Asymmetric hydrogenation

Abstract

Ruthenium (II) complexes possessing an atropisomeric BINAP ligand display spectacular efficiency in enantioselective hydrogenation of prochiral α,β- and β,γ-unsaturated carboxylic acids, allylic and homoallylic alcohols, enamides. etc. in addition, a wide range of functionalized ketones can be hydrogenated with a high degree of enantiofacial selectivity and in a predictable sense. The use of chiral substrates, coupled with dynamic kinetic resolution, further enhances the synthetic utility. A long-sought asymmetric hydrogenation of simple aromatic or olefinic ketones has been realized by use of a combination of BINAP and a chiral 1,2-diamine as co-modifiers of the ruthenium (II) species. The BINAP-based organometallic molecular catalysts can generate a diverse array of natural and unnatural chiral compounds, simply depending on the structures of the unsaturated substrates. Some industrial applications of BINAP-ruthenium are illustrated. © Acta Chemica Scandinavica 1996.