['N#CCCNCCC#N', 'O=CCn1c2ccccc2c(=O)c2ccccc21', 'CCC#N', 'N#CCCNC(=O)Cn1c2ccccc2c(=O)c2ccccc21', 'CC(=O)N(CCC#N)CCC#N', 'O=c1c2ccccc2[nH]c2ccccc12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1c2ccccc2[nH]c2ccccc12.