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

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_NAr-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.