['CO', 'C[C@@H](CCC=O)[C@@H]1CC[C@@H]2[C@@H]3CC[C@@H]4C[C@@]5(CC[C@]4(C)[C@@H]3CC[C@@]21C)CO5', 'CCCCC(=O)OC', 'C[C@@]12CCC[C@@H]1[C@@H]1CC[C@@H]3C[C@@]4(CC[C@]3(C)[C@@H]1CC2)CO4']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1CC2CC[C@H]3C4CC[C@@]5(CO5)C[C@H]4CC[C@H]3[C@H]2C1.