Hydrogen Bonds-Enabled Design of a C₁-Symmetric Chiral Brønsted Acid Catalyst

We have developed new C₁-symmetric, chiral bis-phosphoric acids with an electron-withdrawing group as one of the two substituents. This C₁-symmetric, chiral bis-phosphoric acid with a pentafluorophenyl group performs exceptionally well in the asymmetric Diels-Alder reaction of acrolein, methacrolein, and α-haloacroleins with substituted amidodienes. Control over the atropisomeric catalyst structure, enhancement of the catalytic activity, and differentiation of the asymmetric reaction space is possible by the remote control of the pentafluorophenyl group. Furthermore, we have conducted theoretical studies to clarify the roles of both intra- and intermolecular hydrogen bonds in the C₁-symmetric chiral environment of chiral bis-phosphoric acid catalysts. The developed strategy, C₁-symmetric catalyst design through hydrogen bonding, is potentially applicable to the development of other chiral Brønsted acid catalysts.