- Reshaping the active pocket of esterase Est816 for resolution of economically important racemates
-
Bacterial esterases are potential biocatalysts for the production of optically pure compounds. However, the substrate promiscuity and chiral selectivity of esterases usually have a negative correlation, which limits their commercial value. Herein, an efficient and versatile esterase (Est816) was identified as a promising catalyst for the hydrolysis of a wide range of economically important substrates with low enantioselectivity. We rationally designed several variants with up to 11-fold increased catalytic efficiency towards ethyl 2-arylpropionates, mostly retaining the initial substrate scope and enantioselectivity. These variants provided a dramatic increase in efficiency for biocatalytic applications. Based on the best variant Est816-M1, several variants with higher or inverted enantioselectivity were designed through careful analysis of the structural information and molecular docking. Two stereoselectively complementary mutants, Est816-M3 and Est816-M4, successfully overcame and even reversed the low enantioselectivity, and several 2-arylpropionic acid derivatives with highEvalues were obtained. Our results offer potential industrial biocatalysts for the preparation of structurally diverse chiral carboxylic acids and further lay the foundation for improving the catalytic efficiency and enantioselectivity of esterases.
- Fan, Xinjiong,Fu, Yao,Liu, Xiaolong,Zhao, Meng
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p. 6126 - 6133
(2021/09/28)
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- Method for resolution of (+/-)-2-(3-benzoyl)-phenylpropionic acid
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The invention provides a method for resolution of (+/-)-2-(3-benzoyl)-phenylpropionic acid. According to the method, (+/-)-2-(3-benzoyl)-phenylpropionic acid alkali salt serves as the raw material, (R)-3,4-dimethoxy-N-(1-phenethyl)-benzylamine hydrochloride serves as a resolving agent, and the raw material reacts with the resolving agent in the presence of solvent water to obtain diastereomeric salt of S-(+)-2-(3-benzoyl)-phenylpropionic acid and (R)-3,4-dimethoxy-N-(1-phenethyl)-benzylamine, namely resolving salt; then, the resolving salt is free with acid, and the S-(+)-2-(3-benzoyl)-phenylpropionic acid can be obtained. According to the method for resolution of the (+/-)-2-(3-benzoyl)-phenylpropionic acid, organic solvents do not need to be used in the forming process of the resolving salt, and water serves as a solvent. Besides, the consumption of the resolving agent is reduced by nearly 50%, and therefore the method is a resolving technology with more advantages.
- -
-
Paragraph 0045; 0046
(2018/03/24)
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- Evaluation of the Edman degradation product of vancomycin bonded to core-shell particles as a new HPLC chiral stationary phase
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A modified macrocyclic glycopeptide-based chiral stationary phase (CSP), prepared via Edman degradation of vancomycin, was evaluated as a chiral selector for the first time. Its applicability was compared with other macrocyclic glycopeptide-based CSPs: TeicoShell and VancoShell. In addition, another modified macrocyclic glycopeptide-based CSP, NicoShell, was further examined. Initial evaluation was focused on the complementary behavior with these glycopeptides. A screening procedure was used based on previous work for the enantiomeric separation of 50 chiral compounds including amino acids, pesticides, stimulants, and a variety of pharmaceuticals. Fast and efficient chiral separations resulted by using superficially porous (core-shell) particle supports. Overall, the vancomycin Edman degradation product (EDP) resembled TeicoShell with high enantioselectivity for acidic compounds in the polar ionic mode. The simultaneous enantiomeric separation of 5 racemic profens using liquid chromatography-mass spectrometry with EDP was performed in approximately 3?minutes. Other highlights include simultaneous liquid chromatography separations of rac-amphetamine and rac-methamphetamine with VancoShell, rac-pseudoephedrine and rac-ephedrine with NicoShell, and rac-dichlorprop and rac-haloxyfop with TeicoShell.
- Hellinghausen, Garrett,Lopez, Diego A.,Lee, Jauh T.,Wang, Yadi,Weatherly, Choyce A.,Portillo, Abiud E.,Berthod, Alain,Armstrong, Daniel W.
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p. 1067 - 1078
(2018/08/01)
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- Efficient resolution of profen ethyl ester racemates by engineered Yarrowia lipolytica Lip2p lipase
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Enzyme-catalyzed enantiomer discrimination is still a great challenge for the development of industrial pharmaceutical processes. For the resolution of ibuprofen, naproxen and ketoprofen racemates, three major anti-inflammatory drugs, only lipases from Candida rugosa present a high selectivity if solvent and surfactant use is discarded. However, their catalytic activities are too low. In the present work, we demonstrate that the lipase Lip2p from the yeast Yarrowia lipolytica has a higher catalytic activity than C. rugosa lipases to hydrolyze the ethyl esters of ibuprofen, naproxen and ketoprofen, but its selectivity is not sufficient [E?=?52 (S); 11 (S) and 1.5 (R) respectively]. The enantioselectivity was further improved by site-directed mutagenesis, targeted at the substrate binding site and guided by molecular modelling studies. By investigating the binding modes of the (R)- and (S)-enantiomers in the active site, two amino acid residues located in the hydrophobic substrate binding site of the lipase, namely residues 232 and 235, were identified as crucial for enantiomer discrimination and enzyme activity. The (S) enantioselectivity of Lip2p towards ethyl ibuprofen esters was rendered infinite (E???300) by replacing V232 by an A or C residue. Substitution of V235 by C, M, S, or T amino acids led to a great increase in the (S)-enantioselectivity (E???300) towards naproxen ethyl ester. Finally, the variant V232F enabled the efficient kinetic resolution of ethyl ketoprofen ester enantiomers [(R)-enantiopreference; E???300]. In addition to the increase in selectivity, a remarkable increase in velocity by 2.6, 2.7 and 2.5?times, respectively, was found for ibuprofen, naproxen and ketoprofen ethyl esters.
- Gérard, Doriane,Guéroult, Marc,Casas-Godoy, Leticia,Condoret, Jean-Stéphane,André, Isabelle,Marty, Alain,Duquesne, Sophie
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p. 433 - 441
(2017/03/24)
-
- Enantioselective potential of polysaccharide-based chiral stationary phases in supercritical fluid chromatography
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The enantioselective potential of two polysaccharide-based chiral stationary phases for analysis of chiral structurally diverse biologically active compounds was evaluated in supercritical fluid chromatography using a set of 52 analytes. The chiral selectors immobilized on 2.5?μm silica particles were tris-(3,5-dimethylphenylcarmabate) derivatives of cellulose or amylose. The influence of the polysaccharide backbone, different organic modifiers, and different mobile phase additives on retention and enantioseparation was monitored. Conditions for fast baseline enantioseparation were found for the majority of the compounds. The success rate of baseline and partial enantioseparation with cellulose-based chiral stationary phase was 51.9% and 15.4%, respectively. Using amylose-based chiral stationary phase we obtained 76.9% of baseline enantioseparations and 9.6% of partial enantioseparations of the tested compounds. The best results on cellulose-based chiral stationary phase were achieved particularly with propane-2-ol and a mixture of isopropylamine and trifluoroacetic acid as organic modifier and additive to CO2, respectively. Methanol and basic additive isopropylamine were preferred on amylose-based chiral stationary phase. The complementary enantioselectivity of the cellulose- and amylose-based chiral stationary phases allows separation of the majority of the tested structurally different compounds. Separation systems were found to be directly applicable for analyses of biologically active compounds of interest.
- Kucerova, Gabriela,Kalikova, Kveta,Tesarova, Eva
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supporting information
p. 239 - 246
(2017/05/29)
-
- Facile one-pot preparation of chiral monoliths with a well-defined framework based on the thiol-ene click reaction for capillary liquid chromatography
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A novel chiral cyclodextrin (CD) monolith was easily prepared via a one-pot process based on the thiol-ene click reaction of allyl-β-CD with pentaerythritol tetra-(3-mercaptopropionate) in a fused-silica capillary. The effects of both the composition of prepolymerization solution and reaction temperature on the morphology, permeability, and selectivity of the β-CD chiral monolith were investigated in detail. The conditions were optimized to fabricate a homogeneous and permeable chiral monolith. In this study, the β-CD monolith was used as the stationary phase of capillary liquid chromatography for the chiral separation of several pharmaceutical enantiomers including flavanone, flurbiprofen, naproxen, synephrine, isoprenaline sulfate, ketoprofen, and atropine sulfate monohydrate. Compared to the previously reported two-step method, this one-pot method for the preparation of a β-CD chiral monolith is simple and time-saving. Moreover, good resolutions were obtained for chiral isomers in a shorter analysis time compared to that reported in the literatures. These results indicate that the thiol-ene click chemistry provides a simple and robust method for the preparation of a chiral β-CD monolith.
- Zhang, Peng,Wang, Jiannan,Yang, Haiguan,Su, Linjing,Xiong, Yuhao,Ye, Fanggui
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p. 24835 - 24842
(2016/03/22)
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- Chiral separation of ketoprofen on an achiral NH2 column by HPLC using vancomycin as chiral mobile phase additive
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A high-performance liquid chromatographic method for chiral separation of ketoprofen racemate was developed. (R)- and (S)-ketoprofen enantiomers were separated on a LiChrosorb NH2 column (250?mm?×?4.6?mm, i.d 5?μm) at 20?°C, using 2-propanol/potassium dihydrogen phosphate buffer (pH 6.0, 0.05?M) (50:50 v/v). Containing vancomycin as the mobile phase, at a flow rate of 0.8?ml?min?1 and detection wavelength of UV, the detector was set at 310?nm. Under these conditions, ketoprofen enantiomers could be separated with a selectivity factor (α) of 2.172 and a resolution (Rs) of 4.78 using extremely low concentrations of the vancomycin chiral additive.
- Gherdaoui, Dehbiya,Bekdouche, Hafsa,Zerkout, Said,Fegas, Rachid,Righezza, Michel
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p. 2319 - 2323
(2016/11/06)
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- Reversed-phase high-performance liquid chromatographic separation of some 2-arylpropionic acids using vancomycin as chiral stationary phase
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Abstract A rapid, sensitive and reproducible HPLC method has been developed for enantioseparation of six non-steroidal anti-inflammatory drugs, which are acidic compounds: carprofen, fenoprofen, flurbiprofen, ibuprofen, indoprofen and ketoprofen. The effects of the mobile phase composition on retention times and resolutions of the analytes were studied. A column based on vancomycin immobilized by reductive amination to aldehyde functionalised silica was prepared in house and used. The prepared sorbent shows a great stability and selectivity over a range of pH (4-6), and the separation was carried out using the mobile phase composed of a mixture of 40% of methanol in ammonium nitrate buffer (50 mM) at pH 5.0. Another mobile phase consisted of 50% of methanol in phosphate buffer (5A mM) at pH 5.0 was also prepared and tested. The two mobile phases are the optimum conditions obtained. All experiments were conducted at flow rate 0.6 ml/min, using a UV detector wavelength at λ = 254 nm.
- Bouchair, Nabila,Righezza, Michel,Hamdi, Abderrezak
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p. 921 - 928
(2015/05/05)
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- Synthesis of tertiary and quaternary amine derivatives from wood resin as chiral NMR solvating agents
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Chiral tertiary and quaternary amine solvating agents for NMR spectroscopy were synthesized from the wood resin derivative (+)-dehydroabietylamine (2). The resolution of enantiomers of model compounds [Mosher's acid (3) and its n-Bu4N salt (4)] (guests) by (+)-dehydroabietyl-N,N-dimethylmethanamine (5) and its ten different ammonium salts (hosts) was studied. The best results with 3 were obtained using 5 while with 4 the best enantiomeric resolution was obtained using (+)-dehydroabietyl-N,N-dimethylmethanaminium bis(trifluoromethane-sulfonimide) (6). The compounds 5 and 6 showed a 1:1 complexation behaviour between the host and guest. The capability of 5 and 6 to recognize the enantiomers of various α-substituted carboxylic acids and their n-Bu4N salts in enantiomeric excess (ee) determinations was demonstrated. A modification of the RES-TOCSY NMR pulse sequence is described, allowing the enhancement of enantiomeric discrimination when the resolution of multiplets is insufficient.
- Laaksonen, Tiina,Heikkinen, Sami,W?h?l?, Kristiina
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supporting information
p. 20873 - 20886
(2015/12/23)
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- COMPOSITIONS AND METHODS FOR SUBSTRATE-SELECTIVE INHIBITION OF ENDOCANNABINOID OXYGENATION
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Methods for selectively inhibiting endocannabinoid oxygenation but not arachidonic acid oxygenation. In some embodiments, the methods include contacting a COX-2 polypeptide with an effective amount of a substrate-selective COX-2 inhibitor. Also provided are methods for elevating a local endogenous cannabinoid concentrations; methods of reducing depletion of an endogenous cannabinoid; methods for inducing analgesia; methods of providing anxiolytic therapy; methods for providing anti-depressant therapy; and compositions for performing the disclosed methods.
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Page/Page column 62-63
(2014/02/15)
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- Characterization of a new thermophilic and acid tolerant esterase from Thermotoga maritima capable of hydrolytic resolution of racemic ketoprofen ethyl ester
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A gene coding for a putative thermostable esterase (Tm1160) from the hyperthermophilic bacterium Thermotoga maritima was cloned and expressed in Escherichia coli. The purified enzyme displayed optimal activity at 70 °C and had a half-life of 60 min at 90 °C. It was stable over a range of pHs from 5.0 to 7.5 with an optimum around 5.0-5.5. The enzyme was found to have high acid tolerance and maintained about 50% of its activity even after 60 min of treatment at pH 4.5 and 70 °C. Furthermore, the enzyme exhibited the highest specific activity with p-nitrophenyl butyrate (318 ± 7 s -1 mM-1). Under native conditions, Tm1160 forms a ~74 kDa dimer in solution. In addition, the esterase Tm1160 could enantioselectively hydrolyze the racemic ketoprofen ethyl ester and with an enantiomeric excess (eep) of 91.4% at a conversion of 41.1%, which makes it as a promising biocatalyst for the chiral resolution of (S)-ketoprofen.
- Wei, Tao,Feng, Shengxue,Mao, Duobin,Yu, Xuan,Du, Congcong,Wang, Xihua
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- Substrate-selective inhibition of cyclooxygenase-2: Development and evaluation of achiral profen probes
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Cyclooxygenase-2 (COX-2) oxygenates arachidonic acid and the endocannabinoids 2-arachidonoylglycerol (2-AG) and arachidonoylethanolamide (AEA). We recently reported that (R)-profens selectively inhibit endocannabinoid oxygenation but not arachidonic acid oxygenation. In this work, we synthesized achiral derivatives of five profen scaffolds and evaluated them for substrate-selective inhibition using in vitro and cellular assays. The size of the substituents dictated the inhibitory strength of the analogs, with smaller substituents enabling greater potency but less selectivity. Inhibitors based on the flurbiprofen scaffold possessed the greatest potency and selectivity, with desmethylflurbiprofen (3a) exhibiting an IC50 of 0.11 μM for inhibition of 2-AG oxygenation. The crystal structure of desmethylflurbiprofen complexed to mCOX-2 demonstrated a similar binding mode to other profens. Desmethylflurbiprofen exhibited a half-life in mice comparable to that of ibuprofen. The data presented suggest that achiral profens can act as lead molecules toward in vivo probes of substrate-selective COX-2 inhibition.
- Windsor, Matthew A.,Hermanson, Daniel J.,Kingsley, Philip J.,Xu, Shu,Crews, Brenda C.,Ho, Winnie,Keenan, Catherine M.,Banerjee, Surajit,Sharkey, Keith A.,Marnett, Lawrence J.
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supporting information
p. 759 - 763
(2012/10/29)
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- Enantiodifferentiation of ketoprofen by Japanese firefly luciferase from Luciola lateralis
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Recently, we found that firefly luciferase exhibited (R)-enantioselective thioesterification activity toward 2-arylpropanoic acids. In the case of Japanese firefly luciferase from Luciola lateralis (LUC-H), the E-value for ketoprofen was approximately 20. In this study, we used a spectrophotometric method to measure the catalytic activity of LUC-H. Using this method allowed us to judge the reaction efficiency easily. Our results confirmed that LUC-H exhibits enantioselective thioesterification activity toward a series of 2-arylpropanoic acids. The highest activity was observed with ketoprofen. We also observed high enzymatic activity of LUC-H toward long-chain fatty acids. These results were reasonable because LUC-H is homologous with long-chain acyl-CoA synthetase. To obtain further information about the enantiodifferentiation mechanism of the LUC-H catalyzed thioesterification of ketoprofen, we determined the kinetic parameters of the reaction relative to each of its three substrates: ketoprofen, ATP, and coenzyme A (CoASH). We found that whereas the affinities of each compound are not affected by the chirality of ketoprofen, enantiodifferentiation is achieved by a chirality-dependent difference in the kcat parameter.
- Kato, Dai-Ichiro,Tatsumi, Tomohiro,Bansho, Asami,Teruya, Keisuke,Yoshida, Hiromitsu,Takeo, Masahiro,Negoro, Seiji
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body text
p. 140 - 146
(2012/01/19)
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- Resolution of carboxylic acids using copper(I)-promoted removal of propargylic esters under neutral conditions
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A method for the optical resolution of carboxylic acids is described. Condensation of racemic carboxylic acids with chiral terminal propargyl alcohols gave separable diastereomeric esters. Chromatographic separation followed by heating the individual diastereomers in methanol with catalytic copper(I) halide regenerated the carboxylic acids in good yields and in enantiomeric ratios of ?94%. This method is particularly useful for the resolution of carboxylic acids that are incompatible with conventional ester hydrolysis.
- Ghosh, Partha,Aube, Jeffrey
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experimental part
p. 4168 - 4172
(2011/07/30)
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- Iterative saturation mutagenesis accelerates laboratory evolution of enzyme stereoselectivity: Rigorous comparison with traditional methods
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Efficacy in laboratory evolution of enzymes is currently a pressing issue, making comparative studies of different methods and strategies mandatory. Recent reports indicate that iterative saturation mutagenesis (ISM) provides a means to accelerate directed evolution of stereoselectivity and thermostability, but statistically meaningful comparisons with other methods have not been documented to date. In the present study, the efficacy of ISM has been rigorously tested by applying it to the previously most systematically studied enzyme in directed evolution, the lipase from Pseudomonas aeruginosa as a catalyst in the stereoselective hydrolytic kinetic resolution of a chiral ester. Upon screening only 10 000 transformants, unprecedented enantioselectivity was achieved (E = 594). ISM proves to be considerably more efficient than all previous systematic efforts utilizing error-prone polymerase chain reaction at different mutation rates, saturation mutagenesis at hot spots, and/or DNA shuffling, pronounced positive epistatic effects being the underlying reason.
- Reetz, Manfred T.,Prasad, Shreenath,Carballeira, Jose D.,Gumulya, Yosephine,Bocola, Marco
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experimental part
p. 9144 - 9152
(2010/08/21)
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- Kinetic resolution of (R,S)-pyrazolides containing substituents in the leaving pyrazole for increased lipase enantioselectivity
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With hydrolysis of (R,S)-azolides in water-saturated methyl tert-butyl ether (MTBE) via Candida antarctica lipase B (CALB) as the model system, (R,S)-pyrazolides containing a leaving 3-, 4- or 3,4-substituted-pyrazole moiety are selected as the best substrates for preparing various optically pure carboxylic acids containing an α-chiral center. Great improvements of enzyme activity for the (R)-enantiomers with excellent enantioselectivity (VR/VS > 100) are obtainable, if (R,S)-pyrazolides containing a leaving 3- or 3,4-substituted-pyrazole moiety are employed for the hydrolysis or alcoholysis by methanol in anhydrous MTBE. A detailed kinetic analysis for (R,S)-N-2-phenylpropionylpyrazoles indicates that a bulky 3-substituent such as 3-(3-bromophenyl) or 3-(2-pyridyl) in the leaving pyrazole moiety has profound effects on decreasing the nucleophilic attack and proton transfer of catalytic serine for the slow-reacting enantiomer in anhydrous MTBE, as well as that and substrate affinity for both enantiomers in water-saturated MTBE. The resolution platform is also successfully applied to the hydrolysis of (R,S)-pyrazolides in water-saturated cyclohexane via Candida rugosa lipase (Lipase MY) having opposite enantioselectivity to CALB.
- Wang, Pei-Yun,Wu, Chia-Hui,Ciou, Jyun-Fen,Wu, An-Chi,Tsai, Shau-Wei
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experimental part
p. 113 - 119
(2011/02/21)
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- METHOD FOR PRODUCING OPTICALLY ACTIVE ESTER AND METHOD FOR PRODUCING OPTICALLY ACTIVE CARBOXYLIC ACID
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Disclosed is a method for producing an optically active ester by highly selectively esterifying one enantiomer of a racemic carboxylic acid, while producing an optically active carboxylic acid which is the other enantiomer. An optically active ester is produced while producing an optically active carboxylic acid at the same time by reacting a racemic carboxylic acid with a specific alcohol or phenol derivative in the presence of benzoic anhydride or a derivative thereof and a catalyst such as tetramisole or benzotetramisole, thereby selectively esterifying one enantiomer of the racemic carboxylic acid.
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Page/Page column 12-13
(2010/09/18)
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- An effective kinetic resolution of racemic α-arylpropanoic acids, α-arylbutanoic acids, and β-substituted-α-arylpropanoic acids with bis(9-phenanthryl)methanol as a new achiral nucleophile in the asymmetric esterification using carboxylic anhydrides and the acyl-transfer catalyst
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A general method for the kinetic resolution of racemic α-arylalkanoic acids with achiral alcohols is described. It was determined that bis(9-phenanthryl)methanol is a suitable nucleophile which reacts with the intermediary mixed anhydrides generated from aromatic anhydrides with α-arylpropanoic acids or β-substituted-α-arylpropanoic acids in the presence of (+)-benzotetramisole to produce the corresponding optically active esters with high ee's under very mild conditions.
- Nakata, Kenya,Onda, Yu-Suke,Ono, Keisuke,Shiina, Isamu
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experimental part
p. 5666 - 5669
(2010/11/18)
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- Kinetic resolution of racemic α-arylalkanoic acids with achiral alcohols via the asymmetric esterification using carboxylic anhydrides and acyl-transfer catalysts
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A variety of optically active carboxylic esters are produced by the kinetic resolution of racemic α-substituted carboxylic acids using achiral alcohols, aromatic or aliphatic carboxylic anhydrides, and chiral acyl-transfer catalysts. The combination of 4-methoxybenzoic anhydride (PMBA) or pivalic anhydride with the modified benzotetramisole-type catalyst ((S)-β-Np-BTM) is the most effective for promotion of the enantioselective coupling reaction between racemic carboxylic acids and a novel nucleophile, bis(α-naphthyl) methanol, to give the corresponding esters with high ees. This protocol was successfully applied to the production of nonracemic nonsteroidal anti-inflammatory drugs from racemic compounds utilizing the transacylation process to generate the mixed anhydrides from the acid components with the suitable carboxylic anhydrides.
- Shiina, Isamu,Nakata, Kenya,Ono, Keisuke,Onda, Yu-Suke,Itagaki, Makoto
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supporting information; experimental part
p. 11629 - 11641
(2010/10/04)
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- Two-step enzymatic selective synthesis of water-soluble ketoprofen-saccharide conjugates in organic media
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Ketoprofen-saccharide conjugates were synthesized by selectively enzymatic hydrolysis and acylation. Firstly, the (S)-ketoprofen vinyl ester was prepared by enzymatic hydrolysis of (R,S)-ketoprofen vinyl ester. Then enzymatic transesterification of (S)-ke
- Wang, Hai-Yang,Li, Chao,Wang, Na,Li, Kun,Feng, Xing-Wen,He, Ting,Yu, Xiao-Qi
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experimental part
p. 1905 - 1910
(2009/05/11)
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- (R,S)-azolides as novel substrates for lipase-catalyzed hydrolytic resolution in organic solvents
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Azolides, that is, N-acylazoles, as versatile acylation reagents are well characterized in the literature, in which the azole structure can not only act as a better leaving group but also make the carbonyl carbon more electrophilic and susceptible to nucleophilic attack. It is therefore desirable to combine this unique property and lipase resolution ability in the development of a new resolution process for preparing optically pure carboxylic acids. With the Candida antarctica lipase B (CALB)-catalyzed hydrolysis of (R,S)-N- profenylazoles in organic solvents as the model system, (R,S)-N-profenyl-l,2,4- triazoles instead of their corresponding ester analogues were exploited as the best substrates for preparing optically pure profens, i.e., 2-arylpropionic acids. The structure-reactivity correlations for the (R,S)-azolides in water-saturated methyl tert-butyl ether (MTBE) at 45°C coupled with a thorough kinetic analysis were further employed for elucidating the rate-limiting formation of a tetrahedral adduct without C-N bond breaking or with moderate C-N bond breaking concerted with C-O bond formation in the acylation step. The advantages of easy substrate preparation, high enzyme reactivity and enantioselectivity, and easy recovery of the product and remaining substrate by aqueous extraction demonstrate the potential of using (R,S)-azolides as novel substrates for the enzymatic resolution process.
- Wang, Pei-Yun,Chen, Ying-Ju,Wu, An-Chi,Lin, Yi-Sheng,Kao, Min-Fang,Chen, Jin-Ru,Ciou, Jyun-Fen,Tsai, Shau-Wei
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supporting information; scheme or table
p. 2333 - 2341
(2009/12/27)
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- NEW CHIRAL STATIONARY PHASES FOR CHROMATOGRAPHY BASED ON AROMATIC ALLYL AMINES
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New chiral stationary phases (CSPs) based on chiral selectors covalently bound on a solid support were prepared. Chiral selectors were obtained from enantiomerically pure aromatic amines and 3,5-dinitrobenzoic acid and then linked to the support surface through the allylic double bond. Such obtained materials allow enantioseparation of racemates or enantiomerically enriched compounds. These chiral stationary phases can be used as fillings in chromatographic columns for enantiomer separation of naproxen type drugs and other similar non-steroidal anti-inflammatory drugs (NSAID) by means of high performance liquid chromatography on both the analytical and preparative scale.
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Page/Page column 18-19
(2009/10/22)
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- Cholesterol-diaryl ketone stereoisomeric dyads as models for "clean" type i and type II photooxygenation mechanisms
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Cholesterol (Ch) is a major target for oxidative degradation in cell membranes, a process which can occur by two mechanisms: Type I (via free radicals) and Type II (mediated by 1O2). In the present work, several dyads have been synthesized from β- and α-Ch and ketoprofen (KP) or tiaprofenic acid (TPA). Upon irradiation under anaerobic conditions, KP-α-Ch dyads were efficiently photolyzed, via intramolecular hydrogen abstraction from C-7. By contrast, KP-β-Ch, TPA-α-Ch, and TPA-β-Ch remained unchanged after prolonged irradiation. The transient absorption spectra of KP-α-Ch were assigned to the short-lived biradicals resulting from intramolecular hydrogen abstraction. Interestingly, the spectra and lifetimes obtained for the TPA-derived dyads were very similar to those of the TPA triplet excited state. For the KP-α-Ch dyads, generation of singlet oxygen was expectedly negligible. Conversely, for TPA-α-Ch a ΦΔ value as high as 0.5 was determined. Thus, KP-based dyads are appropriate models for clean type I Ch oxidation, whereas the TPA derivatives are suitable systems for investigation of the purely type II process. The Royal Society of Chemistry.
- Andreu, Inmaculada,Morera, Isabel M.,Bosca, Francisco,Sanchez, Laura,Camps, Pelayo,Miranda, Miguel A.
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supporting information; experimental part
p. 860 - 867
(2008/10/09)
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- Kinetic resolution of racemic carboxylic acids using achiral alcohols by the promotion of benzoic anhydrides and tetramisole derivatives: Production of chiral nonsteroidal anti-inflammatory drugs and their esters
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A variety of optically active carboxylic esters were produced by kinetic resolution of racemic carboxylic acids by using achiral alcohols, benzoic anhydrides, and Birman's tetramisole-type catalysts. Bis(α-naphthyl) methanol is a very effective reagent for producing the corresponding esters with high ee values in the presence of 4-methoxybenzoic anhydride (PMBA) as the coupling reagent by promotion of benzotetramisole derivatives (BTM, α-Np-BTM, and β-Np-BTM). This protocol directly provides chiral carboxylic esters from free carboxylic acids and achiral alcohols by utilizing a transacylation process to generate the mixed anhydrides from the acid components with benzoic anhydride derivatives in the presence of chiral catalysts. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Shiina, Isamu,Nakata, Kenya,Onda, Yu-Suke
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experimental part
p. 5887 - 5890
(2009/05/27)
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- METHOD FOR RESOLVING STEREOISOMERS OF A COMPOUND
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A method is provided for resolution of two stereoisomers, for example enantiomers, from a mixture of same, using a chiral resolving agent to preferentially crystallize one stereoisomer over the other in an organic solvent.
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Page/Page column 12
(2008/06/13)
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- Binding of a chiral drug to a protein: An investigation of the 2-(3-benzoylphenyl)propionic acid/bovine serum albumin system by circular dichroism and fluorescence
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A combined approach using global analysis of circular dichroism multiwavelength data and time resolved fluorescence was applied to investigate the interaction of R-(-)- and S-(+)-ketoprofen with bovine serum albumin in buffer solution at neutral pH. A characterization of the most stable drug : protein adducts of 1:1 and 2:1 stoichiometry, as individual chemical species, was obtained. The stability constants and the absolute circular dichroism spectra of the diastereomeric complexes were determined. The spectra of the 1:1 conjugates are opposite in sign, those of the 2:1 complexes are both negative, but different in shape from each other (peaks at 358 and 342 nm for S-(+)- and R-(-)-ketoprofen, respectively). A tryptophan residue was shown to be involved in the binding of the drug, in the primary site for the R-(-) and in the secondary site for the S-(+) enantiomer, thereby showing that chiral recognition by the protein causes the site of highest affinity being not the same for both optical antipodes. The Owner Societies 2005.
- Monti, Sandra,Manoli, Francesco,Sortino, Salvatore,Morrone, Raffaele,Nicolosi, Giovanni
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p. 4002 - 4008
(2008/02/02)
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- Amides, useful in the inhibition of il-8-induced chemotaxis of neutrophils
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N-(2-aryl-propionyl)-amides of formula (I) are described. The process for their preparation and pharmaceutical preparations thereof are also described. The amides of the invention are useful in the prevention and treatment of tissue damage due to the exacerbate recruitment of polymorphonuclear neutrophils (leukocytes PMN) at the inflammatory sites. In particular, the invention relates to the R enantiomers of N-(2-aryl-propionyl)amides of formula (I) for use in the ihibition of the chemotaxis of neutrophils induced by IL-8. The compounds of the invention are used in the treatment of psoriasis, ulcerative cholitis, glomerular nephritis, acute respiratory insufficiency, idiopathic fibrosis, and rheumatoid arthritis.
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- Thermostable esterase from a thermoacidophilic archaeon: Purification and characterization for enzymatic resolution of a chiral compound
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Homolog to lipolytic enzymes having the consensus sequence Gly-X-Ser-X-Gly, from the Sulfolobus solfataricus P2 genome, were identified by multiple sequence alignments. Among three potential candidate sequences, one (Est3), which displayed higher activity than the other enzymes on the indicate plates, was characterized. The gene (est 3) was expressed in Escherichia coli, and the recombinant protein (Est3) was purified by chromatographic separation. The enzyme is a trimeric protein and has a molecular weight of 32kDa in monomer form in its native structure. The optimal pH and temperature of the esterase were 7.4 and 80°C respectively. The enzyme showed broad substrate specificities toward various p-nitrophenyl esters ranging from C2 to C16. The catalytic activity of the Est3 esterase was strongly inhibited by phenylmethylsulfonyl fluoride (PMSF) and diethyl p-nitrophenyl phosphate. Based on substrate specificity and the action of inhibitors, the Est3 enzyme was estimated to be a carboxylesterase (EC 3.1.1.1). The enzyme with methyl (±)-2-(3- benzoylphenyl)propionate-hydrolyzing activity to (-)-2-(3-benzoylphenyl) propionic acid displayed a moderate degree of enantioselectivity. The product, (-)-2-(3-benzoylphenyl)propionic acid, rather than its methyl ester, was obtained in 80% enantiomeric excess (e.e.p) at 20% conversion at 60°C after a 32-h reaction. This result indicates that S. solfataricus esterase can be used for application in the synthesis of chiral compounds.
- Kim, Seonghun,Lee, Sun Bok
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p. 2289 - 2298
(2007/10/03)
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- Methods for the treatment of tinnitus and other disorders using R(?)ketoptofen
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Methods of treating neuropathic pain, tinnitus, and related disorders are disclosed. These methods comprise the administration of optically pure R(?)-ketoprofen. Also disclosed are pharmaceutical compositions useful in the treatment of neuropathic pain and tinnitus which comprise optically pure R(?)-ketoprofen.
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- Synthesis of a new insoluble polymer-supported chiral alcohol auxiliary and its first application to nucleophilic addition to ketenes
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The preparation of a new optically active alcohol with a carboxylic function that allowed its attachment to an amine-functionalized insoluble polymer is described. Its first use as a polymer supported chiral auxiliary is demonstrated by asymmetric transformation of two racemic aryl propionic acids via ketene formation (95-96% ee).
- Akkari,Calmes,Mai,Rolland,Martinez
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p. 5859 - 5865
(2007/10/03)
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- A practical enzymatic method for preparation of (S)-ketoprofen with a crude Candida rugosa lipase
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A simple and practical method for the preparation of (S)-Ketoprofen (2-(3-benzoylphenyl) propionic acid) has been developed through the hydrolysis of its chloroethyl ester catalyzed by a cheap and commercially available crude Candida rugosa lipase preparation under an extremely acidic condition, pH 2.5, and in the presence of Tween-80. As the reaction was carried out in a shake flask with baffles.
- Wu,Xu,Liu
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p. 3491 - 3496
(2007/10/03)
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- Stereoselective esterase activity of human serum albumin toward ketoprofen glucuronide
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Many carboxylic acid-containing drugs undergo conjugation with D- glucuronic acid in humans, leading to the formation of acyl glucuronides, which are excreted into urine. However, these metabolites can be hydrolyzed back to the parent aglycon; this reaction can be accelerated by human serum albumin (HSA). Although this phenomenon of interaction between the acyl glucuronide and HSA has been described for various drugs, the kinetics of the protein have not been characterized. The aim of this study was to investigate the HSA-mediated mechanism involved in the in vitro hydrolysis by albumin of the acyl glucuronides of (R)- and (S)-ketoprofen (a nonsteroidal anti- inflammatory drug), as model compounds. The conjugates of both ketoprofen enantiomers were incubated, separately or together, with increasing concentrations of albumin (14.5-145 μM) at pH 7.4 and 37°. The reaction followed Michaelis-Menten kinetics and was stereoselective; the (R)- ketoprofen glucuronide was a better substrate than the S-conjugate. To identify the HSA domain involved in the hydrolysis reaction, specific probes of HSA binding sites were used as potential inhibitors. These probes, added at an equimolar probe/glucuronide ratio (145 μM), slightly decreased the hydrolysis (by up to 30%). They affected the reversible binding of (R)- ketoprofen glucuronide to HSA, as shown by CD studies. Because iodoacetic acid did not modify the single free cysteine residue on HSA, this amino acid residue cannot be the reactive one. In addition, the chemical modification of a single tyrosine residue (probably Tyr-411) on HSA by diisopropyl fluorophosphate significantly but weakly affected the hydrolysis of (R)- ketoprofen glucuronide, suggesting that this residue also is not involved in the catalysis. In contrast, the R-conjugate was not bound to modified albumin, as revealed in CD experiments. These results support the existence of distinct sites on HSA for reversible binding and hydrolysis of (R)- ketoprofen glucuronide.
- Dubois-Presle, Nathalie,Lapicque, Francoise,Maurice, Marie-Helene,Fournel-Gigleux, Sylvie,Magdalou, Jacques,Abiteboul, Michel,Siest, Gerard,Netter, Patrick
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p. 647 - 653
(2007/10/03)
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- Cross-linked crystals of Candida rugosa lipase: Highly efficient catalysts for the resolution of chiral esters
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To date, most enzyme-based organic syntheses have employed enzymes in the form of a crude protein extract. The instability and expense of highly purified proteins has all but obviated their use as catalysts for enantioselective hydrolyses. Herein, we describe the use of the major hydrolase from commercial Candida rugosa lipase (CRL) in the form of a cross-linked enzyme crystal (CLEC) for the enantioselective hydrolysis of chiral racemic esters. The enantioselectivity of CRL-CLECs in the hydrolysis of many important chiral esters is vastly superior to that of the crude CRL extract. Since the CRL-CLEC is insoluble, recoverable, and 2-3 orders of magnitude more stable than the soluble protein, the CRL-CLEC is an attractive replacement for the crude enzyme preparation. The use of this catalyst in the resolution of chiral esters 1-11 and in the preparative scale (1a) and multicycle resolution (2a) of important anti-inflammatory drugs is described.
- Lalonde, Jim J.,Govardhan, Chandrika,Khalaf, Nazer,Martinez, Aldo G.,Visuri, Kalevi,Margolin, Alexey L.
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p. 6845 - 6852
(2007/10/02)
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- Effect of micelles and mixed micelles on efficiency and selectivity of antibiotic-based capillary electrophoretic enantioseparations.
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Vancomycin (an oligophenolic, glycopeptide, macrocyclic antibiotic) has been shown to be a superb chiral selector for anionic and neutral compounds. It was found that adding sodium dodecyl sulfate to the run buffer increased efficiency by over 1 order of magnitude, decreased analysis times, and reversed the elution order of the enantiomers. This allows for control of the retention order as well as the resolution of enantiomers in complex mixtures in a single run. A mechanism is proposed which explains all of the observed effects and is verified experimentally. Since vancomycin is present in both the micelle and in free solution, previously proposed micelle-selector models are, at best, limiting cases. A general equation is derived which can be used to describe all possible interactions, including those with the capillary wall, if needed. Also, it is shown that electrophoretic mobilities and not migration times must be used to calculate binding constants of a solute to the micelle, the chiral selector, or both. Furthermore, it is shown that a neutral marker molecule cannot be used to accurately correct mobilities that have been altered due to changes in solution viscosity. While this work utilizes the practical vancomycin-micelle system, the general conclusions and theory apply to most other analogous CE systems as well.
- Rundlett,Armstrong
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p. 2088 - 2095
(2007/10/02)
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- Asymmetric synthesis of ketoprofen: a surprising base catalyst effect during asymmetric addition of pantolactone to methyl (3-benzoylphenyl) ketene
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The best diastereoselectivity of addition of a chiral alcohol to the ketene derived from ketoprofen was obtained with R or S pantolactone (ed=99percent).Depending on the tertiary amine used both for ketene formation and as catalyst during addition, the diastereoisomeric ratio of esters could be strongly modified and even inverted.Mild saponification afforded R or S ketoprofen in enantiomeric excess of up to 99percent.
- Calmes, Monique,Daunis, Jacques,Jacquier, Robert,Natt, Francois
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p. 6875 - 6880
(2007/10/02)
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- Maltooligosaccharides as chiral selectors for the separation of pharmaceuticals by capillary electrophoresis
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Complexation between the linear maltodextrin oligosaccharides and certain enantiomeric compounds of pharmaceutical interest in buffered solutions can lead to an analytically desirable chiral recognition. Different maltodextrins were assessed in their capacity to cause enantiomeric separations under various conditions of capillary electrophoresis. The mechanism of chiral recognition has been probed through electrophoretic mobility and selectivity measurements for different buffer solutions and organic solvent additives. A differential interaction of chiral solutes with the maltodextrin helical entities emerges as the basis of such enantioselectivity. This notion is further supported by 1H- and 13C-NMR experiments. Optimized separations of simendan, ibuprofen, warfarin, and ketoprofen enantiomers are demonstrated together with a chiral determination of ibuprofen in a blood serum sample at the therapeutic level.
- Soini, Helena,Stefansson, Morgan,Rlekkola, Marja-Lllsa,Novotny, Mllos V.
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p. 3477 - 3484
(2007/10/02)
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- Enzymatic enantioselective ester hydrolysis by carboxylesterase NP
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The enzymatic hydrolysis of a series of carboxylic esters by carboxylesterase NP has been investigated in order to determine the scope and limitations of this enzyme. 2-Substituted propionates were hydrolyzed with high enantioselectivity when an aromatic moiety was part of the 2-substituent.Enantioselective hydrolysis could be accomplished with several 2-arypropionates, 2-(aryloxy)propionates and N-arylalanine esters.The propionate esters yielded propionic acids as (S) enantiomers, whereas the alanine esters yielded the (R) enantiomers.Without a 2-aryl substituent, the enzymatic hydrolysis of the propionates occurred at a lower rate without acceptable enantioselectivity.In addition to 2-substituted propionates, only a few other esters were hydrolyzed with high enantioselectivity by carboxylesterase NP, such as some prochiral disubstituted malonates. 1-Phenylethylacetate was the only substrate with chirality in the alcohol part of the ester that was found to be hydrolyzed enantioselectively.Carboxylesterase NP proved to be a powerful enzyme for kinetic resolution of propionate esters with an aromatic ring containing a 2-substituent.
- Smeets, J. W. H.,Kieboom, A. P. G.
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p. 490 - 495
(2007/10/02)
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- ENANTIOSELECTIVE SYNTHESIS AND ABSOLUTE CONFIGURATION OF (+)-α-(3-BENZOYLPHENYL)PROPIONIC ACID
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Asymmetric homogeneous hydrogenation of α-(3-benzoylphenyl)acrylic acid (4), which is preparared in 90percent overall yield from (3-benzoylphenyl)acetic acid (1), affords (+)-α-(3-benzoylphenyl)propionic acid, (+)-5, in 93.7percent chemical and 67.4percent optical yield.The absolute configuration of (+)-5 is correlated with that of (+)-(S)-hydratropic acid via (+)-α-(3-benzylphenyl)propionic acid, (+)-6.The origin of the CD bands of (+)-6 is discussed and comparison of chiroptical data with those of (+)-(S)-hydratropic acid, reveals that (+)-6 has an S configuration.Since (+)-6 is chemically correlated with (+)-5, the absolute S configuration of this enantiomer is confirmed.
- Comisso, Giovanni,Mihalic, Mladen,Kajfez, Franjo,Sunjic, Vitomir,Snatzke, Guenther
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p. 123 - 128
(2007/10/02)
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