Using COC(=O)C1(CCCCCCCCCCCCC2(C(=O)NC3CC3)CC2)CC1 to produce O=C(O)C1(CCCCCCCCCCCCC2(C(=O)NC3CC3)CC2)CC1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.