['NC1CCCCC1', 'O=C(Cl)c1cc([N+](=O)[O-])cc([N+](=O)[O-])c1', 'C1CCCCC1', 'Nc1c([N+](=O)[O-])cc(C(=O)Cl)cc1[N+](=O)[O-]', 'O=CCl', 'O=[N+]([O-])c1cccc([N+](=O)[O-])c1NC1CCCCC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(NC2CCCCC2)cc1.