Using O=C1CCC(=O)N1Br, COC(=O)c1cc2c(C)cccc2n1C(=O)OC(C)(C)C to produce COC(=O)c1cc2c(CBr)cccc2n1C(=O)OC(C)(C)C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.