Using COC(=O)CCc1ncc(O)c(C(=O)OC)c1C(=O)OC, COC(=O)CBr to produce COC(=O)CCc1ncc(OCC(=O)OC)c(C(=O)OC)c1C(=O)OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.