Regioselective/Electro-oxidative Intermolecular [3+2] Annulation for the Preparation of Indolines
Compared with the reported intramolecular electro-oxidative cyclization of alkenyl amines or vinyl anilines for the preparation of pyrrolidines or indolines, the intermolecular version is less studied. Herein, this electrochemical intermolecular oxidative annulation of anilines and alkenes for the preparation of indolines was proceeded under external oxidant-free conditions. The most noteworthy achievement of our work is the facile generation of indolines with quaternary centers at the 2-position. In addition, alkenes and anilines bearing with various functional group can be well tolerated. Remarkably, the electrolyte-free conditions were performed in an electrochemical flow cell, which show application potential for this method.