52923-25-8Relevant articles and documents
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.
Preparation and reactions of certain racemic and optically active cyanohydrins derived from 2-chlorobenzaldehyde, 4-fluorobenzaldehyde, benzo[d][1,3]-dioxole-5-carbaldehyde and 2,3-dihydrobenzo[b][1,4]dioxine-6-carbaldehyde. Antimicrobial and in vitro antitumor evaluation of the products
Yosef, Hisham Abdallah A.,Elmasry,Ibrahim, Nabila M.,Ismael, Eman H. I.,Mahran
, p. 301 - 328 (2017/06/08)
THE CHEMOENZYMATIC reaction of selected aldehydes, namely 2-chlorobenzaldehyde (1a), 4-fluorobenzaldehyde (1b), benzo[d][1,3]dioxole-5-carbaldehyde (1c) and/or 2,3-dihydrobenzo [b] [1,4] dioxine-6-carbaldehyde (1d) with hydrogen cyanide in presence of (R)-oxynitrilase (R)-Pa HNL [EC 4.1.2.10] from almonds, as a chiral catalyst, gave the optically active cyanohydrin enantiomers ( R)-2a-c, respectively. Acetone cyanohydrin (3), was also used, as a transcyanating agent, to give the same products. The racemic cyanohydrins (R,S)-2a-d have been synthesized, as well, by treating compounds 1a-d with aqueous potassium cyanide solution in presence of a saturated solution of sodium metabisulphite (Na2S2O5). The optical purity of cyanohydrins (R)-2a-c was determined through their derivatization with (S)-naproxen chloride (S)-5 to the respective diastereomers (R,2S)-6a-c which were obtained in diastereomeric excess (de) values up to 93 % (1H NMR). Heating compounds (R)-2a,b and / or their racemic analogues (R,S)-2a-c with concentrated hydrochloric acid gave the respective α-hydroxycarboxylic acids 7a-c. Moreover, reduction of cyanohydrins (R,S)-2b,c under different conditions resulted in a hydrodecyanation giving the respective primary alcohols 8a,b. Structures and configurations of the new compounds were confirmed with compatible elementary microanalyses and spectroscopic (IR, 1H NMR, 13C NMR, MS and single crystal X-ray crystallography) measurements. The antimicrobial activity of derivatives 6a-d against four bacterial species (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and two fungi (Aspergillus flavus and Candida albicans) were undertaken. Moreover, compounds (R,2S)-6b, (R,2S)(S,2S)-6b and (R,2S)-6c were screened for their in virto antitumor activity against three human solid cancer cell lines (HCT 116, HepG2 and MCF-7). In general, the tested compounds were found inactive or showed weak activities in comparison with the standard drugs.
Asymmetric hydrogenation reaction of alpha-ketoacids compound
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Paragraph 0031; 0032; 0033; 0037, (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.
