1: 74 percent / CBr4; Ph3P / benzene / 3 h 2: 66 percent / Na2S / aq. ethanol / 4 h / 20 °C 3: 60 percent / Oxone / CH2Cl2 / 50 °C 4: 66 percent / KOH-Al2O3; CBr2F2 / CH2Cl2 View Scheme

Multi-step reaction with 2 steps 1: 74 percent / CBr4; Ph3P / benzene / 3 h2: 66 percent / Na2S / aq. ethanol / 4 h / 20 °C  

Multi-step reaction with 5 steps 1: 73 percent / CBr4, n-Bu3P / diethyl ether / 0.25 h / 0 °C2: 53 percent / Na2S*9H2O / ethanol; H2O / 25 °C3: 79 percent / m-chloroperbenzoic acid / CH2Cl2 / 0.5 h / -30 °C4: pyridine, SO2Cl2 / CH2Cl2 / 0.67 h / -78 °C5: m-chloroperbenzoic acid / CH2Cl2 / 16 h / Ambient temperature  

With  pyridinium p-toluenesulfonate in  methanol 18 h;  Yield given;