• Title/Summary/Keyword: Enantioselective catalysis

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Application of Chiral Ligands Heterogenized over Solid Supports on Enantioselective Catalysis (고체 담체에 고정화된 키랄리간드의 비대칭 촉매반응에의 응용)

  • Lee, Kwang-Yeon;Kawthekar, Rahul B.;Kim, Geon-Joong
    • 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.

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Chiral Mesoporous Silica for Asymmetric Metal-free Catalysis: Enhancement of Chirality thorough Confinement Space by Plug Effect

  • Jeong, Eun-Yeong;Im, Cheong-Rae;Park, Sang-Eon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.199-199
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    • 2011

  • The addition of a carbanion to ${\yen}{\acute{a}}{\yen}{\hat{a}}$-unsaturated carbonyl compounds is of importance in the C-C bond formation reactions for modern pharmaceuticals and organic synthesis. Recently, heterogeneous asymmetric catalysis became more attractive area of research because of the easy recovery and separation of the catalyst from the reaction system. Most of synthetic methods for heterogeneous catalysts were grafting or immobilization of homogeneous catalyst onto the solid supports. Trans-1,2-Diaminocyclohexane(DACH) and L-proline ligands have been enormously used as chiral ligands in several catalytic transformation under homogenous conditions. Our group prepared l-proline functionalized mesoporous silica was synthesized under acidic condition using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer template (EO20PO70EO20, Pluronic P-123, BASF). Furthermore, we successfully directly synthesized trans-1,2 diaminocyclohexane functionalized mesoporous silica by using microwave method. The direct functionalization of chiral ligand into the framework of mesoporous materials is expected to be useful for the heterogeneous asymmetric catalysis. So, we adopt the direct synthesis of chiral ligand functionalized mesoporous silica by using thermal and microwave irradiation. Then, chiral ligand functionalized mesoporous silicas were applied to enantioselective asymmetric catalytic reactions.

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Organocatalytic Enantioselective Michael Addition of α-Nitroacetate to α,β-Unsaturated Enones: A Route to Chiral γ-Nitro Ketones and δ-Keto Esters

  • Moon, Hyoung-Wook;Kim, Dae-Young
    • Bulletin of the Korean Chemical Society
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    • v.32 no.1
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    • pp.291-295
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    • 2011

  • The catalytic enantioselective conjugate addition reaction of $\alpha$-nitroacetate to $\alpha,\beta$-unsaturated enones promoted by chiral bifunctional organocatalysts is described. The treatment of $\alpha$-nitroacetate to $\alpha,\beta$-unsaturated enones afforded the corresponding Michael adducts with high enantioselectivity. The conjugate addition adducts are easily converted to chiral $\gamma$-nitro ketones and $\delta$-keto esters.

  • https://doi.org/10.5012/bkcs.2011.32.1.291 인용 PDF KSCI