• Title/Summary/Keyword: chiral

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Chiral Separation of Arylalcohols by Capillary Electrophoresis Using Sulfonated β-Cyclodextrin and Ag Colloids as Additives

  • Choi, Seong-Ho;Noh, Hyen-Ju;Lee, Kwang-Pill
    • Bulletin of the Korean Chemical Society
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    • v.26 no.10
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    • pp.1549-1554
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    • 2005
  • Chiral separation of arylalcohols such as 1-phenyl-1-propanol, 1-phenyl-2-propanol, and 2-phenyl-1-propanol by capillary electrophoresis was studied using sulfonated $\beta$-cyclodextrin (CD) as a chiral selector and Ag colloids as an additive. The optimum separation condition of arylalcohols was found to be the chiral selector concentration of 6.5 mM, applied voltage of 15 kV, and pH of 7.0. In order to improve chiral separation, an Ag colloid was mixed with a running buffer. The resolution in the Ag colloid-mixed running buffer was considerably superior to that obtained with the sulfonated $\beta$-CD alone. The molar ratio of sulfonated $\beta$-CD to Ag colloid, which is one of critical parameters affecting resolution, was found to be optimum at 65 : 1. In order to elucidate the resolution mechanism, an inclusion-complex of the arylalcohols with sulfonated $\beta$-CD was prepared by mixing and shaking in solution, and then characterized by cyclic voltammetry (CV). The inclusion mechanism was also discussed using experimental results.

Asymmetric Michael Addition of Ketones to Nitroolefins Catalyzed by a New Chiral Catalyst

  • Wang, Lian-Jun;Hu, Feng-Feng
    • Bulletin of the Korean Chemical Society
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    • v.31 no.5
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    • pp.1280-1282
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    • 2010
  • A new chiral catalyst was synthesized and found that it could catalyzed the asymmetric Michael reaction of ketones with nitroolefins smoothly at room temperature, giving the desired adducts in 71 - 92% yields with excellent diastereoselectivities and high enantioselectivities (up to 95% ee).

Surface-plasmon wave at a planar metal-chiral interface

  • Sobahan, K.M.A;Park, Yong-Jun;HwangBo, Chang-Kwon
    • Proceedings of the Optical Society of Korea Conference
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    • 2009.02a
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    • pp.233-234
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    • 2009
  • The theoretical study of a surface-plasmon wave at a planar metal-chiral interface is presented in this communication. It is found that a surface-plasmon wave can be excited at the planar interface of a thin metal film and a structurally dielectric chiral medium, if the exciting plane wave is P-polarized.

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Asymmetric Cyanosilylation of Aldehydes by Chiral Ti-TADDOL Complex

  • Kim, Sung-Soo;Kwak, Ju-Myung;Rajagopal, Gurusamy
    • Bulletin of the Korean Chemical Society
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    • v.27 no.10
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    • pp.1638-1640
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    • 2006
  • A variety of chiral cyanohydrins were readily prepared from aldehydes with TMSCN under the influence of chiral titanium complex formed in situ from $Ti(O^iPr)_4$/TADDOL(I) in the presence of $Ph_3PO$ as additive. The double activation method produces trimethylsilylethers in excellent yield (95%) with moderate enantiomeric excess.

Explorations of the Heteroatom Directed Photoarylation Reaction. A Review of the Photoinitiated Intramolecular Cycloaddition Reactions of Ylide Systems

  • Dittami, James P.
    • Journal of Photoscience
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    • v.10 no.1
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    • pp.21-35
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    • 2003
  • The photoinitiated intramolecular ylide-olefin addition has been developed as an approach for the construction of one ring and two chiral centers, two rings and three chiral centers or three rings and six chiral centers in a single experimental operation from relatively simple starting materials. These investigations have uncovered several interesting and unusual reactions, which are sensitive to controls such as wavelength, temperature and solvent.

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HPLC Resolution of Enantiomers Using Polysaccharide Derivatives as Chiral Stationay Phases

  • Okamoto, Yoshio
    • Proceedings of the PSK Conference
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    • 2002.10a
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    • pp.163-164
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    • 2002
  • In the past two decades, separations of enantiomers (optical isomers) by high-performance liquid chromatography (HPLC) have remarkably advanced [1]. Among many commercially available chiral stationary phases (CSPs) for HPLC, polysaccharide-based CSPs are the most popular ones, which can cover the resolution of a wide range of the chiral compounds [2, 3, 4]. Here, I will explain mainly the HPLC separation of enantiomers using these CSPs. (omitted)

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Organocatalytic Asymmetric Michael Addition of 1,3-Cyclohexanedione to Benzylidenemalonitriles

  • Suh, Chang Won;Kim, Dae Young
    • Bulletin of the Korean Chemical Society
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    • v.35 no.1
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    • pp.98-102
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    • 2014
  • The organocatalytic enantioselective Michael addition reaction promoted by chiral binaphthyl-modified squaramide catalyst have been developed, allowing facile synthesis of the corresponding chiral 2-amino-4H-chromenes derivatives with excellent enantioselectivity (up to 99% ee). The method reported represents a practical entry for the preparation of chiral 2-amino-4H-chromenes derivatives.