['CO', 'CC(C)N(CC=O)Cc1ccc([N+](=O)[O-])cc1', 'COC(C)=O', 'CC(C)NCc1ccc([N+](=O)[O-])cc1', 'COC(=O)CNC(C)C', 'Cc1ccc([N+](=O)[O-])cc1', 'CCC', 'COC(=O)CNCc1ccc([N+](=O)[O-])cc1', 'O=[N+]([O-])c1ccccc1', 'COC(=O)CN(C)C(C)C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.