Using CCOC(=O)C1CCCN(C(=O)OC(C)(C)C)C1, ClCCBr to produce CCOC(=O)C1(CCCl)CCCN(C(=O)OC(C)(C)C)C1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.