['C=CCNCC=C', 'CS(=O)(=O)c1nc(C=O)c2ccccn12', 'C=CC', 'C=CCNC(=O)c1nc(S(C)(=O)=O)n2ccccc12', 'C=CCN(C=O)CC=C', 'CS(=O)(=O)c1ncc2ccccn12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccn2cncc2c1.