Using O=C([O-])[O-], O=C(O)C(O)c1ccc2c(c1)Nc1nccnc1S2 to produce COC(=O)C(O)c1ccc2c(c1)Nc1nccnc1S2, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.