['CO', 'CCCc1[nH]nc(N)c1-c1ccccc1', 'CCC', 'COc1cccc(-c2c[nH]nc2N)c1', 'COc1ccccc1', 'CCCc1cc(N)n[nH]1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-c2cn[nH]c2)cc1.