['Cc1ccccc1[N+](=O)[O-]', 'O=c1ccc([N+](=O)[O-])c[nH]1', 'O=[N+]([O-])c1ccccc1', 'Cn1cc([N+](=O)[O-])ccc1=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1ccccn1Cc1ccccc1.