['O=C[C@H]1CCCC(=O)N1', 'O=C1CNC2CCCCC2N1', 'O=C1CCCCN1', 'O=CN1CC(=O)NC2CCCCC21']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C1CN(C(=O)[C@H]2CCCC(=O)N2)C2CCCCC2N1.