['CO', 'O=CCCN1CCN(c2ccc([N+](=O)[O-])nc2)CC1', 'CCC(=O)OC', 'O=[N+]([O-])c1ccc(N2CCNCC2)cn1', 'O=[N+]([O-])c1ccccn1', 'COC(=O)CCN1CCNCC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cncc(N2CCNCC2)c1.