External Photosensitizer-Free, Purple Light-Mediated C–H Alkylation of Heterocycles with Unactivated Alkyl Iodides

Herein, we describe an operationally simple and photosensitizer-free direct C–H alkylation of heterocycles protocol driven by purple light irradiation, which exhibits excellent scalability and broad functional group tolerance. Investigations into substrate scope confirm the versatility of this strategy, demonstrating high compatibility with various heterocycles, including benzothiazoles, benzimidazoles, azauracils, coumarins, isoquinolines, aza-uridine, and others. Mechanistic studies reveal that the photodriven alkylation proceeds via a sequential excited benzothiazole oxidation of Et3N, α-aminoalkyl radical-promoted halogen atom transfer, radical–radical coupling, and rearomatization.