['Cc1ccc2c(c1)[C@H](N)CCC2', 'O=CN[C@H]1c2ccccc2C[C@H]1O', 'N[C@H]1c2ccccc2C[C@H]1O', 'Cc1ccc2c(c1)[C@H](NC=O)CCC2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(N[C@@H]1CCCc2ccccc21)N[C@@H]1CCc2ccccc21.