Metal—Ligand Bifunctional Catalysis for Asymmetric Hydrogenation

Department of Chemistry and Research Center for Materials Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan.
Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences (Impact Factor: 2.15). 05/2005; 363(1829):901-12; discussion 1035-40. DOI: 10.1098/rsta.2004.1536
Source: PubMed


Chiral diphosphine/1,2-diamine-Ru(II) complexes catalyse the rapid, productive and enantioselective hydrogenation of simple ketones. The carbonyl-selective hydrogenation takes place via a non-classical metal-ligand bifunctional mechanism. The reduction of the C=O function occurs in the outer coordination sphere of an 18e trans-RuH2(diphosphine)(diamine) complex without interaction between the unsaturated moiety and the metallic centre. The Ru atom donates a hydride and the NH2 ligand delivers a proton through a pericyclic six-membered transition state, directly giving an alcoholic product without metal alkoxide formation. The enantiofaces of prochiral ketones are differentiated on the chiral molecular surface of the saturated RuH2 species. This asymmetric catalysis manifests the significance of 'kinetic' supramolecular chemistry.

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    • "There are few, if any, greater challenges to specificity and integrity of products than that demanded in enantiomeric catalysis. It is illuminating, in the light of earlier comments, to reflect on the approaches that have been developed by Ryoji Noyori (Noyori et al. 2005) and Barry Sharpless. On the one hand, they have designed catalysts which remove a good deal of the 'mobility parameter' by, for very good reasons, basing their strategies on rigid chelate complexes. "
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