['O=C1CNCN1CC(F)(F)F', 'Nc1ncc(Cl)cc1[SH](=O)=O', 'CC(F)(F)F', 'Nc1ncc(Cl)cc1S(=O)(=O)N1CNC(=O)C1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1CN(S(=O)(=O)c2cccnc2)CN1.