Using COC(=O)CCCCC1Oc2ccc(C(O)CCc3cccs3)cc2O1 to produce O=C(O)CCCCC1Oc2ccc(C(O)CCc3cccs3)cc2O1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.