Ph. D. THESIS 2009

H 3C
H 3C
O
O
O
C
C
O
O
1a
O
O
C
C
O
O
O
CH 3
CH 3
8
H 3C
H
O
O
O
C
C
H 3C
O
O
O
O
CH 3
Scheme 2. The keto-enol tautomeric equilibrium
In Figure 1 is presented a fragment of the 1 H-NMR spectrum (CDCl3, 500
MHz) of compound 1. The 1 H NMR spectrum of 1 consists of 2H triplet at δ=
1.93(J=3.0 Hz), another 2H triplet at δ= 3.22(J=3.0 Hz), singlets at δ= 3.29
(2H), δ= 3.76 (6H), δ= 3.83 (6H), and δ= 12.33 (2H) ppm.
Figu re 1 . Th e 1
H-NMR sp e ct r u m (CDCl , 5 0 0 MHz, fr a gm e n t )
3
o f co m p o u n d 1
The fact that the hydrogen atoms at 1-C/5-C and those at 9-C give rise to
triplets indicate that the bridgehead hydrogen atoms are equivalent and
establishes the C2 symmetry of the molecule. Also, the broadening of both
peaks suggests a weak coupling between the protons at 2-C /6-C and those at 9-
C, which are connected in W path [7].
1b
C
C
O
O
O
H
CH 3