Using O=C([O-])[O-], CCOc1ccc(-c2nc(-c3ccc(O)cc3O)cs2)cc1OCC to produce CCOc1ccc(-c2nc(-c3cc(C(=O)O)c(O)cc3O)cs2)cc1OCC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.