['CC1CNCC(C)O1', 'Cc1nn(CC(C)O)c(C)c1[N+](=O)[O-]', 'Cc1n[nH]c(C)c1[N+](=O)[O-]', 'CC(O)CN1CC(C)OC(C)C1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cnn(CCCN2CCOCC2)c1.