['O=[SH](=O)c1cnc2n1CCC2', 'FC(F)(F)C1CCNCC12CCC2', 'FC(F)F', 'O=S(=O)(c1cnc2n1CCC2)N1CCCC2(CCC2)C1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=S(=O)(c1cnc2n1CCC2)N1CCCC2(CCC2)C1.