1: 1.) NBS, AIBN; 2.) silica gel, H2O / 1.) CCl4; 2.) THF, r.t. 2: 22 percent / TMSOTf, molecular sieves 4 Angstroem / CH2Cl2; diethyl ether / 7.5 h 3: 41 percent / aq. 80percent AcOH / 40 h / 45 °C 4: 82 percent / 0.1N NaOH / CH2Cl2; methanol / 0.33 h / 0 °C 5: 95 percent / 0.1N NaOH / 0.33 h / Ambient temperature View Scheme

Multi-step reaction with 2 steps 1: HgO(yellow), 20percent H2SO4 / tetrahydrofuran / Heating2: p-TsOH / benzene / Heating  

Multi-step reaction with 3 steps 1: 1.) NBS, AIBN; 2.) silica gel, H2O / 1.) CCl4; 2.) THF, r.t.2: 20 percent / TMSOTf, molecular sieves 4 Angstroem / CH2Cl2; diethyl ether / 7.5 h3: 53 percent / aq. 80percent AcOH