['O=CO', 'CCc1ccc(-c2ccn(C)n2)cc1', 'CC', 'Cn1nc(-c2ccccc2)cc1C(=O)O', 'CCc1ccccc1', 'Cn1nccc1C(=O)O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-c2cc[nH]n2)cc1.