['Cc1csc([N+](=O)[O-])c1', 'Oc1ccccc1N1CCNCC1', 'Oc1ccccc1', 'Cc1cc([N+](=O)[O-])sc1N1CCNCC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(N2CCN(c3cccs3)CC2)cc1.