• KSBB Journal
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• v.15 no.6
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• pp.541-547
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• 2000

Simulated moving bed (SMB) chromatography has been investigated in order to separate chiral compounds for pharmaceutical use. SMB utilizes the principle of true moving bed (TMB) chromatography, and has the advantages of low solvent usage, flexible configuration of columns and hardwares, and high productivity of the chiral compounds over the TMB. Large scale separation of xylene isomers and saccharides has been conducted since 1960s. However, the application of SMB in the fine chemical industries is still in the infant stage. The study of SMB for the chiral compounds production was initiated in the mid 1990s and further researches are actively undergoing. This review summarizes the principle of SMB as well as the chemistry of chiral stationary phase and chiral compounds.

• Bulletin of the Korean Chemical Society
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• v.16 no.6
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• pp.489-492
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• 1995

A new synthetic route to chiral liquid crystal dopant, 4-[2-(7S-methylnonanyl)oxy-5-pyrimidinyl]phenyl(2S,3S)-2-chloro-3-methylpentanoate (1), starting from 4-nitrophenylacetic acid is described. The key intermediate methylthiopyrimidine compound (8) has been synthesized from 4-nitrophenylacetic acid by Vilsmyer-Haack reaction followed by the formation of pyrimidine ring, and then converted to chiral ester (1) by the replacement of nitro group by (2S,3S)-2-chloro-3-methylpentanoic acid 2 through the formation of diazonium salt.

• Applied Chemistry for Engineering
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• v.17 no.6
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• pp.565-574
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• 2006

The trend towards the application of single enantiomers of chiral compounds is undoubtedly increasing. Among the various methods to obtain one single enantio-riched compound selectively, enantioselective catalysis is the most attractive method. Especially, it is important to increase the activity, selectivity and lifetime of usually expensive chiral catalysts with a minute quantity in the enantioselective synthesis. Immobilization of active homogeneous catalysts is a fashionable topic in asymmetric catalysis, providing the inherent advantage of easy separation and better handling properties. Many different ways have been investigated to improve the enantioselectivity of products and to recycle the catalysts. This review mainly focused on the present scope and limitations of different types of enantioselective heterogeneous catalysts.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2938-2942
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• 2009

New receptors 1-3 that bind stereoselectively amino alcohols and convert chirality of amino acidsvia imine bond formation were synthesized. The receptors have uryl (1), thiouryl (2) and guanidinium (3) groups all with additional phenylcarbonyl motifs, which are effective hydrogen bonding donors and play a key role in the stereoselective recognitions. The stereoselectivities were measured from the integration of $^1HNMR$ peaks. Compound 1 and 2 showed the stereoselectivities for the imine formation with amino alcohols ($K_R/K_S$) in the range of 2${\sim}$4, and compound 3 in the range of 4${\sim}$8. Chirality conversion efficienciesof 1-3 for amino acids, i.e. D/L ratio at equilibrium, are in the range of 1.5${\sim}$5.6, showing a little higher efficiency with 3. The additional phenylcarbonyl motifs in 1-3 were revealed not to contribute to significant enhancement of the selectivities.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.363.1-363.1
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• 2002

Costunolide. a sesquiterpene lactone is isolated from Magnolia Sieboldi. It is known to possess antitumour and anti-inflammatory activities. This compound is synthesized from Ihe easily available decalin dione using the ring cleavage approach to construct the ten-membered ring system. The two keys points in this work are the chiral inductionon the allyl alcohol moiety using Sharpless epoxidation reaction and opening of the eopxide with an organocuprate reagent which leads to a $\alpha$-exomethylene lactone. (omitted)

• KSBB Journal
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• v.19 no.4
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• pp.263-268
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• 2004

The separation method using chiral stationary phase in preparation of chiral compound was wildly used, but in this work, supercritical fluid chromatography was suggested in the stability to resolve the chiral mixtures. To determine the optimum operating condition of the racemic ibuprofen, the retention factor and resolution with change in pressures, temperatures and the contents of IPA % (vol.) in CO$_2$ were investigated. The retention factor was decreased with increase in pressure and decrease in temperature. The factor was also influenced by the content of IPA in mobile phase, while the resolution was worse with a increase in IPA %. From the experimental results, the desirable separation condition was 130 bar, 311.15 K and 4% IPA in CO$_2$. Compared to the asymmetric peak shape by liquid chromatography, that of supercritical fluid chromatography was symmetric which was a favorable condition for preparative separation.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.115-118
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• 2018

Dipyrromethane 2 functionalized with 3-chloropropyl group on the meso carbon undergoes an unusual intramolecular electrophilic aromatic substitution reaction in the presence of $NaN_3$ instead of a simple nucleophilic substitution reaction. As a result, a new chiral dipyrromethane 1 was synthesized. In this reaction, the ${\beta}$-carbon of the pyrrole ring functions as a nucleophile while the carbon next to the chlorine atom acts as an electrophile. Interestingly, this reaction progresses even in the absence of an acid catalyst. Compound 1 was fully characterized by $^1H-^1H$ and $^1H-^{13}C$ COSY NMR spectroscopic analyses and the high resolution EI mass spectrometry.

• Korean Journal of Crystallography
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• v.11 no.2
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• pp.89-94
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• 2000

A crystallographic unit cell can be transformed into another one by a 3×3 transformantion matrix. If the determinant of the transformation matrix has a negative value, the newly transformed unit cell becomes a left-handed cell. The best way of transforming the left-handed cell to the right-handed one is to multiply each element of the transformation matrix by-1, and its corresponding transformation matrix must be applied tot he atomic coordinates of a noncentrosymmetric crystal so as to maintain the absolute configuration unchanged. The behaviour of absolute configuration caused by transforming the crystallographic unit cell was examined theoretically and experimentally on the compound (S)-(+)-4-phenyl-1-[4-aminobenzoyl) indoline-5-sulfonyl]-4,5-dihydro-2-imidazolone hydrochloride.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1371-1377
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• 2013

A new synthetic route to N-Cbz-cis-(3R,4R)-3-methylamino-4-methylpiperidine, key intermediate for CP-690,550, was disclosed with L-malic acid as the chiral pool starting material. The title compound was obtained in 16 steps with a total yield of 26% and more than 98% ee.

• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1395-1402
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• 2013

Reductases convert some achiral ketone compounds into chiral alcohols, which are important materials for the synthesis of chiral drugs. The Saccharomyces cerevisiae reductase YOR120W converts ethyl-4-chloro-3-oxobutanoate (ECOB) enantioselectively into (R)-ethyl-4-chloro-3-hydroxybutanoate ((R)-ECHB), an intermediate of a pharmaceutical. As YOR120W requires NADPH as a cofactor for the reduction reaction, a cofactor recycling system using Bacillus subtilis glucose dehydrogenase was employed. Using this coupling reaction system, 100 mM ECOB was converted to (R)-ECHB. A homology modeling and site-directed mutagenesis experiment were performed to determine the NADPH-binding site of YOR120W. Four residues (Q29, K264, N267, and R270) were suggested by homology and docking modeling to interact directly with 2'-phosphate of NADPH. Among them, two positively charged residues (K264 and R270) were experimentally demonstrated to be necessary for NADPH 2'-phosphate binding. A mutant enzyme (Q29E) showed an enhanced enantiomeric excess value compared with that of the wild-type enzyme.