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.

Full-text preview

Available from:
  • Source
    • "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. "
    [Show abstract] [Hide abstract]
    ABSTRACT: For Abstract see ChemInform Abstract in Full Text.
    Preview · Article · Nov 2005 · ChemInform
  • [Show abstract] [Hide abstract]
    ABSTRACT: Chiral arene-N-tosylethylenediamine-Ru(II) complexes can be made to effect both asymmetric transfer hydrogenation and asymmetric hydrogenation of simple ketones through a slight functional modification and by switching reaction conditions. [Ru(OSO2CF3){(S,S)-TsNCH(C6H5)CH(C6H5)NH2}(eta(6)-p-cymene)] catalyzes the asymmetric hydrogenation of acetophenone in methanol to afford (S)-1-phenylethanol with 96% ee in 100% yield. Like the transfer hydrogenation catalyzed by similar Ru catalysts with basic 2-propanol or a formic acid/triethylamine mixture, this hydrogenation proceeds through a metal-ligand bifunctional mechanism. The reduction of the C=O function occurs via an intermediary 18e RuH species in its outer coordination sphere without metal-substrate interaction. The high catalytic efficiency relies on the facile ionization of the Ru triflate complex in methanol. The turnover rate is dependent on hydrogen pressure and medium acidity and basicity. The RuCl analogue can be used as a precatalyst, albeit less effectively. Unlike the well-known diphosphine-1,2-diamine-Ru(II)-catalyzed hydrogenation that proceeds in a basic alcohol, this reaction takes place under slightly acidic conditions, creating new opportunities for asymmetric hydrogenation.
    No preview · Article · Aug 2006 · Chemistry - An Asian Journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
    No preview · Article · Nov 2006 · Science
Show more