,8-trimethyl-1,7-dioxaspiro[5.5]undecane, a pheromone component of the shield bug Cantao Parentum, through intermediate cyclopropanol derivatives in the key stages of carbon chain
Mineeva
p. 398 - 405
(2014/06/09)

Altering the substrate specificity of reductase CgKR1 from Candida glabrata by protein engineering for bioreduction of aromatic α-keto esters
A versatile keto ester reductase CgKR1, exhibiting a broad substrate spectrum, was obtained from Candida glabrata by genome data mining. It showed the highest activity toward an aliphatic β-keto ester, ethyl 4-chloro-3-oxobutanoate (COBE), but much lower activity toward bulkier α-keto esters with an aromatic group, such as methyl ortho- chlorobenzoylformate (CBFM) and ethyl 2-oxo-4-phenylbutyrate (OPBE). By rational design of the active pocket, the substrate specificity of the reductase was significantly altered and this tailor-made reductase showed a much higher activity toward aromatic α-keto esters (～7-fold increase in k cat/Km toward CBFM) and lower activity toward aliphatic keto esters (～12-fold decrease in kcat/Km toward COBE). Meanwhile, the thermostability of the reductase was enhanced by a consensus approach. Such improvements may yield practical catalysts for the asymmetric bioreduction of these aromatic α-keto esters
Huang, Lei,Ma, Hong-Min,Yu, Hui-Lei,Xu, Jian-He
p. 1943 - 1948
(2014/07/07)

Whole-cell biocatalysis in deep-eutectic-solvents/aqueous mixtures
Whole-cell biocatalysis with the use of baker's yeast is demonstrated in different mixtures of water with deep eutectic solvents (DESs; choline chloride/glycerol, 1:2 mol/mol). Enantioselective ketone reduction is observed for long reaction times (>200 h), which suggests that the whole cells remain stable in these neoteric solvents. By changing the proportion of the DES added, a complete inversion of enantioselectivity is observed, from approximately 95 % enantiomeric excess (ee) (S) in pure water to approximately 95 % ee (R) in the pure DES. Presumably, some (S)-oxidoreductases present in baker's yeast are inhibited by DESs. DESpicably good: Whole-cell biocatalysis with the use of baker's yeast is demonstrated in different mixtures of water with deep eutectic solvents (DESs). Enantioselective ketone reduction is observed for long reaction times (>200 h), which suggests that the whole cells remain stable in these neoteric solvents. By changing the proportion of the DES added, a complete inversion of enantioselectivity is observed.
Maugeri, Zaira,Dominguez De Maria, Pablo
p. 1535 - 1537
(2014/06/24)

Heterogeneous versus homogeneous copper(II) catalysis in enantioselective conjugate-addition reactions of boron in water
We have developed CuII-catalyzed enantioselective conjugate-addition reactions of boron to α,β-unsaturated carbonyl compounds and α,β,γ,δ-unsaturated carbonyl compounds in water. In contrast to the previously reported CuI catalysis that required organic solvents, chiral CuII catalysis was found to proceed efficiently in water. Three catalyst systems have been exploited: cat. 1: Cu(OH)2 with chiral ligand L1; cat. 2: Cu(OH)2 and acetic acid with ligand L1; and cat. 3: Cu(OAc)2 with ligand L1. Whereas cat. 1 is a heterogeneous system, cat. 2 and cat. 3 are homogeneous systems. We tested 27 α,β-unsaturated carbonyl compounds and an α,β-unsaturated nitrile compound, including acyclic and cyclic α,β-unsaturated ketones, acyclic and cyclic β,β- disubstituted enones, acyclic and cyclic α,β-unsaturated esters (including their β,β-disubstituted forms), and acyclic α,β-unsaturated amides (including their β,β-disubstituted forms). We found that cat. 2 and cat. 3 showed high yields and enantioselectivities for almost all substrates. Notably, no catalysts that can tolerate all of these substrates with high yields and high enantioselectivities have been reported for the conjugate addition of boron. Heterogeneous cat. 1 also gave high yields and enantioselectivities with some substrates and also gave the highest TOF (43 200 h-1) for an asymmetric conjugate-addition reaction of boron. In addition, the catalyst systems were also applicable to the conjugate addition of boron to α,β,γ, δ-unsaturated carbonyl compounds, although such reactions have previously been very limited in the literature, even in organic solvents. 1,4-Addition products were obtained in high yields and enantioselectivities in the reactions of acyclic α,β,γ,δ-unsaturated carbonyl compounds with diboron 2 by using cat. 1, cat. 2, or cat. 3. On the other hand, in the reactions of cyclic α,β,γ,δ-unsaturated carbonyl compounds with compound 2, whereas 1,4-addition products were exclusively obtained by using cat. 2 or cat. 3, 1,6-addition products were exclusively produced by using cat. 1. Similar unique reactivities and selectivities were also shown in the reactions of cyclic trienones. Finally, the reaction mechanisms of these unique conjugate-addition reactions in water were investigated and we propose stereochemical models that are supported by X-ray crystallography and MS (ESI) analysis. Although the role of water has not been completely revealed, water is expected to be effective in the activation of a borylcopper(II) intermediate and a protonation event subsequent to the nucleophilic addition step, thereby leading to overwhelmingly high catalytic turnover. Copyright
Kitanosono, Taku,Xu, Pengyu,Kobayashi, Shu
supporting information
p. 179 - 188
(2014/01/06)

Synthesis of BINAP ligands with imidazole tags for highly enantioselective Ru-catalyzed asymmetric hydrogenation of β-keto esters in ionic liquid systems
The imidazole-tagged BINAP ligands were synthesized and used for Ru-catalyzed asymmetric hydrogenation of β-keto esters in ionic liquid (IL) systems. The Ru-BINAP catalysts with the imidazolium tags show high catalytic activity and enantioselectivity, which closely parallel the performance of unmodified BINAP. The catalyst recycling experiments using [bmim]Tf 2N/MeOH system demonstrated that introducing imidazolium moieties to the BINAP backbone can effectively enhance the affinity of the Ru-catalysts to the IL, reduce Ru leaching and improve catalysts stability, and after several cycles no significant loss of activity and enantioselectivity was observed.
Jin, Xin,Kong, Fang-Fang,Yang, Zhi-Qiang,Cui, Fei-Fei
p. 22 - 26
(2013/06/27)

CHIRAL SPIRO-PYRIDYLAMIDOPHOSPHINE LIGAND COMPOUND, SYNTHESIS METHOD THEREFOR AND APPLICATION THEREOF
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)

Carbanion-accelerated claisen rearrangements: Asymmetric induction with chiral phosphorus-stabilized anions
The carbanion-accelerated Claisen rearrangement has been extended to include phosphorus carbanion-stabilizing groups. The appropriately substituted allyl vinyl ethers are synthesized by the nucleophilic addition of allyl oxides to phosphorus-substituted allenes, which are obtained in one step from simple starting materials. The phosphorus-stabilized, carbanion-accelerated Claisen rearrangements proceed rapidly at room temperature in high yield, and the rearrangements are highly site- and stereoselective. The first examples of asymmetric induction in the Claisen rearrangement with chiral, phosphorus, anion-stabilizing groups are described. The observed asymmetric induction is highly dependent on the structure of the auxiliary and the metal counterion involved. Both internal and relative diastereoselectivity are high. A model for the observed sense of internal diastereoselectivity is proposed that is founded in the current understanding of the structure of phosphorus-stabilized anions.
Denmark, Scott E.,Marlin, John E.,Rajendra
p. 66 - 82
(2013/04/23)

Highly enantioselective double reduction of phenylglyoxal to (R)-1-phenyl-1,2-ethanediol by one NADPH-dependent yeast carbonyl reductase with a broad substrate profile
The activity and enantioselectivity of a carbonyl reductase from Pichia pastoris GS115 were evaluated with a series of carbonyl compounds including aryl aldehydes, ketones, α- and β-ketoesters. This recombinant enzyme possessed a broad substrate profile with the ability of reducing both aldehydes and ketones. Especially, the enzyme catalyzed the double reduction of phenylglyoxal to (R)-1-phenyl-1,2-ethanediol with 99% yield and 99% ee by coupling with d-glucose dehydrogenase for the regeneration of cofactor NADPH, representing the first example of effective reduction of both aldehyde and ketone functional groups in one molecule by using only one enzyme. Furthermore, this study provides valuable information for guiding the future application of this versatile biocatalyst.
Li, Zhe,Liu, Weidong,Chen, Xi,Jia, Shiru,Wu, Qiaqiang,Zhu, Dunming,Ma, Yanhe
p. 3561 - 3564
(2013/04/24)

Stereospecific reduction of methyl o-chlorobenzoylformate at 300 g·L-1 without additional cofactor using a carbonyl reductase mined from Candida glabrata
In order to search for oxidoreductases suitable for the preparation of methyl (R)-o-chloromandelate [(R)-CMM], the key intermediate for clopidogrel, the homologous proteins of Gre2p were expressed in Escherichia coli, among which CgKR1 showed the most satisfactory activity and stereoselectivity towards methyl o-chlorobenzoylformate (CBFM). Using the crude enzyme of CgKR1 and glucose dehydrogenase (GDH), as much as 300 g·L-1 of CBFM was almost stoichiometrically converted to (R)-CMM with excellent enantiomeric excess (98.7% ee). More importantly, the reaction could be performed without external addition of an expensive cofactor. The substrate profile indicates that keto esters serve as the most suitable substrate, which was confirmed by gram-scale preparations. Homology modeling and docking analysis revealed the molecular basis for the high stereoselectivity of CgKR1. These demonstrate not only the feasibility of in silico mining of novel enzymes based on sequence homology but also the applicability of this new reductase for the practical production of optically active (R)-CMM. Copyright
Ma, Hongmin,Yang, Linlin,Ni, Yan,Zhang, Jie,Li, Chun-Xiu,Zheng, Gao-Wei,Yang, Huaiyu,Xu, Jian-He
experimental part
p. 1765 - 1772
(2012/08/08)

Asymmetric syntheses of the sex pheromones of pine sawflies, their homologs and stereoisomers
We describe efficient and flexible enantioselective syntheses of the active enantiomers of the pheromones of pine sawflies, including the species Diprion jingyuanensis, their homologs and, stereoisomers, as well as those identified from the Chinese species Diprion jingyuanensis, i.e., 126. A total of 48 compounds, including acetates 78-101 and propanoates 102-125, have been synthesized. Our general approach towards these compounds originated from the commercially available chirons diethyl (S)- and (R)-malates, as well as ethyl (R)-3-hydroxybutanoate. The Seebach asymmetric methylation was employed in a key step to control additional configuration. Copyright
Zheng, Jian-Feng,Lan, Hong-Qiao,Yang, Rui-Feng,Peng, Qi-Long,Xiao, Zhen-Hua,Tuo, Shi-Chuan,Hu, Kong-Zhen,Xiang, Yong-Gang,Wei, Zhen,Huang, Pei-Qiang,Zhang, Zhen
p. 1799 - 1808,10
(2012/12/12)

Efficient reduction of ethyl 2-oxo-4-phenylbutyrate at 620 ?l -1 by a bacterial reductase with broad substrate spectrum
A β-ketoacyl-ACP reductase (FabG) gene from Bacillus sp. ECU0013 was heterologously overexpressed in Escherichia coli and the encoded protein was purified to homogeneity. The recombinant reductase could reduce a broad spectrum of prochiral ketones including aromatic ketones and keto esters and showed the highest activity in the asymmetric reduction of ethyl 2-oxo-4-phenylbutyrate (OPBE). Using E. coli cells coexpressing both FabG and glucose dehydrogenase (GDH) genes, as much as 620 ?L-1 of OPBE was almost stoichiometrically converted to ethyl (S)-2-hydroxy-4-phenylbutyrate [(S)-HPBE] with excellent (>99%) enantiomeric excess. More importantly, the process could be performed smoothly without external addition of an expensive cofactor as usually done and could be scaled up very easily. All these positive features demonstrate the applicability of this reductase for the large-scale production of optically active α-hydroxy acids/esters.
Ni, Yan,Li, Chun-Xiu,Zhang, Jie,Shen, Nai-Dong,Bornscheuer, Uwe T.,Xu, Jian-He
supporting information; experimental part
p. 1213 - 1217
(2011/07/09)

Enantioselective hydrogenation of α-ketoesters over alkaloid-modified platinum nanowires
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.
experimental part
p. 3070 - 3074
(2011/12/16)

Highly stereoselective reduction of prochiral ketones by a bacterial reductase coupled with cofactor regeneration
A carbonyl reductase gene (yueD) from Bacillus sp. ECU0013 was heterologously overexpressed in Escherichia coli, and the encoded protein (BYueD) was purified to homogeneity and characterized. The NADPH-dependent reductase showed a broad substrate spectrum towards different aromatic ketones, and α- and β-ketoesters. Although the enantioselectivity was high to moderate for the reduction of α-ketoesters, all the tested β-ketoesters and aromatic ketones were reduced to the corresponding chiral alcohols in enantiomerically pure forms. Furthermore, the practical applicability of this enzyme was evaluated for the reduction of ethyl 4-chloro-3-oxobutanoate (1a). Using Escherichia coli cells coexpressing BYueD and glucose dehydrogenase, 215 g L-1 (1.3 M) of 1a was stoichiometrically converted to ethyl (R)-4-chloro-3-hydroxybutanoate ((R)-1b) in an aqueous-toluene biphasic system by using a substrate fed-batch strategy, resulting in an overall hydroxyl product yield of 91.7% with enantiomeric purity of 99.6% ee.
Ni, Yan,Li, Chun-Xiu,Wang, Li-Juan,Zhang, Jie,Xu, Jian-He
experimental part
p. 5463 - 5468
(2011/09/12)

NEW ORTHO-FUNCTIONALIZED P-CHIRAL ARYLPHOSPHINES AND DERIVATIVES: THEIR PREPARATION AND USE IN ASYMMETRIC CATALYSIS
The invention relates to novel organo phosphorus P-chiral optically active compounds of formula (I) having a hydroxyl, mercapto, amino, carboxyl, sulfonyl group on aryl near a phosphorus atom, to the preparation and the use thereof in then asymmetrical catalysis of unsaturated compounds. Novel acylphosphine optically pure ligands embodied in the form of transition metal complexes exhibit an increased activity and enantloselectivity, in particular in asymmetrical hydrogenation, in comparison with the same type Uganda such as DiPAMP.
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Page/Page column 22; 23

(2010/07/04)

Enantioselective ketoester reductions in water: A comparison between microorganism-and ruthenium-catalyzed reactions
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
experimental part
p. 1211 - 1215
(2010/10/20)

Total synthesis of (+)-demethoxycardinalin 3
The total synthesis of (+)-demethoxycardinalin 3 is described. The synthetic strategy features the synthesis of dimeric Fischer carbene and its use in a bidirectional Doetz benzannulation reaction to set the dimeric structure of the cardinalins. The oxa-Pictet-Spengler reaction was used to construct the pyran rings. The synthesis is completed in seven steps and an overall yield of 7%.
Fernandes, Rodney A.,Mulay, Sandip V.
supporting information; experimental part
p. 7029 - 7032
(2010/11/19)

Metal-free catalytic boration at the β-position of α,β-unsaturated compounds: A challenging asymmetric induction
Enantiomerlcally enriched secondary organoboronates containing β-carbonyl functional groups have been prepared using an unprecedented organocatalytic system (see scheme). The use of chiral tertiary phosphorus compounds induced ee values of up to 95 % in the absence of transition metals. (Figure Presented).
Bonet, Amadeu,Gulyas, Henrik,Fernandez, Elena
supporting information; experimental part
p. 5130 - 5134
(2010/11/04)

A chiral 6-membered n -heterocyclic carbene copper(I) complex that induces high stereoselectivity
A chiral 6-membered annulated N-heterocyclic (6-NHC) copper complex that catalyzes β-borylations with high yield and enantioselectivity was developed. The chiral 6-NHC copper complex is easy to prepare on the gram scale and is very active, showing 10000 turnovers at 0.01 mol % of catalyst without significant decrease of enantioselectivity and with useful reaction rates.
Park, Jin Kyoon,Lackey, Hershel H.,Rexford, Matthew D.,Kovnir, Kirill,Shatruk, Michael,McQuade, D. Tyler
supporting information; experimental part
p. 5008 - 5011
(2010/12/25)

On the microbial reduction of ethyl α-methylacetoacetate
In the present work several microorganisms were screened in the reduction of methyl and ethyl acetoacetates. Good to excellent ees were obtained with up to quantitative substrate conversions. These microorganisms were also tested in the reduction of ethyl α-methylacetoacetate with good des and excellent ees. It was noticed that Kluyveromyces marxianus and Trichoderma harzianum were found to lead to products of opposite configuration with the use of methyl or ethyl acetoacetates, which is a very unusual finding.
Ramos, Aline de Souza,Ribeiro, Joyce Benzaquem,Vazquez, Leonardo,Fiaux, Sorele Batista,Leite, Selma Gomes Ferreira,Cruz, Renata de Andrade,Ramos, Maria da Conceicao Klaus V.,Neto, Francisco Radler de Aquino,Antunes, Octavio A.C.
experimental part
p. 559 - 561
(2009/09/06)

Synthesis, coordination behaviour, structural features and use in asymmetric hydrogenations of bifep-type biferrocenes
A protocol for the synthesis of C2- and C1-symmetric 2,2″-diarylphosphino-substituted biferrocenes (bifep-type ligands) is presented and the preparation of four representatives is described [(S p,Sp)-2-R12P-2″- R 22P-1,1″-biferrocene; 1 (bifep): R1 = R2 = Ph; 2: R1 = Ph, R2 = Cy; 3: R1 = R2 = 3,5-Me2C6H3; 4: R1 = 3,5-Me2-4-OMe-C6H2, R2 = 3,5-(CF3)2C6H3]. In addition, the synthesis of three palladium(ii) complexes ([PdX2(L)], 10: L = 1, X = Cl; 11: L = 4, X = Cl; 12: L = 1, X = C6F5 and of four bifep ruthenium complexes (13: [RuCl(p-cymene)(1)]PF6; 14: [RuI(p-cymene)(1)]PF6; 15: [RuCl(benzene)(1)]PF6; 16: [RuI(p-cymene)(1)]I) is reported. In the solid state the biferrocene unit of complexes 10, 11 and 15 adopt either a (P)-shaped (10) or an (M)-shaped (11, 15) conformation. In solution, palladium complexes 10 and 11 are present as equilibrium mixtures of rapidly interconverting (P)- and (M)-shaped conformers. Rhodium- and iridium-mediated asymmetric hydrogenations of a number of olefins and one imine give products with only low to moderate enantiomeric excess, while in the ruthenium-catalyzed hydrogenation of ketones a maximum e.e. of 82% is obtained. The low enantioselectivities are assumed to be related to the conformational flexibility of bifep-type ligands.
Espino, Gustavo,Xiao, Li,Puchberger, Michael,Mereiter, Kurt,Spindler, Felix,Manzano, Blanca R.,Jalon, Felix A.,Weissensteiner, Walter
experimental part
p. 2751 - 2763
(2009/06/28)

Study on effects of modification conditions of powdered nickel-cobalt catalysts on enantioselectivity of hydrogenation of ethyl acetoacetate
An effect of modification conditions of powdered nickel-cobalt catalysts on enantioselectivity of hydrogenation of ethyl acetoacetate has been studied. Addition of NaBr to the modifying solution of RR-(+)-tartaric acid does not improve enantioselectivity of the catalyst. When the Ni-Co catalysts are modified with amino acids, the best results are obtained with L-β-plienylalanine (17% ee).
Zubareva,Dorokhin,Klabunovskii
scheme or table
p. 499 - 501
(2010/08/07)

Axially chiral P-N ligands for the copper catalyzed β-borylation of α,β-unsaturated esters
The synthesis and resolution of a new axially chiral Quinazolinap ligand are reported. The application of this and other related P-N ligands to the copper catalyzed β-borylation of α,β-unsaturated esters resulted in conversions of up to 100% and ee values
Fleming, William J.,Mueller-Bunz, Helge,Lillo, Vanesa,Fernandez, Elena,Guiry, Patrick J.
supporting information; experimental part
p. 2520 - 2524
(2009/10/30)

Reduction of carbonylic and carboxylic groups by plant cell cultures
The transformation of aliphatic and aromatic acids to their corresponding alcohols, involving two reductive steps, is difficult to perform biologically due to its low redox potential. For this reason, the reduction of nonactivated carboxylic acids has been described for only a limited number of substrates and confined to a few microbial groups (fungi, clostridia, and archea). Nine species of cultured plant cells were able to reduce cinnamic, hexanoic, and octanoic acids to the corresponding primary alcohols with yields ranging from 2 to 80% (w/w). Aldehyde was detected only for three species during the reduction of cinnamic acid, confirming that the second reductive step from aldehyde to alcohol is faster than the first, from acid to aldehyde. Lyophilized cells from some of the cultures were used in buffer and solvent-water systems to obtain the reduction of carbonylic (ethyl acetoacetate) and carboxylic (cinnamic and hexanoic acids) groups.
Villa, Raffaella,Molinari, Francesco
experimental part
p. 693 - 696
(2009/04/04)

Asymmetric carbonyl reductions with microbial ketoreductases
The biocatalytic reduction of β-keto esters and some aromatic ketones in the presence of a variety of ketoreductases from different microbial origins was investigated. The prochiral selectivity was generally high and both product enantiomers could be obtained by a proper choice of enzyme. Aromatic ketones reacted slower than the esters but the prochiral selectivity was often high. The organic cosolvent tolerance of these enzymes was rather variable but useful activity could be maintained in a number of cases. Reduction of the oxidized cofactors NAD and NADP, employing 2-propanol as a sacrificial reductant, was catalyzed by the ketoreductases from Rhodococcus erythropolis and Lactobacillus kefir, respectively.
Sorgedrager, Menno J.,Van Rantwijk, Fred,Huisman, Gjalt W.,Sheldon, Roger A.
scheme or table
p. 2322 - 2328
(2009/10/23)

Diastereofacial selectivity in aldol-type condensation induced by optically pure α-sulfinyl acetate with α-substituted aldehydes
Highly diastereoselective aldol-type condensations induced by the chiral magnesium enolate of tert-butyl p-tolyl sulfinyl acetate were performed with optically pure alkyl or hydroxy α-substituted aldehydes. The addition of chiral α-sulfinyl acetate to var
Bauder, Claude
p. 2243 - 2246
(2008/09/19)

Chiral Diphosphonites as Ligands in the Ruthenium-Catalyzed Enantioselective Reduction of Ketones, B-Ketoesters and Ketimines
Chiral ruthenium complexes are disclosed, obtained by reaction of a ruthenium salt with a chiral diphosphonite. Chiral diols with the general structure given in scheme 1 are preferably used as chiral diphosphonites. Said ruthenium complexes can be simply and economically obtained and provide high enantioselectivity on reduction of ketones, β-ketoesters and ketimines.
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Page/Page column 8-9

(2008/12/04)

Orchestration of concurrent oxidation and reduction cycles for stereoinversion and deracemisation of sec-alcohols
Black and white are opposites as are oxidation and reduction. Performing an oxidation, for example, of a sec-alcohol and a reduction of the corresponding ketone in the same vessel without separation of the reagents seems to be an impossible task. Here we show that oxidative cofactor recycling of NADP + and reductive regeneration of NADH can be performed simultaneously in the same compartment without significant interference. Regeneration cycles can be run in opposing directions beside each other enabling one-pot transformation of racemic alcohols to one enantiomer via concurrent enantioselective oxidation and asymmetric reduction employing defined alcohol dehydrogenases with opposite stereo- and cofactor-preference. Thus, by careful selection of appropriate enzymes, NADH recycling can be performed in the presence of NADP+ recycling to achieve overall, for example, deracemisation of sec-alcohols or stereoinversion representing a possible concept for a "green" equivalent to the chemical-intensive Mitsunobu inversion.
Voss, Constance V.,Gruber, Christian C.,Faber, Kurt,Knaus, Tanja,Macheroux, Peter,Kroutil, Wolfgang
supporting information; experimental part
p. 13969 - 13972
(2009/02/07)

Deracemization of secondary alcohols through a concurrent tandem biocatalytic oxidation and reduction
(Chemical Equation Presented) Breaking the mirror: A purified alcohol dehydrogenase (ADH) for stereoselective reduction and whole cells of a microorganism for enantioselective oxidation operated concurrently to effect the stereoinversion of one enantiomer of a racemic secondary alcohol and provide the optically pure alcohol in >99% yield (see scheme). R,R′ = alkyl.
Voss, Constance V.,Gruber, Christian C.,Kroutil, Wolfgang
p. 741 - 745
(2008/12/20)

Asymmetric reduction of substituted α- and β-ketoesters by Bacillus pumilus Phe-C3
The enantioselective reduction of substituted α- and β-ketoesters using resting cells of Bacillus pumilus Phe-C3 was investigated. Effects of substrate concentration on the catalytic efficiency of the microorganism were studied. Preparative scale productions were carried out under the optimized conditions with 62.4-91.0% yields and 90.2-97.1% ee. The cells retained 80% of initial activity after recycling for six times.
He, Chunmao,Chang, Dongliang,Zhang, Jie
p. 1347 - 1351
(2008/12/20)

Transformation of racemic ethyl 3-hydroxybutanoate into the (R)-enantiomer exploiting lipase catalysis and inversion of configuration
Racemic ethyl 3-hydroxybutanoate rac-1 was transformed into ethyl (R)-acetoxybutanoate (ee = 92%) with 85-90% chemical yields using enantioselective acylation with isopropenyl acetate in the presence of Candida antarctica lipase B (CAL-B, Novozym 435) under solvent-free conditions, followed by mesylation of the unreacted (S)-alcohol in the reaction mixture and inversion of configuration with cesium acetate in DMF in one pot. When the (R)-acetoxybutanoate was subjected to alcoholysis with ethanol and CAL-B, enantiopure (R)-1 (ee >99%) was produced.
Turcu, Mihaela C.,Kiljunen, Eero,Kanerva, Liisa T.
p. 1682 - 1687
(2008/02/11)