['c1ccccc1', 'CCn1c(/C=C/C=O)nc2ccccc21', 'CC(=O)c1ccccc1', 'CCn1c(C)nc2ccccc21', 'CC', 'O=C(/C=C/c1nc2ccccc2[nH]1)c1ccccc1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(/C=C/c1nc2ccccc2[nH]1)c1ccccc1.