Using COC(=O)COc1cccc(C=CC(=O)c2c(O)c3ccccc3[nH]c2=O)c1 to produce O=C(O)COc1cccc(C=CC(=O)c2c(O)c3ccccc3[nH]c2=O)c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.