Using CCOC(=O)COc1cc(F)ccc1C(=O)NCc1nc2c(F)c(F)cc(F)c2s1 to produce O=C(O)COc1cc(F)ccc1C(=O)NCc1nc2c(F)c(F)cc(F)c2s1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.