Using O=C(C(F)(F)F)C(F)(F)F, Brc1cc(Br)cc(Br)c1 to produce OC(c1cc(Br)cc(Br)c1)(C(F)(F)F)C(F)(F)F, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.