['CCNCC#N', 'CN1C(=O)c2ccc(C=O)cc2C1=O', 'CC', 'CN1C(=O)c2ccc(C(=O)NCC#N)cc2C1=O', 'CC#N', 'CCNC(=O)c1ccc2c(c1)C(=O)N(C)C2=O', 'CCN(C=O)CC#N', 'CN1C(=O)c2ccccc2C1=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1NC(=O)c2ccccc21.