['CO', 'O=C(O)c1ccn(-c2ccc(F)cc2)n1', 'O=CO', 'COc1cnn(-c2ccc(F)cc2)c1', 'Fc1ccccc1', 'COc1c[nH]nc1C(=O)O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-n2cccn2)cc1.