['CC(C)(C)O', 'CC[C@H](C)[C@H](NC=O)C(=O)NN', 'CC(C)(C)OC=O', 'CC[C@H](C)[C@H](N)C(=O)NN', 'CC(C)C', 'CC[C@H](C)[C@H](NC(=O)O)C(=O)NN', 'CC(C)(C)OC(N)=O', 'CC[C@H](C)CC(=O)NN']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is None.