['CNCC(C)C#N', 'Cc1cc2ncn(CC(C)O)c2cc1C', 'CC(C)C#N', 'CNCC(O)Cn1cnc2cc(C)c(C)cc21', 'CC(O)CN(C)CC(C)C#N', 'Cc1cc2nc[nH]c2cc1C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2[nH]cnc2c1.