Using CC(C)(C)OC(=O)COc1cc2c(=O)ccn3c4cc(Br)ccc4c(c1)c23 to produce O=C(O)COc1cc2c(=O)ccn3c4cc(Br)ccc4c(c1)c23, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.