['CO', 'O=Cc1cc(C(F)(F)F)nc2ccc(Br)cc12', 'COC=O', 'FC(F)(F)c1ccc2cc(Br)ccc2n1', 'FC(F)F', 'COC(=O)c1ccnc2ccc(Br)cc12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2ncccc2c1.