['CC1(C)COCCN1', 'O=Cc1n[nH]c2ccc([N+](=O)[O-])cc12', 'CC1(C)COCCN1C=O', 'O=[N+]([O-])c1ccc2[nH]ncc2c1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(c1n[nH]c2ccccc12)N1CCOCC1.