Using CCCCC12Cc3cc(OCOC)ccc3C1=C(C)C(=O)C(CC=O)C2 to produce CCCCC12Cc3cc(O)ccc3C1=C(C)C(=O)C(CC=O)C2, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.