Asymmetric Cycloisomerization of o‐Alkenyl‐N‐Methylanilines to Indolines by Iridium‐Catalyzed C(sp3)−H Addition to Carbon–Carbon Double Bonds

Highly enantioselective cycloisomerization of N ‐methylanilines, bearing o ‐alkenyl groups, into indolines is established. An iridium catalyst bearing a bidentate chiral diphosphine effectively promotes the intramolecular addition of the C(sp³)−H bond across a carbon–carbon double bond in a highly enantioselective fashion. The reaction gives indolines bearing a quaternary stereogenic carbon center at the 3‐position. The reaction mechanism involves rate‐determining oxidative addition of the N ‐methyl C−H bond, followed by intramolecular carboiridation and subsequent reductive elimination.