['CO', 'Cc1nc(-c2ccc(F)cc2)sc1C=O', 'COC=O', 'Cc1csc(-c2ccc(F)cc2)n1', 'Fc1ccccc1', 'COC(=O)c1scnc1C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-c2nccs2)cc1.