Using CC(=O)O, CCC(=O)C1=C(O)CC(c2ccc(SC)cc2)CC1=O to produce CCC(=O)C1=C(O)CC(c2ccc(S(C)=O)cc2)CC1=O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.