['CO', 'Cc1nn(C)c(N)c1-c1cccc(F)c1', 'COC', 'Cn1ncc(-c2cccc(F)c2)c1N', 'Fc1ccccc1', 'COCc1cc(N)n(C)n1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-c2cn[nH]c2)cc1.