['CC(C)(C)N', 'COCCOCCC=O', 'CO', 'CCOCCC(=O)NC(C)(C)C', 'CCOC', 'CC(C)(C)NC(=O)CCO', 'COCCO', 'CCC(=O)NC(C)(C)C', 'CC(C)C', 'COCCOCCC(N)=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is None.