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

Abstract

A quinine-derived thiourea-promoted enantioselective aza-Friedel−Crafts reaction of 3-aminobenzofurans with isatinderived ketimines is developed, providing a variety of 3benzofuran-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.