Copper-Catalyzed [3 + 2] Annulation of O‑Acyl Oximes with 4‑Sulfonamidophenols for the Synthesis of 5‑Sulfonamidoindoles and 2‑Amido-5-sulfonamidobenzofuran-3(2H)‑ones

A copper-catalyzed [3 + 2] annulation of O-acyl oximes with 4-sulfonamidophenols is developed. The advantage of this method lies in the concurrent double activation of two substrates to form nucleophilic enamines and electrophilic quinone monoimines. The substituent on the α-carbon of O-acyl oxime determines two different reaction pathways, thereby leading to the selective generation of 5-sulfonamidoindoles and 2-amido-5-sulfonamidobenzofuran-3­(2H)-ones.