['CO[C@H]1C[C@@H](C=O)N(C)C1', 'O=C1NCC2CNCCN12', 'CO', 'CN1CCC[C@H]1C(=O)N1CCN2C(=O)NCC2C1', 'CO[C@H]1CCN(C)C1', 'O=CN1CCN2C(=O)NCC2C1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C([C@@H]1CCCN1)N1CCN2C(=O)NCC2C1.