1: 48 percent / benzenesulfonyl chloride, pyridine 2: 44 percent / Zn, dibromoethane / tetrahydrofuran / 1.12 h / Heating 3: 30 percent / SOCl2, pyridine / CH2Cl2 / 0.08 h / Heating 4: 76 percent / 50percent aq. HF / tetrahydrofuran / 18 h / Ambient temperature View Scheme