['CO', 'Nc1onc(C(F)(F)F)c1-c1ccccc1', 'FC(F)F', 'COc1ccccc1-c1cnoc1N', 'COc1ccccc1', 'Nc1cc(C(F)(F)F)no1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-c2cnoc2)cc1.