Using COC(=O)c1ccc2c(c1)C=CC(=O)CO2, ClC(Cl)(Cl)Br to produce COC(=O)c1ccc2c(c1)C=CC(=C(Cl)Cl)CO2, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.