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