['C[C@@H]1CNC[C@H](C)O1', 'O=CCn1ccc2ccccc21', 'c1ccc2[nH]ccc2c1', 'CC(=O)N1C[C@@H](C)O[C@@H](C)C1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(Cn1ccc2ccccc21)N1CCOCC1.