Asymmetric binary acid catalysis: chiral phosphoric acid as dual ligand and acid.

Recently, chiral Brønsted acids as dual ligand and acid catalysts in the context of metal catalysis have been developed. Such binary catalytic systems synergistically integrate chiral Brønsted acids and metal catalysts as a result of their weakly coordinating behaviors. The resulting binary acid catalysts have enabled effective reactions of a range of olefins/aromatics, beyond the scope of typical acid catalysis. Our endeavors in developing asymmetric binary acid catalysis are summarized in this feature article.