['CCN1CCNC1=O', 'CN[C@@H]1COC[C@H]1O', 'O[C@H]1CCOC1', 'CNCCN1CCNC1=O', 'O=C1NCCN1', 'CCN(C)[C@@H]1COC[C@H]1O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1NCCN1CCN[C@H]1CCOC1.