['CO', 'Nc1n[nH]c(C(F)(F)F)c1-c1ccccc1', 'FC(F)F', 'COc1ccc(-c2c[nH]nc2N)cc1', 'COc1ccccc1', 'Nc1cc(C(F)(F)F)[nH]n1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-c2cn[nH]c2)cc1.