['CNCCC(C)C', 'Cc1sc2nc(CCC=O)[nH]c(=O)c2c1C', 'CCC(C)C', 'CNC(=O)CCc1nc2sc(C)c(C)c2c(=O)[nH]1', 'CCC(=O)N(C)CCC(C)C', 'Cc1sc2nc[nH]c(=O)c2c1C']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1[nH]cnc2sccc12.