• Title/Summary/Keyword: Catalysis

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Synthesis of Cyclohexene Derivatives from 1,5-Enynes via Gold-Catalysis and Iodocyclization: A Comparative Study and Applications in the Synthesis of 7/5- or 8/5-Fused Rings and Biaryls

  • Lee, Young-Un;Lim, Choong-Min;Kim, Sung-Hwan;Shin, Seung-Hoon
    • Bulletin of the Korean Chemical Society
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    • v.31 no.3
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    • pp.670-677
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    • 2010
  • A comparative study on the Au(I)-catalyzed and IBr-promoted tandem cyclization of 1,5-enyne was reported. This study provides a meaningful mechanistic insight to the concerted nature of this tandem reaction and also provides interesting applications in the synthesis of 7/5- or 8/5-fused bicycles and biaryls.

Transition metal-mediated/catalyzed fluorination methodology developed in the 2000s

  • Bae, Dae Young;Lee, Eunsung
    • Journal of Radiopharmaceuticals and Molecular Probes
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    • v.3 no.2
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    • pp.122-128
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    • 2017
  • In the 2000s, there has been a significant advance on carbon-fluorine (C-F) bond formation reactions via transition metal mediated or catalyzed methods. Of course, for the past 10 years, transition metal catalysis improves C-F bond formation in terms of practicality and even can be applied to C-18F bond formation reaction. In this mini-review, we summarize various transition metal mediated or catalyzed fluorination reactions, which were developed in the mid-2000s.

Development of Ferrocene-Containing Metal Catalysts for Asymmetric Synthesis (페로센을 이용한 비대칭 유기합성용 금속 촉매의 개발)

  • Oh, Yunghee;Choi, Mi-Jin
    • Applied Chemistry for Engineering
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    • v.10 no.5
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    • pp.804-807
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    • 1999
  • New copper complexes with a ligand, L(L=N,N'-cyclohexane bis(ferrocenylmethylene)amine) which was obtained from ferrocene carboxaldehyde and 1,2-diaminocyclohexane with a mole ratio of 2:1, were prepared and characterized. Those were adapted to asymmetric catalysis. The copper(II) complexes do not work in cyclopropanation of styrene and ethyl diazoacetate but copper(I) complex catalyzes. The Cu(I)LOTf (OTf=trifluorometanesulfonate) shows a good regioselectivity giving high trans to cis ratio of up to 80:20.

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ONIOM and Its Applications to Material Chemistry and Catalyses

  • Morokuma, Keiji
    • Bulletin of the Korean Chemical Society
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    • v.24 no.6
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    • pp.797-801
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    • 2003
  • One of the largest challenges for quantum chemistry today is to obtain accurate results for large complex molecular systems, and a variety of approaches have been proposed recently toward this goal. We have developed the ONIOM method, an onion skin-like multi-level method, combining different levels of quantum chemical methods as well as molecular mechanics method. We have been applying the method to many different large systems, including thermochemistry, homogeneous catalysis, stereoselectivity in organic synthesis, solution chemistry, fullerenes and nanochemistry, and biomolecular systems. The method has recently been combined with the polarizable continuum model (ONIOM-PCM), and was also extended for molecular dynamics simulation of solution (ONIOM-XS). In the present article the recent progress in various applications of ONIOM and other electronic structure methods to problems of homogeneous catalyses and nanochemistry is reviewed. Topics include 1. bond energies in large molecular systems, 2. organometallic reactions and homogeneous catalysis, 3. structure, reactivity and bond energies of large organic molecules including fullerenes and nanotubes, and 4. biomolecular structure and enzymatic reaction mechanisms.

Catalysis Reaction for the Formation of Hydrogen Cyanide from Metal Complex (금속착물로부터 HCN 생성에 대한 촉매반응연구)

  • 박흥재
    • Journal of Environmental Science International
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    • v.3 no.4
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    • pp.439-443
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    • 1994
  • In aqueous acid solution ${[Cr(CN)_6]}^{3-}$ aquates via a series of stepwise stereospecific reactions to give ${[Cr{(H_2O)}_6]}^{3+}$as the final product.Some of the intermediate cyanoaquo complexes in the sequence have been isolated.These complexes aquate by both acid independent and acid denpendent pathways, the latter involving protonation of the cyano ligands followed by aquation of the singly protonated species. The kinetic data for the aquation of {[CrCN{(H_2O)}_5]}^{2+}$ are consistent with the transition state structure ${[{(H_2O)}_4Cr(CN)-OH-Cr{(H_2O)}_5]}^{3+}$. Addition of $Cr^{2+}$ to solutions of cyanocobalt(III) complexes produces the metastable intermediate${[CrNC{(H_2O)}_5]}^{2+}$ This isomerizes to in a $Cr^{2+}$-catalyzed reaction which occurs by a ligand-bridged electron-change mechnism. From acid catalysis on these aquation reactions, it product HCN. Especially, $HSO_3$-ions do the role of catalyst in the formation of HCN from $CrCN^{3-}$

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