Bifunctional Thiourea-Catalyzed Enantioselective Aza-Friedel-Crafts Reaction of 3-Aminobenzofurans with Isatin-Derived Ketimines.

A quinine-derived thiourea-promoted enantioselective aza-Friedel-Crafts reaction of 3-aminobenzofurans with isatin-derived ketimines is developed, providing a variety of 3-benzofuran-3-amino-2-oxindoles bearing a quaternary stereocenter with good to excellent yields (72-95%) and moderate to excellent enantioselectivities (48-97%). The synthetic potential of this concise and efficient protocol is revealed by gram-scale preparation and further transformation of the adduct to an optically pure spirocyclic oxindole.