Catalytic asymmetric hydrogenation of aldehydes

Abstract
Racemic α-arylaldehydes provide the corresponding primary alcoholsvia dynamic kinetic resolution in excellent enantioselectivities and yields upon hydrogenation using a Noyori ruthenium catalyst; for example, the biologically active (S)-enantiomer of the non-steroidal anti-inflammatory drug ibuprofen could be synthesized via catalytic enantioselective hydrogenation of aldehyde1f followed by oxidation with potassium permanganate in 76% isolated yield and 96 : 4 er.