['CC(C)(C)O', 'Nn1cnc2sc3c(c2c1=O)CCN(C=O)C3', 'CC(C)(C)OC=O', 'Nn1cnc2sc3c(c2c1=O)CCNC3', 'CC(C)C', 'Nn1cnc2sc3c(c2c1=O)CCN(C(=O)O)C3']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1[nH]cnc2sc3c(c12)CCNC3.