['O=C1CCCCN1', 'Cc1nc(CC(C)(C)C)no1', 'CC(C)(C)C', 'O=C1CCCC(Cc2ncno2)N1', 'CC1CCCC(=O)N1', 'CC(C)(C)Cc1ncon1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1CCCC(Cc2ncno2)N1.