['CC', 'O=C([O-])c1cc([N+](=O)[O-])c(N2CC[NH2+]CC2)c([N+](=O)[O-])c1', 'CC[NH+]1CCNCC1', 'O=C([O-])c1cc([N+](=O)[O-])cc([N+](=O)[O-])c1', 'O=C[O-]', 'CC[NH+]1CCN(c2c([N+](=O)[O-])cccc2[N+](=O)[O-])CC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(N2CC[NH2+]CC2)cc1.