Journal of the American Chemical Society 2005-05-25

A class of ruthenium(II) catalyst for asymmetric transfer hydrogenations of ketones.

Aidan M Hayes, David J Morris, Guy J Clarkson, Martin Wills

Index: J. Am. Chem. Soc. 127 , 7318-7319, (2005)

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Abstract

Ruthenium dimer 6 (readily available in two steps from TsDPEN) is converted directly to monomeric asymmetric transfer hydrogenation catalyst 3 in situ under the conditions employed for ketone reduction. Catalyst 3 is a significantly more active catalyst for this application than the untethered derivative, exhibits higher enantioselectivities across a range of substrates, and appears to be highly stable to the reaction conditions. It is active at loadings of as low as 0.01 mol %, and reductions at the 0.1 mol % level are complete within 20 min at 80 degrees C without significant loss of enantioselectivity.