['CO', 'CCc1c(-c2ccccc2)nn(C)c1N', 'CC', 'COc1cccc(-c2cc(N)n(C)n2)c1', 'COc1ccccc1', 'CCc1cnn(C)c1N']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-c2cc[nH]n2)cc1.