• Journal of the Korean Chemical Society
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• v.28 no.6
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• pp.399-402
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• 1984

The S-enantiomer of the 6,6'-dimethyl-2,2'-dia minobiphenyl (dmdabp) has been obtained by resolving dmdabp with l-tartaric acid. The square planar dichloro platinum(II) complex has been prepared with the optically active S-dmdabp, which is found to take the conformation in the [Pt(S-dmdabp)Cl$_2]$ complex.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.31-34
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• 1999

Membrane technology can be applied in two ways to produce pure enantiomers. In one case, a membrane separation process can be combined with an enantiospecific reaction to obtain so-called 'enantiospecific membrane reactor'. These systems are useful to carry out asymmetric synthesis or kinetic resolution and simultaneously separate the produced enantiomer. As for general membrane reactors, the result is a were compact system with a higher conversion; in fact, removal of a product drives equilibrium-limited reactions towards completion. The other way to apply membrane technology to chiral production is the use of intrinsically enantioselective membranes that are able to distinguish between two isomers favouring preperential transport of only one isomer in absence of reaction. In This paper, the current development of chiral membrane processes will be discussed.

• Analytical Science and Technology
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• v.17 no.1
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• pp.85-89
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• 2004

Fragrance components of lilac (Syringa vulgaris) blossom have been characterized in this paper. The accurate characterization of fragrances collected from lilac blossom was carried out by solid-phase trapping-solvent extraction and gas chromatography-ion trap mass spectrometry. According to lilac species, the chemical compositions were significantly different. Benzaldehyde, phenylacetaldehyde, and ${\alpha}$-farnesene were found as the predominant component of white lilac blossom whereas benzaldehyde, ${\alpha}$-pinene, and ocimene were those of pale purple lilac. The enantiomeric analysis of ${\alpha}$-pinene in lilac blossom was found in the form of ( ).

• Journal of Applied Biological Chemistry
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• v.49 no.1
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• pp.21-23
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• 2006

As part of a program to discover bioactive natural products from marine organisms, two new enantiomers, ent-3,6-Epidioxy-4,6,8,10-tetraethyltetradeca-7,11-dienoic acid and ent-[3,5-Diethyl-5-(2-ethyl-hex-3-enyl)-5H-furan-2-ylidene]-acetic acid methyl ether, were isolated from a sponge Plakortis sp. These compounds showed strong in vitro antiproliferative effects on promastigotes of Leishmania mexicania, flagellate protozoan that causes leishmaniasis. Structures were assumed by interpretation of NMR spectroscopic data and optical rotation. Both compounds exhibited significant antileishmanial activities in vitro with $IC_{50}$ of 1.0-23.0 ${\mu}g/ml$.

• Food Science and Biotechnology
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• v.17 no.6
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• pp.1310-1315
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• 2008

This study was to investigate the influence of pH on the antioxidant activity of melanoidins formed from glucose (Glc) and fructose (Fru) with lysine enantiomers in the Maillard reaction. Melanoidins formed from D-isomers were found to be effective antioxidants in different in vitro assays with regard to the ferrous ion chelating activity, 1, l-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging activities, ferric reducing/antioxidant power (FRAP), and 2,2'-azinobis(3-ethylbenothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity. In particular, the chelating activity of these melanoidins at a pH of 7.0 was greater than those with pH of 4.0 and 10.0. The chelating activity and DPPH radical scavenging activity of the melanoidins formed from the Glc systems were higher than those of the melanoidins formed from the Fru systems. However, the FRAP and ABTS radical scavenging activity of these melanoidins were not different according to pH level, with exceptions being the Fru systems.

• Bulletin of the Korean Chemical Society
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• v.17 no.12
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• pp.1117-1123
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• 1996

Chiral recognition models for resolving π-basic N-acyl-α-(1-naphthyl)alkylamines and π-acidic N-(3,5-dinitrobenzoyl)-α-amino alkyl esters on a (S)-tyrosine-derived chiral stationary phase (CSP) containing both π-basic and π-acidic interaction site have been proposed. In the models, the CSP was supposed to interact with the analytes through the π-π interaction between the 3,5-dinitrophenyl or the 3,5-dimethylphenyl group of the CSP and the 1-naphthyl or the 3,5-dinitrophenyl group of the analyte, and through the hydrogen bonding interaction between the appropriate N-H hydrogen of the CSP and the appropriate carbonyl oxygen of the analyte. In this instance, the alkyl substituent of the pertinent enantiomer of the analyte was found to intercalate between the adjacent strands of the bonded phase and consequently control the trends of the separation factors.

• Archives of Pharmacal Research
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• v.18 no.2
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• pp.69-74
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• 1995

In order to improve physico-chemical properties and to enhance stability of drugs, amino acid salt has been widely adoptd in pharmaceutical synthesis. Acetylsalicylic acid lysinate is one of the widely used analgesics and it is a good example of t5his synthesis. In the case of bacetylsalicylic acid lysinate synthesis, racemization of natrually occurred lysine is esential because the racemic lysine salt of the drug shows better yield, crystallinity and dryness than that of the L-lysine salt. To esatablish a simple, practical and economical process for L-lysine racemization, L-lysine treatments with phosphoric acid and with acetic acid were compared and the optimum conditions for its process and derivatization were investigated by chiral separation methods using GC_MS spectroscopy.

• Archives of Pharmacal Research
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• v.23 no.6
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• pp.568-573
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• 2000

A reversed-phase high-performance liquid chromatographic method was developed to determine the optical purity of bevantolol enantiomers. (S)-(-)-Menthyl chloroformate((-)-MCF), (S)-(-)-$\alpha$-methylbenzyl isocyanate((-)-MBIC) and 2,3,4,6-tetra-O-acetyl-$\beta$-D-glucopyranosyl isothiocyanate(GITC), which can react with the secondary amine group of bevantolol were investigated as chiral derivatization reagents. Among them indirect chiral HPLC method using CITC gave the best result. The derivatization proceeded quantitatively within 20 min at room temperature. Separation of the enantiomers as diastereomers was achieved by reversed-phase HPLC within 20min using ODS column. Different ratios of (S)-(-)-bevantolol and (R)-(+)-bevantolol were prepared. Enantiomeric separation of these mixtures took place on a chiralcel OD column or, after derivatization with GITC, on a ODS column. No racemization was found during the experiment. This method allowed determination of 0.05% of either enantiomer in the presence of its stereoisomer and method validation showed adequete linearity over the required range.

• Bulletin of the Korean Chemical Society
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• v.31 no.3
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• pp.678-682
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• 2010

A doubly tethered chiral stationary phase (CSP) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid were applied to the liquid chromatographic resolution of racemic tocainide, an antiarrhythmic agent, and its analogues. The chiral recognition efficiency of the doubly tethered CSP for tocainide and its analogues was generally greater than that of the corresponding singly tethered CSP especially in terms of the resolution ($R_S$). The resolution of tocainide and its analogues on the doubly tethered CSP were dependent on the content and the type of the organic and acidic modifiers in aqueous mobile phase and the column temperature. Especially, the retention behaviors of analytes on the doubly tethered CSP with the variation of the content of organic modifier in aqueous mobile phase were opposite to those on the corresponding singly tethered CSP and these opposite retention behaviors were rationalized by the lipophilicity differences of the two CSPs.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1715-1718
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• 2012

2-Hydroxy-6-(1-(3-phenylurylphenyl)ethoxy)-benzaldehyde ($\mathbf{2}$) has been synthesized in racemic form from 1,3-Dihydroxybenzene via formylation and reaction with 3-phenyluryl-methylbenzylbromide. The optically pure form of $\mathbf{2}$ was separated by normal silica column chromatography from the imine diastreomer which was obtained by the reaction of racemic mixture of $\mathbf{2}$ with optically pure leucinol. The absolute configuration of the separated enantiomer of $\mathbf{2}$ was decided from the energy calculation of the corresponding imine diastereomers. The activity of $\mathbf{2}$ as a chirality conversion reagent (CCR) for amino acids was determined by $^1H$ NMR analysis. The efficiency of $\mathbf{2}$ is not better than the previous CCRs based on binaththol. Compound $\mathbf{2}$, however, has lower molecular weight compared to other CCRs. This work demonstrates that asymmetric carbon can control the selectivity of amino acids.