Organocatalytic, Enantioselective Friedel-Crafts Reaction of Indoles in the Carbocyclic Ring and Electron-Rich Phenols.

An efficient method has been successfully developed to achieve the asymmetric C-H functionalization of indoles in the carbocyclic ring via organocatalysis, and a variety of tetrahydropyranoindoles were synthesized in good yields with excellent stereoselectivities. Further study on thermodynamic calculations indicated that the process was promoted by generating more thermodynamically stable products. This strategy, together with traditional C-3 functionalization of hydroxyindoles, could realize the switchable, regiodivergent asymmetric modification of indoles.