['CO', 'Cc1ccc2oc(C(=O)N(C)CC(C)C=O)cc2c1', 'CNCC(C)C(=O)OC', 'Cc1ccc2oc(C=O)cc2c1', 'COC(=O)C(C)C', 'CNC(=O)c1cc2cc(C)ccc2o1', 'Cc1ccc2occc2c1', 'COC(=O)C(C)CN(C)C=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2occc2c1.