['CO', 'Cc1nn(Cc2ccncc2)c(=O)s1', 'Cc1n[nH]c(=O)s1', 'COc1cc(C)ccn1', 'Cc1nn(C)c(=O)s1', 'COc1ccccn1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=c1scnn1Cc1ccncc1.