Using COC(=O)c1ccc2c(=O)[nH]c(Cc3cccc(Cl)c3)nc2c1 to produce O=C(O)c1ccc2c(=O)[nH]c(Cc3cccc(Cl)c3)nc2c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.