['CCOC1CCCNC1', 'O=Cc1cc([N+](=O)[O-])cc([N+](=O)[O-])c1', 'CC', 'O=C(c1cc([N+](=O)[O-])cc([N+](=O)[O-])c1)N1CCCC(O)C1', 'CCO', 'O=C(c1cc([N+](=O)[O-])cc([N+](=O)[O-])c1)N1CCCCC1', 'CCOC1CCCN(C=O)C1', 'O=[N+]([O-])c1cccc([N+](=O)[O-])c1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(c1ccccc1)N1CCCCC1.