['C/C=C/C=C/C=O', 'OCc1nnnn1-c1ccccc1', 'C/C=C/C=C/C(=O)O', 'Cc1nnnn1-c1ccccc1', 'CC', 'C/C=C/C(=O)OCc1nnnn1-c1ccccc1', 'C/C=C/C', 'CC(=O)OCc1nnnn1-c1ccccc1', 'C/C=C/C=C/C(=O)OC', 'c1ccc(-n2cnnn2)cc1', 'c1ccccc1', 'C/C=C/C=C/C(=O)OCc1nnn[nH]1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(-n2cnnn2)cc1.