Using O=C(OCc1ccccc1)c1ccc(OCc2ccccc2)c(C(=O)OCc2ccccc2)c1 to produce O=C(O)c1ccc(OCc2ccccc2)c(C(=O)O)c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.