- Highly Efficient Deracemization of Racemic 2-Hydroxy Acids in a Three-Enzyme Co-Expression System Using a Novel Ketoacid Reductase
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Enantiopure 2-hydroxy acids (2-HAs) are important intermediates for the synthesis of pharmaceuticals and fine chemicals. Deracemization of racemic 2-HAs into the corresponding single enantiomers represents an economical and highly efficient approach for synthesizing chiral 2-HAs in industry. In this work, a novel ketoacid reductase from Leuconostoc lactis (LlKAR) with higher activity and substrate tolerance towards aromatic α-ketoacids was discovered by genome mining, and then its enzymatic properties were characterized. Accordingly, an engineered Escherichia coli (HADH-LlKAR-GDH) co-expressing 2-hydroxyacid dehydrogenase, LlKAR, and glucose dehydrogenase was constructed for efficient deracemization of racemic 2-HAs. Most of the racemic 2-HAs were deracemized to their (R)-isomers at high yields and enantiomeric purity. In the case of racemic 2-chloromandelic acid, as much as 300 mM of substrate was completely transformed into the optically pure (R)-2-chloromandelic acid (> 99% enantiomeric excess) with a high productivity of 83.8 g L?1 day?1 without addition of exogenous cofactor, which make this novel whole-cell biocatalyst more promising and competitive in practical application.
- Xue, Ya-Ping,Wang, Chuang,Wang, Di-Chen,Liu, Zhi-Qiang,Zheng, Yu-Guo
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- Resolving synthetic method for paramethoxymandelic acid
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The present invention relates to a resolving synthetic method for paramethoxymandelic acid. The method comprises the following steps of: by taking chiral alpha-phenylethylamine acid as a resolving agent, carrying out a salt forming reaction on the paramet
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- An efficient enzymatic aminolysis for kinetic resolution of aromatic α-hydroxyl acid in non-aqueous media
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A new and highly efficient enzymatic aminolysis approach for kinetic resolution of aromatic α-hydroxy acid in non-aqueous media has been developed. The corresponding α-hydroxyl acid ester was employed as the substrate, and commercially available Candida antarctica lipase B is used as the biocatalyst, anhydrous ammonia is the resolving agent. Reactions can be proceeded smoothly in organic solvent at ambient temperatures. High concentration of substrate is allowed due to the application of organic media and the products are obtained in yields of up to 49% with ee values of up to 99%, and with E value of >300, representing an appealing and promising protocol for large-scale preparations.
- Chen, Shan,Liu, Fuyan,Zhang, Kuan,Huang, Hansheng,Wang, Huani,Zhou, Jiaying,Zhang, Jing,Gong, Yiwei,Zhang, Dela,Chen, Yiping,Lin, Chang,Wang, Bo
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supporting information
p. 5312 - 5314
(2016/11/16)
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- One-pot, single-step deracemization of 2-hydroxyacids by tandem biocatalytic oxidation and reduction
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A facile and efficient one-pot, single-step method for deracemizing a broad range of 2-hydroxyacids to (R)-2-hydroxyacids was established by combination of resting cells of an (S)-hydroxyacid dehydrogenase-producing microorganism and an (R)-ketoacid reductase-producing microorganism.
- Xue, Ya-Ping,Zheng, Yu-Guo,Zhang, Ya-Qin,Sun, Jing-Lei,Liu, Zhi-Qiang,Shen, Yin-Chu
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supporting information
p. 10706 - 10708
(2013/11/06)
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- Highly enantioselective hydrogenation of aryl vinyl ketones to allylic alcohols catalyzed by the tol-binap/Dmapen ruthenium(II) complex
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(Chemical Equation Presented) Binap catalyst doesn't dmapen expectations: In basified 2-propanol, [RuCl2{(S)-tol-binap}{(R)-dmapen}] (1, see picture, Ar=4-CH3C6H4) catalyzes the highly enantioselective hydrogenation of a series of aryl vinyl ketones and affords the allylic alcohols in high yields with up to 98% ee. Formation of the saturated ketones and alcohols is suppressed with triphenylphosphine when necessary.
- Arai, Noriyoshi,Azuma, Keita,Nii, Noriyuki,Ohkuma, Takeshi
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supporting information; experimental part
p. 7457 - 7460
(2009/03/12)
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- Ester derivatives
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This invention relates to compounds which exhibit selective muscarinic M3 receptor antagonism, have little side effects, are suitable for inhalation therapy and are useful as treating agents of respiratory system diseases, of the general formula (I); 1[in which A signifies a group expressed by a formula (a0) or (b0); 2Ar signifies optionally substituted aryl or heteroaryl; B1 and B2 signify aliphatic hydrocarbon; R1 signifies fluorine-substituted cycloalkyl; R2, R3 and R4 signify lower alkyl, single bond or alkylene bonded to B1, or R2 and R3 are united to signify alkylene; R5 and R7 signify hydrogen, lower alkyl, or a single bond or alkylene bonded to B2; R6 signifies hydrogen, lower alkyl or a group expressed as —N(R8)R9; and X?signifies an anion].
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Page/Page column 30
(2008/06/13)
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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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- Chiral discrimination upon crystallisation of the diastereomeric salts of 1-arylethylamines with mandelic acid or p-methoxymandelic acid: Interpretation of the resolution efficiencies on the basis of the crystal structures
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The crystal structures of the diastereomeric salts of 1-arylethylamines with mandelic acid or p-methoxymandelic acid have been studied. This revealed that there was correlation between the efficiencies of the optical resolutions of the amines with the resolving reagents and the crystal structures of the salts. A characteristic hydrogen-bond layer, consisting of stable columnar structures and having a planar boundary surface, was found to be common to the less-soluble salt crystals; these crystals were considered to be stabilised from the viewpoint of both their hydrogen-bonding and van der Waals interactions. In contrast, in the corresponding more-soluble salts and in those diastereomeric salts which could not be separated by crystallisation, no such particularly stabilised crystal structure was formed; there only existed either columnar structures or planar boundary surfaces in these crystals. These results strongly suggest that for successful resolution it is necessary to realise a hydrogen-bond layer, consisting of stable columns and having planar boundary surfaces, in the crystals of one of the pair of diastereomeric salts. In order to achieve such a crystal structure, complementarity in molecular length between a target racemate and a resolving reagent must be considered the most important and fundamental factor.
- Kinbara, Kazushi,Sakai, Kenichi,Hashimoto, Yukihiko,Nohira, Hiroyuki,Saigo, Kazuhiko
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p. 2615 - 2622
(2007/10/03)
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- Tylosin derivative and method for preparing the same
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The compound 4''-O-p-Methoxymandeloyltylosin. The compound has excellent antibacterial activity and a reduced inhibitory activity on animal cells. Also are a method for preparing the compound, a pharmaceutical composition comprising the compound, and a me
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- Enantioselectivity of carbonic anhydrase catalyzed hydrolysis of mandelic methyl esters
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We report the first enantioselective hydrolysis of esters catalyzed by caebonic anhydrase.We found that mandelic methyl esters are good substrates for carbonic anhydrase.The R enantiomers are better substrates and enantiomeric excess values are moderate (40-51percent).
- Chenevert, Robert,Letourneau, Martin
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p. 314 - 316
(2007/10/02)
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- Semisynthetic cephalosporins. Synthesis and structure activity relationships of 7 mandelamido 3 cephem 4 carboxylic acids
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The synthesis, microbiological profile, and in vivo effectiveness in laboratory animals of a broad spectrum cephalosporin, 7(R) mandelamidocephalosporanic acid (1), are described. A number of derivatives and analogs of 1 were prepared and their structure activity relationships are discussed.
- Hoover,Dunn,Jakas,Lam,Taggart,Guarini,Phillips
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