Chiral Phosphoric Acid-Catalyzed Enantioselective Dearomative Electrophilic Hydrazination: Access to Chiral Aza-Quaternary Carbon Indolenines

Direct enantioselective synthesis of chiral aza-quaternary carbon indolenines through the dearomative electrophilic hydrazination of 2,3-disubstituted indoles has been achieved. This catalytic asymmetric strategy leads to the efficient construction of a series of enantioenriched aza-quaternary carbon indolenines in high yields and excellent stereoselectivities. The synthetic practicality of this reaction has been demonstrated by the enantioselective modification and derivatization of drug molecules. In-situ infrared and density functional theory calculations suggest that our catalytic system could overcome the background reaction to achieve effective enantioselective dearomatization.