Using O=C1c2cccc(Cl)c2C(=O)c2c(Cl)cccc21, CCOC(=O)CC(=O)OCC to produce CCOC(=O)C(C(=O)OCC)=C1c2cccc(Cl)c2C(=O)c2c(Cl)cccc21, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.