Using COC(=O)C(=O)c1ccc(OCCOc2ccc(OC)c(OC)c2)cc1 to produce COc1ccc(OCCOc2ccc(C(=O)C(=O)O)cc2)cc1OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.