['CN', 'O=[N+]([O-])c1ccccc1S(=O)(=O)N1CCc2cc([SH](=O)=O)ccc21', 'O=[N+]([O-])c1ccccc1[SH](=O)=O', 'CNS(=O)(=O)c1ccc2c(c1)CCN2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=S(=O)(c1ccccc1)N1CCc2ccccc21.