Using [Cl-], O=C(F)C(F)(OC(F)(F)C(F)(F)C(F)(F)F)C(F)(F)F to produce O=C(Cl)C(F)(OC(F)(F)C(F)(F)C(F)(F)F)C(F)(F)F, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.