['C=CCN', 'O=CCn1c(CO)c[nH]c1=S', 'C=CC', 'NC(=O)Cn1c(CO)c[nH]c1=S', 'C=CCNC(C)=O', 'OCc1c[nH]c(=S)[nH]1', 'CO', 'C=CCNC(=O)Cn1cc[nH]c1=S']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is S=c1[nH]cc[nH]1.