Stereospecific synthesis and catalytic activity of L-histidylidene metal complexes
|Title:||Stereospecific synthesis and catalytic activity of L-histidylidene metal complexes||Authors:||Monney, Angèle
|Permanent link:||http://hdl.handle.net/10197/6598||Date:||May-2012||Abstract:||We report on the synthesis, metal coordination, and catalytic impact of histidylidene, a histidine-derived N-heterocyclic carbene (NHC) ligand. The histidinium salt 3, comprising methyl substituents at both heterocyclic nitrogens and protected at the C- and N-terminus of the amino acid, was rhodated and iridated by a transmetallation protocol using Ag2O. Ambient temperature and short reaction times were pivotal for full retention of configuration at the a-carbon. The stereospecificity of the reaction was conveniently probed by P-31 NMR spectroscopy after transmetallation with rhodium(I) and coordination of enantiopure (S)-Ph-binepine. The histidylidene rhodium complexes are highly efficient catalysts for the mild hydrosilylation of ketones. For the cationic complexes [Rh(cod)(histidylidene)(phosphine)](+), lowering the temperature shifted the rate-limiting step of the catalytic reaction to an earlier stage that is not enantioselective. Hence the asymmetric induction-which is governed by the chiral phosphine-did not improve at low temperature.||Funding Details:||European Research Council||Type of material:||Journal Article||Publisher:||Royal Society of Chemistry||Copyright (published version):||2012 The Royal Society of Chemistry||Keywords:||N-heterocyclic-carbene;Solid-phase synthesis;Chiral ionic liquids;Asymmetric catalysis;Amino-acid;Rhodium complexes;Enantioselective catalysis;Hydrosilylation catalysts;Artificial metalloenzymes;Combinatorial libraries||DOI:||10.1039/c2dt30799e||Language:||en||Status of Item:||Peer reviewed|
|Appears in Collections:||Chemistry Research Collection|
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