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Showing 1 to 20 of 26 for “"precatalysts"”.
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Nickel precatalysts as enabling tools for catalytic coupling reactions
… synthesized and are presented as a library of precatalysts suitable for a wide variety of nickel-catalyzed transformations. These complexes are easily synthesized from low-cost NiCl₂-6H₂O or NiBr₂-3H₂O and the desired ligand followed by addition of 1 equiv of Grignard reagent. A selection of …
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Monometallic and multimetallic complexes as precatalysts in the hydroformylation of olefins
… h-1 ). Comparable catalytic performance of both precatalysts was obtained when milder reaction conditions (85 ℃, 20 bar for 4 h) were adopted in the evaluation of the mononuclear complex against the low generation dendritic trinuclear complex. The mercury poisoning experiments revealed a dual …
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Lanthanide-Based Precatalysts For Carbon-Carbon Bond-Forming Reactions In Aqueous Media
… <p> Several Ln<sup>3+</sup>-based Lewis acid precatalysts that were designed for Mukaiyama aldol reactions have been shown to be enantioselective, water-tolerant, and recoverable. Limiting the usefulness of these precatalysts are high ligand loadings and long reaction times that are necessary …
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Novel palladium precatalysts and their application in cross- coupling reactions and copper-catalyzed enantioselective ring formation
… of easily prepared, phosphine-ligated palladium precatalysts based on the 2-aminobiphenyl scaffold have been prepared. The role of the precatalyst-associated labile halide (or pseudohalide) in the formation and stability of the palladacycle has been examined. It was found that replacing the …
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s-, p-, and f-block metals-mediated novel iron-based compounds as precatalysts for efficient alkaline OER
… the reaction, these compounds primarily act as precatalysts, inevitably reconstructing into (oxy)hydroxides (FeOxHy) that exhibit low or non-conductivity and easily dissolve Fe atoms. Additionally, the reconstructed FeOxHy suffers from insufficient exposure of surface active sites and inadequate …
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Synthesis and use of bench-stable precatalysts with heck-type activation and progress towards the continuous-flow synthesis of atorvastatin
… of bench-stable N-heterocyclic carbene nickel precatalysts for homogeneous nickel-catalysis. The nickel(II) complexes are readily activated to Ni⁰ in situ under mild conditions, via a proposed Heck-type mechanism. The precatalysts are able to facilitate carbonyl-ene, hydroalkenylation, and …
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Karakterisering van Grubbs-tipe prekatalisatore met behulp van kernmagnetiese resonansspektroskopie
Since the development of the ruthenium containing precatalysts Grubbs 1 (1) and Grubbs 2 (2), there was an increase in the development of new precatalysts. The NMR characterization could not cope with this. The NMR characterization mainly consists of 1H, 31P, COSY and rarely 13C. Due to the high …
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Synthesis and Application of Air-Stable Secondary Phosphine Oxide, Oxime, and Amine-Phosphine Palladium(II) Complexes in Transfer Hydrogenation and Cross-Coupling Reactions
… species. Our work focused on the development of precatalysts with an established 1:1 L:Pd ratio. Specifically, we were interested in the synthesis of palladium(II) precatalysts with the general formula (R3P)Pd(amine)Cl2, using di-tert-butylneopentylphosphine and trineopentylphosphine. Under …
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New adaptations of analytical tools for the study of dynamic interactions of lanthanide-based catalysis in aqueous media
… goal because they are water-tolerant Lewis acid precatalysts that can catalyze a wide range of important carbon-carbon and carbon-heteroatom bond-forming reactions such as the aldol, nitro-aldol, Mannich, Diels-Alder, Michael, Mukaiyama aldol, and Friedal-Crafts reactions due to their hard, …
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The Pd-catalyzed fluorination of (hetero)aryl bromides and triflates
… described 2-aminobiphenyl-based sulfonate precatalysts were ineffective, readily activated [(L-Pd) 2COD] (COD = cyclooctadiene) complexes proved to be general precatalysts for these reactions. Further structural and reactivity studies of this new family of precatalysts are presented. …
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Towards polyethylene-based materials with non-alternatively incorporated carbon monoxide monomer
… Specifically, phosphine sulfonate palladium(II) precatalysts derived from the in situ complexation of palladium(II) acetate and phosphine sulfonate, were found to facilitate the copolymerization of ethylene and carbon monoxide, typically yielding polyketones with a CO composition ranging from 40 …
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Development and Applications of Pd Catalysts for C-N Cross-Coupling Reactions
… Chapter 2 A new class of one-component Pd precatalysts bearing biarylphosphine ligands is described. These precatalysts are air- and thermally-stable, are easily-activated under normal reaction conditions at or below room temperature, and ensure the formation of the highly-active …
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Aminopyridinato-Ligand-Stabilized Lanthanoid Complexes: Synthesis, Reactivity, Ethylene and Isoprene Polymerization
… investigated in regard to their properties as precatalysts for the polymerization of ethylene or isoprene und their ability to form hydrido complexes or cations. Previous investigations carried out in our group have shown that aminopyridinate-stabilized organoyttrium cations exhibit very high …
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Carbon-trifluoromethyl bond forming reactions and palladium-catalyzed cyanation of (hetero)aryl halides
… halides is disclosed. By employing palladacycle precatalysts, cyanide binding during catalyst formation is minimized, allowing for low catalyst loadings even with unactivated aryl chlorides. The method utilizes a non-toxic cyanide source and exhibits excellent functional group tolerance, …
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Recent advances in palladium-catalyzed carbon-carbon and carbon-boron bond forming processes
… catalyst systems derived from palladium precatalysts and monophosphine ligands for the Suzuki-Miyaura cross-coupling reaction of heteroaryl boronic acids and esters has been developed. This method allows for the preparation of a wide variety of heterobiaryls in good to excellent yields …
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Neue Heterazoliumsalze aus Prolin und Pyroglutaminsäure und Anwendungen in Carben-katalysierten asymmetrischen nucleophilen Acylierungen
… from easily accessible L-pyroglutaminoles. The precatalysts were successfully utilised in the first asymmetric intramolecular crossed benzoin reaction generating acyloines in high yields and good enantioselectivities. A novel N-methyl triazolium salt gave the best results reported so far as the …
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New Pre-Catalysts for Olefin Polymerisation and Ring-Opening Polymerisation of Lactides/Lactones
… significantly in the case of the niobium precatalysts which were two orders of magnitude above the previously reported compounds. The reactions between 1,3-dipropoxy-p-tert-butyl-calix[4]arene (L30H2), hexahomotrioxacalix[3]arene (L31H3) or tripropoxy-p-tert-butylcalix[4]arene (L32H) with …
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Carbene catalyzed asymmetric nucleophilic acylations with novel triazolium salts
… benzoin condensation. Furthermore, these carbene precatalysts have been applied to intramolecular Stetter reaction with good efficiency and moderate selectivity. Based on the strategy of carbene design, we have developed different N-substituted triazolium salts, which successfully catalyzed the …
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Studies In the Optimization of the Suzuki-Miyaura Reaction
… are actually formed from the variety of popular precatalysts used. There is in fact little evidence that these precursors produce bis-ligated Pd(0) complexes and it is possible that the rate limiting factor may be catalyst formation. If so, then the development of an optimized method for forming …
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Group 4 metal and vanadium bis(phenolato) complexes : synthesis, structure and olefin polymerisation activity
… thus giving access to enantiomerically pure precatalysts. In contrast to 1,4-dithiabutanediyl-bridged [OSSO] ligands, [2,2’-(HOC6H2-6-R1-4-R2)2SC6H10S] are so efficient in directing and maintaining the configuration of their respective titanium complexes that large ortho-substituents are not …
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