['CC1CNC1', 'O=CC1CCC(C(F)(F)F)NC1=O', 'CC1CN(C=O)C1', 'O=C1CCCC(C(F)(F)F)N1', 'FC(F)F', 'CC1CN(C(=O)C2CCCNC2=O)C1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1NCCCC1C(=O)N1CCC1.