['CCC1CCNCC1', 'O=CC1CCC(F)(F)C1', 'FC1(F)CCCC1', 'CCC1CCN(C=O)CC1', 'CC', 'O=C(C1CCC(F)(F)C1)N1CCCCC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(C1CCCC1)N1CCCCC1.