['CC(C)(C)O', 'CCOCC(C)NC(=O)CCNC=O', 'CCOCC(C)N', 'CC(C)(C)OC(=O)NCCC=O', 'CC(C)(C)OC=O', 'CCOCC(C)NC(=O)CCN', 'CC', 'CC(CO)NC(=O)CCNC(=O)OC(C)(C)C', 'CCO', 'CC(C)NC(=O)CCNC(=O)OC(C)(C)C', 'CC(C)C', 'CCOCC(C)NC(=O)CCNC(=O)O', 'CCCOCC', 'CC(C)(C)OC(=O)NCCC(N)=O', 'CC(C)(C)OC(N)=O', 'CCOCC(C)NC(=O)CC']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is None.