['Clc1ccccc1', 'O=[N+]([O-])CCc1c[nH]c2ccccc12', 'c1ccc2[nH]ccc2c1', 'O=[N+]([O-])CCc1ccccc1Cl']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc(Cc2c[nH]c3ccccc23)cc1.