Using O=CO, COc1cc(-c2cnc3[nH]cc(C(=O)C4(C)CCC(O)CC4)c3n2)cc(OC)c1OC to produce COc1cc(-c2cnc3[nH]cc(C(=O)C4(C)CCC(OC=O)CC4)c3n2)cc(OC)c1OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.