['NC1CC1', 'Cc1cc(C)n(C(C)C=O)n1', 'C1CC1', 'Cc1cc(C)n(C(C)C(N)=O)n1', 'Cc1cc(C)[nH]n1', 'CCC(=O)NC1CC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(Cn1cccn1)NC1CC1.