CuSO4-catalyzed three-component reaction of α-diazo ester, water and isatin: an efficient approach to oxindole derivatives

A highly efficient three-component reaction of α-diazo ester, water and isatin was developed by using CuSO4 as the catalyst. In this reaction, water was used as both a reactant and the solvent. With this highly environmentally benign and economical protocol, a series of 3-hydroxyindolin-2-one derivatives were efficiently produced in good yields with moderate to high diastereoselectivities.