['CC(C)(C)CC=O', 'N#CC(C(=O)CN)c1ccc2ccccc2n1', 'CC(C)(C)CC(N)=O', 'CC(=O)C(C#N)c1ccc2ccccc2n1', 'c1ccc2ncccc2c1', 'CC(C)(C)CC(=O)NCC(=O)CC#N']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2ncccc2c1.