Copper‐catalyzed oxidative intramolecular cyclization for the synthesis of 2‐hydroxy‐indolin‐3‐ones

The synthesis of substituted 2‐hydroxy‐indolin‐3‐ones has attracted considerable attention due to the frequent presence of the indole nucleus in numerous natural products and biologically active molecules. Herein, a direct access to 2‐hydroxy‐indolin‐3‐ones through copper‐catalyzed oxidative intramolecular cyclization of N‐(2‐acetylphenyl)picolinamide has been developed. This method exhibits good functional group tolerance, atom‐economy and avoids the pre‐functionalization of substrates.