['CC(=O)O', 'O=c1cc(CF)c2ccc(O)cc2o1', 'O=C(O)CO', 'O=c1cc(CF)c2ccccc2o1', 'CF', 'O=C(O)COc1ccc2ccc(=O)oc2c1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1ccc2ccccc2o1.