Development of iridium-catalyzed asymmetric hydrogenation: New catalysts, new substrate scope

The asymmetric hydrogenation of olefins is a tremendously powerful tool used to synthesize chiral molecules. The field was pioneered using rhodium- and ruthenium- based catalysts; however, catalysts based on both of these metals suffer from limitations, such as the need for directing substituents near or even adjacent to the olefin. Iridium-based catalysts do not suffer from this flaw and can thus hydrogenate a wide variety of olefins, including some tetra substituted ones. It is also possible for iridium-based catalysts to hydrogenate hetero-π bonds such as those found in hetero-aromatic rings. This review summarizes the contributions made to this field by our research group over the past few years.