Asymmetric transfer hydrogenation of ketones promoted by manganese(I) pre-catalysts supported by bidentate aminophosphines

A series of commercially available chiral amino-phosphines, in combination with Mn(CO)(5)Br, has been evaluated for the asymmetric reduction of ketones, using isopropanol as hydrogen source. With the most selective ligand, the corresponding manganese complex was synthesized and fully characterized. A series of ketones (20 examples) was hydrogenated in the presence of 0.5 mol% of the manganese pre-catalyst at 30 degrees C, affording the chiral alcohols in high yields with enantiomeric excesses up to 99%.