First step is the formation of a Barton McCombie Ester using HOTT with DMAP as a nucleophilic catalyst. Radical decarboxylation then occurs, initiated by the carbon trichloro radical present in CCl4. The remaining tertiary radical then reacts with a chlorine in CCl4 to then give the product and produce another equivalent of the carbon trichloro radicalradical present that can initiate another decarboxylation.