Visible-Light-Driven Self-Sensitized Photocatalysis: TBAI-Assisted Dioxygenation of 3-Salicyloylindoles

The integration of tandem radical reactions with indole skeletal modification offers an innovative strategy for the efficient construction of nitrogen/oxygen-containing heterocyclic frameworks. Herein we report a novel synthetic approach based on 3-salicyloylindoles. Under visible-light irradiation in an oxygen atmosphere and with the cooperative action of tetrabutylammonium iodide (TBAI), a substrate self-sensitized process enables dual oxidation at C3/C4 of indoles under mild conditions, leading to the efficient assembly of a series of functionalized chromenopyranone derivatives. Notably, this reaction system operates without the need for external photosensitizers or strong oxidants, utilizing only oxygen as the terminal oxidant at room temperature.