Using C1=CCCC1, COC(=O)C1C(=O)CC(OC(C)=O)C1CC(=O)O to produce COC(=O)CC1C(OC(C)=O)CC(=O)C1C(=O)OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.