title: A new class of "tethered" ruthenium(II) catalyst for asymmetric transfer hydrogenation reactions.
abstract: Ruthenium dimer 4 is converted directly to monomeric asymmetric transfer hydrogenation catalyst 2 under the conditions employed for ketone reduction. Using 0.25 mol % of either 4 or 0.5 mol % of 2 in formic acid/triethylamine, it is possible to achieve ketone reduction in quantitative conversion and with ee's as high as 98%. Complex 2 is a robust "single-reagent" catalyst which offers significant scope for modification toward specific substrates. The synthesis and applications of an analogous complex derived from (1R,2S)-norephedrine are also described.
authors.affiliation: Asymmetric Catalysis Group, Department of Chemistry, University of Warwick, Coventry, CV4 7AL.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Hannedouche
authors.forename: Guy J
authors.initials: GJ
authors.lastname: Clarkson
authors.forename: Martin
authors.initials: M
authors.lastname: Wills