['CO', 'CCN(CC#N)S(=O)(=O)c1cccc([N+](=O)[O-])c1', 'CC', 'COc1ccc([N+](=O)[O-])cc1S(=O)(=O)NCC#N', 'CC#N', 'CCNS(=O)(=O)c1cc([N+](=O)[O-])ccc1OC', 'CCNCC#N', 'COc1ccc([N+](=O)[O-])cc1[SH](=O)=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.