['CO', 'NC(=O)c1nnn(-c2ccccc2)c1N', 'NC=O', 'COc1cccc(-n2nncc2N)c1', 'COc1ccccc1', 'NC(=O)c1nn[nH]c1N']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-n2ccnn2)cc1.