['CC(C)C=O', 'NCCNC(=O)NNC(=O)c1cccs1', 'CC(C)C(=O)NCCN', 'O=CNNC(=O)c1cccs1', 'CC(C)C(N)=O', 'CCNC(=O)NNC(=O)c1cccs1', 'CCNC(=O)C(C)C', 'NC(=O)NNC(=O)c1cccs1', 'c1ccsc1', 'CC(C)C(=O)NCCNC(=O)NNC=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccsc1.