Using O=C1CCC(=O)N1Br, CCOC(=O)c1ncc2onc(-c3ccccc3)c2c1O to produce CCOC(=O)c1nc(Br)c2onc(-c3ccccc3)c2c1O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.