['CO', 'COc1ccccc1-c1n[nH]c(=S)o1', 'COc1cccc(-c2n[nH]c(=S)o2)c1', 'S=c1[nH]nco1', 'COc1ccc(OC)cc1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is S=c1[nH]nc(-c2ccccc2)o1.