- Preparation method of (R)-(+)-2-(4-hydroxyphenoxy) propionic acid
-
The invention provides a preparation method of (R)-(+)-2-(4-hydroxyphenoxy) propionic acid, and belongs to the technical field of pesticide intermediates. Phenol compounds (parachlorophenol, p-bromophenol, p-iodophenol or p-hydroxybenzenesulfonic acid) are adopted as raw materials and react with (S)-(-)-2-chloropropionic acid to synthesize R-(+)-2-(4-chlorophenoxy) propionic acid, and the (R)-(+)-2-(4-hydroxyphenoxy) propionic acid is obtained after hydrogen hydrolysis. The raw material phenol compound used in the invention is low in price and simple in process operation; and the method avoids using hydroquinone as a raw material, and solves the problems of high raw material cost, difficult product purification and low product quality caused by hydroquinone disubstituted impurities generated in the reaction when hydroquinone is used as a raw material for synthesis in the traditional method.
- -
-
Paragraph 0056-0057; 0063-0064; 0066-0067
(2021/04/21)
-
- Anti-hepatic fibrosis compound, preparation, preparation method and application
-
The invention belongs to the technical field of medicines, in particular to an anti-hepatic fibrosis compound, a preparation, a preparation method and application, and the structural formula of the anti-hepatic fibrosis compound is shown in the specification. The anti-hepatic fibrosis compound can obviously improve hepatic fibrosis, improve liver function indexes, reduce extracellular matrix accumulation of collagen and the like in extracellular interstitial substances, reduce the degree of hepatic fibrosis and inhibit the formation and development of hepatic fibrosis.
- -
-
Paragraph 0029-0031
(2021/03/05)
-
- Access to Optically Enriched α-Aryloxycarboxylic Esters via Carbene-Catalyzed Dynamic Kinetic Resolution and Transesterification
-
Optically active α-aryloxycarboxylic acids and their derivatives are important functional molecules. Disclosed here is a carbene-catalyzed dynamic kinetic resolution and transesterification reaction for access to this class of molecules with up to 99% yields and 99:1 er values. Addition of a chiral carbene catalyst to the ester substrate leads to two diastereomeric azolium ester intermediates that can quickly epimerize to each other and thus allows for effective dynamic kinetic resolution to be realized. The optically enriched ester products from our reaction can be quickly transformed to chiral herbicides and other bioactive molecules.
- Liu, Bin,Song, Runjiang,Xu, Jun,Majhi, Pankaj Kumar,Yang, Xing,Yang, Song,Jin, Zhichao,Chi, Yonggui Robin
-
supporting information
p. 3335 - 3338
(2020/04/30)
-
- Anti-hepatic fibrosis compound and preparation as well as preparation method and application of compound
-
The invention belongs to the technical field of medicines, and in particular relates to an anti-hepatic fibrosis compound and a preparation as well as a preparation method and application of the compound. A structural formula of the anti-hepatic fibrosis compound is shown in the specification. The anti-hepatic fibrosis compound can obviously improve hepatic fibrosis, improve liver function indexes, reduce accumulation of extracellular matrixes such as collagen in extracellular interstitial substances, reduce the degree of the hepatic fibrosis and inhibit the formation and development of the hepatic fibrosis.
- -
-
Paragraph 0030; 0031
(2020/01/12)
-
- Compounds For The Treatment Of Neuromuscular Disorders
-
The present invention relates to compounds suitable for treating, ameliorating and/or preventing neuromuscular disorders, including the reversal of drug-induced neuromuscular blockade. The compounds as defined herein preferably inhibit the ClC-1 ion channel. The compounds include phenoxy propanoic acid, phenoxy propanoate, and phenoxy butanoate compounds.
- -
-
Paragraph 1145; 1147; 1202
(2019/07/03)
-
- Synthesis method of(R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy] propionic acid
-
The invention discloses a method for synthesizing cyhalofop butyl intermediate(R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy] propionic acid.(S)-2-chloropropionic acid methyl ester and p-chlorophenol are used as raw materials, an etherification reaction is performed under an alkaline condition to generate(R)-2-(4-hydroxyphenoxy)propionic acid, and the etherification product and 3-fluoro-4-hydroxybenzonitrile generate the(R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy] propionic acid under the action of an acid-binding agent. According to the method, the problems of serious excessive hydroquinone servingas a raw material, massive use of an inorganic base and generation of dietherification byproducts in synthesis are avoided. The method is high in atom utilization rate, high in reaction yield and lowin production cost.
- -
-
Paragraph 0011; 0013; 0015; 017; 0019; 0021
(2019/12/25)
-
- Preparation method of phenoxycarboxylic acid herbicide
-
The invention provides a preparation method of a phenoxycarboxylic acid herbicide, wherein the preparation method includes the steps: S1, carrying out condensation reaction of phenol or o-cresol withchlorocarboxylic ester under the action of an alkaline substance to obtain phenoxycarboxylic ester, wherein the chlorocarboxylic ester has the general formula of ClR1COOR, R1 is C1-3 alkylene or alkylidene, and R is C1-10 alkyl or C3-10 cycloalkyl; S2, carrying out selective chlorination of phenoxycarboxylic ester with a chlorinating agent under the action of a first catalyst and a second catalyst, to obtain chlorobenzoxycarboxylic ester, wherein the first catalyst is selected from Lewis acid, the second catalyst is C5-22 thioether compounds, thiazole compounds, isothiazole compounds or thiophene compounds; and S3, carrying out acidolysis reaction of chlorobenzoxycarboxylic ester, to obtain the phenoxycarboxylic acid herbicide represented by the formula I, wherein R3 is H, Cl or CH3. The preparation method can improve the product quality and the operation environment of a production site, and has low quantity of three wastes.
- -
-
-
- A method for preparing chloro-benzene oxygen carboxylic acid (by machine translation)
-
The invention provides a method for preparing carboxylic acid chloro-benzene oxygen, comprising the following steps: S1) phenoxy fatty alcohol in the catalyst B A and under the action of the catalyst, and the chlorinating agent to 2 bit and/or 4 bit selective chlorination reaction, to obtain chloro-benzene oxygen fatty alcohol; said catalyst A is Lewis acid; said catalyst B is C5 - 22 of the thioether, thiazole, isothiazole, thiophene or their halogenated derivatives; S2) [...] fatty alcohol and water, under the action of a catalyst, and an oxidizing agent for the selective catalytic oxidation reaction, get chloro-benzene oxygen carboxylic acid. The invention through the re-design of the process route, the catalyst and the chlorinating agent fine screening, effectively reduces the energy consumption, the selectivity of the dichloride to improve at the same time avoiding the losses of the active ingredient, the resulting chloro-benzene oxygen carboxylic acid content can be up to 98.5% or more, the total yield can be up to 99% or more. (by machine translation)
- -
-
Paragraph 0065; 0067
(2019/01/08)
-
- 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)
-
- A phenoxy carboxylic acid herbicide preparation method (by machine translation)
-
The invention provides a phenoxy carboxylic acid herbicide preparation method, including: S1, will be [...], alkaline substance mixed with the chlorinated carboxylic acid ester, in the one-pot condensation reaction in anhydrous system, phenoxy carboxylic acid ester obtained; the ClR states the chloro- carboxylic acid ester of the formula is1 COOR, R1 Is C1 - 3 alkylene or alkylidene, R is C1 - 10 alkyl or C3 - 10 cycloalkyl; S2, the [...] ester in the 1st and 2nd catalyst under the action of a catalyst, with the chlorinating agent to carry out the selective chlorination of, get [...] ester; the Lewis acid catalyst is selected from 1st, 2nd catalyst is C5 - 22 of the thioether compound, thiazole compound, isothiazole compound or thiophene compound; S3, will the [...] ester to acid hydrolysis reaction, as shown in formula I phenoxy carboxylic acid herbicide, R3 Is H, Cl or CH3 . This invention can improve the quality of the products and the operating environment of production, three waste low. (by machine translation)
- -
-
Paragraph 0085; 0088
(2019/01/08)
-
- Preparation method of phenoxycarboxylic acid herbicide
-
The invention provides a preparation method of a phenoxycarboxylic acid herbicide, wherein the preparation method includes the steps: S1, carrying out reaction of anhydrous phenol with an active metalto form phenoxide, and carrying out condensation reaction of the phenoxide with chlorocarboxylic ester to obtain phenoxycarboxylic ester, wherein the chlorocarboxylic ester has the general formula ofClR1COOR, R1 is C1-3 alkylene or alkylidene, and R is C1-10 alkyl or C3-10 of cycloalkyl; S2, carrying out selective chlorination of the phenoxycarboxylic ester with a chlorinating agent in the presence of a first catalyst and a second catalyst to obtain chlorobenzoxycarboxylic ester, wherein the first catalyst is selected from Lewis acid, and the second catalyst is C5-22 thioether, thiazole, isothiazole or thiophene compounds; and S3, carrying out acidolysis reaction of chlorobenzoxycarboxylic ester to obtain the phenoxycarboxylic acid herbicide represented by the formula I, wherein R3 is H,Cl or CH3. The preparation method can improve the product quality and the operation environment of the production site, and has low quantity of three wastes.
- -
-
Paragraph 0085; 0088; 0117; 0120
(2019/01/08)
-
- Preparation method of phenoxy carboxylic acid herbicide
-
The invention provides a preparation method of a phenoxy carboxylic acid herbicide, comprising the following steps: S1, carrying out a condensation reaction between a phenolic compound and hydroxycarboxylic ester under the action of a catalyst so as to obtain phenoxycarboxylic ester, wherein the catalyst is one or more of protonic acid, solid acid and a supported catalyst; S2, carrying out 2- and/or 4- selecting chlorination reaction between phenoxycarboxylic ester and a chloridizing agent in the presence of a first catalyst and a second catalyst, so as to obtain chlorinated phenoxycarboxylicester, wherein the first catalyst is selected from Lewis acid, and the second catalyst is selected from a C5-C22 thioether compound, a C5-C22 thiazole compound, a C5-C22 isothiazole compound or a C5-C22 thiophene compound; and S3, carrying out an acidolysis reaction on chlorinated phenoxycarboxylic ester so as to obtain the phenoxy carboxylic acid herbicide. By the method, product quality and thelive environment of production can be improved, and ''three wastes (waste gas, waste water and industrial residue)'' are minimized.
- -
-
Paragraph 0091; 0094
(2019/01/08)
-
- Highly Enantioselective Hydrogenation of Amides via Dynamic Kinetic Resolution Under Low Pressure and Room Temperature
-
High-throughput screening and lab-scale optimization were combined to develop the catalytic system trans-RuCl2((S,S)-skewphos)((R,R)-dpen), 2-PrONa, and 2-PrOH. This system hydrogenates functionalized α-phenoxy and related amides at room temperature under 4 atm H2 pressure to give chiral alcohols with up to 99% yield and in greater than 99% enantiomeric excess via dynamic kinetic resolution.
- Rasu, Loorthuraja,John, Jeremy M.,Stephenson, Elanna,Endean, Riley,Kalapugama, Suneth,Clément, Roxanne,Bergens, Steven H.
-
supporting information
p. 3065 - 3071
(2017/03/11)
-
- COMPOUNDS FOR USE IN TREATING NEUROMUSCULAR DISORDERS
-
The present invention relates to compositions comprising compounds for use in treating, ameliorating and/or preventing neuromuscular disorders. The compounds as defined herein preferably inhibit the ClC-1 ion channel. The invention further relates to methods of treating, preventing and/or ameliorating neuromuscular disorders, by administering said composition to a person in need thereof.
- -
-
Page/Page column 103; 104
(2017/01/02)
-
- SUBSTITUTED AMINO TRIAZOLES, AND METHODS USING SAME
-
Disclosed are novel substituted amino triazoles of Formula (I), and pharmaceutically acceptable salts thereof. The compounds of Formula (I) are inhibitors of Acidic mammalian chitinase (AMCase) and are useful, in a non-limiting example, for treating asthma. Also provided are pharmaceutical compositions containing at least one compound of the present invention, or a pharmaceutically acceptable salt, hydrate or solvate thereof, and at least one pharmaceutically acceptable carrier, solvent, adjuvant or diluent, and methods of using such compounds and/or compositions to treat asthma and/or to monitor asthma treatment.
- -
-
Page/Page column 62; 71
(2015/07/07)
-
- Optimization of benzoxazole-based inhibitors of Cryptosporidium parvum inosine 5′-monophosphate dehydrogenase
-
Cryptosporidium parvum is an enteric protozoan parasite that has emerged as a major cause of diarrhea, malnutrition, and gastroenteritis and poses a potential bioterrorism threat. C. parvum synthesizes guanine nucleotides from host adenosine in a streamlined pathway that relies on inosine 5′-monophosphate dehydrogenase (IMPDH). We have previously identified several parasite-selective C. parvum IMPDH (CpIMPDH) inhibitors by high-throughput screening. In this paper, we report the structure-activity relationship (SAR) for a series of benzoxazole derivatives with many compounds demonstrating CpIMPDH IC50 values in the nanomolar range and >500-fold selectivity over human IMPDH (hIMPDH). Unlike previously reported CpIMPDH inhibitors, these compounds are competitive inhibitors versus NAD +. The SAR study reveals that pyridine and other small heteroaromatic substituents are required at the 2-position of the benzoxazole for potent inhibitory activity. In addition, several other SAR conclusions are highlighted with regard to the benzoxazole and the amide portion of the inhibitor, including preferred stereochemistry. An X-ray crystal structure of a representative E·IMP·inhibitor complex is also presented. Overall, the secondary amine derivative 15a demonstrated excellent CpIMPDH inhibitory activity (IC 50 = 0.5 ± 0.1 nM) and moderate stability (t1/2 = 44 min) in mouse liver microsomes. Compound 73, the racemic version of 15a, also displayed superb antiparasitic activity in a Toxoplasma gondii strain that relies on CpIMPDH (EC50 = 20 ± 20 nM), and selectivity versus a wild-type T. gondii strain (200-fold). No toxicity was observed (LD 50 > 50 μM) against a panel of four mammalian cells lines.
- Gorla, Suresh Kumar,Kavitha, Mandapati,Zhang, Minjia,Chin, James En Wai,Liu, Xiaoping,Striepen, Boris,Makowska-Grzyska, Magdalena,Kim, Youngchang,Joachimiak, Andrzej,Hedstrom, Lizbeth,Cuny, Gregory D.
-
p. 4028 - 4043
(2013/06/27)
-
- (R,S)-2-chlorophenoxyl pyrazolides as novel substrates for improving lipase-catalyzed hydrolytic resolution
-
The best reaction condition of Candida antartica lipase B as biocatalyst, 3-(2-pyridyl)pyrazole as leaving azole, and water-saturated methyl t-butyl ether as reaction medium at 45°C were first selected for performing the hydrolytic resolution of (R,S)-2-(4-chlorophenoxyl) azolides (1-4). In comparison with the kinetic resolution of (R,S)-2-phenylpropionyl 3-(2-pyridyl)pyrazolide or (R,S)-α-methoxyphenylacetyl 3-(2-pyridyl)pyrazolide at the same reaction condition, excellent enantioselectivity with more than two order-of-magnitudes higher activity for each enantiomer was obtained. The resolution was then extended to other (R,S)-3-(2-pyridyl)pyrazolides (5-7) containing 2-chloro, 3-chloro, or 2,4-dichloro substituent, giving good (E > 48) to excellent (E > 100) enantioselectivity. The thermodynamic analysis for 1, 2, and 4-7 demonstrates profound effects of the acyl or leaving moiety on varying enthalpic and entropic contributions to the difference of Gibbs free energies. A thorough kinetic analysis further indicates that on the basis of 6, the excellent enantiomeric ratio for 4 and 7 is due to the higher reactivity of (S)-4 and lower reactivity of (R)-7, respectively.
- Kao, Min-Fang,Lu, Pei-Yu,Kao, Jou-Yan,Wang, Pei-Yun,Wu, An-Chi,Tsai, Shau-Wei
-
-
- A new method for production of chiral 2-aryloxypropanoic acids using effective kinetic resolution of racemic 2-aryloxycarboxylic acids
-
We report a novel method for the preparation of 2-aryloxypropanoic acids by kinetic resolution of racemic 2-aryloxypropanoic acids using enantioselective esterification. The usage of pivalic anhydride (Piv2O) as an activating agent, bis(a-naphthyl)methanol ((α-Np)2CHOH) as an achiral alcohol, and (+)-benzotetramisole ((+)-BTM) as a chiral acyl-transfer catalyst enables the effective separation of various racemic 2-aryloxypropanoic acids to afford optically active carboxylic acids and the corresponding esters with high enantioselectivities. Furthermore, theoretical calculations of the transition states required to form the chiral esters successfully proved the enantiomer recognition mechanism of the asymmetric esterification.
- Tengeiji, Atsushi,Nakata, Kenya,Ono, Keisuke,Shiina, Isamu
-
p. 1227 - 1252
(2013/08/23)
-
- Purification and Gene cloning of an enantioselective thioesterification enzyme from Brevibacterium Ketoglutamicum KU1073, a deracemization bacterium of 2-(4-Chlorophenoxy)propanoic acid
-
We succeeded in the purification and gene cloning of a new enzyme, α-methyl carboxylic acid deracemizing enzyme 1 (MCAD1) from Brevibacterium ketoglutamicum KU1073, which catalyzes the (S)-enantioselective thioesterification reaction of 2-(4-chlorophenoxy)propanoic acid (CPPA). The cloned gene of MCAD1 contained an ORF of 1,623 bp, encoding a polypeptide of 540 amino acids. In combination with cofactors ATP, coenzyme A (CoASH), and Mg 2±, MCAD1 demonstrated perfect enantioselectivity toward CPPA. The optimal pH and temperature for reaction were found to be 7.25 and 30 °C. Under these conditions, the Km and kcat values for (S)-CPPA were 0:92 ± 0:17mM and 0:28 ± 0:026 s-1 respectively. The results for substrate specificity revealed that MCAD1 had highest activity toward fatty acid tails with a medium chain-length (C8). This result indicates that MCAD1 should be classified into a family of medium-chain acyl-CoA synthetase. This novel activity has never been reported for this family.
- Kato, Dai-Ichiro,Yoshida, Hiromitsu,Takeo, Masahiro,Negoro, Seiji,Ohta, Hiromichi
-
p. 2405 - 2412
(2013/01/09)
-
- Synthesis of 2-aryloxypropanoic acids analogues of clofibric acid and assignment of the absolute configuration by 1H NMR spectroscopy and DFT calculations
-
A new set of optically active 2-aryloxypropanoic acids has been synthesized through a simple strategy, in good yields and excellent enantiomeric excesses. Their absolute configuration was assigned by means of a NMR-based approach consisting of the derivatization of the carboxylic acids with ethyl mandelate and the comparison of the chemical shifts of the obtained diastereomers. The effectiveness of such an approach has been tested against a larger set of chiral α-substituted-carboxylic acids and by performing high level density functional theory (DFT) calculations on a set of low energy conformations for each diastereomeric derivative. The employed computational procedure has enabled us to find a semiquantitative relationship between the experimental NMR data and the theoretically calculated energy gaps which confirms the theoretical foundations of the NMR strategy and allows to understand when and why it is most likely to fail.
- Ammazzalorso, Alessandra,Bettoni, Giancarlo,De Filippis, Barbara,Fantacuzzi, Marialuigia,Giampietro, Letizia,Giancristofaro, Antonella,Maccallini, Cristina,Re, Nazzareno,Amoroso, Rosa,Coletti, Cecilia
-
p. 989 - 997
(2008/09/21)
-
- A great improvement of the enantioselectivity of lipase-catalyzed hydrolysis and esterification using co-solvents as an additive
-
Addition of co-solvents such as tetrahydrofuran resulted in a great improvement of the enantioselectivity of lipase-catalyzed hydrolysis of butyl 2-(4-substituted phenoxy)propanoates in an aqueous buffer solution. On the other hand, lipase lyophilized from an aqueous solution containing the co-solvents catalyzed highly enantioselective esterification of 2-(4-substituted phenoxy)propionic acids, 2-(4-isobutylphenyl)propionic acid (ibuprofen), and 2-(6-methoxy-2-naph-thyl)propionic acid (naproxen) in an organic solvent. An increase in the E value up to two orders of magnitude was observed for some substrates. The origin of the enantioselectivity enhancement caused by the co-solvent addition was mainly attributed to a significant deceleration in the initial reaction rate for the incorrectly binding enantiomer, as compared with that for the correctly binding enantiomer. From the results of FT-1R, CD, and ESR spectra, the co-solvent addition was also found to bring about a partial destruction of the tertiary structure of lipase.
- Nishigaki, Tomohiro,Yasufuku, Yoshitaka,Murakami, Sayuri,Ebara, Yasuhito,Ueji, Shin-Ichi
-
experimental part
p. 617 - 622
(2009/04/11)
-
- Identification of anthranilic acid derivatives as a novel class of allosteric inhibitors of hepatitis C NS5B polymerase
-
A series of potent anthranilic acid-based inhibitors of the hepatitis C NS5B polymerase has been identified. The inhibitors bind to a site on NS5B between the thumb and palm regions adjacent to the active site as determined by X-ray crystallography of the enzyme-inhibitor complex. Guided by both molecular modeling and traditional SAR, the enzyme activity of the initial hit was improved by approximately 100-fold, yielding a series of potent and selective NS5B inhibitors with IC50 values as low as 10 nM. These compounds were also inhibitors of the HCV replicon in cultured HUH7 cells.
- Nittoli, Thomas,Curran, Kevin,Insaf, Shabana,DiGrandi, Martin,Orlowski, Mark,Chopra, Rajiv,Agarwal, Atul,Howe, Anita Y. M.,Prashad, Amar,Floyd, M. Brawner,Johnson, Bernard,Sutherland, Alan,Wheless, Karen,Feld, Boris,O'Connell, John,Mansour, Tarek S.,Bloom, Jonathan
-
p. 2108 - 2116
(2008/02/06)
-
- Highly enantioselective insertion of carbenoids into O-H bonds of phenols: An efficient approach to chiral α-aryloxycarboxylic esters
-
A highly efficient copper-catalyzed asymmetric carbenoid insertion into O-H bonds of phenols has been realized by using chiral spiro bisoxazoline ligands, affording α-aryloxypropionates and the related propionic acids in high yields with excellent enantiomeric excesses. Copyright
- Chen, Chao,Zhu, Shou-Fei,Liu, Bin,Wang, Li-Xin,Zhou, Qi-Lin
-
p. 12616 - 12617
(2008/03/14)
-
- Chlorination of 2-phenoxypropanoic acid with NCP in aqueous acetic acid: Using a novel ortho-para relationship and the para/meta ratio of substituent effects for mechanism elucidation
-
(Graph Presented) Rate constants were measured for the oxidative chlorodehydrogenation of (R,S)-2-phenoxypropanoic acid and nine ortho-, ten para- and five meta-substituted derivatives using (R,S)-1-chloro-3-methyl-2,6- diphenylpiperidin-4-one (NCP) as chlorinating agent. The kinetics was run in 50% (v/v) aqueous acetic acid acidified with perchloric acid under pseudo-first-order conditions with respect to NCP at temperature intervals of 5 K between 298 and 318 K, except at the highest temperature for the meta derivatives. The dependence of rate constants on temperature was analyzed in terms of the isokinetic relationship (IKR). For the 20 reactions studied at five different temperatures, tne isokinetic temperature was estimated to be 382 K, which suggests the preferential involvement of water molecules in the rate-determining step. The dependence of rate constants on meta and para substitution was analyzed using the tetralinear extension of the Hammett equation. The parameter λ for the para/meta ratio of polar substituent effects was estimated to be 0.926, and its electrostatic modeling suggests the formation of an activated complex bearing an electric charge near the oxygen atom belonging to the phenoxy group. A new approach is introduced for examining the effect of ortho substituents on reaction rates. Using IKR-determined values of activation enthalpies for a set of nine pairs of substrates with a given substituent, a linear correlation is found between activation enthalpies of ortho and para derivatives. The correlation is interpreted in terms of the selectivity of the reactant toward para- or ortho-monosubstituted substrates, the slope of which being related to the ortho effect. This slope is thought to be approximated by the ratio of polar substituent effects from ortho and para positions in benzene derivatives. Using the electrostatic theory of through-space interactions and a dipole length of 0.153 nm, this ratio was calculated at various positions of a charged reaction center along the benzene C1-C4 axis, being about 2.5 near the ring and decreasing steeply with increasing distance until reaching a minimum value of -0.565 at 1.3 nm beyond the aromatic ring. Activation enthalpies and entropies were estimated for substrates bearing the isoselective substituent in either ortho and para positions, being demonstrated that they are much different from the values for the parent substrate. The electrophilic attack on the phenolic oxygen atom by the protonated chlorinating agent is proposed as the rate-determining step, this step being followed by the fast rearrangement of the intermediate thus formed, leading to products containing chlorine in the aromatic ring.
- Segurado, Manuel A. P.,Reis, Joao Carlos R.,De Oliveira, Jaime D. Gomes,Kabilan, Senthamaraikannan,Shanthi, Manohar
-
p. 5327 - 5336
(2008/02/07)
-
- Metal ions dramatically enhance the enantioselectivity for lipase-catalysed reactions in organic solvents
-
We propose a simple and a powerful method to enhance the enantioselectivity for lipase-catalysed transformations in organic solvents by an addition of metal ion-containing water to the reaction mixture. In this paper, various metal ions such as LiCl or MgCl2 are tested to improve the enantioselectivity for the model reactions. The enantioselectivities obtained are dramatically enhanced, the E values of which are about 100-fold as compared with the ordinary conditions without a metal ion, for example, E = 200 by addition of LiCl. Furthermore, lowering the reaction temperature led to an almost perfect enantioselectivity of lipase in the presence of a metal ion, for example, E = 1300 by addition of LiCl. Also, a mechanism for the drastic enhancement by metal ions is discussed briefly on the basis of the EPR spectroscopic study and the initial rate for each enantiomer of the substrate. The Royal Society of Chemistry 2006.
- Okamoto, Takashi,Yasuhito, Ebara,Ueji, Shin-Ichi
-
p. 1147 - 1153
(2008/02/03)
-
- Microbial deracemization of α-substituted carboxylic acids: Control of the reaction path
-
A novel approach to preparing optically active α-substituted carboxylic acids using the whole cells of Nocardia diaphanozonaria JCM 3208 is described. When 2-phenylthiopropanoic acid and 2-methyl-3-phenylpropanoic acid were subjected to the reaction under aerobic conditions, the oxidation reaction proceeded preferentially rather than deracemization of these substrates. Herein, we report the design of reaction conditions to increase the deracemization activity in preference to oxidation reactions. In addition, we have successfully detected a metabolic intermediate in the reaction mixture of 2-methyl-3-phenylpropanoic acid, which indicates that the deracemization is a competitive reaction against the α-oxidation pathway of fatty acid metabolism.
- Kato, Dai-Ichiro,Miyamoto, Kenji,Ohta, Hiromichi
-
p. 2965 - 2973
(2007/10/03)
-
- Enantioselective hydrolysis of some 2-aryloxyalkanoic acid methyl esters and isosteric analogues using a penicillin G acylase-based HPLC monolithic silica column
-
A technique based on liquid chromatography has been developed to facilitate studies of enantioselectivity in penicillin G acylase (PGA)-catalyzed hydrolysis of some 2-aryloxyalkanoic acid methyl esters and isosteric analogues. PGA was covalently immobilized on an aminopropyl monolithic silica support to create an immobilized HPLC-enzyme reactor. Two sets of experimental data were drawn to calculate the enantioselectivity (E) of the kinetically controlled enantiomer-differentiating reaction, the degree of substrate conversion and the enantiomeric excess of the product. The developed enzymatic reactor was coupled through a switching valve to an achiral analytical column for separation and quantitation of the hydrolysis products. The enantiomeric excess was determined off-line on a PGA-chiral stationary phase. In this way, highly precise E values were determined. A computational study related to the hydrolysis of the considered racemic esters was also carried out in order to unambiguously clarify both the substrate specificity and the enantioselectivity displayed by PGA.
- Massolini, Gabriella,Calleri, Enrica,Lavecchia, Antonio,Loiodice, Fulvio,Lubda, Dieter,Temporini, Caterina,Fracchiolla, Giuseppe,Tortorella, Paolo,Novellino, Ettore,Caccialanza, Gabriele
-
p. 535 - 542
(2007/10/03)
-
- Synthesis of chiral 1-[ω(4-chlorophenoxy)alkyl]-4-methylpiperidines and their biological evaluation at σ1, σ2, and sterol δ8-δ7 isomerase sites
-
Sumitomo's patented σ ligand 1-[3-(4-chlorophenoxy)propyl]-4-methylpiperidine (15), which has been claimed as agent for CNS disorders and neuropathies, and its lower homologue 12 were prepared along with related chiral (4-chlorophenoxy)alkylpiperidines. They were tested at σ1, σ2, and sterol Δ8-Δ7 isomerase (SI) sites by in vitro radioligand binding assays, to evaluate the influence of a chiral center in the alkyl chain on the selective σ1 binding relative to other σ family sites. Generally high σ1-site affinities were found, so that the chirality introduced by a methyl substitution resulted in slight differences. Nevertheless, the shorter oxyethylenic chain was beneficial to increase σ1 selectivity. However, the (-)-(S)-4-methyl-1-[2-(4-chlorophenoxy)1-methylethyl]piperidine ((-)-(S)-17) reached the highest σ1 affinity (Ki = 0.34 nM) and the best selectivity relative to the σ2 site (547-fold). Compound (-)-(S)-17 displayed also a moderate selectivity (11-fold) relative to the SI site.
- Berardi, Francesco,Loiodice, Fulvio,Fracchiolla, Giuseppe,Colabufo, Nicola Antonio,Perrone, Roberto,Tortorella, Vincenzo
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p. 2117 - 2124
(2007/10/03)
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- Microbial deracemization of α-substituted carboxylic acids: Substrate specificity and mechanistic investigation
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A new enzymatic method for the preparation of optically active α-substituted carboxylic acids is reported. This technique is called deracemization reaction, which provides us with a route to obtain the enantiomerically pure compounds, theoretically in 100% yield starting from the racemic mixture. This means that the synthesis of a racemate is almost equal to the synthesis of the optically active compound, and this concept is entirely different from the commonly accepted one in the asymmetric synthesis. Using the growing cell system of Nocardia diaphanozonaria JCM3208, racemates of 2-aryl- and 2-aryloxypropanoic acid are deracemized smoothly and (R)-form-enriched products are recovered in high chemical yield (>50%). In addition, using optically active starting compounds and deuterated derivatives as well as inhibitors, we have disclosed the fact that a new type of enzyme takes part in this biotransformation, and that the reaction proceeds probably via the same mechanism as that in rat liver.
- Kato, Dai-Ichiro,Mitsuda, Satoshi,Ohta, Hiromichi
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p. 7234 - 7242
(2007/10/03)
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- Application of cyclam-capped β-cyclodextrin-bonded silica particles as a chiral stationary phase in capillary electrochromatography for enantiomeric separations
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Two novel types of substituted cyclam-capped β-cyclodextrin (β-CD)-bonded silica particles have been prepared and used as chiral stationary phases in capillary electrochromatography (CEC). The two stationary phases have a chiral selector with three recognition sites: β-CD, cyclam, and the latter's sidearm. They exhibit excellent enantioselectivities in CEC for a wide range of compounds as a result of the cooperative functioning of the anchored β-CD and cyclam. After inclusion of the metal ion (Ni2+) from the running buffer into the substituted cyclams and their sidearm ligands, the bonded stationary phases become positively charged and can provide extra electrostatic interactions with ionizable solutes and enhance the dipolar interactions with some polar neutral solutes. This enhances the host-guest interaction with some solutes and improves chiral recognition and enantioselectivity. These new types of stationary phases exhibit great potential for fast chiral separations in CEC.
- Gong, Yinhan,Lee, Hian Kee
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p. 1348 - 1354
(2007/10/03)
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- Microbial deracemization of alpha-substituted carboxylic acids.
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An enzyme system of Nocardia diaphanozonaria JCM 3208 catalyzes the inversion of the chirality of various alpha-substituted carboxylic acids, such as 2-phenylpropanoic acid and 2-phenoxypropanoic acid derivatives, via a novel deracemization reaction.
- Kato, Dai-ichiro,Mitsuda, Satoshi,Ohta, Hiromichi
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p. 371 - 373
(2007/10/03)
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- A new biocatalyst for the preparation of enantiomerically pure 2-arylpropanoic acids
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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.
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p. 1431 - 1434
(2007/10/03)
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- Dimethyl sulfoxide as a co-solvent dramatically enhances the enantioselectivity in lipase-catalysed resolutions of 2-phenoxypropionic acyl derivatives
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We recently reported that the enantioselectivity for subtilisin-catalysed hydrolysis of ethyl 2-(4-substituted phenoxy)-propionates in aqueous buffer is found to be dramatically enhanced by addition of dimethyl sulfoxide (DMSO). In our present work, as one of the useful methods for improving the enzyme's enantioselectivity, this approach using DMSO is tested for both hydrolysis and transesterification catalysed by various lipases. For instance, for Candida rugosa lipase-catalysed hydrolysis in aqueous buffer containing DMSO, the optimum additive conditions (50-65 vol% DMSO) markedly enhance the enantioselectivity toward the substrates used, as compared with that for no-additive conditions, in spite of a decrease in the enzymatic activity. On the other hand, for Pseudomonas cepacia lipase-catalysed hydrolysis, the addition of DMSO to the reaction medium enhances the enantioselectivity with an increase in the enzymatic activity. Also, the DMSO effect on the enantioselectivity can apply to the lipase-catalysed transesterification in organic solvent. A mechanism for the DMSO-induced enhancement of the lipase's enantioselectivity is briefly discussed on the basis of the values of the initial rates obtained for each enantiomer of the substrate used.
- Watanabe, Keiichi,Ueji, Shin-Ichi
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p. 1386 - 1390
(2007/10/03)
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- Kinetics and mechanism of thermal gas-phase elimination of α-substituted carboxylic acids: Role of relative basicity of α-substituents and acidity of incipient proton
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2-Phenoxypropanoic acid together with five of its aryl derivatives, its phenylthio and its N-phenylamino analogues were pyrolyzed at 494-566 K. The reactions were homogeneous, polar and free from catalytic and radical pathways, and obeyed a first-order rate equation. The limits of the Arrhenius log A (s-1) and E (kJ mol-1) values obtained for these reactions averaged 11.98 ± 1.71 and 158.1 ± 17.4, respectively. Analysis of the pyrolysates showed the elimination products to be carbon monoxide, acetaldehyde and the corresponding phenol, thiophenol or aniline compounds. The pyrolysis of 2-phenoxy- and 2-(N-phenylamino)-1-propanol was also investigated over the temperature range 638-792 K. The kinetic results and products analysis lend support to a reaction pathway involving a five-membered cyclic polar transition state. Copyright
- Al-Awadi, Nouria A.,Kaul, Kamini,El-Dusouqui, Osman M. E.
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p. 499 - 504
(2007/10/03)
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- Enantioselectivity of alcohol-treated Candida rugosa lipase in the kinetic resolution of racemic methyl 2-aryloxypropionates in water and aqueous organic media
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Racemic methyl 2-aryloxypropionates (±)-1 were subjected to hydrolysis in water and in a series of two-phase aqueous organic media in the presence of Candida rugosa lipase (CRL). The biocatalytic material used was the enzyme of commercial CRL purified by treatment with different alcohols. The purification of CRL and the reaction medium play an important role in the enantioselection of racemates (±)-1. While it is not possible to use the same protocol for all substrates, by combining the different ways of purifying the enzyme with the various reaction media, it is possible to achieve high enantioselectivities of racemic esters. (C) 1999 Elsevier Science Ltd.
- Cipiciani, Antonio,Bellezza, Francesca,Fringuelli, Francesco,Stillitano, Massimiliano
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p. 4599 - 4605
(2007/10/03)
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- Resolution of (±)-mandelic- and (±)-2-(chlorophenoxy)propionic-acid derivatives by crystallization of their diastereomeric amides with (R)- or (S)-α-arylethylamines
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An alternative and cost effective route for the resolution in high ees (95-99%) of (±)-mandelic-and (±)-2-(chlorophenoxy)propionic- acid derivatives is reported. The key step involves the covalent derivatization and separation of their diastereomeric amides with (R)- or (S)-α- arylethylamines.
- Jourdain, Franck,Hirokawa, Takahiko,Kogane, Tamizo
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p. 2307 - 2310
(2007/10/03)
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- Direct resolution of α-monoalkyl-α-aryloxyacetic acids via ester or imide derivatives
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This paper describes a simple procedure for the resolution of racemic α-monoalkyl α-aryloxyacetic acids, using the chromatographic separation of their covalent derivatives. (R)-Ethyl mandelate, (R)-pantolactone and (S)-4-(1-methylethyl)-2-oxazolidinone are the resolving agents involved in the formation of equimolecular diastereomeric mixtures of esters or imides. Chromatographic resolutions were performed by means of gas chromatography (GC), thin-layer chromatography (TLC) and flash chromatography. Successive hydrolysis of separated diastereomers provided optically pure aryloxyacetic acids.
- Amoroso, Rosa,Bettoni, Giancarlo,Tricca, Maria Luisa,Loiodice, Fulvio,Ferorelli, Savina
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- Candida cylindracea lipase-mediated kinetic resolution of α-substituted α-aryloxyacetic acid methyl esters
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Hydrolysis of several α-alkyl-α-aryloxyacetic acid methyl esters and of α-methyl-α-(n-propyl)-α-(p-chlorophenoxy)acetic acid methyl ester were performed in the presence of Candida cylindracea lipase. The α-alkyl-α-aryloxyacetic acid methyl esters and α-methyl-α-(n-propyl)-α-(p-chlorophenoxy)acetic acid methyl ester were incubated in buffer phosphate (pH 7-8). The reaction mixture, containing the unreacted ester and corresponding acid, showed enantiomeric excesses (ee) up to 81%. The extent of conversion was quite low for the α-methyl-α-(n-propyl)-α-(p-chlorophenoxy)acetic acid methyl ester, the corresponding acid was obtained with ee > 98%.
- Noya,Ferorelli,Franchini,Scilimati,Sinicropi,Tortorella
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p. 293 - 296
(2007/10/03)
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- Candida Rugosa lipase: Enantioselectivity enhancements in organic solvents
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Chiral resolutions of carboxylic acids (1-3) and alcohol (4) were carried out through esterification or transesterification in organic solvents using cross-linked enzyme crystals (CLEC) of Candida rugosa lipase (CRL). Comparison of these results with those of crude CRL reveal significant differences. As was seen in resolution through hydrolysis, a marked improvement in enantioselectivity is realized with the CLEC. Additionally, the stability afforded the enzyme in CLEC form leads to a higher activity in organic solvent.
- Persichetti, Rose A.,Lalonde, Jim J.,Govardhan, Chandrika P.,Khalaf, Nazer K.,Margolin, Alexey L.
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p. 6507 - 6510
(2007/10/03)
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- Presynaptic cholinergic modulators as potent cognition enhancers and analgesic drugs. 2. 2-Phenoxy-, 2-(phenylthio)-, and 2-(phenylamino)alkanoic acid esters
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Further modifications of the leads ((R)-(+)-hyoscyamine and (p- chlorophenyl)propionic acid α-tropanyl ester), which show analgesic and nootropic activities as a consequence of increased central presynaptic ACh release, are reported. 2-Phenoxy- and 2-(phenylthio)alkanoic acid esters showed the best results. Several members of these classes possess analgesic properties which are comparable to that of morphine and at the same time are able to reverse dicyclomine-induced amnesia. Confirmation was found that the mechanism of action is due to an increase in ACh release at central muscarinic synapses and that both auto- and heteroreceptors controlling ACh release are very likely involved. According to the results obtained with (R)- (+)-hyoscyamine, analgesic activity is stereochemistry dependent, since the R-(+)-enantiomers are always more efficacious than the corresponding S-(-)- ones. On the basis of their potency and acute toxicity, compounds (±)-28 (SM21) and (±)-42 (SM32) were selected for further study.
- Gualtieri,Bottalico,Calandrella,Dei,Giovannoni,Mealli,Romanelli,Scapecchi,Teodori,Galeotti,Ghelardini,Giotti,Bartolini
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p. 1712 - 1719
(2007/10/02)
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- Optical resolution of aryloxypropionic acids and their esters by HPLC on cellulose tris-3,5-dimethyl-triphenylcarbamate derivative
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Chiral chromatographic resolution of a series of antiphlogistic 2- aryloxypropionic acids and their methyl and ethyl esters was performed using a Chiralcel OD column. The CSP selected resolved most of the acids and esters efficiently, the enantiomers being well separated without requiring time consuming analysis. Chromatographic separation of R enriched samples was performed to determine the correct elution order. Using eluting systems such as hexane and 2-propanol, or hexane, 2-propanol and formic acid, the S enantiomer of all acids and esters was always found to elute first. We also considered the role of electron-donating or electron-withdrawing substituents (at the aryloxylic moiety) on the chiral resolution. It was shown that the electronic features of the substituents have more influence on the chiral interactions between the solutes and the CSP than their steric hindrance. Finally we determined, by molecular models, the interaction between CSP and solutes. In this way were able to determine all the potential sites for interactions, which are compatible with the conformations of the compounds and the structure of the stationary phase, and point out those interactions which enable chiral resolution.
- Azzolina,Collina,Ghislandi
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p. 1401 - 1416
(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 Hydrolysis of Aryloxypropionic Esters by Bovine Serum Albumin: Enhancement in Selectivity by β-Cyclodextrin
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Bovine serum albumin catalyzed hydrolysis of racemic aryloxypropionic esters affords appreciable enantioselectivity.The effect of β-cyclodextrin this process of hydrolysis has been studied.
- Kamal, Ahmed,Ramalingam, T.,Venugopal, N.
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- Enantioselective inhibition: a strategy for improving the enantioselectivity of biocatalytic systems
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Dextromethorphan (DM) and levomethorphan (LM) were found to be effective enantioselective inhibitors of Candida cylindracea lipase-catalyzed hydrolysis of a variety of (±)-arlypropionic and (±)-(arloxy)propionic esters. The enantioselectivity of the biocatalytic resolution of (±)-methyl 2-(2,4-dichlorophenoxy)propionate (DCPP) was enhanced 20-fold in the presence of either DM or LM. A general model for enantioselective inhibition has been developed, and a quantitative expression has been derived to show the underlying parameters that govern enantioselective inhibition. To define the mechanism of action of DM, a series of kinetic inhibition experiments was conducted with enantiomerically pure (R)-(+)-DCPP and (S)-(-)-DCPP. The observed inhibition pattern was that of partial noncompetitive inhibition for (R)-(+)-DCPP and that of pure noncompetitive inhibition for (S)-(-)-DCPP.
- Guo,Sih
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p. 6836 - 6841
(2007/10/02)
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- Process for producing optically active 2-phenoxypropionic acid
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There is provided a process for producing an optically active 2-phenoxypropionic acid, which comprises allowing an optically active lactic ester represented by the following formula (I) to react with a phenol represented by the following formula (II) in the copresence of a reagent A and a reagent B defined below to form an optically active 2-phenoxypropionic ester represented by the following formula (III), and liberating an optically active 2-phenoxypropionic acid represented by the following formula (IV) from the optically active 2-phenoxypropionic ester: STR1 wherein R1 represents a group to form a monovalent ester, which can be eliminated from the compound (III) under weakly basic to acidic conditions and R2 represents a hydrogen atom or 1 to 5 substituents which do not interfere in the reaction between the compounds (I) and (II); a reagent A being at least one compound selected from the group consisting of trialkylphosphine, trialkylphosphite, triarylphosphine and triarylphosphite; and a reagent B being at least one compound selected from the group consisting of dialkylazodicarboxylate and diarylazodicarboxylate.
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- Enzyme catalysed hydrolysis of chlorophenoxypropionates
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We report on the enzymatic hydrolysis of methyl 2-phenoxypropionate and of the following chlorinated derivatives: methyl o-chloro-, m-chloro-, p-chloro-, and o,p-dichloro-2-phenoxypropionates. α-Chymotripsyn, lipase, and pig liver esterase have an R enantioselectivity whereas subtilisin has an S enantioselectivity.Enantiomeric excess (e.e.) cover a wide range (from 5 to 100percent).
- Chenevert, Robert,D'Astous, Linda
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p. 1219 - 1222
(2007/10/02)
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- Stereospecificity of the Chloride Ion Channel: The Action of Chiral Clofibric Acid Analogues
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2-(p-Chlorophenoxy)isobutyric acid (clofibric acid (1) or CPIB) is a drug known to block chloride membrane conductance (GCl) in rat striated muscle.In the present study chiral analogues of CPIB (2-(p-chlorophenoxy)propionic acid (2) and 2-(p-chlorophenoxy)butyric acid (3)) have been tested to evaluate the influence of chirality on Cl ion flux in the channel.The results showed that the chloride channel conductance strongly depends on the absolute configuration: in fact, the S-(-) isomers of the tested compounds strongly decreased the GCl of skeletal muscle membrane, whereas the R-(+) isomers were virtually ineffective.These data allow the hypothesis that, like other ion channels present in various biological systems, the chloride channel of skeletal muscle membrane could also have a stereospecific binding site (or receptor) regulating chloride ion flux.
- Bettoni, Giancarlo,Loiodice, Fulvio,Tortorella, Vincenzo,Conte-Camerino, Diana,Mambrini, Mercede,et al.
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p. 1267 - 1270
(2007/10/02)
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