['CCO', 'O=Cc1cnc2c(Cl)cc([N+](=O)[O-])cc2c1Cl', 'CC', 'O=C(O)c1cnc2c(Cl)cc([N+](=O)[O-])cc2c1Cl', 'CCOC=O', 'O=[N+]([O-])c1cc(Cl)c2nccc(Cl)c2c1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2ncccc2c1.