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