Ph. D. THESIS 2009

Figure 3. The 1 H-NMR spectrum (CDCl 3, 500 MHz, fragment) of compound 2
Thus, the 2H multiplet at resonance δ= 2.20 ppm(J=3.0 Hz) is ascribed to the
protons located at 9-C, whereas the most deshielded 2H multiplet at δ= 2.86
ppm (J=3.0 Hz) corresponds to the bridgehead protons belonging to 1-C/5-C.
The bridge protons 9-H2 are splitted by the 1-H and 5-H protons due to a vicinal
coupling. The broadening of these peaks suggests an additional weak coupling
in W path between the equatorial protons at 2,4,6,8-C and those at 9-C, whereas
the protons 1-H and 5-H are coupled with the axial protons at 2,4,6,8-C. These
two triplets suggest also the equivalence of the bridgehead protons and the C2
symmetry of the molecule.
The 4H doublet at δ= 2.41 ppm is attributed to the equatorial protons at
2,4,6,8-C , which are connected with the corresponding axial protons through
an AB geminal coupling (J=15.5 Hz). The lack of supplementary splitting of
the doublet indicates that an equatorial-equatorial vicinal coupling with the
bridgehead protons at 1-C/5-C is not possible because a dihedral angle close to
90. The axial protons at 2,4,6,8-C are more deshielded and appear as a
doublet of doublets at δ= 2.58 ppm due to the both splitting originating from
the AB geminal coupling with the equatorial protons and the vicinal coupling
with the protons 1-H/5-H.
The most deshielded signal in the spectrum (Figure 4) has low intensity and is
situated at δ= 208.59 ppm, very close to the chemical shift of the carbonyl in
the cyclohexanone.
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