Ruthenium-catalyzed asymmetric hydrogenation of β-keto- enamines: An efficient approach to chiral γ-amino alcohols

A highly efficient and enantioselective hydrogenation of unprotected beta-ketoenamines catalyzed with ruthenium(II) dichloro{(S)-(-)-2,2'-bis[di(3,5-xylyl)phosphino]-1,1'-binaphthyl}[(2S)-(+)-1,1-bis(4-methoxyphenyl)-3-methyl-1,2-butanediamine] {Ru[(S)-xylbinap][(S)-daipen]Cl2} has been successfully developed. This methodology provides a straightforward access to free ?-secondary amino alcohols, which are key building blocks for a variety of pharmaceuticals and natural products, with high yields (> 99 parts per thousand) and excellent enantioselectivities (up to 99 parts per thousand ee) in all cases.