Using COC(=O)C1(O)CCOc2c(OC(F)(F)F)cc(Cl)cc21 to produce O=C(O)C1(O)CCOc2c(OC(F)(F)F)cc(Cl)cc21, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.