Using COC(=O)c1cc(=O)c2cc3c(=O)cc(C(=O)OC)[nH]c3c(Cl)c2[nH]1 to produce O=C(O)c1cc(=O)c2cc3c(=O)cc(C(=O)O)[nH]c3c(Cl)c2[nH]1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.