['OCC1(F)CCNC1', 'c1nnc(C2CC2)o1', 'CO', 'FC1CCN(c2nnc(C3CC3)o2)C1', 'C1CC1', 'OCC1(F)CCN(c2nnco2)C1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is C1CCN(c2nnc(C3CC3)o2)C1.