['O=[SH](=O)C1COC1', 'C[C@@H]1CNCCN1S(=O)(=O)C1COC1', 'C[C@@H]1CN(S(=O)(=O)C2COC2)CCN1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=S(=O)(C1COC1)N1CCN(S(=O)(=O)C2COC2)CC1.