1.1: 60 percent / Bu4NI / dimethylsulfoxide / 12 h / 80 °C 2.1: 80 percent / aq. NaOH; aq. H2O2 / methanol / 3 h / 20 °C 3.1: aq. KOH / methanol / 12 h / 90 °C 4.1: CF3COOH / CH2Cl2 / 1.5 h / 20 °C 4.2: 4.5 mg / Dowex-50 H(1+) View Scheme