• Title/Summary/Keyword: coupling reaction

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Asymmetric Synthesis of 12-epi-$PGF_{2α}$ by a Palladium-Mediated, Three-Component Coupling Reaction

  • 이남호;Richard C. Larock
    • Bulletin of the Korean Chemical Society
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    • v.16 no.9
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    • pp.859-863
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    • 1995
  • The prostaglandin analogue 12-epi-PGF2α (2) has been synthesized from optically active cis-4-t-butyldimethylsilyloxy-2-cyclopenten-1-ol (4b) in 4 steps in an overall yield of 21%. An extremely efficient Pd(Ⅱ)-mediated, three-component coupling reaction is employed to obtain the key intermediate 9.

Synthesis and Characterization of Low Molecular Weight Poly(methyl acrylate)-b-Polystyrene by a Combination of ATRP and Click Coupling Method

  • Hasneen, Aleya;Kim, Su-Jeong;Paik, Hyun-Jong
    • Macromolecular Research
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    • v.15 no.6
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    • pp.541-546
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    • 2007
  • The combination of atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of well-defined block copolymers. Bromo terminated poly(methyl acrylate) (pMA-Br) was prepared by an ATRP initiator, ethyl-2-bromoisobutyrate (EBiB). Subsequently, the bromine chain end of pMA-Br was converted to an azide group by simple nucleophilic substitution reaction. ${\alpha}-Alkyn-{\omega}-bromo-functionalized$ polystyrene was also synthesized by ATRP using the alkyn-functionalized initiator, propargyl-2-bromoisobutyrate (PgBiB). In both cases, the conversion was limited to a low level to ensure a high degree of chain end functionality. Then the coupling reaction between the azide end group in $pMA-N_3$ and alkyn-functionalized PgBiB-pSt was performed by Cu(I)catalysis. This coupling reaction was monitored by gel permeation chromatography (GPC). The synthesized block copolymer was characterized by FT-IR, $^1H-NMR$ spectroscopy and $^1H-^1H$ COSY correlation spectroscopy.

Synthesis of Palladium Nanoparticles Encapsulated in Phosphine Ligand-Grafted Mesoporous Silicas and Their Application to Suzuki Cross-Coupling Reaction (팔라듐 나노입자가 담지된 메조포러스 실리카의 제조와 이를 이용한 Suzuki Cross-Coupling 반응의 적용연구)

  • Kim, Sang-Wook;Joo, Jin
    • Clean Technology
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    • v.17 no.1
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    • pp.13-18
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    • 2011
  • Phosphine ligand-grafted mesoporous silica materials with large pores were prepared for the ligand-modified heterogeneous Pd nanocatalysts. New heterogeneous catalytic system was developed using palladium nanoparticles encapsulated in phosphine ligand-grafted mesoporous silica. The catalyst showed good catalytic activities for Suzuki cross-coupling using bromobenzene derivatives due to excellent phosphine ligand effects. Catalytic results showed nanoparticie catalysts can be recycled twice with decreased yields.

Effect of Functionalized Binary Silane Coupling Agents by Hydrolysis Reaction Rate on the Adhesion Properties of 2-Layer Flexible Copper Clad Laminate (이성분계 실란 커플링제의 가수분해속도 조절에 의한 2-FCCL의 접착특성 변화 연구)

  • Park, U-Joo;Park, Jin-Young;Kim, Jin-Young;Kim, Yong-Seok;Ryu, Jong-Ho;Won, Jong-Chan
    • Polymer(Korea)
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    • v.35 no.4
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    • pp.302-307
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    • 2011
  • The parameters of silanol formation reaction of organosilane including solvent type, solution concentration, pH and hydrolysis time influence the adhesion property of 2 layer flexible copper clad laminate (FCCL). Especially, the hydrolysis reaction time of silane coupling agent affects the formation of the silanol groups and their self-condensation to generate oilgomeric structure to enhance the surface treatment as an adhesive promoter. In our study, we prepared the binary silane coupling agents to control hydrolysis reaction rate and surface energy after treatment of silane coupling agents for increasing the adhesive property between a copper layer and a polyimide layer. The surface morphology of rolled copper foil, as a function of the contents of the coated binary silane coupling agent, was fully characterized. As fabricated 2-layer FCCL, we observed that adhesive properties were changed by hydrolysis rate and surface energy.

Palladium-Catalyzed Cross-Coupling Reaction and Gold-Catalyzed Cyclization for Preparation of Ethyl 2-Aryl 2,3-Alkadienoates and α-Aryl γ-Butenolides

  • Mo, Jun-Tae;Hwang, Hoon;Lee, Phil-Ho
    • Bulletin of the Korean Chemical Society
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    • v.32 no.spc8
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    • pp.2911-2915
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    • 2011
  • Efficient synthetic method for the preparation of ethyl 2-aryl-2,3-alkadienoates through Pd-catalyzed selective allenyl cross-coupling reactions of aryl iodides with organoindiums generated in situ from indium and ethyl 4-bromo-2-alkynoate was developed. The cyclization reaction of ethyl 2-aryl-2,3-alkadienoates catalyzed by $AuCl_3$ and AgOTf in the presence of AcOH or TfOH produced various ${\alpha}$-aryl ${\gamma}$-butenolides or ${\gamma}$-substituted ${\alpha}$-aryl ${\gamma}$-butenolides.

Enzymatic Synthesis of L-tert-Leucine with Branched Chain Aminotransferase

  • Seo, Young-Man;Yun, Hyung-Don
    • Journal of Microbiology and Biotechnology
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    • v.21 no.10
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    • pp.1049-1052
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    • 2011
  • In this study, we demonstrated the asymmetric synthesis of L-tert-leucine from trimethylpyruvate using branched-chain aminotransferase (BCAT) from Escherichia coli in the presence of L-glutamate as an amino donor. Since BCAT was severely inhibited by 2-ketoglutarate, in order to overcome this here, we developed a BCAT/aspartate aminotransferase (AspAT) and BCAT/AspAT/pyruvate decarboxylase (PDC) coupling reaction. In the BCAT/AspAT/PDC coupling reaction, 89.2 mM L-tert-leucine (ee>99%) was asymmetrically synthesized from 100 mM trimethylpyruvate.

Coupling Reaction of CO2 with Epoxides by Binary Catalytic System of Lewis Acids and Onium Salts

  • Bok, Taekki;Noh, Eun Kyung;Lee, Bun Yeoul
    • Bulletin of the Korean Chemical Society
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    • v.27 no.8
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    • pp.1171-1174
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    • 2006
  • Various off-the-shelf Lewis acids in conjunction with various onium salts are screened for coupling reaction of $CO_2$ with epoxides. Among the tested ones, $VCl_3/n-Bu_4NOAc$, $VCl_3/(n-Bu_4NCl$ or PPNCl), $FeCl_3/ n-Bu_4NOAc$, and $FeCl_3/ n-Bu_4NOAc$are proved to be highly active. Propylene oxide, epichlorohydrin, styrene oxide, and cyclohexene oxide can be converted over 90% yields to the corresponding cyclic carbonates without the use of organic solvents under mild conditions by 0.1-1.0 mol% catalyst charge.

Synthesis of Graphene Oxide Based CuOx Nanocomposites and Application for C-N Cross Coupling Reaction

  • Choi, Jong Hoon;Park, Joon B.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.176.1-176.1
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    • 2014
  • Graphene has attracted an increasing attention due to its extraordinary electronic, mechanical, and thermal properties. Especially, the two dimensional (2D) sheet of graphene with an extremely high surface to volume ratio has a great potential in the preparation of multifunctional nanomaterials, as 2D supports to host metal nanoparticles (NPs). Copper oxide is widely used in various areas as antifouling paint, p-type semiconductor, dry cell batteries, and catalysts. Although the copper oxide(II) has been well known for efficient catalyst in C-N cross-coupling reaction, copper oxide(I) has not been highlighted. In this research, CuO and Cu2O nanoparticles (NPs) dispersed on the surface of grapehene oxide (GO) have been synthesized by impregnation method and their morphological and electronic structures have been systemically investigated using TEM, XRD, and XAFS. We demonstrate that both CuO and Cu2O on graphene presents efficient catalytic performance toward C-N cross coupling reaction. The detailed structural difference between CuO and Cu2O NPs and their effect on catalytic performance are discussed.

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Graphene Based Cu Oxide Nanocomposites for C-N Cross Coupling Reaction

  • Choi, Jong Hoon;Park, Joon B.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.138.2-138.2
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    • 2013
  • Copper oxide is a multi-functional material being used in various research areas including catalysis, electrochemical materials, oxidizing agents etc. Among these areas, we have synthesized and utilized graphene based copper oxide nanocomposites (CuOx/Graphene) for the catalytic applications (C-N cross coupling reaction). Briefly, Cu precursors were anchored on the graphite oxide(GO) sheets being exfoliated and oxidized from graphite powder. Two different crystalline structures of Cu2O and CuO on graphene and GO were prepared by annealing them in Ar and O2 environments, respectively. The morphological and electronic structures were systemically investigated using FT-IR, XRD, XPS, XAFS, and TEM. Here, we demonstrate that the catalytic performance was found to depend on oxidative states and morphological structures of CuOx graphene nanocomposites. The relationship between the structure of copper oxides and catalytic efficiency toward C-N cross coupling reaction will be discussed.

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