Using CCOC(=O)CCC(=O)OCC, COc1cc(C=O)cc(OC)c1OC to produce COc1cc(C=C(CC(=O)O)C(=O)O)cc(OC)c1OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.