Using O=S([O-])([O-])=S, COC(=O)C1=Cc2cc(-c3ccc(OC)cc3)ccc2SCC1 to produce COC(=O)C1=Cc2cc(-c3ccc(OC)cc3)ccc2S(=O)(=O)CC1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.