N-bromosuccinmide in dichloromethane T=10°C; 2 h;

2,2'-azo-bisisobutyronitrile; tri-n-butyl-tin hydride; toluene-4-sulfonic acid 1) benzene, 80 deg C, 1.5 h, 2) benzene, room temp., 15 min; Yield given. Multistep reaction;