['CCC1(O)CNC1', 'O=CC[C@@H]1NC(=O)NC1=O', 'O=C1CNC(=O)N1', 'CCC1(O)CN(C(C)=O)C1', 'CC', 'O=C1NC(=O)[C@H](CC(=O)N2CC(O)C2)N1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1NC(=O)[C@H](CC(=O)N2CCC2)N1.