Visible-Light-InducedSulfonylation Cyclization toGenerate Indole-Fused Medium-Sized <i>N</i>‑Heterocyclesin 2‑Me-THF

A novel visible-light-induced sulfonylation cyclization to indole-fused medium-sized <i>N</i>-heterocycles was established under room temperature with biomass-derived 2-Me-THF as the solvent. This reaction proceeds in the absence of external photocatalyst, additive, metal salts, and base. Broad substrate scope, good functional group compatibility, and large-scale synthesis and derivatization via iodination, nitration, chlorination, cyanation, and selenylation demonstrate the utility of this protocol. A radical cyclization route was proposed based on radical inhibition experiments, visible-light irradiation on–off test, apparent quantum efficiency calculation, and UV–vis absorption spectroscopic studies.