Using COC(=O)c1ccc2sc(C)cc2c1, O=C(Cl)c1ccc(Cl)cc1Cl to produce COC(=O)c1ccc2sc(C)c(C(=O)c3ccc(Cl)cc3Cl)c2c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.