Transition-Metal-Free C(sp3)–H Hydroxylation of 2‑Oxindoles with Peroxides via Radical Cross-Coupling Reaction in Water

Without employing any transition metal, organic solvent or other additive, a novel, economical, and environmentally attractive strategy has been described for the C­(sp3)–H hydroxylation of 2-oxindoles with peroxides via radical cross-coupling reaction exposed to air in water. This transformation features a wide substrate scope, operational simplicity, and mild reaction conditions, thus offering a concise approach to various 3-hydroxy-2-oxindoles. In addition, a radical pathway was involved in this hydroxylation through mechanistic studies.