Synthesis of (E)‐3‐Alkylideneindolin‐2‐ones by an Iron‐Catalyzed Aerobic Oxidative Condensation of Csp3–H Bonds of Oxindoles and Benzylamines

A novel synthetic route for the construction of ( E )‐3‐alkylideneindolin‐2‐ones through iron‐catalyzed aerobic oxidative condensation of oxindoles with benzylamines has been developed. This oxidative reaction involves a sequence of C–H activation, amine self‐condensation, nucleophilic addition, and C–C double bond formation. The synthetic importance of this protocol has been demonstrated by preparing tyrosine kinase inhibitors, anticonvulsant and antitumor agents, and other valuable 3‐alkylideneindolin‐2‐one derivatives. Key intermediates are isolated and a plausible mechanistic pathway for the reaction has been discussed.