['CCO', 'CC(C)N(CC=O)CC(=O)NC(=O)NC(C)(C)C', 'CC(C)(C)NC(N)=O', 'CCOC(=O)CN(CC=O)C(C)C', 'CC(C)(C)NC=O', 'CCOC(=O)CN(CC(N)=O)C(C)C', 'CC(C)(C)N', 'CCOC(=O)CN(CC(=O)NC=O)C(C)C', 'CC', 'CC(C)N(CC(=O)O)CC(=O)NC(=O)NC(C)(C)C', 'CCOC(C)=O', 'CC(C)NCC(=O)NC(=O)NC(C)(C)C', 'CCOC(=O)CNC(C)C', 'CC(=O)NC(=O)NC(C)(C)C', 'CC(C)C', 'CCOC(=O)CN(CC(=O)NC(N)=O)C(C)C', 'CCC', 'CCOC(=O)CNCC(=O)NC(=O)NC(C)(C)C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is None.