• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1807-1811
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• 2004

Supercritical fluid chromatography (SFC) was considered for separating racemic ibuprofen. The chromatographic column (3.9 ${\times}$ 150 mm) was packed with Kromasil$^{\circledR}$ CHI-TBB, and the mobile phase was supercritical carbon dioxide with modifier of IPA. The experimental variables were the content of IPA, and temperature and pressure of supercritical mobile phase. To determine the separation condition, the empirical equation of retention factor and resolution was proposed. In the case of retention factor, the empirical equation was in the form, $k\;=\;a{\rho}\;+b/F\;+\;c\;({\rho}/F)\;+\;d$. The empirical equation for resolution was proposed as a linear form, $R\;=\;a{\rho}\;+\;bF\;+\;c$.

• Bulletin of the Korean Chemical Society
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• 제23권9호
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• pp.1291-1294
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• 2002

Various racemic N-protected ${\alpha}-amino$ acids such as N-t-BOC-(tert-butoxycarbonyl), N-CBZ-(benzyloxycarbonyl) and N-FMOC-(9-fluorenylmethyloxycarbonyl) ${\alpha}-amino$ acids were resolved as their anilide and 3,5-dimethylanilde derivatives on an HPLC chira l stationary phase (CSP) developed by modifying a commercial (S)-leucine CSP. The chromatographic resolution results were compared to those on the commercial (S)-leucine CSP. The resolutions were greater on the modified CSP than those on the commercial CSP with only one exception, the resolution of N-t-BOC-phenylglycine anilide. In addition, the chromatographic resolution behaviors were quite consistent except for the resolution of N-protected phenylglycine derivatives, the (S)-enantiomers being retained longer. Based on the chromatographic resolution behaviors and with the aid of CPK molecular model studies, we proposed a chiral recognition mechanism for the resolution of N-protected ${\alpha}-amino$ acid derivatives. However, for the resolution of N-protected phenylglycine derivatives, a second chiral recognition mechanism, which competes in the opposite sense with the first chiral recognition mechanism, was proposed. The two competing chiral recognition mechanisms were successfully used in the rationalization of the chromatographic behaviors for the resolution of N-protected phenylglycine derivatives.

• Journal of Microbiology and Biotechnology
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• 제7권5호
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• pp.318-322
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• 1997

In order to isolate a microorganism having preferential degradation of D-carnitine from DL-carnitine, a bacterium assimilating D-carnitine as a sole carbon and energy source was isolated from soil by enrichment culture and partially identified as Enterobacter sp. Also, a mutant having lessened L-carnitine decomposition rates was selected with nitrosoguanidine mutagenesis, which led to decrease the specific activities of carnitine dehydrogenase (7.6-fold) and ${\beta}$-hydroxybutyrate dehydrogenase (9.5-fold) as compared to the wild strain. Meanwhile, optimal culture conditions for optical resolution of DL-carnitine were investigated. Under optimal conditions, 3.53 g/l L-carnitine was obtained from 20 g/l DL-carnitine, which corresponded to 35.3% L-carnitine yield and 97.9% optical purity.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.648-651
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• 2001

Kinetic resolution of various racemic aromatic epoxides by newly isolated Aspergillus niger LK has been investigated, and enantioselectivity of whole-cell biocatalyst was analyzed. The epoxide hydrolase (EHase) of A. niger LK was cloned using RT-PCR. The sequence homology was compared with that of other microbial EHase and the gene for EHase was characterized at molecular level.

• 약학회지
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• 제53권2호
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• pp.60-68
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• 2009

In terms of chiral issue, two enantiomers of chiral drugs often differ significantly in their pharmacological, toxicological and pharmacokinetic profile. Chiral switches of racemic drugs have been redeveloped as single enantiomers. Several chiral resolution techniques in chirotechnology are introduced and the most used chiral HPLC chromatographic method among several chiral analysis techniques is described with its several advantages. Several types of chiral HPLC columns derived from their chiral selectors are discussed with their property and applications for enantiomer separation.

• Bulletin of the Korean Chemical Society
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• 제29권2호
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• pp.313-318
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• 2008

An enantioselective ring opening of racemic terminal epoxides has been achieved by using heterobimetallic cobalt salen complexes with variety of nucleophiles. They were proven to be highly enantioselective and reactive for the synthesis of valuable chiral building blocks in enantio-riched forms up to 98% ee.

• Bulletin of the Korean Chemical Society
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• 제29권9호
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• pp.1850-1852
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• 2008

• Bulletin of the Korean Chemical Society
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• 제25권11호
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• pp.1707-1710
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• 2004

• Bulletin of the Korean Chemical Society
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• 제16권5호
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• pp.439-443
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• 1995

Both enantiomers of (S)-(-)-2-(diphenylphosphino)-2'-mercapto-1,1'-binaphthyl and their derivatives were obtained by synthesis from racemic 2,2'-dihydroxy-1,1'-binaphthyl and subsequent resolution. The utilities of these ligands were investigated briefly. And among these, S-methyl derivative 15 has proved to be an effective ligand for Pd-catalyzed allylic alkylation.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.220.3-220.3
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• 2003

Enantiomers of pindolol were prepared by chromatographic method. Racemic pindolol was derivatized with S-(-)-menthyl chloroformate((-)-MCF) forming its diastereomer, R-(+)-pindolol-(-)-MCF and S-(-)-pindolol-(-)-MCF. The diastereomer mixture was then chromatographically resolved to each diastereomer. Each diastereomer was further hydrolyzed with alkali to each enantiomer quantitatively. Racemization was not occurred in this process. Pindolol enantiomers were recovered producing good yield over 30% over all process.