1: potassium hydroxide; water / methanol / 16 h / 30 °C 2: perchloric acid / water / 1 h / 20 °C 3: 1-hydroxy-3H-benz[d][1,2]iodoxole-1,3-dione; trifluoroacetic acid / dimethyl sulfoxide / 40 h / 40 °C 4: water; sodium hydroxide / 0.5 h View Scheme