['CO', 'CC(C=O)CN(C)C(=O)Cn1c(=O)oc2ccccc21', 'CNCC(C)C(=O)OC', 'O=CCn1c(=O)oc2ccccc21', 'COC(=O)C(C)C', 'CNC(=O)Cn1c(=O)oc2ccccc21', 'O=c1[nH]c2ccccc2o1', 'COC(=O)C(C)CN(C)C(C)=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1[nH]c2ccccc2o1.