['FC(F)F', 'Cc1nc(-c2coc3c4c(ccc3c2=O)OCO4)cs1', 'Cc1nccs1', 'O=c1cc(C(F)(F)F)oc2c3c(ccc12)OCO3']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1c(-c2cscn2)coc2c3c(ccc12)OCO3.