['O=CCC(F)(F)F', 'Cn1cnc([N+](=O)[O-])c1N1CCNCC1', 'Cn1cnc([N+](=O)[O-])c1', 'O=C(CC(F)(F)F)N1CCNCC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ncc(N2CCNCC2)[nH]1.