['O=CO', 'CC1(C)CN2C(=O)[C@@H](n3cccc3)[C@H]2S1', 'c1cc[nH]c1', 'CC1(C)S[C@@H]2CC(=O)N2[C@H]1C(=O)O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1[C@@H](n2cccc2)[C@H]2SCCN12.