pyridine; dibromotriphenyl-phosphorane in tetrachloromethane; dichloromethane Ambient temperature;

1: 75 percent / 48percent aq. HBr / heptane / Heating 2: 95 percent / PPTS 3: 1) Mg, 2) 0.1 M Li2CuCl4 / 1) THF, 2) below 5 deg C, 3 h; rt 4: p-toluenesulphonic acid / methanol / 4 h / Heating 5: 85 percent / PPh3Br2, pyridine / CH2Cl2; CCl4 / Ambient temperature View Scheme

1: 95 percent / PPTS 2: 1) Mg, 2) 0.1 M Li2CuCl4 / 1) THF, 2) below 5 deg C, 3 h; rt 3: p-toluenesulphonic acid / methanol / 4 h / Heating 4: 85 percent / PPh3Br2, pyridine / CH2Cl2; CCl4 / Ambient temperature View Scheme

1: 1) Mg, 2) 0.1 M Li2CuCl4 / 1) THF, 2) below 5 deg C, 3 h; rt 2: p-toluenesulphonic acid / methanol / 4 h / Heating 3: 85 percent / PPh3Br2, pyridine / CH2Cl2; CCl4 / Ambient temperature View Scheme

1: 1) Mg / 1) THF, 2) -70 deg C to room temperature, 2 h 2: 82 percent / m-chloroperbenzoic acid / CH2Cl2 / 0 - 5 °C 3: 64 percent / H5IO6 / tetrahydrofuran; diethyl ether / 2 h / 0 - 5 °C 4: 1) Mg / 1) THF, 2) 2 h, 0 deg C; room temperature View Scheme