['CO', 'Cn1cc(/C=C2\\Oc3cc(O)ccc3C2=O)c2ccccc21', 'O=C1COc2cc(O)ccc21', 'COc1ccc2c(c1)c(C)cn2C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1/C(=C/c2c[nH]c3ccccc23)Oc2ccccc21.