['C1CCCNCC1', 'O=Cc1c[nH]c(=O)c([N+](=O)[O-])c1', 'O=CN1CCCCCC1', 'O=c1[nH]cccc1[N+](=O)[O-]']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(c1ccc(=O)[nH]c1)N1CCCCCC1.