['CO', 'COC(=O)c1ccc(Cl)c(S(=O)(=O)NNC=O)c1', 'COC(=O)NNS(=O)(=O)c1cc(C=O)ccc1Cl', 'COC=O', 'COC(=O)NNS(=O)(=O)c1ccccc1Cl']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.