Using COC(=O)Oc1ccc(C(=O)Oc2ccc3ccc(=O)oc3c2)cc1 to produce O=C(Oc1ccc2ccc(=O)oc2c1)c1ccc(O)cc1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.