Atroposelective Synthesis of Axially Chiral 3-Arylindoles by Copper-Catalyzed Asymmetric Cross-Coupling of Indoles with Quinones and Naphthoquinones

A copper-catalyzed direct asymmetric coupling of C2 sterically-hindering-group-substituted indoles with quinone and naphthoquinone esters was developed by using the spirocyclic pyrrolidine oxazoline (SPDO) ligand, which was accomplished by metal catalysis for the first time. Diverse structures of axially chiral 3-arylindoles were obtained with good to high enantioselectivities in good to high yields. This protocol can be expanded to implement β-coupling with naphthoquinone esters, providing an alternative way to prepare β-substituted derivatives of both naphthols and naphthoquinones.