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