['CC(C)C/C(N)=N/O', 'Cc1cc([N+](=O)[O-])cc2c1OCOC2', 'CO/N=C(\\N)CC(C)C', 'O=[N+]([O-])c1ccc2c(c1)COCO2']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2c(c1)COCO2.