['CO', 'O=C[C@@H]1CC[C@@H](C(=O)[O-])[NH2+]1', 'COC=O', 'O=C([O-])[C@@H]1CCC[NH2+]1', 'O=C[O-]', 'COC(=O)[C@@H]1CCC[NH2+]1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1CC[NH2+]C1.