['COCCN', 'CC(C=O)NS(C)(=O)=O', 'CO', 'CCNC(=O)C(C)NS(C)(=O)=O', 'CCOC', 'CC(NS(C)(=O)=O)C(N)=O', 'CS(N)(=O)=O', 'CCC(=O)NCCOC', 'C[SH](=O)=O', 'COCCNC(=O)C(C)N']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is None.