['CCO', 'COc1c(N)cc(C=O)cc1N', 'CC', 'COc1c(N)cc(C(=O)O)cc1N', 'CO', 'CCOC(=O)c1cc(N)cc(N)c1', 'CCOC=O', 'COc1c(N)cccc1N']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.