Using COC(=O)CCc1nc(-c2cc(Cl)cc(C(F)(F)F)c2)co1 to produce O=C(O)CCc1nc(-c2cc(Cl)cc(C(F)(F)F)c2)co1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.