The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
Alfred F Noels - One of the best experts on this subject based on the ideXlab platform.
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Kharasch Addition catalysed by half sandwich ruthenium complexes enhanced activity of ruthenacarboranes
Tetrahedron Letters, 2003Co-Authors: Oscar Tutusaus, Sebastien Delfosse, Albert Demonceau, Alfred F Noels, Clara Vinas, Francesc TeixidorAbstract:Abstract Ruthenium complexes of the type [RuH(η5-CB)(PPh3)2] {CB is a monoanionic charge-compensated carborane ligand such as [9-SR2-7,8-C2B9H10]− and [9-SR2-7-CH3-7,8-C2B9H9]−} efficiently catalyse the Kharasch Addition of CCl4 across olefins and, with maximum total turnover numbers of 9000 and initial turnover frequencies of 1900 h−1 at 40°C, highly surpass their Ru–Cp# analogues in these reactions.
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highly efficient Kharasch Addition catalysed by rucl cp pph3 2
Tetrahedron Letters, 2000Co-Authors: Francois Simal, Albert Demonceau, Lise Wlodarczak, Alfred F NoelsAbstract:Abstract Air-stable and readily available RuCl(Cp*)(PPh3)2 is so far the best ruthenium-based catalyst precursor for promoting the Addition of CCl4 and CHCl3 across olefins at a temperature as low as 40°C.
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radical reactions catalysed by ruthenium ii complexes with anionic carborane phosphine ligands Kharasch Addition to olefins and controlled polymerisation
Tetrahedron Letters, 2000Co-Authors: Francois Simal, Albert Demonceau, Alfred F Noels, Francesc Teixidor, S Sebille, Rosario Nunez, Mar M Abad, Clara VinasAbstract:Abstract Ruthenium-carborane complexes 1 – 3 mediated the Kharasch Addition of carbon tetrachloride across olefins with high yields which markedly depended on the catalyst and the substrate used. In Addition, the atom transfer radical polymerisation of methyl methacrylate could be carried out in a highly controlled way.
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Kharasch Addition and controlled atom transfer radical polymerisation atrp of vinyl monomers catalysed by grubbs rutheniumcarbene complexes
Tetrahedron Letters, 1999Co-Authors: Francois Simal, Albert Demonceau, Alfred F NoelsAbstract:The Grubbs' rutheniumcarbene complexes, RuCl2(CHPh)(PR3)2, mediate the Kharasch Addition of CCl4 across olefins, and the controlled atom transfer radical polymerisation of vinyl monomers with high yields and selectivities which markedly depend on the phosphine ligands of the complex (R=phenyl, cyclopentyl, and cyclohexyl).
Gerard Van Koten - One of the best experts on this subject based on the ideXlab platform.
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mechanistic aspects of the Kharasch Addition reaction catalyzed by organonickel ii complexes containing the monoanionic terdentate aryldiamine ligand system c6h2 ch2nme2 2 2 6 r 4
Organometallics, 1997Co-Authors: Lucia A Van De Kuil, D M Grove, J W Zwikker, Leonardus W Jenneskens, Robert A Gossage, And Wiendelt Drenth, Gerard Van KotenAbstract:The Addition reaction of polyhalogenated alkanes to alkenes (Kharasch Addition reaction) is homogeneously catalyzed in the absence of O2 under mild reaction conditions (25 °C) by the arylnickel complexes [NiII{C6H2(CH2NMe2)2-2,6-R-4}Br] (R = H, MeC(O), Cl, MeO, NH2) and shows a high selectivity for the 1:1 adduct. Kinetic data on the catalytic system with [Ni{C6H3(CH2NMe2)2-2,6}Br] (R = H; abbreviated as [Ni(NCN)Br]), methyl methacrylate, and CCl4 reveal a rate of reaction that is first order in nickel complex and in alkene. In our series of para-substituted arylnickel catalysts, the rate of catalysis increases with the electron donating character of the para substituents on the aryl ligand and this rate correlates directly with the NiII/NiIII redox potential. These data, together with separate spectroscopic studies and results from individual experiments employing other solvents, other polyhalogenated alkanes such as CBr4 and CF3CCl3 and other alkene substrates such as styrene, 1-octene, and cyclohexene,...
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homogeneous catalysts based on silane dendrimers functionalized with arylnickel ii complexes
Nature, 1994Co-Authors: Joan W J Knapen, D M Grove, Alexander Van Der Made, Janine C De Wilde, Piet W N M Van Leeuwen, Peter Wijkens, Gerard Van KotenAbstract:AT the interface between heterogeneous and homogeneous catalysis there is great scope for the development of new materials that combine the advantages and/or minimize disadvantages associated with each of these classes. In particular there is a need for homogeneous catalysts with properties that allow their ready removal from a product-containing solution. One approach to such materials is to anchor homogeneous catalysts to soluble polymer supports1; we have recently prepared such catalytic materials in which the active centre is an organometallic species2,3. One disadvantage encountered when anchoring catalytic metal sites to polymers is the difficulty of accurate control of the number and location of these sites. Here we report an alternative approach—the synthesis of polysilane dendrimers (highly branched macromolecules4–6) which are functionalized at their periphery with metal-containing catalytically active sites. These dendrimers show regiospecific catalytic activity for the Kharasch Addition of polyhalogenoalkanes to carbon–carbon double bonds. It should be possible to remove the nanoscale catalytic macromolecules of this type from the solution of products using filtration methods.
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organonickel ii complexes containing aryl ligands with chiral pyrrolidinyl ring systems syntheses and use as homogeneous catalysts for the Kharasch Addition reaction
Recueil des Travaux Chimiques des Pays-Bas, 1994Co-Authors: Lucia A Van De Kuil, Anthony L Spek, Yvonne S J Veldhuizen, D M Grove, J W Zwikker, Leonardus W Jenneskens, W Drenth, Wilberth J J Smeets, Gerard Van KotenAbstract:New chiral organonickel(II) complexes 3a-d have been synthesized containing monoanionic terdentate ligands of the type 2,6-bis[(1-pyrrolidinyl)methyl]phenyl. Chirality is introduced at the nitrogen donor atoms, which are part of the pyrrolidinyl ring systems, by placing substituents on the 2 or 5 positions of the rings. The complexes have been characterized variously by 1H- and 13C-NMR spectroscopy, UV/Vis spectroscopy and X-ray crystallography. Crystals of 3b are monoclinic, space group P21, with a = 11.572(2), b = 11.804(2), c = 13.249(3) A, β = 107.00(2)°, Z = 4, final R = 0.043 for 3043 observed reflections. Crystals of 3c are tetragonal, space group P412121, with a = b = 12.2957(14) A, c = 26.418(3) A, Z = 8, final R = 0.052 for 1479 observed reflections. Crystals of 3d are tetragonal, space group P412121, with a = b = 11.0869(5), c = 21.718(2) A, Z = 4, final R = 0.046 for 1469 observed reflections. The catalytic ability of the nickel complexes in the Addition reaction of polyhalogenated compounds with alkenes (Kharasch Addition) is markedly influenced by the geometry around the nickel atom and only 3a and 3b prove to be effective catalysts. The highest enantiomeric excesses of 16-17% obtained with 3b and L-menthyl methacrylate in this catalytic reaction indicate that the C2 chiral fence produced by the Me-substituted pyrrolidinyl rings is not very effective for the transfer of chiral information.
Yasuhiro Iwasawa - One of the best experts on this subject based on the ideXlab platform.
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immobilized metal ion containing ionic liquids preparation structure and catalytic performances in Kharasch Addition reaction and suzuki cross coupling reactions
Journal of Molecular Catalysis A-chemical, 2008Co-Authors: Takehiko Sasaki, Chongmin Zhong, Mizuki Tada, Takao Kume, Yasuhiro IwasawaAbstract:Abstract A series of immobilized metal ion-containing ionic liquids on silica surfaces (ImmM_IL) were prepared and characterized by EXAFS, UV–vis, TGA, and elemental analysis. The prepared ImmCu2+_IL was found to be more active than unsupported [Bmim]2CuCl4 ionic liquid and reusable for Kharasch Addition reaction between CCl4 and styrene. The prepared ImmPd2+_IL was active and reusable for Suzuki cross-coupling between phenylboronic acid and arylhalide. Throughout this study the present catalyst preparation method was confirmed to give efficient and reusable catalysts.
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immobilized metal ion containing ionic liquids preparation structure and catalytic performance in Kharasch Addition reaction
Chemical Communications, 2005Co-Authors: Takehiko Sasaki, Chongmin Zhong, Mizuki Tada, Yasuhiro IwasawaAbstract:Immobilized metal ion-containing ionic liquid catalysts were prepared by the reaction between silyl-functionalized imidazolium ionic molecules and surface silanol groups of silica, followed by Addition of MnCl2, FeCl2, CoCl2, NiCl2, CuCl2, or PdCl2; only the immobilized copper catalyst, which has a sandwiched CuCl42− moiety, was very active for the Kharasch reaction between styrene and CCl4.
Francois Simal - One of the best experts on this subject based on the ideXlab platform.
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highly efficient Kharasch Addition catalysed by rucl cp pph3 2
Tetrahedron Letters, 2000Co-Authors: Francois Simal, Albert Demonceau, Lise Wlodarczak, Alfred F NoelsAbstract:Abstract Air-stable and readily available RuCl(Cp*)(PPh3)2 is so far the best ruthenium-based catalyst precursor for promoting the Addition of CCl4 and CHCl3 across olefins at a temperature as low as 40°C.
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radical reactions catalysed by ruthenium ii complexes with anionic carborane phosphine ligands Kharasch Addition to olefins and controlled polymerisation
Tetrahedron Letters, 2000Co-Authors: Francois Simal, Albert Demonceau, Alfred F Noels, Francesc Teixidor, S Sebille, Rosario Nunez, Mar M Abad, Clara VinasAbstract:Abstract Ruthenium-carborane complexes 1 – 3 mediated the Kharasch Addition of carbon tetrachloride across olefins with high yields which markedly depended on the catalyst and the substrate used. In Addition, the atom transfer radical polymerisation of methyl methacrylate could be carried out in a highly controlled way.
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Kharasch Addition and controlled atom transfer radical polymerisation atrp of vinyl monomers catalysed by grubbs rutheniumcarbene complexes
Tetrahedron Letters, 1999Co-Authors: Francois Simal, Albert Demonceau, Alfred F NoelsAbstract:The Grubbs' rutheniumcarbene complexes, RuCl2(CHPh)(PR3)2, mediate the Kharasch Addition of CCl4 across olefins, and the controlled atom transfer radical polymerisation of vinyl monomers with high yields and selectivities which markedly depend on the phosphine ligands of the complex (R=phenyl, cyclopentyl, and cyclohexyl).
Albert Demonceau - One of the best experts on this subject based on the ideXlab platform.
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Kharasch Addition catalysed by half sandwich ruthenium complexes enhanced activity of ruthenacarboranes
Tetrahedron Letters, 2003Co-Authors: Oscar Tutusaus, Sebastien Delfosse, Albert Demonceau, Alfred F Noels, Clara Vinas, Francesc TeixidorAbstract:Abstract Ruthenium complexes of the type [RuH(η5-CB)(PPh3)2] {CB is a monoanionic charge-compensated carborane ligand such as [9-SR2-7,8-C2B9H10]− and [9-SR2-7-CH3-7,8-C2B9H9]−} efficiently catalyse the Kharasch Addition of CCl4 across olefins and, with maximum total turnover numbers of 9000 and initial turnover frequencies of 1900 h−1 at 40°C, highly surpass their Ru–Cp# analogues in these reactions.
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highly efficient Kharasch Addition catalysed by rucl cp pph3 2
Tetrahedron Letters, 2000Co-Authors: Francois Simal, Albert Demonceau, Lise Wlodarczak, Alfred F NoelsAbstract:Abstract Air-stable and readily available RuCl(Cp*)(PPh3)2 is so far the best ruthenium-based catalyst precursor for promoting the Addition of CCl4 and CHCl3 across olefins at a temperature as low as 40°C.
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radical reactions catalysed by ruthenium ii complexes with anionic carborane phosphine ligands Kharasch Addition to olefins and controlled polymerisation
Tetrahedron Letters, 2000Co-Authors: Francois Simal, Albert Demonceau, Alfred F Noels, Francesc Teixidor, S Sebille, Rosario Nunez, Mar M Abad, Clara VinasAbstract:Abstract Ruthenium-carborane complexes 1 – 3 mediated the Kharasch Addition of carbon tetrachloride across olefins with high yields which markedly depended on the catalyst and the substrate used. In Addition, the atom transfer radical polymerisation of methyl methacrylate could be carried out in a highly controlled way.
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Kharasch Addition and controlled atom transfer radical polymerisation atrp of vinyl monomers catalysed by grubbs rutheniumcarbene complexes
Tetrahedron Letters, 1999Co-Authors: Francois Simal, Albert Demonceau, Alfred F NoelsAbstract:The Grubbs' rutheniumcarbene complexes, RuCl2(CHPh)(PR3)2, mediate the Kharasch Addition of CCl4 across olefins, and the controlled atom transfer radical polymerisation of vinyl monomers with high yields and selectivities which markedly depend on the phosphine ligands of the complex (R=phenyl, cyclopentyl, and cyclohexyl).
