iodine; triphenyl bismuth dibromide in cyclohexane T=45°C; 2.5 h;

1: 74 percent / calcium hydride, tetra-n-butylammonium iodide / toluene / Heating 2: 59 percent / azobis(isobutyronitrile), SO2Cl2 / CCl4 / 2.5 h / -10 °C / Irradiation 3: 1.) DBU, 2.) ozone / 1.) 150 min, 90 deg C, 2.) CH2Cl2/methanol, -78 deg C 4: 86 percent / 0.15 M aqueous LiOH / tetrahydrofuran / 4 h / Heating 5: 1.) pyridinium chlorochromate, sodium acetate, 2.) 0.15 M aqueous LiOH / 1.) CH2Cl2, 1 h, room temperature, 2.) THF, 5 min, room temperature View Scheme