['OCCO', 'O=CCN1C(=O)c2ccccc2S1(=O)=O', 'CCO', 'O=C(O)CN1C(=O)c2ccccc2S1(=O)=O', 'CC(=O)OCCO', 'O=C1NS(=O)(=O)c2ccccc21']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1NS(=O)(=O)c2ccccc21.