Using O=CC1(C2NCCc3c2[nH]c2ccc(Cl)cc32)CCC1, NO to produce O=C(NO)C1(C2NCCc3c2[nH]c2ccc(Cl)cc32)CCC1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.