Reduction of Carbonyl Compounds with Chiral Oxazaborolidine Catalysts: A New Paradigm for Enantioselective Catalysis and a Powerful New Synthetic Method

High enantioselectivity can be achieved when chiral oxazaborolidines are used as catalysts in the reduction of ketones by borane. In the transition state on the way to the complex chiral compounds, the two reactants are activated and held in close proximity by the catalyst, as shown below.