['CO', 'CCOCCNc1ccc([N+](=O)[O-])c2cccnc12', 'CCOC', 'O=[N+]([O-])c1ccc(NCCO)c2ncccc12', 'COCCO', 'CCNc1ccc([N+](=O)[O-])c2cccnc12', 'CCOCCOC', 'Nc1ccc([N+](=O)[O-])c2cccnc12', 'COCCOCCN', 'O=[N+]([O-])c1cccc2ncccc12']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccc2ncccc2c1.