1: 72 percent / NBS, α,α'-azobis(isobutyronitrile) / CCl4 / 3 h / Heating 2: 70 percent / aq. HCl / tetrahydrofuran / 0.25 h / Ambient temperature 3: trifluoroacetanhydride, pyridine / diethyl ether / 0.25 h / Ambient temperature View Scheme

With  N-bromosuccinmide; azobisisobutyronitrile in  tetrachloromethane 3 h;  Heating;   

Multi-step reaction with 2 steps 1: 72 percent / NBS, α,α'-azobis(isobutyronitrile) / CCl4 / 3 h / Heating2: 70 percent / aq. HCl / tetrahydrofuran / 0.25 h / Ambient temperature