['O=[N+]([O-])c1ccccc1', 'CC1CNCC(c2ccccc2)O1', 'c1ccccc1', 'CC1CN(c2ccccc2[N+](=O)[O-])CCO1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(C2CN(c3ccccc3)CCO2)cc1.