['CC', 'N#CCCNCn1c(=O)oc2cc(Br)ccc21', 'CCC#N', 'CCNCn1c(=O)oc2cc(Br)ccc21', 'CCN(C)CCC#N', 'O=c1[nH]c2ccc(Br)cc2o1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1[nH]c2ccccc2o1.