1: AcOH; H2SO4 / CH2Cl2 / 20 °C 2: N-methylmorpholine N-oxide / acetonitrile / 5 h / 20 °C 3: NH2SO3H; NaClO2 / dioxane; H2O / 0.83 h / 20 °C 4: KOH / methanol / 2 h / 50 °C 5: 91 percent / 3 h / 170 °C View Scheme

Fe(CO)9 in hexane 1 h; Heating;