Using C=CCc1c(O)ccc2c(=O)c3c(Cl)cccc3oc12, O=C([O-])[O-] to produce O=C(O)C1Cc2c(ccc3c(=O)c4c(Cl)cccc4oc23)O1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.