Invasive Stink Bugs and Related Species (Pentatomoidea)

694 Invasive Stink Bugs and Related Species (Pentatomoidea)

Given that the insect-produced compound had been shown to have the (6R,7S)-configuration as described
above, the correlation with (1R,4R)-menthenol proved that the O. poecilus had to be (3R,6R,7S)-1,10 -
bisaboladien-3-ol ( 50 ) (Figure 15.9). Terhune et al. (1975) identified a zingiberenol in the essential
oil of ginger (Zingiber officinale Roscoe) rhizomes without determining its absolute configuration.
Khrimian et al. (2015) found not one but two stereoisomeric zingiberenols in ginger, bisaboladienol 50
and (3S,6R,7S)-1,10-bisaboladien-3-ol.
Using Y-tube olfactometer bioassays, de Oliveira et al. (2013) showed that the male-produced phero-
mone was attractive only to females. Also, females responded to odors from males only in the morning
hours, and they responded as well to synthetic mixtures of isomers containing the identified pheromone
50 as to the odors from males. Results from field trials of zingiberenol 50 , either as a pure compound or
as a mixture of isomers, have not yet been reported.

15.2.13 Pallantia macunaima Grazia [Pentatomidae: Pentatominae: Pentatomini]

Fávaro et al. (2013) identified the first ketone pentatomid pheromone, the male-produced sex pheromone
of the important Brazilian soybean pest, Pallantia macunaima, as (6R,10S)-6,10,13-trimethyltetradecan-
2- one ((6R,10S)- 53 ). This compound elicited strong electroantennogram responses from antennae of
females but not males. Male-produced volatiles, as well as the synthetic pheromone, were attractive to
females, but not to males, in Y-tube olfactometer bioassays. The trivial name, pallantione, was assigned
to this novel pheromone.
The chemical structure of pallantione was elucidated by a combination of GC-FTIR, GC-MS, and
microchemical reactions (hydrogenation, LiAlH 4 reduction/silylation, formation of tosylhydrazone, then
LiAlH 4 and LiAlD 4 reductions) and confirmed by synthesis. The mixture of all four stereoisomers of
6,10,13-trimethyltetradecan-2-one was synthesized from geranyl acetone through intermediate aldehyde
54 via Wittig olefination and hydrogenation (Figure 15.10) (Fávaro et al. 2013).
The individual stereoisomers of pallantione were prepared (Figure 15.11) from commercial (R)- and
(S)-propylene oxides (Muraki et al. 2013). The key steps in these syntheses were SN2 displacements of
secondary tosylates with carbanions that proceeded with almost complete inversion at the chiral centers.
Thus, to achieve chain elongation by two carbons and install a methyl group at the 3-position, tosyl-
ate 55 was treated with the enolate of dimethyl malonate to afford 56 , which was decarboxylated to
give the ester 57 with a chiral methyl branch. Ester 57 then was reduced to the corresponding primary
alcohol, and the latter was converted to iodide (R)- 58. Analogously, (R)-propylene oxide was converted
to iodide (S)- 58. The other chiral building blocks were also made from (R)- and (S)-propylene oxides.
Thus, reaction between (R)-propylene oxide and 1-butenylmagnesium bromide produced a secondary
alcohol, which was then tosylated to give 59. SN2 reaction between 59 and the anion derived from methyl
phenyl sulfone then gave (S)- 60 with a chiral methyl. Sulfone (S)- 60 was alkylated with iodide (R)- 58
to complete the carbon skeleton, followed by removal of the sulfone from 61 and conversion of the

H H H

OH OH

-H 2 O

(-)-Zingiberene Oebalus poecilus pheromone 50 (1R,4R)-Menthenol

FIGURE 15.9 Structure of Oebalus poecilus pheromone 50 correlated with (-)-zingiberene and (1R,4R)-menthenol.

O

O

O O O

54 53

a b

FIGURE 15.10 Non-stereoselective synthesis of Pallantia macunaima pheromone 53. a) 1. HOCH 2 CH 2 OH/H+, 2. SeO 2 /
t-BuOOH, 3. PCC; b) (CH 3 ) 2 CHCH 2 Ph 3 Br/n-BuLi, 2. H 2 /Pd-C; 3. HO 2 CCO 2 H/MeOH.