Using O=[N+]([O-])c1ccc2c(N3CCc4ccc(Cl)cc43)ncnc2c1 to produce Nc1ccc2c(N3CCc4ccc(Cl)cc43)ncnc2c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.