['CC', 'N#CCCNCn1ncc2ccccc2c1=O', 'CCC#N', 'CCNCn1ncc2ccccc2c1=O', 'CCN(C)CCC#N', 'O=c1[nH]ncc2ccccc12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1[nH]ncc2ccccc12.