['CC(C)CN', 'Cc1cc2nc(C)c(CCC=O)c(C)n2n1', 'CC(C)C', 'Cc1cc2nc(C)c(CCC(N)=O)c(C)n2n1', 'CCC(=O)NCC(C)C', 'Cc1cc(C)n2nc(C)cc2n1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cnc2ccnn2c1.