['CC12CN3CN(C1)CC(C)(C3)C2', 'O=[N+]([O-])c1ccc(-c2ccccc2)o1', 'O=[N+]([O-])c1ccco1', 'CC12CN3CC(C)(CN(C1)C3c1ccccc1)C2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1coc(-c2ccc(C3N4CC5CC(C4)CN3C5)cc2)c1.