Copper-Catalyzed\nDearomative [3 + 2] Annulation of\nIndoles with 2‑Iodoacetic Acid

An efficient copper-catalyzed dearomative [3 + 2] annulation\nof\nindoles with 2-iodoacetic acid is developed. By employing Cu(OTf)<sub>2</sub>/2,2′-bis(2-oxazoline) as the catalyst and LPO as the\noxidant, a series of indoline-fused butyrolactones were synthesized\nin moderate to good yields. The reaction features mild conditions,\na broad substrate scope, and readily available starting materials.\nFurthermore, synthetic transformations of the products were conducted\nto demonstrate the practical utility of this reaction.