Asymmetric Counterion Pair Catalysis: An Enantioselective Brønsted Acid‐Catalyzed Protonation

Abstract

Abstract A new asymmetric Brønsted acid‐catalyzed cascade reaction involving a 1,4‐addition, enantioselective protonation and 1,2‐addition has been developed. This organocatalytic cascade not only provides for the first time 3‐ and 2,3‐substituted tetrahydroquinolines and octahydroacridines in good yields with high dia‐ and enantioselectivities under mild reaction conditions but additionally represents the first example of a chiral Brønsted acid‐catalyzed protonation reaction in an organocatalytic domino reaction. Furthermore, the new Brønsted acid‐catalyzed hydride‐proton‐hydride transfer cascade can be applied to prepare new molecular scaffolds with up to three new stereocenters in an efficient one‐pot reaction sequence.