CeCl3·7H2O/IBX-promoted oxidation of 3-alkylindoles to 3-hydroxyoxindoles

3-Alkylindoles undergo smooth oxidation with IBX in the presence of CeCl3·7H2O in aqueous acetonitrile at ambient temperature to afford the corresponding 3-hydroxyoxindoles in high yields. This method is very useful for the direct preparation of 3-hydroxyoxindoles from 3-alkylindoles. Operational simplicity, mild and neutral reaction conditions in aqueous solution are the key features of this protocol.