Using O=S([O-])O, CCOC(=O)c1cc(Cl)c2c(c1C)C(=O)CCS2 to produce CCOC(=O)c1cc(Cl)c2c(c1C)C(=O)CCS2(=O)=O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.