Using BrC(Br)(Br)Br, Cc1cc(CO)cnc1N(C(=O)OC(C)(C)C)C(=O)OC(C)(C)C to produce Cc1cc(CBr)cnc1N(C(=O)OC(C)(C)C)C(=O)OC(C)(C)C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.