['CCO', 'CCOC(=O)CSc1c(SCC=O)c(=O)c1=O', 'CC', 'CCOC(=O)CSc1c(SCC(=O)O)c(=O)c1=O', 'CCOC(C)=O', 'CCOC(=O)CSc1c(S)c(=O)c1=O', 'CCOC(=O)CS', 'CCOC(=O)CSc1cc(=O)c1=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1ccc1=O.