The catalytic hydrogenation of alkenes, ketones, and imines is arguably one of the most important transformations in chemistry. Powerful asymmetric versions have been realizedthat require metal catalysts or the use of a stoichiometric amount of metal hydrides ...
The hydrogenation of unsaturated organic compounds, such as olefins, carbonyls and imines is one of the most important and utilized transformation in both academia and in the chemical industry. With the ever increasing number of biologically active substances with hydrogen as part of the stereocenter, it is not surprising that the development of efficient asymmetric reductions has become acentral researcharea in enantioselective catalysis.
Hydrogenation of the double bond in alkenes requires a catalyst. This transformation occurs stereospecifically by synaddition and, when there is a choice, from the least hindered side of the molecule. This principle underlies the development of enantioselective hydrogenation using chiral catalysts.
Intramolecular H-bonding or chelation by an adjacent functionality, such as a hydroxyl group, can direct the approach of a metal catalyst to favor hydrogenation of one diastereotopic π-face over another. The most effective catalysts for directed hydrogenation are the coordinatively unsaturated Crabtree's catalyst and the 2,5-norbornadiene-Rh(I) catalyst…