Using CCOC(=O)c1cn2nc(Cn3nnc4ccc(Br)cc43)ccc2n1 to produce O=C(O)c1cn2nc(Cn3nnc4ccc(Br)cc43)ccc2n1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.