['C=CCN', 'O=CCNc1ccccc1[N+](=O)[O-]', 'C=CC', 'NC(=O)CNc1ccccc1[N+](=O)[O-]', 'C=CCNC(C)=O', 'Nc1ccccc1[N+](=O)[O-]', 'C=CCNC(=O)CN', 'O=[N+]([O-])c1ccccc1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.