Journal of the American Chemical Society · 2015 · 116 citations · 28 references
Natural SciencesChemical EngineeringChemistryCatalysisOrganic ChemistryReaction EngineeringCatalyst CharacterizationCatalyst DesignCatalyst PreparationCatalyst SynthesisCatalytic MaterialsHeterocyclic ChemistryCatalyst Precursor DesignCatalytic ActivityCatalytic FunctionalizationCatalytic SynthesisHydrogenationHydrogenation CatalysisHydrogenation ReactionsRuthenium-catalyzed Coupling
Bis-N-heterocyclic carbene (NHC) aminopincer ligands were successfully applied for the first time in the catalytic hydrogenation of esters. We have isolated and characterized a well-defined catalyst precursor as a dimeric [Ru2(L)2Cl3]PF6 complex and studied its reactivity and catalytic performance. Remarkable initial activities up to 283,000 h(-1) were achieved in the hydrogenation of ethyl hexanoate at only 12.5 ppm Ru loading. A wide range of aliphatic and aromatic esters can be converted with this catalyst to corresponding alcohols in near quantitative yields. The described synthetic protocol makes use of air-stable reagents available in multigram quantities, rendering the bis-NHC ligands an attractive alternative to the conventional phosphine-based systems.
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An overview of N-heterocyclic carbenes
Matthew N. Hopkinson, Christian Richter, Michael Schedler et al. · Nature · 2014 · 4.2K citations