['COCCO', 'Cc1cc(=O)oc2cc(O)c(CCC=O)cc12', 'CO', 'CCOC(=O)CCc1cc2c(C)cc(=O)oc2cc1O', 'CCOC', 'Cc1cc(=O)oc2cc(O)c(CCC(=O)O)cc12', 'CCC(=O)OCCOC', 'Cc1cc(=O)oc2cc(O)ccc12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1ccc2ccccc2o1.