(6Z,9Z,12Z)-6,9,12-Octadecatriene and (3Z,6Z,9Z,12Z)-3,6,9,12-icosatetraene, the novel sex pheromones produced by emerald moths

Article abstract of DOI:10.1016/j.tetlet.2009.06.027

(6Z,9Z,12Z)-6,9,12-Octadecatriene and (3Z,6Z,9Z,12Z)-3,6,9,12-icosatetraene, hydrocarbons unsaturated more highly than usual lepidopteran Type II pheromones, were identified from geometrid females of Hemithea tritonaria and Thalassodes immissaria intaminata, respectively. The triene was synthesized by a double Wittig reaction between hexanal and an ylide derived from (Z)-1,6-diiodo-3-hexene, and the tetraene was synthesized by a coupling between (Z)-3-undecenal and an ylide derived from (3Z,6Z)-1-iodo-3,6-nonadiene. Each synthetic compound attracted males of the corresponding emerald moths in a field.

Full text of DOI:10.1016/j.tetlet.2009.06.027

Tetrahedron Letters 50 (2009) 4738–4740
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Tetrahedron Letters
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(6Z,9Z,12Z)-6,9,12-Octadecatriene and (3Z,6Z,9Z,12Z)-3,6,9,12-icosatetraene,
the novel sex pheromones produced by emerald moths
Rei Yamakawa a, Nguyen Duc Do a, Yasushi Adachi a, Masakatsu Kinjo b, Tetsu Ando a,
*
a Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
b Iriomote Station, Tropical Biosphere Research Center, University of the Ryukyus, Uehara, Taketomi-cho, Okinawa 907-1541, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
(6Z,9Z,12Z)-6,9,12-Octadecatriene and (3Z,6Z,9Z,12Z)-3,6,9,12-icosatetraene, hydrocarbons unsaturated
more highly than usual lepidopteran Type II pheromones, were identified from geometrid females of
Hemithea tritonaria and Thalassodes immissaria intaminata, respectively. The triene was synthesized by
a double Wittig reaction between hexanal and an ylide derived from (Z)-1,6-diiodo-3-hexene, and the
tetraene was synthesized by a coupling between (Z)-3-undecenal and an ylide derived from (3Z,6Z)-1-
iodo-3,6-nonadiene. Each synthetic compound attracted males of the corresponding emerald moths in
a field.
Received 30 April 2009
Revised 29 May 2009
Accepted 5 June 2009
Available online 9 June 2009
Keywords:
Lepidopteran sex pheromone
Polyenyl hydrocarbons
GC-EAD analysis
Ó 2009 Elsevier Ltd. All rights reserved.
Diimide reduction
Sex pheromones, which have been identified from about 600 le-
pidopteran species, are mainly classified into two major groups,
that is, unsaturated C10–C18 fatty alcohols and their derivatives
(Type I) and C17–C23 unbranched polyenyl hydrocarbons and their
epoxides (Type II).1 Type II compounds, which are biosynthesized
from linolenic and linolic acids included in dietary leaves and uni-
versally have double bond(s) and epoxy ring(s) at the 3,6,9- or 6,9-
positions, are secreted by female moths in highly evolved families,
such as Geometridae, Lymantriidae, and Arctiidae. Since these fam-
ilies are composed of many species, further structurally modified
components are necessary to develop diverse species-specific com-
munication systems. Geometridae is classified into several subfam-
ilies, such as Larentiinae, Ennominae, and Geometrinae. Sex
pheromones have been exclusively studied in species in the former
two subfamilies and not in those in the last subfamily, which in-
cludes many species, such as emerald moths with green wings.2
This context indicates that it is highly possible to find new phero-
mone compounds from the species in Geometrinae. The Iriomote
Islands (latitude 24°190N), located in the subtropics, are inhabited
by numerous insect species. In order to understand Type II phero-
mones in depth, we collected the male and female moths in this
group using a light trap and analyzed their pheromone extracts
using GC equipped with an electroantennogram detector (GC-
EAD)3 and GC–MS. Consequently, in addition to known unsatu-
rated hydrocarbons, we could find novel Type II pheromones in
the extracts.
In the GC-EAD analysis of pheromone gland extracts of Hemi-
thea tritonaria females on a high-polar column,4 two components
(X1 and X2) elicited remarkable responses from male antennae of
this species (Fig. 1A). While the structure of X1 is still unknown,
X2 was estimated to be a C18 triene because its retention time is al-
most the same as that of authentic (3Z,6Z,9Z)-3,6,9-octadecatriene.
The detection of M+ at m/z 248 on the GC–MS analysis4 confirmed
this speculation, but the mass spectrum of X2 (Fig. 1B) was differ-
ent from that of the 3,6,9-triene.1,5 Up to date, the 4,6,9- and the
6,9,11-triene have been known as pheromone components or attr-
actants.1,2 In the GC–MS analysis with the polar column, the tR of
X2 (13.04 min) was shorter than that of the authentic trienes with
a conjugated dienyl structure, such as (6Z,9Z,11E)-6,9,11-octadec-
atriene (13.92 min).6 These results indicate that X2 is an unconju-
gated C18 triene previously unidentified from any other insects.
The double-bond positions of X2 were determined by diimide
reduction of the pheromone extract [10 female equivalent (FE)].7
GC–MS analysis of the crude products showed two octadecadienes
and two octadecenes. The tR (12.73 min) and mass spectrum of the
major diene showed good agreement with those of authentic
(6Z,9Z)-6,9-octadecadiene.8 While we tried DMDS derivatization9
of the produced monoenes to confirm the double-bond positions,
we were not successful because of the limited amount of phero-
mone extract available. The monoenes, however, were produced
in a ratio of approximately 1:2, and the tRs (12.39 and 12.48 min)
were the same as those of monoenes derived by the diimide reduc-
tion of (6Z,9Z)-6,9-octadecadiene, indicating that X2 was
(6Z,9Z,12Z)-6,9,12-octadecatriene 1 with a symmetrical structure.
Finally, the structure was confirmed by synthesis applying the
* Corresponding author. Tel./fax: +81 42 388 7278.
E-mail address: antetsu@cc.tuat.ac.jp (T. Ando).
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.06.027

R. Yamakawa et al. / Tetrahedron Letters 50 (2009) 4738–4740
4739
150 (M-98)
79
A
B
(%)
100
79
X
X
2
1
(-H)
67
150
EAD
150
50
93
0.1mV
M+
248
107
121
FID
135
0
150
200
250
50
100
15
10
m/z
Rt (min)
C
D
100
220 (+H)
(%)
79
Y
Y
2
178 (M-98)
79
1
Y
3
(-H)
0.1mV
91
148
EAD
67
50
0
105
119
M+
274
178
133
220
249
250
148
FID
150
200
50
100
m/z
10
15
25
20
Rt (min)
Figure 1. Analyses of the sex pheromone components of two Geometrinae species; (A) GC-EAD analysis of the pheromone gland extract of Hemithea tritonaria, indicating two
EAG-active components (X1: tR 12.6 min and X2: tR 14.4 min), (B) mass spectrum of X2, (C) GC-EAD analysis of the pheromone gland extract of Thalassodes immissaria
intaminata, indicating three EAG-active components (Y1: tR 12.6 min, Y2: tR 17.2 min, and Y3: tR 21.9 min), and (D) mass spectrum of Y2.
method reported by Pohnert and Boland10 (Fig. 2A). Starting from
3-hexyne-1,6-diol, 1,6-diiodo-(Z)-3-hexene 2 was prepared.6 With
the phosphonium salt of 2, bis(ylide) 3 was prepared and coupled
doubly with hexanal to yield the objective (6Z,9Z,12Z)-triene 1,11
which showed the same GC–MS data as the natural pheromone
component and strong EAG activity on an antenna of the H. triton-
aria male.
On the other hand, pheromone glandextracts of Thalassodesimm-
issaria intaminata females included many compounds, but its GC-
EAD analysis consistently showed three active compounds (Y1–Y3,
Fig. 1C). While the structures of Y1 and Y3 were not determined,
M+ at m/z 274 in GC–MS analysis indicated that Y2 was a C20 tetraene
(Fig. 1D). The tR of Y2 (15.50 min) is shorter than those of authentic
1,3,6,9- and 3,6,9,11-tetraenes, such as (Z3,Z6,Z9)-1,3,6,9-icosatetr-
aene (16.66 min).6 The mass spectrum of Y2 showed a characteristic
base ion at m/z 79 as the compounds with a homoconjugated trienyl
structure did. The double-bond positions of Y2 were also examined
by diimide reduction of the crude pheromone extract (40 FE).7 The
short-time reduction (2 h) produced several products, including
(3Z,6Z,9Z)-3,6,9-icosatriene (tR 15.15 min),8 and the long-time
i, ii
iii, iv
HO
OH
Ph3P
PPh3
A
I
I
(68%)
2
3
v
(53% from 2)
1
B
vi, vii
i, viii (87%)
THPO
HO
HO
or ix, viii (77%)
(75%)
5
6a (Z)
6b (E)
PPh3
O
x
8
H
(81% from 6a)
(84% from 6b)
(73% from 7a)
(79% from 7b)
xi
7a (Z)
7b (E)
4a (Z,Z,Z,Z)
4b (Z,Z,Z,E)
Figure 2. Synthetic routes to polyenyl hydrocarbons; (A) (6Z,9Z,12Z)-6,9,12-octadecatriene (1) and (B) (3Z,6Z,9Z,12Z)-3,6,9,12-icosatetraene (4a) and the (3Z,6Z,9Z,12E)-
isomer (4b). Reagents: (i) H2/Pd–BaSO4–quinoline/MeOH; (ii) I2–PPh3/imidazole/Et2O–MeCN; (iii) PPh3/benzene; (iv) NaN(SiMe3)3/THF; (v) CH3(CH2)4CHO; (vi) DHP/PTSA;
(vii) (1) BuLi/THF, (2) CH3(CH2)7Br/HMPA; (viii) PTSA/EtOH; (ix) Li/EtNH2; (x) IBX/DMSO; (xi) ylide 8/THF.

4740
R. Yamakawa et al. / Tetrahedron Letters 50 (2009) 4738–4740
reduction (6 h) produced a mixture of icosane and four icosenes. The
monones showed three peaks in a ratio of approximately 2:1:1
(14.22, 14.32, and 14.51 min) with the same tRs as those of mono-
enes produced by the reduction of the authentic 3,6,9-triene. We
speculated that 9-icosene and 8-icosene (=12-icosene) might have
similar chromatographic behaviors and Y2 might be
(3Z,6Z,9Z,12Z)-3,6,9,12-icosatetraene 4a or the (3Z,6Z,9Z,12E)-iso-
mer 4b.
Based on this speculation, we synthesized the two tetraenes
starting from 3-butyn-1-ol (Fig. 2B). After protection of the alcohol
as THP ether, 1-bromoheptane was coupled with it, giving
3-undecynyl compound 5. Partial hydrogenation with Pd-BaSO4-
quinoline and deprotection of 5 gave (Z)-3-undecen-1-ol 6a, and
the Birch reduction and deprotection of 5 gave the (E)-isomer 6b.
By oxidation with 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide
addition to analyzing the pheromone extracts of other species
caught using a light trap, we are systematically synthesizing
(6Z,9Z,12Z)-trienes and (3Z,6Z,9Z,12Z)-tetraenes with a C17–C23
chain and accumulating their GC–MS data to confirm the character-
istic fragmentations, shown in Figure 1. For the identification of
natural pheromones, diagnostic ions are very useful. We are also
using the synthetic compounds in field surveys to find new male
attractants. The male attractants found by random screening tests
may yield important information for pheromone studies. The re-
sults will be reported in due course.
Acknowledgments
We are grateful to Drs. F. Mochizuki and T. Fukumoto of Shin-
Etsu Chemical Co., Ltd for supplying 3-hexyne-1,6-diol and
(3Z,6Z)-3,6-nonadien-1-ol and Dr. S. Hashimoto for identification
of geometrid species. This study was supported in part by a
Grand-in-Aid for Scientific Research (20380031) from the Ministry
of Education, Culture, Sports, Science, and Technology of Japan.
(IBX), these alcohols were converted into the corresponding b,c-
unsaturated aldehydes, 7a and 7b. Their NMR data12 confirmed
that the oxidation proceeded without isomerization to a stable
(E)-2-enal.13 These aldehydes were separately coupled with the
ylide 8, which was prepared from the phosphonium salt of an io-
dide derived from (3Z,6Z)-3,6-nonadien-1-ol,6 to give the objective
(3Z,6Z,9Z,12Z)-tetraene 4a and its (3Z,6Z,9Z,12E)-isomer 4b.14 GC
separation of the two geometrical isomers was not achieved under
our conditions, and both isomers showed almost the same GC–MS
data as the natural pheromone component. While GC–MS analysis
of the diimide reduction of both 4a and 4b also showed the same
2:1:1 peaks of monoenes as those of the natural pheromone, the
EAG activity of 4a was higher than that of 4b against the antennae
of the T. i. intaminata males.
References and notes
1. Ando, T.; Inomata, S.; Yamamoto, M. Top. Curr. Chem. 2004, 239, 51–96.
2. (a) Ando, T., Internet database 2009, http://www.tuat.ac.jp/~antetsu/
LepiPheroList.htm.; (b) El-Sayed, A. M., Internet database 2009, http://
www.pherobase.com/.
3. (a) Struble, D. L.; Arn, H. In Techniques in Pheromone Research; Hummel, H. E.,
Miller, T. A., Eds.; Springer-Verlag: New York, 1984; pp 161–178; (b) Inomata,
S.; Watanabe, A.; Nomura, M.; Ando, T. J. Chem. Ecol. 2005, 31, 1429–1442.
4. All GC analyses were conducted with HP-5890 Series II gas chromatograph
equipped with
a
DB-23 column (0.25 mm ID ꢀ 30 m, 0.25 lm film, J&W
Scientific). The column temperature program was 50 °C for 2 min, 10 °C/min to
Although our next objective was to determine the structures of
the other EAG-active components, X1, Y1, and Y3, we carried out a
field evaluation of each synthetic hydrocarbon as a single compo-
nent in the coppices of the Iriomote Islands from December 2008
to January, 2009. In the preliminary field trials in a season of low
population density, traps baited with 1 and 4a (each 0.2 mg dose
on a white rubber septum) attracted several males of H. tritonaria
and T. i. intaminata, respectively. No males were caught by the 4b
traps and the control one. This result suggests that 1 and 4a are the
principal components of their pheromones. Moreover, we identi-
fied 1 from a pheromone gland extract of Pamphlebia rubrolimbrar-
ia rubrolimbraria and (6Z,9Z,12Z)-6,9,12-icosadecatriene from that
of Maxates versicauda microptera as an EAG-active component.
The mass spectrum of the C20 analogue showed the characteristic
ions of the 6,9,12-trienes at m/z M-98 and 150.15 These two species
are also emerald moths classified into Geometrinae.
Up to date, 1,3,6,9-tetraenyl, 3,6,9,11-tetraenyl, and 4,6,9-
trienyl pheromones have been found from species in highly
evolved families.1,2 These components commonly possess a conju-
gated dienyl structure. Recently, (3Z,6Z,9Z,12Z,15Z)-3,6,9,12,15-
tricosapentaene and pentacosapentaene were identified from three
species in Pyralidae,16 many other species of which solely produce
Type I pheromones. Lures baited with these novel pyralid phero-
mone components only did not trigger male attraction, while they
showed a synergistic effect on Type I pheromone compounds. The
pentaenes may be biosynthesized from linolenic acid by two addi-
tional desaturation steps, such as the biosynthesis of arachidonic
160 °C, and 4 °C/min to 220 °C.
5. Millar, J. G. Annu. Rev. Entomol. 2000, 45, 575–604.
6. Yamamoto, M.; Yamakawa, R.; Oga, T.; Takei, Y.; Kinjo, M.; Ando, T. J. Chem.
Ecol. 2008, 34, 1057–1064.
7. After the removal of the solvent of a crude pheromone extract, the residue was
treated with a N2H4 solution (0.3 ml of N2H4 in 10 ml of ethanol, 0.1 ml) and a
H2O2 solution (0.04 ml of 30% H2O2 in 10 ml of ethanol, 0.1 ml). After warming
at 65 °C for several hours, the reaction mixture was acidified with 1 N HCl and
extracted with hexane.
8. Ando, T.; Ohsawa, H.; Ueno, T.; Kishi, H.; Okamura, Y.; Hashimoto, S. J. Chem.
Ecol. 1993, 19, 787–798.
9. Buser, H.-R.; Arn, H.; Guerin, P.; Rauscher, S. Anal. Chem. 1983, 55, 818–822.
10. Pohnert, G.; Boland, W. Eur. J. Org. Chem. 2000, 1821–1826.
11. Spectral data for synthetic (6Z,9Z,12Z)-6,9,12-octadecatriene 1: 1H NMR: d 0.98
(6H, t, J = 7 Hz), ꢁ1.3 (12H, m), 2.06 (4H, dt, J = 7, 7 Hz), 2.81 (4H, dd, J = 6,
6 Hz), 5.37 (6H, m). 13C NMR: d 14.09, 22.61, 25.65, 27.25, 29.36, 31.56, 127.67,
128.28, 130.41.
12. Spectral data for 3-undecenal: (Z)-isomer 7a, 1H NMR: d 0.88 (3H, t, J = 7 Hz),
1.27 (8H, m), 1.37 (2H, m), 2.03 (2H, dt, J = 7, 7 Hz), 3.19 (2H, ddd, J = 7, 2, 2 Hz),
5.54 (1H, dtt, J = 11, 7, 2 Hz), 5.71 (1H, dtt, J = 11, 7, 2 Hz), 9.66 (1H, t, J = 2 Hz).
13C NMR: d 14.11, 22.66, 27.65, 29.17, 29.21, 29.33, 31.82, 42.59, 117.95,
135.58, 199.84. IR (neat): 2925, 2854, 2719, 1728, 1466, 1385, 723 cmꢂ1. (E)-
isomer 7b, 1H NMR: d 0.88 (3H, t, J = 7 Hz), 1.27 (8H, m), 1.37 (2H, m), 2.06 (2H,
dt, J = 7, 7 Hz), 3.11 (2H, dd, J = 7, 2 Hz), 5.49 (1H, dt, J = 16, 7 Hz), 5.62 (1H, dt,
J = 16, 7 Hz), 9.65 (1H, t, J = 2 Hz). 13C NMR: d 14.10, 22.67, 29.10, 29.15, 29.17,
31.83, 32.74, 47.35, 118.97, 137.06, 200.51. IR (neat): 2925, 2854, 2717, 1728,
1466, 1383, 970 cmꢂ1
.
13. Islam, MD. A.; Yamamoto, M.; Sugie, M.; Naka, H.; Tabata, J.; Arita, Y.; Ando, T. J.
Chem. Ecol. 2007, 33, 1763–1773.
14. Spectral data for synthetic 3,6,9,12-icosatetraene: (3Z,6Z,9Z,12Z)-isomer 4a, 1H
NMR d: 0.88 (3H, d, J = 7 Hz), 0.98 (3H, t, J = 7.5 Hz), ꢁ1.3 (10H, m), 2.06 (4H,
m), 2.82 (6H, m), 5.37 (8H, m). 13C NMR d: 14.13, 14.28, 20.57, 22.69, 25.56,
25.63, 25.66, 27.28, 29.25, 29.31, 29.69, 31.89, 127.06, 127.57, 127.95, 128.00,
128.49, 128.52, 130.48, 132.02. (3Z,6Z,9Z,12E)-isomer 4b, 1H NMR d: 0.88 (3H,
d, J = 7 Hz), 0.97 (3H, t, J = 7.5 Hz), ꢁ1.3 (10H, m), 1.98 (2H, dt, J = 6.5, 6.5 Hz),
2.08 (2H, dq, J = 7.5, 7.5 Hz), 2.76 (2H, m), 2.81 (4H, m), ꢁ5.4 (8H, m). 13C NMR
d: 14.12, 14.29, 20.56, 22.69, 25.54 (ꢀ2), 29.17, 29.21, 29.54, 30.47, 31.87,
32.59, 127.05, 127.87, 127.95, 128.00, 128.17, 128.18, 131.05, 131.94.
15. GC–MS data for (6Z,9Z,12Z)-6,9,12-icosatriene: tR 14.66 min, m/z (relative
intensity), 276 (3%, [M]+), 178 (38%, [Mꢂ98]+), 150 (44%), 80 (100%), 79 (98%).
16. (a) Leal, W. S.; Parra-Pedrazzoli, A. L.; Kaissling, K.-E.; Morgan, T. I.; Zalom, F. G.;
Pesak, D. J.; Dundulis, E. A.; Burks, C. S.; Higbee, B. S. Naturwissenschaften 2005,
92, 139–146; (b) Millar, J. G.; Grant, G. G.; McElfresh, J. S.; Strong, W.; Rudolph,
C.; Stein, J. D.; Moreira, J. A. J. Chem. Ecol. 2005, 31, 1229–1234.
acid from linolic acid (desaturation at the
x12- and x15-positions).
The geometrid pheromones found in this study are new natural
products, which can be derived from linolic or linolenic acids by
only one desaturation at the
x12-position. It would be interesting
to determine whether this limited desaturation is characteristic of
the pheromones of Geometrinae species. The answer may be found
through further research of many lepidopteran pheromones. In