Using CCOC(=O)C1C(C(OC(C)=O)C(Cl)(Cl)C(F)(F)F)C1(C)C to produce CCOC(=O)C1C(C=C(Cl)C(F)(F)F)C1(C)C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.