Using Br, O=C1CCc2cc(-c3cccc(C(F)(F)F)c3)ccc21 to produce O=C1c2ccc(-c3cccc(C(F)(F)F)c3)cc2CC1Br, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.