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Organometallic Catalysis (organometallic + catalysis)
Selected AbstractsDitopic Cyclodextrin-Based Receptors: New Perspectives in Aqueous Organometallic CatalysisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Natacha Six Abstract The mass transfer properties of mono- and ditopic ,-cyclodextrin-based receptors have been evaluated in a biphasic palladium-catalyzed Tsuji,Trost reaction and compared to one of the best mass-transfer promoters, namely the randomly methylated ,-cyclodextrin. While monotopic receptors appeared to be poor mass-transfer promoters of long alkyl chain allyl carbonates or urethanes, cooperative effects have been evidenced with ditopic cyclodextrin-based receptors, opening new perspectives in aqueous organometallic catalysis. [source] Properties and Catalytic Activities of New Easily-Made Amphiphilic Phosphanes for Aqueous Organometallic CatalysisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Michel Ferreira Abstract Mono- and disulfonated amphiphilic versions of triphenylphosphane (PPh3) and cyclohexyl(phenyl)phosphane were easily synthesized from commercial reagents and sulfuric acid. The behaviour of these phosphanes in solution was investigated by surface tension, isothermal titration calorimetry, nuclear magnetic resonance and cryo-transmission electron microscopy. Two different supramolecular assemblies were evidenced according to the degree of sulfonation. The monosulfonated phosphanes formed well organized micelle-like aggregates while the disulfonated phosphanes formed heterogeneous and disorganized vesicle-like assemblies. The efficiency of these amphiphilic phosphanes was evaluated in the aqueous biphasic, palladium-catalyzed cleavage of allyl alkyl carbonates. [source] Polymer-Supported, Carbon Dioxide-Protected N-Heterocyclic Carbenes: Synthesis and Application in Organo- and Organometallic CatalysisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010Gajanan Manohar Pawar Abstract The synthesis of a resin-supported, carbon dioxide-protected N-heterocyclic carbene (NHC) and its use in organocatalysis and organometallic catalysis are described. The resin-bound carbon dioxide-protected NHC-based catalyst was prepared via ring-opening metathesis copolymerization of 1,4,4a,5,8,8a-hexahydro-1,4,5,8- exo,endo -dimethanonaphthalene (DMNH6) with 3-(bicyclo[2.2.1]hept-5-en-2-ylmethyl)-1-(2-propyl)-3,4,5,6-tetrahydropyrimidin-1-ium-2-carboxylate (M1), using the well-defined Schrock catalyst Mo[N -2,6-(2-Pr)2 -C6H3](CHCMe2Ph)(OCMe3)2 and was used for a series of organocatalytic reactions, i.e., for the trimerization reaction of isocyanates, as well as for the cyanosilylation of carbonyl compounds. In the latter reaction, turn-over numbers (TON) up to 5000 were achieved. In addition, the polymer-supported, carbon dioxide-protected N-heterocyclic carbene served as an excellent progenitor for various polymer-supported metal complexes. It was loaded with a series of rhodium(I), iridium(I), and palladium(II) precursors and the resulting Rh-, Ir-, and Pd-loaded resins were successfully used in the polymerization of phenylacetylene, in the hydrogen transfer reaction to benzaldehyde, as well as in Heck-type coupling reactions. In the latter reaction, TONs up to 100,000 were achieved. M1, as a non-supported analogue of poly-M1- b -DMNH6, as well as the complexes PdCl2[1,3-bis(2-Pr)tetrahydropyrimidin-2-ylidene]2 (Pd-1) and IrBr[1-(norborn-5-ene-2-ylmethyl)-3-(2-Pr)-3,4,5,6-tetrahydropyrimidin-2-ylidine](COD) (Ir-1) were used as homogeneous analogues and their reactivity in the above-mentioned reactions was compared with that of the supported catalytic systems. In all reactions investigated, the TONs achieved with the supported systems were very similar to the ones obtained with the unsupported, homogeneous ones, the turn-over frequencies (TOFs), however, were lower by up to a factor of three. [source] Sulfobutyl Ether-,-Cyclodextrins: Promising Supramolecular Carriers for Aqueous Organometallic CatalysisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2005Philippe Blach Abstract The potentialities of sulfobutyl ether-,-CDs derivatives as supramolecular carrier in a biphasic Tsuji,Trost reaction catalyzed by a water-soluble palladium complex of trisulfonated triphenylphosphine have been investigated. The efficiency of these cyclodextrins (CDs) strongly depends on the average molar substitution degree of cyclodextrin and the highest rate enhancements were obtained with cyclodextrins containing about 7 sulfobutyl ether groups. This result was attributed to the absence of a strong interaction between this cyclodextrin and the trisulfonated triphenylphosphine used to dissolve the catalyst in the aqueous phase and to the presence of an extended hydrophobic cavity allowing a better molecular recognition between the substrate and the cyclodextrin. This constitutes the first example of a non-interacting ,-cyclodextrin/phosphine couple with high catalytic activities. [source] Enantiopure Fluorous Amino-Derivatives: Synthesis and Some Applications in Asymmetric Organometallic Catalysis.CHEMINFORM, Issue 3 2005Jerome Bayardon Abstract For Abstract see ChemInform Abstract in Full Text. [source] Ditopic Cyclodextrin-Based Receptors: New Perspectives in Aqueous Organometallic CatalysisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Natacha Six Abstract The mass transfer properties of mono- and ditopic ,-cyclodextrin-based receptors have been evaluated in a biphasic palladium-catalyzed Tsuji,Trost reaction and compared to one of the best mass-transfer promoters, namely the randomly methylated ,-cyclodextrin. While monotopic receptors appeared to be poor mass-transfer promoters of long alkyl chain allyl carbonates or urethanes, cooperative effects have been evidenced with ditopic cyclodextrin-based receptors, opening new perspectives in aqueous organometallic catalysis. [source] Polymer-Supported, Carbon Dioxide-Protected N-Heterocyclic Carbenes: Synthesis and Application in Organo- and Organometallic CatalysisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010Gajanan Manohar Pawar Abstract The synthesis of a resin-supported, carbon dioxide-protected N-heterocyclic carbene (NHC) and its use in organocatalysis and organometallic catalysis are described. The resin-bound carbon dioxide-protected NHC-based catalyst was prepared via ring-opening metathesis copolymerization of 1,4,4a,5,8,8a-hexahydro-1,4,5,8- exo,endo -dimethanonaphthalene (DMNH6) with 3-(bicyclo[2.2.1]hept-5-en-2-ylmethyl)-1-(2-propyl)-3,4,5,6-tetrahydropyrimidin-1-ium-2-carboxylate (M1), using the well-defined Schrock catalyst Mo[N -2,6-(2-Pr)2 -C6H3](CHCMe2Ph)(OCMe3)2 and was used for a series of organocatalytic reactions, i.e., for the trimerization reaction of isocyanates, as well as for the cyanosilylation of carbonyl compounds. In the latter reaction, turn-over numbers (TON) up to 5000 were achieved. In addition, the polymer-supported, carbon dioxide-protected N-heterocyclic carbene served as an excellent progenitor for various polymer-supported metal complexes. It was loaded with a series of rhodium(I), iridium(I), and palladium(II) precursors and the resulting Rh-, Ir-, and Pd-loaded resins were successfully used in the polymerization of phenylacetylene, in the hydrogen transfer reaction to benzaldehyde, as well as in Heck-type coupling reactions. In the latter reaction, TONs up to 100,000 were achieved. M1, as a non-supported analogue of poly-M1- b -DMNH6, as well as the complexes PdCl2[1,3-bis(2-Pr)tetrahydropyrimidin-2-ylidene]2 (Pd-1) and IrBr[1-(norborn-5-ene-2-ylmethyl)-3-(2-Pr)-3,4,5,6-tetrahydropyrimidin-2-ylidine](COD) (Ir-1) were used as homogeneous analogues and their reactivity in the above-mentioned reactions was compared with that of the supported catalytic systems. In all reactions investigated, the TONs achieved with the supported systems were very similar to the ones obtained with the unsupported, homogeneous ones, the turn-over frequencies (TOFs), however, were lower by up to a factor of three. [source] | ||||||||||