['CO', 'CN(CC=O)C(=O)CN1CCNCC1', 'CNCC(=O)OC', 'O=CCN1CCNCC1', 'COC(C)=O', 'CNC(=O)CN1CCNCC1', 'C1CNCCN1', 'COC(=O)CN(C)C(C)=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1CNCCN1.