Chiral Phosphoric Acids as Versatile Catalysts for Enantioselective Transformations

Chiral phosphoric acids derived from axially chiral biaryls and related chiral Brønsted acids have emerged as an attractive and widely applicable class of enantioselective organocatalysts for a variety of organic transformations. This review focuses on recent achievements in the development of enantioselective transformations using these axially chiral phosphoric acids and their analogues as chiral Brønsted acid catalysts. The contents are arranged according to the specific types of carbon-carbon bond-forming reactions, followed by carbon-heteroatom bond-forming reactions and functional group transformations, including reduction and oxidation. Further applications to combined phosphoric acid and metal complex catalytic systems and new aspects in the development of chiral Brønsted acid catalysts are also highlighted.