Using CCc1cc2c(cc1OCOC)CCC1C2CCC2(C)C(=O)CCC12 to produce CCc1cc2c(cc1OCOC)CCC1C2CCC2(C)C(O)CCC12, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.