['CO', 'Cc1c(C(=O)N(C)CC(C)C=O)oc2ccccc12', 'CNCC(C)C(=O)OC', 'Cc1c(C=O)oc2ccccc12', 'COC(=O)C(C)C', 'CNC(=O)c1oc2ccccc2c1C', 'Cc1coc2ccccc12', 'COC(=O)C(C)CN(C)C=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2occc2c1.