Using CCOC(=O)C(C)(C)Oc1cccc(Cl)c1, O=C(Br)CBr to produce CCOC(=O)C(C)(C)Oc1ccc(C(=O)CBr)c(Cl)c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.