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

Metal-Free C(<i>sp</i>³)–H Amination of 2‑Oxindoles in Water: Facile Synthesis of 3‑Substituted 3‑Aminooxindoles

A novel metal-free C­(<i>sp</i>³)–H amination of 2-oxindoles with alkylamines to afford C–N coupling products under mild conditions has been exploited. A series of 3-substituted 2-oxindoles and primary/secondary amines substrates were found to be well tolerated, affording the corresponding 3-substituted 3-aminooxindoles in 43%–92% yields. This method uses the economical and environmentally friendly “I₂–TBHP” system, and the mechanistic studies revealed that the procedure undergoes through a radical pathway