Using BrC(Br)(Br)Br, COC(=O)C(Oc1c(Cl)cc(CO)cc1Cl)c1ccccc1 to produce COC(=O)C(Oc1c(Cl)cc(CBr)cc1Cl)c1ccccc1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.