['CC(C)N', 'Cc1c(C(=O)C(C#N)C=O)oc2c(C)cccc12', 'CCC', 'Cc1c(C(=O)C(C#N)C(N)=O)oc2c(C)cccc12', 'CC(C)NC(=O)C(C#N)C=O', 'Cc1coc2c(C)cccc12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2occc2c1.