['COCCN', 'Nc1c2c(nn1CC=O)CSC2', 'CO', 'CCNC(=O)Cn1nc2c(c1N)CSC2', 'CCOC', 'NC(=O)Cn1nc2c(c1N)CSC2', 'COCCNC(C)=O', 'Nc1[nH]nc2c1CSC2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1[nH]nc2c1CSC2.