['CO', 'N#CCOc1ccc(C=O)cc1[N+](=O)[O-]', 'CC#N', 'COC(=O)c1ccc(O)c([N+](=O)[O-])c1', 'N#CCO', 'COC(=O)c1cccc([N+](=O)[O-])c1', 'COC=O', 'N#CCOc1ccccc1[N+](=O)[O-]']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.