Using CCOC(=O)c1c(F)c(F)c(C(C(=O)OCC)C(=O)OCC)c(F)c1C(=O)OCC to produce O=C(O)Cc1c(F)c(F)c(C(=O)O)c(C(=O)O)c1F, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.