Using COC(=O)c1nc(C(=O)OC)c(C(=O)OC)nc1C(=O)OC to produce COC(=O)C1NC(C(=O)OC)C(C(=O)OC)NC1C(=O)OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.