['CO', 'CN(CCCC=O)C(=O)C1CCOC1', 'O=CC1CCOC1', 'CNCCCC(=O)OC', 'CCCC(=O)OC', 'CNC(=O)C1CCOC1', 'C1CCOC1', 'COC(=O)CCCN(C)C=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1CCOC1.