Regiodivergent C3 and C4 Amination of Quinolines via Radical and Ionic Pathways

ABSTRACT Controlling the site of amination on N‐heteroarenes is pivotal for rapid exploration of structure–activity relationships, yet a single‐precursor platform that toggles between C3 and C4 amination of quinolines has remained elusive. Here we report a regiodivergent method that channels quinoline amination to C3 or C4 through orthogonal radical and ionic manifolds. Under visible‐light, donor‐assisted electron‐donor–acceptor (EDA) conditions, homolytic N─N cleavage of N‐aminoquinolinium salts generates N‐centered radicals that selectively install amino groups at C3 via capture by an enamine intermediate (radical pathway) formed through traceless nucleophile‐induced dearomatization. In the absence of light and donor, the same quinolinium salt undergoes a two‐electron ionic process: S N Ar‐type addition of amines at C4, followed by base‐promoted rearomatization to furnish C4‐aminated products. The method proceeds under mild conditions, accommodates a broad range of quinolines and amine partners, and enables late‐stage diversification. Mechanistic experiments support an EDA‐initiated origin for the C3 manifold and an ionic mechanism for C4, establishing condition‐gated control over quinoline C─N bond formation.