Using O=[N+]([O-])O, COCC1COc2ccc(C(=O)O)cc2O1 to produce COCC1COc2cc([N+](=O)[O-])c(C(=O)O)cc2O1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.