['O=CO', 'O=C(/C=C/c1cc2ccccc2o1)c1ccccc1O', 'O=C(O)c1cccc(O)c1', 'O=C/C=C/c1cc2ccccc2o1', 'Cc1cc2ccccc2o1', 'CC(=O)c1ccc(C(=O)O)cc1O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(/C=C/c1cc2ccccc2o1)c1ccccc1.