['CO', 'O=CCOCc1ccc2c(c1)OCO2', 'COC(C)=O', 'OCc1ccc2c(c1)OCO2', 'COC(=O)CO', 'Cc1ccc2c(c1)OCO2', 'COCC(=O)OC', 'c1ccc2c(c1)OCO2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2c(c1)OCO2.