Using O=[N+]([O-])[O-], Cc1ccc2c(c1C)OC(C)(C)C2=O to produce Cc1c([N+](=O)[O-])cc2c(c1C)OC(C)(C)C2=O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.