['CC(N)C(N)=O', 'CSc1nc(C=O)c2ccccn12', 'CCC(N)=O', 'CSc1nc(C(N)=O)c2ccccn12', 'CC(NC=O)C(N)=O', 'CSc1ncc2ccccn12', 'CS', 'CC(NC(=O)c1ncn2ccccc12)C(N)=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccn2cncc2c1.