1: 82 percent / 2,3-dichloro-5,6-dicyano-1,4-benzoquinone / CH2Cl2; H2O / 2.5 h 2: 90 percent / trifluoroacetic acid / CH2Cl2 / 2.5 h / 20 °C 3: 30 percent aq. H2O2; KHCO3 / methanol; acetonitrile / 24 h / 20 °C View Scheme

1: 82 percent / 2,3-dichloro-5,6-dicyano-1,4-benzoquinone / CH2Cl2; H2O / 2.5 h 2: 90 percent / trifluoroacetic acid / CH2Cl2 / 2.5 h / 20 °C View Scheme