Atroposelective Phosphoric Acid Catalyzed Three-Component Cascade Reaction: Enantioselective Synthesis of Axially Chiral N-Arylindoles.

An efficient organocatalytic atroposelective three-component cascade reaction of 2,3-diketoesters, aromatic amines, and 1,3-cyclohexanediones has been developed for the highly enantioselective synthesis of axially chiral N-arylindoles. The success of this method derives from the use of a newly developed second-generation chiral spirocyclic phosphoric acid as the catalyst. In addition, this protocol was extended to the synthesis of an axially chiral monophosphorus ligand.