Fe(II)-Catalyzed Intramolecular of C(sp2)−H and C(sp3)−H Amination of Anthranils: Modular Strategy for the Synthesis of N-Heterocycles

We report the first Fe-catalyzed intramolecular C–H amination of anthranils for the synthesis of carbazoles, indoles, indolines, and imidazolidinones under redox-neutral conditions. This protocol efficiently enables both sp² and challenging sp³ C–H aminations, exhibiting broad substrate scope and excellent functional group tolerance. A significant advantage of this method is the use of anthranil as a safe nitrene precursor, eliminating the need for hazardous azides. Mechanistic studies indicate an Electrophilic Aromatic Substitution (EAS)-type pathway, which contrasts sharply with our previous Co(III)-catalyzed system that proceeds via an electrocyclization mechanism. Notably, Fe(II)-catalyzed sp³ C–H functionalization also enabled the construction of indolines and dihydroquinazolinone scaffolds. Overall, this work establishes a sustainable and practical approach for accessing diverse N-heterocycles via intramolecular amination using anthranil as nitrene precursor.