['CCOCC(C)N', 'Nc1ccc(C=O)cc1[N+](=O)[O-]', 'CC', 'CC(CO)NC(=O)c1ccc(N)c([N+](=O)[O-])c1', 'CCO', 'CC(C)NC(=O)c1ccc(N)c([N+](=O)[O-])c1', 'CCCOCC', 'NC(=O)c1ccc(N)c([N+](=O)[O-])c1', 'CCOCC(C)NC=O', 'Nc1ccccc1[N+](=O)[O-]']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.