['CC(=O)O', 'FC(F)(F)c1cccc2c(S)ccnc12', 'FC(F)F', 'O=C(O)CSc1ccnc2ccccc12', 'O=C(O)CS', 'FC(F)(F)c1cccc2cccnc12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2ncccc2c1.