7138-34-3Relevant academic research and scientific papers
Resolution of halogenated mandelic acids through enantiospecific co-crystallization with levetiracetam
Peng, Yangfeng,Wang, Jie
, (2021/09/18)
The resolution of halogenated mandelic acids using levetiracetam (LEV) as a resolving agent via forming enantiospecific co-crystal was presented. Five halogenated mandelic acids, 2-chloromandelic acid (2-ClMA), 3-chloromandelic acid (3-ClMA), 4-chloromandelic acid (4-ClMA), 4-bromomandelic acid (4-BrMA), and 4-fluoromandelic acid (4-FMA), were selected as racemic compounds. The effects of the equilibrium time, molar ratio of the resolving agent to racemate, amount of solvent, and crystallization temperature on resolution performance were investigated. Under the optimal conditions, the resolution efficiency reached up to 94% and the enantiomeric excess (%e.e.) of (R)-3-chloromandelic acid was 63%e.e. All five halogenated mandelic acids of interest in this study can be successfully separated by LEV via forming enantiospecific co-crystal, but the resolution performance is significantly different. The results showed that LEV selectively co-crystallized with S enantiomers of 2-ClMA, 3-ClMA, 4-ClMA, and 4-BrMA, while it co-crystallized with R enantiomers of 4-FMA. This indicates that the position and type of substituents of racemic compounds not only affect the co-crystal configuration, but also greatly affect the efficiency of co-crystal resolution.
Synthesis of α-hydroxycarboxylic acids from various aldehydes and ketones by direct electrocarboxylation: A facile, efficient and atom economy protocol
Singh, Kishanpal,Sohal, Harvinder Singh,Singh, Baljit
, p. 839 - 845 (2021/04/09)
In present work, the formation of α-hydroxycarboxylic acids have been described from various aromatic aldehydes and ketones via direct electrocarboxylation method with 80-92% of yield without any side product and can be purified by simple recrystallization using sacrificial Mg anode and Pt cathode in an undivided cell, CO2at (1 atm) was continuously bubbled in the cell throughout the reaction using tetrapropylammonium chloride as a supporting electrolyte in acetonitrile. The synthesized compounds obtained in fair to excellent yield with a high level of purity. The characterization of electrocarboxylated compounds was done with spectroscopic techniques like IR, NMR (1H & 13C), mass and elemental analysis.
Semirational Design of Fluoroacetate Dehalogenase RPA1163 for Kinetic Resolution of α-Fluorocarboxylic Acids on a Gram Scale
Chen, Bo,Li, Min,Li, Yanwei,Ma, Ming,Tian, Shaixiao,Tong, Wei,Wang, Jian-Bo,Xu, Guangyu,Yue, Yue,Zhang, Hongxia
, p. 3143 - 3151 (2020/03/23)
Here the synthetic utility of fluoroacetate dehalogenase RPA1163 is explored for the production of enantiomerically pure (R)-α-fluorocarboxylic acids and (R)-α-hydroxylcarboxylic acids via kinetic resolution of racemic α-fluorocarboxylic acids. While wild-type (WT) RPA1163 shows high thermostability and fairly wide substrate scope, many interesting yet poorly or moderately accepted substrates exist. In order to solve this problem and to develop upscaled production, in silico calculations and semirational mutagenesis were employed. Residue W185 was engineered to alanine, serine, threonine, or asparagine. The two best mutants, W185N and W185T, showed significantly improved performance in the reactions of these substrates, while in silico calculations shed light on the origin of these improvements. Finally, 10 α-fluorocarboxylic acids and 10 α-hydroxycarboxylic acids were prepared on a gram scale via kinetic resolution enabled by WT, W185T, or W185N. This work expands the biocatalytic toolbox and allows a deep insight into the fluoroacetate dehalogenase catalyzed C-F cleavage mechanism.
Enantioseparation of chiral mandelic acid derivatives by supercritical fluid chromatography
Ding, Jiawei,Zhang, Ming,Dai, Huixue,Lin, Chunmian
, p. 1245 - 1256 (2018/09/25)
Mandelic acid and its derivatives are important chiral analogs which are widely used in the pharmaceutical synthetic industry. The present study investigated the enantiomeric separation of six mandelic acids (mandelic acid, 2-chloromandelic acid, 3-chloromandelic acid, 4-chloromandelic acid, 4-bromomandelic acid, 4-methoxymandelic acid) on the Chiralpak AD-3 column by supercritical fluid chromatography. The influences of volume fraction of trifluoroacetic acid, type and percentage of modifier, column temperature, and backpressure on the separation efficiency were investigated. And the enantiomer elution order was determined. The results show that, for a given modifier, the retention factor, the separation factor, and the separation resolution decreased gradually with increasing the volume ratio of the modifier. At the same volume ratio of modifier, the retention factor of the mandelic acid and its derivatives increased in the order of methanol, ethanol, and isopropanol, except 3-chloromandelic acid. The separation factor and the separation resolution decreased with the increase of column temperature (below the temperature limit). The backpressure affected the enantioseparation process: As the backpressure increased, a corresponding decrease in retention factor was observed. Under the same chiral column conditions, the SFC method exhibited faster and more efficient separation with better enantioselectivity than the HPLC method.
Highly Efficient Deracemization of Racemic 2-Hydroxy Acids in a Three-Enzyme Co-Expression System Using a Novel Ketoacid Reductase
Xue, Ya-Ping,Wang, Chuang,Wang, Di-Chen,Liu, Zhi-Qiang,Zheng, Yu-Guo
, p. 1 - 13 (2018/04/26)
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.
The Synthesis of Chiral α-Aryl α-Hydroxy Carboxylic Acids via RuPHOX-Ru Catalyzed Asymmetric Hydrogenation
Guo, Huan,Li, Jing,Liu, Delong,Zhang, Wanbin
, p. 3665 - 3673 (2017/09/11)
A ruthenocenyl phosphino-oxazoline-ruthenium complex (RuPHOX?Ru) catalyzed asymmetric hydrogenation of α-aryl keto acids has been successfully developed, affording the corresponding chiral α-aryl α-hydroxy carboxylic acids in high yields and with up to 97% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 5000 S/C) and the resulting products can be transformed to several chiral building blocks, biologically active compounds and chiral drugs. (Figure presented.).
Enantioselective resolution of 4-chloromandelic acid by liquid–liquid extraction using 2-chloro-N-carbobenzyloxy-L-amino acid
Lu, Ruichen,He, Quan,Feng, Cai,Peng, Yangfeng
, p. 708 - 715 (2017/10/17)
A liquid–liquid extraction resolution of 4-chloro-mandelic acid (4-ClMA) was studied by using 2-chloro-N-carbobenzyloxy-L-amino acid (2-Cl-Z-AA) as a chiral extractant. Important factors affecting the extraction efficiency were investigated, including the type of chiral extractant, pH value of aqueous phase, initial concentration of chiral extractant in organic phase, initial concentration of 4-ClMA in aqueous phase, and resolution temperature. It was observed that the concentration of (R)-4-ClMA was much higher than that of (S)-4-ClMA in organic phase due to a higher stability of the complex formed between (R)-4-ClMA and 2-Cl-Z-AA. A separation factor (α) of 3.05 was obtained at 0.02 mol/L 2-Cl-Z-Valine dissolved in dichloromethane, pH of 2.0, concentration of 4-ClMA of 0.11 mmol/Land T of 296.7K.
Asymmetric hydrogenation reaction of alpha-ketoacids compound
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Paragraph 0037; 0044, (2016/10/10)
The invention relates to the technical field of organic chemistry, especially to an asymmetric hydrogenation reaction of an alpha-ketoacids compound. The asymmetric hydrogenation reaction comprises a scheme shown in the description. In the scheme, R1 is phenyl, substituted phenyl, naphthyl, substituted naphthyl, C1-C6 alkyl, or aralkyl; a substituent group is C1-C6 alkyl, C1-C6 alkoxy, or halogen; and the number of the substituent group is 1-3. In the scheme, M is a chiral spiro-pyridylamino phosphine ligand iridium complex having a structure shown in the description. In the structure, R is hydrogen, 3-methyl, 4-tBu, or 6-methyl.
Solid phase behavior in the chiral systems of various 2-hydroxy-2-phenylacetic acid (mandelic acid) derivatives
Von Langermann, Jan,Temmel, Erik,Seidel-Morgenstern, Andreas,Lorenz, Heike
, p. 721 - 728 (2015/03/30)
The solid phase behavior of a series of monosubstituted F-, Cl-, Br-, I-, and CH3- and two 2,4-halogen-disubstituted 2-hydroxy-2-phenylacetic acid (mandelic acid) derivatives was investigated. The study includes detailed information about melting temperature, melting enthalpy, X-ray diffraction data, as well as selected binary phase diagrams of the respective chiral systems. Aside from the known metastable conglomerate 2-chloromandelic acid, evidence for two more metastable conglomerates was found.
Design of nitrilases with superior activity and enantioselectivity towards sterically hindered nitrile by protein engineering
Xue, Ya-Ping,Shi, Cheng-Ci,Xu, Zhe,Jiao, Biao,Liu, Zhi-Qiang,Huang, Jian-Feng,Zheng, Yu-Guo,Shen, Yin-Chu
, p. 1741 - 1750 (2015/06/02)
Abstract The enantioselective hydrolysis of ortho-chloromandelonitrile with nitrilase is one of the most attractive approaches to prepare (R)-ortho-chloromandelic acid. To date, efforts to develop this nitrilase-mediated process were plagued by either insufficient eep (enantiomeric excess of product) or low activity due to the steric hindrance from the ortho-substituted substrate. To improve the nitrilase potential for producing (R)-ortho-chloromandelic acid, an enhancement of both activity and enantioselectivity towards sterically hindered nitriles would be highly desirable. Molecular docking of the (R)-ortho-chloromandelonitrile into the active site of wild-type 2A6 nitrilase (nitA) allowed the identification of proximal nitA active site residues. Several residues (52, 132, 189 and 190) were selected as targets for single and double point mutation to improve nitA activity and enantioselectivity towards ortho-chloromandelonitrile. Targeted mutagenesis yielded several nitA variants with superior activity and enantioselectivity. The best mutant T132A/F189T exhibited a 4.37-fold higher specific activity (7.39 U/mg) towards ortho-chloromandelonitrile than the wild-type nitA. More importantly, the enantioselectivity (E) was improved from 17.34 to >200, resulting in a highly enantiopure product. Molecular docking experiments further support the enhanced activity and enantioselectivity shown experimentally and the structural effects of this amino acid substitution on the active site of nitA are provided. The amino acids at sites 189 and 132 determine the activity and enantioselectivity towards ortho-chloromandelonitrile. With mutant T132A/F189T as a catalyst, a maximum of 450 mM of (R)-ortho-chloromandelic acid was produced with a 90% conversion and >99% eep within 3 h. This is the first time that a high productivity of (R)-ortho-chloromandelic acid of up to 671.76 g L-1d-1 using a nitrilase-mediated approach is reported. The engineered T132A/F189T variant represents a promising and competitive biocatalyst for practical application in synthesizing (R)-ortho-chloromandelic acid.
