['C1CCNCC1', 'O=CCC1(C(=O)O)CCCC1', 'O=CO', 'O=C(CC1CCCC1)N1CCCCC1', 'O=C(O)C1CCCC1', 'CC(=O)N1CCCCC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(CC1CCCC1)N1CCCCC1.