['CO', 'Cc1ccc(-c2c[nH]c(=S)n2CC=O)cc1', 'COC(C)=O', 'Cc1ccc(-c2c[nH]c(=S)[nH]2)cc1', 'Cc1ccccc1', 'COC(=O)Cn1cc[nH]c1=S']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is S=c1[nH]cc(-c2ccccc2)[nH]1.