['O=CO', 'CC(C)(C)c1ccn(-c2ccccc2)n1', 'CC(C)C', 'O=C(O)c1cnn(-c2ccccc2)c1', 'c1ccccc1', 'CC(C)(C)c1n[nH]cc1C(=O)O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-n2cccn2)cc1.