- Iterative saturation mutagenesis accelerates laboratory evolution of enzyme stereoselectivity: Rigorous comparison with traditional methods
-
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
-
-
Read Online
- Efficient resolution of profen ethyl ester racemates by engineered Yarrowia lipolytica Lip2p lipase
-
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
-
-
Read Online
- Reversed-phase high-performance liquid chromatographic separation of some 2-arylpropionic acids using vancomycin as chiral stationary phase
-
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
-
-
Read Online
- A practical enzymatic method for preparation of (S)-ketoprofen with a crude Candida rugosa lipase
-
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
-
-
Read Online
- Thermostable esterase from a thermoacidophilic archaeon: Purification and characterization for enzymatic resolution of a chiral compound
-
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
-
-
Read Online
- Chiral separation of ketoprofen on an achiral NH2 column by HPLC using vancomycin as chiral mobile phase additive
-
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
-
-
Read Online
- Effect of micelles and mixed micelles on efficiency and selectivity of antibiotic-based capillary electrophoretic enantioseparations.
-
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
-
-
Read Online
- Comparison of the enzymatic activity of commercial and semipurified lipase of Candida cylindracea in the hydrolysis of the esters of (R,S) 2-aryl propionic acids
-
A semipurified lipase of Candida cylindradea (LS) - easily obtained from commercial crude lipase (LC) - is used in the enantioselective hydrolysis of (R,S) 2-arylpropionates. The semipurification treatment diminishes the lipase activity more than the esterase activity. The addition of lactose (24 h) increases both activities. LS is more active than LC - at the same amount of protein - in the hydrolysis of (R,S) 2-aryl propionates. This semipurification showed a remarkable improvement in yield in the enantioespecific hydrolysis of these esters.
- Hernaiz, Maria J.,Sanchez-Montero, Jose M.,Sinisterra, Jose V.
-
-
Read Online
- 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
-
p. 6126 - 6133
(2021/09/28)
-
- Palladium-Catalyzed Asymmetric Markovnikov Hydroxycarbonylation and Hydroalkoxycarbonylation of Vinyl Arenes: Synthesis of 2-Arylpropanoic Acids
-
Asymmetric hydroxycarbonylation is one of the most fundamental yet challenging methods for the synthesis of carboxylic acids. Herein, we reported the development of a palladium-catalyzed highly enantioselective Markovnikov hydroxycarbonylation of vinyl arenes with CO and water. A monodentate phosphoramidite ligand L6 plays vital role in the reaction. The reaction tolerates a range of functional groups, and provides a facile and atom-economical approach to an array of 2-arylpropanoic acids including several commonly used non-steroidal anti-inflammatory drugs. The catalytic system has also enabled an asymmetric Markovnikov hydroalkoxycarbonylation of vinyl arenes with alcohols to afford 2-arylpropanates. Mechanistic investigations suggested that the hydropalladation is irreversible and is the regio- and enantiodetermining step, while hydrolysis/alcoholysis is probably the rate-limiting step.
- Guan, Zheng-Hui,Ren, Zhi-Hui,Wang, Yuan,Yang, Hui-Yi,Yao, Ya-Hong,Zou, Xian-Jin
-
supporting information
p. 23117 - 23122
(2021/09/18)
-
- Evaluation of the Edman degradation product of vancomycin bonded to core-shell particles as a new HPLC chiral stationary phase
-
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.
-
p. 1067 - 1078
(2018/08/01)
-
- Method for synthesizing dexketoprofen intermediate
-
The invention belongs to the technical field of medicines, and particularly relates to a method for synthesizing a dexketoprofen intermediate. The dexketoprofen intermediate is prepared by asymmetricsynthesis of Darzens reaction. The method can improve the selectivity of the reaction, reduce the loss of raw materials, improve the yield and simplify the operation process, and is conducive to industrial production.
- -
-
Paragraph 0030-0032
(2019/01/16)
-
- Enantioselective potential of polysaccharide-based chiral stationary phases in supercritical fluid chromatography
-
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
-
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
-
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
-
p. 24835 - 24842
(2016/03/22)
-
- Synthesis of tertiary and quaternary amine derivatives from wood resin as chiral NMR solvating agents
-
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
-
supporting information
p. 20873 - 20886
(2015/12/23)
-
- Towards a green enantiomeric esterification of R/S-ketoprofen: A theoretical and experimental investigation
-
Methanol, ethanol, 1- and 2-propanol were used as reactants and solvents in the esterification of R/S-ketoprofen catalyzed with Novozym 435. The interaction of the alcohols with Novozym 435 was studied at a molecular level through various spectroscopic techniques and molecular modeling. The results evidenced the dissolution of the polymeric support, loss of active protein, strong adsorption of the alcohols, modification of the secondary structure of the protein and smoothing of the inner structure of the biocatalyst's beads upon extended contact with the alcohols. Nevertheless, none of those drawbacks influences the specific activity and enantiomeric excess toward S(+)-enantiomer that remain unaltered upon extended contact with ethanol, 1- and 2-propanol as acyl acceptors. However, theoretical calculations demonstrated that methanol introduces steric and electronic hindrance within the step of the coordination of the R/S-ketoprofen with the catalytic triad.
- Toledo, María Victoria,José, Carla,Collins, Sebastián E.,Ferreira, María Luján,Briand, Laura E.
-
-
- Substrate evaluation of rhodococcus erythropolis SET1, a nitrile hydrolysing bacterium, demonstrating dual activity strongly dependent on nitrile sub-structure
-
Assessment of Rhodococcus erythropolis SET1, a novel nitrile hydrolysing bacterial isolate, has been undertaken with 34 nitriles, 33 chiral and 1 prochiral. These substrates consist primarily of β-hydroxy nitriles with varying alkyl and aryl groups at the β position and containing in several compounds different substituents α to the nitrile. In the case of β-hydroxy nitriles without substitution at the α position, acids were the major products obtained, along with recovered nitrile after biotransformation, as a result of suspected nitrilase activity of the isolate. Unexpectedly, amides were found to be the major hydrolysis product when the β-hydroxy nitriles possessed a vinyl group at this position. To probe this behaviour further, additional related substrates were evaluated containing electron-withdrawing groups at the α position, and amide was also observed upon biotransformation in the presence of SET1. Therefore this novel isolate has also demonstrated NHase activity with nitriles that appears to be substrate-dependent.
- Coady, Tracey M.,Coffey, Lee V.,O'Reilly, Catherine,Lennon, Claire M.
-
supporting information
p. 1108 - 1116
(2015/02/19)
-
- Laccase-Mediator System for Alcohol Oxidation to Carbonyls or Carboxylic Acids: Toward a Sustainable Synthesis of Profens
-
By combining two green and efficient catalysts, such as the commercially available enzyme laccase from Trametes versicolor and the stable free radical 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), the oxidation in water of some primary alcohols to the corresponding carboxylic acids or aldehydes and of selected secondary alcohols to ketones can be accomplished. The range of applicability of bio-oxidation is widened by applying the optimized protocol to the oxidation of enantiomerically pure 2-arylpropanols (profenols) into the corresponding 2-arylpropionic acids (profens), in high yields and with complete retention of configuration.
- Galletti, Paola,Pori, Matteo,Funiciello, Federica,Soldati, Roberto,Ballardini, Alberto,Giacomini, Daria
-
p. 2684 - 2689
(2016/12/23)
-
- Enantiospecific, nickel-catalyzed cross-couplings of allylic pivalates and arylboroxines
-
We have developed an enantiospecific, nickel-catalyzed cross-coupling of unsymmetric 1,3-disubstituted allylic pivalates with arylboroxines. The success of this reaction relies on the use of BnPPh2 as a supporting ligand for the nickel(0) catalyst and NaOMe as a base. This method shows excellent functional group tolerance and broad scope in both the allylic pivalate and arylboroxine, enabling the preparation of 1,3-diaryl allylic products in high yields with excellent levels of regioselectivity and stereochemical fidelity.
- Srinivas, Harathi D.,Zhou, Qi,Watson, Mary P.
-
supporting information
p. 3596 - 3599
(2014/07/21)
-
- Characterization of a new thermophilic and acid tolerant esterase from Thermotoga maritima capable of hydrolytic resolution of racemic ketoprofen ethyl ester
-
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
-
-
- Enantioselective α-arylation of aldehydes via the productive merger of iodonium salts and organocatalysis
-
The enantioselective α-arylation of aldehydes has been accomplished using diaryliodonium salts and a combination of copper and organic catalysts. These mild catalytic conditions provide a new strategy for the enantioselective construction and retention of enolizable α-formyl benzylic stereocenters, a valuable synthon for the production of medicinal agents. As one example, this new asymmetric protocol has been applied to the rapid synthesis of (S)-ketoprofen, a commercially successful oral and topical analgesic.
- Allen, Anna E.,MacMillan, David W. C.
-
p. 4260 - 4263
(2011/06/21)
-
- Enantiodifferentiation of ketoprofen by Japanese firefly luciferase from Luciola lateralis
-
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
-
experimental part
p. 140 - 146
(2012/01/19)
-
- Resolution of carboxylic acids using copper(I)-promoted removal of propargylic esters under neutral conditions
-
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
-
experimental part
p. 4168 - 4172
(2011/07/30)
-
- METHOD FOR PRODUCING OPTICALLY ACTIVE ESTER AND METHOD FOR PRODUCING OPTICALLY ACTIVE CARBOXYLIC ACID
-
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.
- -
-
Page/Page column 12-13
(2010/09/18)
-
- 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
-
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
-
experimental part
p. 5666 - 5669
(2010/11/18)
-
- Use of a robust dehydrogenase from an archael hyperthermophile in asymmetric catalysis-dynamic reductive kinetic resolution entry into (s)-profens
-
Described is an efficient heterologous expression system for Sulfolobus solfataricus ADH-10 (Alcohol Dehydrogenase isozyme 10) and its use in the dynamic reductive kinetic resolution (DYRKR) of 2-arylpropanal (Profen-type) substrates. Importantly, among the 12 aldehydes tested, a general preference for the (S)-antipode was observed, with high ee's for substrates corresponding to the NSAIDs (nonsteroidal anti-inflammatory drugs) naproxen, ibuprofen, flurbiprofen, ketoprofen, and fenoprofen. To our knowledge, this is the first application of a dehydrogenase from this Sulfolobus hyperthermophile to asymmetric synthesis and the first example of a DYRKR with such an enzyme. The requisite aldehydes are generated by Buchwald-Hartwig-type Pd(0)-mediated α-arylation of tert-butyl propionate. This is followed by reduction to the aldehyde in one [lithium diisobutyl tert-butoxyaluminum hydride (LDBBA)] or two steps [LAH/Dess-Martin periodinane]. Treatment of the profenal substrates with SsADH in 5% EtOH/phosphate buffer, pH 9, with catalytic NADH at 80 °C leads to efficient DYRKR, with ee's exceeding 90% for 9 aryl side chains, including those of the aforementioned NSAIDs. An in silico model, consistent with the observed broad side chain tolerance, is presented. Importantly, the SsADH-10 enzyme could be conveniently recycled by exploiting the differential solubility of the organic substrate/product at 80 °C and at rt. Pleasingly, SsADH-10 could be taken through several thermal cycles, without erosion of ee, suggesting this as a generalizable approach to enzyme recycling for hyperthermophilic enzymes. Moreover, the robustness of this hyperthermophilic DH, in terms of both catalytic activity and stereochemical fidelity, speaks for greater examination of such archaeal enzymes in asymmetric synthesis.
- Friest, Jacob A.,Maezato, Yukari,Broussy, Sylvain,Blum, Paul,Berkowitz, David B.
-
supporting information; experimental part
p. 5930 - 5931
(2010/07/05)
-
- One-step oxidation of 2-arylpropanols to 2-arylpropionic acids: Improving sustainability in the synthesis of profens
-
Three oxidation procedures were evaluated for the synthesis of optically pure 2-arylpropionic acids. Efficient, mild, and eco-friendly conditions were obtained with the system comprising TEMPO, NaClO, and NaClO2. Thus a series of profens were obtained in good to excellent yields. Georg Thieme Verlag Stuttgart New York.
- Galletti, Paola,Pori, Matteo,Giacomini, Daria
-
experimental part
p. 2644 - 2648
(2010/11/18)
-
- Kinetic resolution of racemic α-arylalkanoic acids with achiral alcohols via the asymmetric esterification using carboxylic anhydrides and acyl-transfer catalysts
-
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
-
supporting information; experimental part
p. 11629 - 11641
(2010/10/04)
-
- Combination Therapies for Treating Metabolic Disorders
-
This invention is directed to pharmaceutical combinations comprising an antioxidant agent, an anti-inflammatory agent, and optionally at least one other anti-diabetic agent useful for treating metabolic disorders. This invention also encompasses pharmaceutically acceptable compositions comprising an antioxidant agent, an anti-inflammatory agent, optionally at least one other anti-diabetic agent, and at least one pharmaceutically acceptable carrier. The combinations and compositions of this invention are useful as methods for treating metabolic disorders including diabetes, particularly Type I and Type II diabetes, as well as diseases and disorders associated with diabetes, including but not limited to atherosclerosis, cardiovascular disease, inflammatory disorders, nephropathy, neuropathy, retinopathy, β-cell dysfunction, dyslipidemia, LADA, metabolic syndrome, hyperglycemia, insulin resistance, and/or chronic obstructive pulmonary disease in a mammal, particularly a diabetic mammal, and specifically a human patient. This invention is particularly directed to pharmaceutical compositions comprising an lipoic acid, one or more anti-inflammatories selected from the group consisting of diflunisal, diclofenac, dexibuprofen, dexketoprofen, naproxen, and salicylate, and optionally one or more pharmaceutically acceptable carriers. The compositions of this invention are useful as methods for treating metabolic disorders including type II diabetes, insulin resistance, beta-cell dysfunction, and hyperglycemia in a patient, particularly a diabetic patient.
- -
-
-
- NEW CHIRAL STATIONARY PHASES FOR CHROMATOGRAPHY BASED ON AROMATIC ALLYL AMINES
-
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.
- -
-
Page/Page column 18-19
(2009/10/22)
-
- 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
-
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
-
experimental part
p. 5887 - 5890
(2009/05/27)
-
- METHOD FOR RESOLVING STEREOISOMERS OF A COMPOUND
-
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.
- -
-
Page/Page column 12
(2008/06/13)
-
- (S)-3-methyl-2-phenylbutylamine, a versatile agent to resolve chiral, racemic carboxylic acids
-
(S)-Ibuprofen 2, (S)-ketoprofen 3, and (S)-naproxen 4 are all obtained by optical resolution of the respective racemates with (S)-3-methyl-2-phenylbutylamine (PBA) 1: (S)-2, 98.7% ee, 39.8% yield; (S)-3, 99.4% ee, 36.7% yield; (S)-4, 99.2% ee, 35.1% yield. (S)-PBA 1 is also useful in resolving other racemic carboxylic acids of pharmaceutical importance; (R)-2-hydroxy-4-phenylbutanoic acid (HPBA) 5, a key intermediate for ACE inhibitors such as benazapril 7, and (S)-2-benzylsuccinic acid (BSA) 6, a key intermediate for hypoglycemic KAD-1229 8, are obtained in 99% ee and 34.4% yield, and in 99% ee and 32.2% yield, respectively.
- Chikusa, Yasuo,Fujimoto, Taizo,Ikunaka, Masaya,Inoue, Toru,Kamiyama, Shunji,Maruo, Koichi,Matsumoto, Jun,Matsuyama, Keisuke,Moriwaki, Masafumi,Nohira, Hiroyuki,Saijo, Shigeya,Yamanishi, Masato,Yoshida, Kazuto
-
p. 291 - 296
(2013/09/06)
-
- Synthesis of a new insoluble polymer-supported chiral alcohol auxiliary and its first application to nucleophilic addition to ketenes
-
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
-
p. 5859 - 5865
(2007/10/03)
-
- A new biocatalyst for the preparation of enantiomerically pure 2-arylpropanoic acids
-
A new biocatalyst, a strain of Pseudomonas fluorescens MTCCB0015, is described, which produces ibuprofen, ketoprofen and flurbiprofen as enantiomerically pure (S)-2-arylpropanoic acids from their corresponding racemic esters. 2-Arylpropanoic acids are an important class of non-steroidal anti-inflammatory compounds, whose anti-inflammatory activity is mainly due to the (S)-enantiomer.
- Kumar, Ish,Manju, Kavita,Jolly, Ravinder S.
-
p. 1431 - 1434
(2007/10/03)
-
- Enhancement of the enantioselectivity of lipase OF catalyzed hydrolysis
-
By rational purification of lipase OF on a mercurial affinity column three fractions were identified as responsible for the improved enantioselectivity without compromising the total activity of the crude enzyme. These three portions of lipase OF have remarkably different abilities to differentiate between the enantiomers of α-arylpropionic acids in the lipase catalyzed hydrolysis of the corresponding esters.
- Chang, Yuan-Fung,Tai, Dar-Fu
-
p. 177 - 179
(2007/10/03)
-
- Process for optically resolving 2-(3-benzoylphenyl) propionic acid
-
Provided is a process for separating (S)- or (R)-2-(3-benzoylphenyl)propionic acid from a mixture of (S)- and (R)-2-(3-benzoylphenyl)propionic acid, which comprises (1) reacting the mixture of (S)- and (R)-2-(3-benzoylphenyl)propionic acid with (S)- or (R)-3-methyl-2-phenylbutylamine in a suitable solvent to form a diastereomer salt of (S)-2-(3-benzoylphenyl)propionic acid with (S)-3-methyl-2-phenylbutylamine or a diastereomer salt of (R)-2-(3-benzoylphenyl)propionic acid with (R)-3-methyl-2-phenylbutylamine; (2) separating the diastereomer salt from the reaction mixture; and (3) liberating the separated diastereomer salt to give (S)- or (R)-2-(3-benzoylphenyl)propionic acid. According to the present process, it is possible to obtain optically active (S)- or (R)-2-(3-benzoylphenyl)propionic acid having 99% or more of high optical purity in a high yield. Thus, the present process is a practical and efficient process which can simplify purification steps and can be applied for an industrial production process.
- -
-
-
- (R)- and (S)-3-Hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone, New Chiral Auxiliaries for the Asymmetric Synthesis of α-Arylpropanoic Acids.
-
Reaction of rac-α-arylpropanoyl chlorides with (R)- and (S)-3-hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone (R)- and (S)-1, in the presence of triethylamine, under standard esterification conditions, gave (R,R)- and (S,S)-3, respectively, with high diastereoselectivity.Controlled acidic hydrolysis afforded the corresponding (R)- or (S)-α-arylpropanoic acids with high enantioselectivity, the chiral auxiliary being recovered efficiently.
- Camps, Pelayo,Gimenez, Silvia
-
p. 991 - 1000
(2007/10/03)
-
- Enantioselective syntheses of 2-arylpropanoic acid non-steroidal antiinflammatory drugs and related compounds
-
(S)-2-[4′-(2″-Methylpropyl)phenylpropanoic acid (ibuprofen) and (S)-2-(3′-benzoylphenyl)propanoic acid (ketoprofen) have been synthesised in high enantiomeric excess. Control of stereochemistry was achieved by a combination of Sharpless epoxidalion followed by catalytic hydrogenolysis of the introduced benzylic epoxide oxygen bond. Also, the coupling of organic compounds in the presence of palladium with enantiopure 2-(3-iodophenyl)propanoic and 2-(4-iodophenyl)propanoic acids, prepared by the methodology above, is a general method for the synthesis of optically active arylpropanoic acids.
- Hamon, David P.G.,Massy-Westropp, Ralph A.,Newton, Josephine L.
-
p. 12645 - 12660
(2007/10/02)
-
- Stereoselective esterase activity of human serum albumin toward ketoprofen glucuronide
-
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
-
p. 647 - 653
(2007/10/03)
-
- Cross-linked crystals of Candida rugosa lipase: Highly efficient catalysts for the resolution of chiral esters
-
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.
-
p. 6845 - 6852
(2007/10/02)
-
- Maltooligosaccharides as chiral selectors for the separation of pharmaceuticals by capillary electrophoresis
-
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.
-
p. 3477 - 3484
(2007/10/02)
-
- Asymmetric synthesis of ketoprofen: a surprising base catalyst effect during asymmetric addition of pantolactone to methyl (3-benzoylphenyl) ketene
-
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
-
p. 6875 - 6880
(2007/10/02)
-
- Intermediates and their use in the preparation of s-ketoprofen
-
The present invention relates to novel 2-arylpropenoic acids, derivatives thereof, processes for their preparation and their use in the preparation of S-ketoprofen.
- -
-
-
- Alternative syntheses of (S)-ketoprofen based on dimethyl L-tartrate
-
Two alternative asymmetric syntheses of (S)-ketoprofen, starting from 3-benzylpropiophenone or 3-propionylbenzophenone and dimethyl L-tartrate as chiral auxiliary, are described.
- Camps,Farres,Mauleon,Palomer,Carganico
-
p. 1739 - 1758
(2007/10/02)
-
- Synthesis of Arylpropanoic Acids From Optically Active 2-(Iodophenyl)propanoic Acids
-
The coupling of organozinc compounds with homochiral 2-(3-iodophenyl)propanoic and 2-(4-iodophenyl)propanoic acids in the presence of palladium is a general method for the synthesis of optically active arylpropanoic acids.
- Hamon, David P. G.,Massy-Westropp, Ralph A.,Newton, Josephine L.
-
p. 5333 - 5336
(2007/10/02)
-
- ASYMMETRIC SYNTHESIS OF IBUPROFEN AND KETOPROFEN
-
(S)-2-propanoic acid (ibuprofen) and (S)-2-(3'-benzoylphenyl)propanoic acid (ketoprofen) have been synthesised in high enantiomeric excess.Control of the stereochemistry was achieved by a combination of Sharpless epoxidation followed by catalytic hydrogenolysis of the introduced benzylic epoxide oxygen bond.
- Hamon, David P. G.,Massy-Westropp, Ralph A.,Newton, Josephine L.
-
p. 1435 - 1438
(2007/10/02)
-
- Chemoenzymatic synthesis of pure enantiomeric 2-aryl propionic acids
-
A new chemoenzymatic procedure to obtain pure enantiomeric 2-arylpropionic acids is described. The one pot synthesis of (±)-2-arylpropionic acids is carried out by addition of dichlorocarbene to the C=O bond of arylmethylketones and hydrogenolysis of the additon product. The racemic mixture is resolved by enantiospecific hydrolysis of the racemic ethyl esters using native lipase from Candida rugosa. The good yields, the accessibility of the starting arylmethylketones and the stereospecificity of the enzymatic hydrolysis make the process interesting in order to obtain the same non steroidal antiinflammatory drugs such as Ibuprofen or Naproxen.
- Garcia,Del Campo,Llama,Sanchez-Montero,Sinisterra
-
p. 8433 - 8440
(2007/10/02)
-
- Enzymatic enantioselective ester hydrolysis by carboxylesterase NP
-
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.
-
p. 490 - 495
(2007/10/02)
-
- Resolution of ketoprofen
-
A method for resolving (±)-(α)-(3-benzoylphenyl) propionic acid is disclosed. The method comprises: i) converting said propionic acid with (-)-cinchonidine in a solvent comprising a mixture of an aliphatic ester and an alkyl alcohol; ii) separating teh diastereomeric salt from such conversion; iii) purifying said separated diastereomeric salt by a single recrystallization; and iv) isolating highly pure (+)-α-(3-benzoylphenyl) propionic acid without any further recrystallization.
- -
-
-
