Enantioselective nucleophilic catalysis with "Planar-Chiral" heterocycles.

Although Lewis bases (e.g., tertiary phosphines, tertiary amines, and pyridines) serve as nucleophilic catalysts for a wide array of reactions, there have been relatively few reports of enantioselective nucleophilic catalysts. In this Account, we describe the design and synthesis of a new family of chiral nucleophilic catalysts, specifically, planar-chiral heterocycles. These complexes provide good levels of enantiomeric excess in the addition of alcohols to ketenes, the rearrangement of O-acylated azlactones, and the kinetic resolution of secondary alcohols.