['CC(=O)[O-]', 'c1ccc2[nH]c(N3CC[NH2+]CC3)nc2c1', 'c1ccc2[nH]cnc2c1', 'O=C([O-])C[NH+]1CCNCC1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2[nH]c(N3CC[NH2+]CC3)nc2c1.