1: 96 percent / aq. NaOH / propan-2-ol / 0.5 h / 60 °C 2: 48 percent / benzenesulfonyl chloride, pyridine 3: 44 percent / Zn, dibromoethane / tetrahydrofuran / 1.12 h / Heating 4: 30 percent / SOCl2, pyridine / CH2Cl2 / 0.08 h / Heating 5: 76 percent / 50percent aq. HF / tetrahydrofuran / 18 h / Ambient temperature View Scheme