['CC(C)(C)C(=O)NCC=O', 'CCC(CC)c1nnc(N)s1', 'CC(C)(C)C=O', 'CCC(CC)c1nnc(NC(=O)CN)s1', 'CC(C)(C)C(N)=O', 'CCC(CC)c1nnc(NC(C)=O)s1', 'CCC(CC)c1nncs1', 'CC(C)(C)C(=O)NCC(N)=O', 'CCCCC', 'CC(C)(C)C(=O)NCC(=O)Nc1nncs1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1nncs1.