['CC(C)(CC=O)CC(=O)O', 'Nc1cc(N2CCOC2=O)ccc1F', 'CC(C)(CC(N)=O)CC(=O)O', 'O=C1OCCN1c1ccc(F)cc1', 'O=C1NCCO1', 'CC(C)(CC(=O)O)CC(=O)Nc1ccccc1F']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1OCCN1c1ccccc1.