['CO', 'CC1(C)[C@H](C(N)=O)CC[C@]1(C)C=O', 'COC=O', 'C[C@H]1CC[C@@H](C(N)=O)C1(C)C', 'NC=O', 'COC(=O)[C@@]1(C)CCCC1(C)C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1CCCC1.