Ph. D. THESIS 2009

Figure 16. 13 C NMR spectrum APT (CDCl3, 75 MHz, fragment) of 3
The 13 C NMR spectrum of compound 3 (Figure23) displays different signals
for the secondary carbon atoms of the positions 2' and 4' (δ=68.22 ppm and
δ=70.09 ppm) of the dioxane ring, their diastereotopicity being correlated with
the presence of the rigid bicyclic fragment in the ketalic part of the heterocycle.
Also the primary carbon atoms belonging to the methyl groups at 3'-C exhibits
a unique signal very shielded at δ=22.64 ppm due to the flipping of the
heterocycle.
The peaks located at δ=32.59 and 96.84 ppm are assigned to the quaternary
carbon atoms at the position 3' and 7 of the flexible ring, the last one being
more deshielded due to the vicinity of the oxygen atoms from position 1' and 5'.
The signals corresponding to the carbon atoms of the carbocycle are situated in
the range 25-50 ppm of the spectrum as follows: δ==28.69 for 1-C/5-C,
δ==30.20 for 9-C, δ==37.27 for 6-C/8-C and δ==45.53 for 2-C/4-C. The small
signal at δ==207.11 ppm corresponds to the ketone carbonyl carbon at position
3 of the carboxycle and prove that the acetalization of diketone 2 underwent
exclusively with obtaining of the monospirane instead dispirane compound.
1.6.3. Mass spectra of monospirane
The 70 eV mass spectra of 5',5'-dimethyl-spiro{bicyclo[3.3.1]nonane-3,2'-
[1',3'-dioxane]}-7-one 3 and 5',5'-bis(bromomethyl)spiro{bicyclo[3.3.1]nonane-
3,2'-[1',3'-dioxane]}-7-one 4 (Figure 17) reveal high abundance peaks for the
molecular ions [M] +· , 238 and 394, respectively. This fact indicate indicating
very stable molecules, unlike the data found for other highly ramified
molecules with dioxane sequence [16-18]. Also, there are proofs that support
the fact that only spiro-monodioxane compounds have been obtained through
acetalization reaction of compound 2.
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