Using COC(=O)CC(=O)OC, COC1CCC(C)(C)N1C(=O)OC(C)(C)C to produce COC(=O)C(C(=O)OC)C1CCC(C)(C)N1C(=O)OC(C)(C)C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.