in dichloromethane 1) reflux; 2) 1 h, 20 deg C;

1: 86 percent / azobis(isobutyronitrile), Br2 / CCl4 / 3 h / 77 °C / Irradiation 2: 81 percent / CH2Cl2 / 1) reflux; 2) 1 h, 20 deg C View Scheme