Using BrCCCCCBr, CCOC(=O)CCc1c(O)ccc2ccc(OCC(=O)OCC)cc12 to produce CCOC(=O)CCc1c(OCCCCCBr)ccc2ccc(OCC(=O)OCC)cc12, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.