264
J. C. Pardo-Novoa and C. M. Cerda-García-Rojas
Table 1 Calculated and experimental coupling constants of lippifolianones (64–66), valeranone
(69), and morelianone (70) a
3 J H,H /Hz
64
65
66
Calc
Obs
Calc
Obs
Calc
Obs
2α,3α
3.5
– b
4.0
4.8
5.8
5.7
2α,3β
3.0
– b
2.6
3.3
11.5
11.4
2β,3α
13.2
11.6
12.3
11.4
2.3
1.7
2β,3β
3.8
5.5
4.2
4.8
5.3
6.3
3α,4
12.3
13.0
11.7
12.8
–
–
3β,4
3.4
5.5
3.2
4.8
–
–
8α,9
2.2
2.0
5.3
5.8
5.6
5.8
8β,9
6.2
5.0
8.4
8.2
8.9
8.3
3 J H,H
69
3 J H,H
70
Calc
Obs
Calc
Obs
1α,2α
3.6
3.9
1α,2α
6.4
5.9
1α,2β
2.8
2.8
1α,2β
11.7
13.2
1β,2α
13.1
13.4
1α,11
3.0
2.4
1β,2β
4.1
5.3
1β,2α
1.1
1.0
2α,3α
4.8
4.8
1β,2β
6.4
5.4
2α,3β
13.0
13.5
1β,11
3.7
4.0
2β,3α
2.0
2.1
2α,3
5.3
– b
3β,3β
4.4
7.5
2β,3
11.4
12.7
6α,7
3.0
3.5
3,4
2.2
2.4
6β,7
12.3
12.7
4,5
1.0
1.0
7,8α
3.4
3.5
4,9
0.6
1.0
7,8β
12.3
12.5
5,11
1.2
1.3
7,11
5.8
5.8
8α,9
3.3
3.4
8α,9α
4.1
4.5
8β,9
2.8
2.9
8α,9β
2.8
2.6
9,10
3.4
3.1
8β,9α
13.1
13.2
10,11
6.9
5.9
8β,9β
3.9
4.1
a Measured at 300 MHz in CDCl 3
b Not observed due to signal overlapping
dichroism data and the anomalous dispersion effect detected in the X-ray diffraction analysis of brominated derivative 67. The structural information obtained for
the lippifolianes was also useful in establishing a biosynthetic relationship with
africanane derivatives, such as 68, also isolated from the same species [29].