Using CI, COC(=O)C(CC(=O)c1ccc(S(C)(=O)=O)cc1)C(C)=O to produce COC(=O)C(C)(CC(=O)c1ccc(S(C)(=O)=O)cc1)C(C)=O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.