Aqueous Copper Nitrate Catalyzed Synthesis of 3‐Alkylideneoxindoles from α‐Diazo‐β‐ketoanilides. Issue 18 (6th May 2014) - Mo, Shanyan
Abstract: An economical, practical, and green protocol with which to synthesize 3‐alkylideneoxindoles from α‐diazo‐β‐ketoanilides has been developed. The approach employs inexpensive Cu(NO3 )2 · 3H2 O as catalyst and environmentally friendly water as solvent, and achieves moderate to excellent yields. The method has good tolerance to a range of N ‐alkyl and N ‐aryl groups, including electron‐withdrawing and electron‐donating groups on the aromatic ring, ortho ‐, meta ‐, and para ‐substituents, and β‐aliphatic and β‐aromatic keto groups. A plausible mechanism involving intramolecular aromatic metal carbene electrophilic addition as the key step is proposed. Abstract : Inexpensive Cu(NO3 )2 · 3H2 O catalyst and environmentally friendly water solvent are employed for the transformation of α‐diazo‐β‐ketoanilides into 3‐alkylidene‐oxindoles. The process is easily handled, economical, environmentally friendly, and can be used to convert a broad range of substrates in moderate to excellent yields. An intramolecular aromatic metal carbene electrophilic addition mechanism is proposed.