Ph. D. THESIS 2009

m u lt ip let a t a t δ ==1 .7 6 p p m . Th e m o r e co m p lex p a t t er n o f
t h e sp ect r u m is d u e t o t h e n o n -eq u iv a len ce o f t h e
b r id geh ea d p r o t o n s 1 -H a n d 5 -H.
Figure 20 1 H NMR spectrum of compound anti-5b (300 MHz, DMSO-d 6)
The 1 H NMR spectrum of anti isomer (Figure 21) displays a 2H small
broad signal at far down-field (δ==10.12 ppm), assigned to the protons
belonging to the oxime moieties. The strong deshielding of these protons
indicates their participation in the H-bonds.
At δ=2.99 ppm it presents a 2H doublet (J=15.3 Hz) ascribed to the equatorial
protons located at 2-C/6-C due to the geminal coupling with the axial protons
(AB system). It displays also a slight tendency of splitting due to the weak
coupling in a W path with the bridgehead protons 1-H and 5-H.
In the range 2.07-2.26 ppm the spectrum shows several overlapped peaks,
integrated for 6H, corresponding to the equatorial and axial protons at 4-C/8-C
as well as to the axial protons at 2-C/6-C.
The spectrum displays also a well separated signal (δ=1.85 ppm, dd) for the
equivalent bridgehead protons at the position 1 and 5. Its pattern suggests a
vicinal coupling with the equatorial protons at 2-C/6-C and 4-C/8-C, as well as
a weak coupling with the axial ones (specific interactions have been observed
in 2D COSY spectrum).
Th e 2 H sign a l a t δ =1 .7 6 p p m is a ssign ed t o t h e p r o t o n s
lo ca t ed a t p o sit io n 9 a n d a p p e a r s a s a m u lt ip let d u e t o t h e
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