Synthesis of a natural insect repellent isolated from thrips

Article abstract of DOI:10.1016/j.tet.2004.05.036

A convenient, high yield procedure for the synthesis of (11Z)-11,19-eicosadienyl acetate (1) has been developed. This compound shows strong repellent activity against ants.

Full text of DOI:10.1016/j.tet.2004.05.036

Tetrahedron 60 (2004) 6001–6004
Synthesis of a natural insect repellent isolated from thrips
a
Rene Csuk, Anja Niesen, Gunther Tschuch and Gerald Moritz
a
b
b
,
*
´
a
¨
Institut fur Organische Chemie, Martin-Luther-Universitat Halle-Wittenberg, Kurt-Mothes-Str. 2, D-06120 Halle (Saale), Germany
Institut fur Zoologie, Abt. Entwicklungsbiologie, Martin-Luther-Universitat Halle, Domplatz 4, D-06108 Halle (Saale), Germany
¨
b
¨
¨
Received 17 February 2004; revised 3 May 2004; accepted 10 May 2004
Available online 8 June 2004
Abstract—A convenient, high yield procedure for the synthesis of (11Z)-11,19-eicosadienyl acetate (1) has been developed. This compound
shows strong repellent activity against ants.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
an hitherto unknown compound of m/z¼336 was detected.
From the presence of a m/z¼61 and a very small m/z¼276 as
well as from the results of an in situ dimethyl disulfide
derivatisation8 a (11Z)-11,19-eicosadienyl acetate structure
(1) for this compound seemed most likely. Although a direct
determination of the absolute configuration of the internal
double bond from the GC-MS data was not possible, we
assigned a (11Z) configuration to 1 since (E)-isomers are
only scarcely found in insect allomones and pheromones. In
order to prove these assumptions as well as to investigate its
repellent activity against ants a straightforward synthesis of
1 was called for.
The principal approach to prevention of vector-borne
diseases is avoidance. Although vaccines or chemoprophyl-
actic drugs are available against important vector-borne
diseases such as yellow fever and malaria, the use of
repellents against biting arthropods is highly recommended.
In addition, fire-ants, leaf-cutter-ants, termites and other
insects are very serious pests1 in the tropics causing severe
damage both to crops and reforestation.
For personal protection most authorities recommend
repellents containing N,N-diethyl-m-toluamide (DEET)2,3
whereas the use of permethrin-containing repellents is
limited to clothing, shoes and gear. Due to several
limitations due to toxic side effects,4 so-called ‘natural
repellents’ have been in the focus of interest5–7 for quite a
long time and they can be regarded as an alternative to
several repellents used up to now.
Retrosynthetic analysis revealed a suitably protected
11-dodecynol as an ideal starting material. Thus,
10-bromo-decanol (2) was protected as its tetrahydro-
pyranyl acetal by treatment of 2 with 3,4-dihydro-2H-
pyran (DHP) in the presence of catalytic amounts of
pyridinium p-toluene sulfonate (PPTS)10,11 to afford 3 in
80% isolated yield. Reaction of 3 with lithium acetylide
ethylenediamine complex12 gave 79% of 4 that was allowed
to react with 8-chloro-1-octene (5) in the presence of n-BuLi
to yield the 19-icosen-11-ynyl-tetrahydropyranyl acetal 6.
Compound 5 was easily accessed from commercially
available 1,5-dichloro-pentane (7) and allylmagnesium
chloride13,14 in the presence of LiCl and CuCl2.
2. Results and discussion
During our own efforts in the development of insect
repellent compounds8 we became interested in the compo-
sition of the low volatile defensive secretion excreted by
Suocerathrips linguis (Thysanoptera, Phlaeothripidae)9—
small insect living on leaves of Sansevieria plants.
The deprotection of 6 with an ion exchange resin in
methanol proceeded very smoothly and gave 19-icosen-11-
yn-1-ol (8) in almost quantitative yield. Acetylation of 8
gave 98% of the corresponding acetate 9 that was subjected
to a partial hydrogenolysis using the Lindlar catalyst in
hexane containing quinoline. Chromatographic work-up
finally gave 92% of the target compound 1.
GC-MS analysis of this defensive secretion against ants
revealed the presence of a multi-component mixture
containing several well-known acetates of long chain
(mono-un)-saturated (C16· · ·C20) alcohols. Additionally
Keywords: Insect repellent.
*
The GC-MS spectra of synthesised 1 were identical to the
compound obtained from S. linguis in every aspect. In order
Corresponding author. Tel.: þ49-345-5525660; fax: þ49-345-5527030;
e-mail address: csuk@chemie.uni-halle.de
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.05.036

6002
R. Csuk et al. / Tetrahedron 60 (2004) 6001–6004
to prove the anti-repellent activity of 1 a bio-assay was
performed using colonies of the ant Myrmica rubra.
Evaluation of these data reveals, that a 10% solution of
(11Z)-1 retreats .85–90% of the ants looking for prey.
Thus this assay showed 1 as an excellent repellent since the
food protected by 1 was left nearly untouched by the
predators.
3.1.1. 10-Bromodecyltetrahydro-2H-2-pyranyl ether (3).
A solution of 10-bromo-1-decanol (2) (3.0 g, 11.39 mmol)
containing DHP (1.43 g, 17.0 mmol) and PPTA (28 mg,
0.11 mmol) in dry dichloromethane (50 ml) was stirred for 2
days at room temperature, then an aq. solution of Na2CO3
(2 M, 11 ml) was added, the layers were separated and the
organic phase was dried (K2CO3). The solvents were
removed and the residue purified by chromatography (silica
gel, hexane/ethyl acetate 9:1) to afford 3 (2.92 g, 80%) as a
colourless liquid. Rf (hexane/ethyl acetate 9:1)¼0.5; IR
(film): n¼2927s, 2854s, 1465m, 1455m, 1440m, 1383m,
1365m, 1352m, 1322m, 1260m, 1200s, 1184m, 1163m,
1136s, 1120s, 1078s, 1034s, 988m, 905m, 869m, 815m,
It seems reasonable to assume that 1 spreads fast on surfaces
and in predators like ants and mites—using mainly olfactory
sense—a coating of sensory organs will make these insects
‘blind’. In consequence, the ants are not longer able to find
their prey; additionally, it can be expected that they get
serious problems to evaluate their own trail pheromones.
1
722m, 646m, 564w cm21; H NMR (400 MHz, CDCl3):
d¼1.25–1.35 (m, 10H, CH2), 1.40 (m, 2H, CH2), 1.45–1.60
(m, 6H, CH2), 1.70 (m, 1H, CH2), 1.80 (m, 3H, CH2–
CH2Br, CH2, THP), 3.35 (m, 3H, CH2Br, CH2–O), 3.45 (m,
The synthesis of analogues and their biological screening
against a variety of insects is presently under investigation
in our laboratories (Scheme 1).
2
3
1H, CH2, THP), 3.70 (ddd, JH,H¼9.5 Hz, JH,H¼6.84 Hz,
2JH,H¼6.84 Hz, 1H, CH2), 3.85 (m, 1H, CH2, THP), 4.55
3
3
(dd, JH,H¼4.35 Hz, JH,H¼2.48 Hz, 1H, CH); 13C NMR
(100 MHz, CDCl3): d¼19.8 (CH2, THP), 25.6 (CH2, THP),
26.2 (CH2), 28.2 (CH2), 28.8 (CH2), 29.4 (CH2), 29.5 (CH2),
29.5 (CH2), 29.8 (CH2), 30.9 (CH2, THP), 32.9 (CH2–
CH2Br), 34.0 (CH2–Br), 62.3 (CH2–O, THP), 67.7 (CH2–
O), 98.8 (CH); MS (GC-MS, e.i., 70 eV): m/z (%)¼85 (100),
101 (8), 115 (2), 137 (2), 163 (1), 190 (1), 219 (1), 241 (1), 247
(2), 267 (1), 292 (1), 319 (3); HRMS for C15H29BrO2: calcd
320.13509; found: 320.13511. Anal. calcd for C15H29BrO2
(321.29): C, 56.07; H, 9.10; found: C, 55.87; H, 9.21.
3.1.2. 11-Dodecynyltetrahydro-2H-2-pyranyl ether (4).
To a suspension of the lithium acetylide ethylendiamine
complex (2.9 g, 32 mmol) in dry DMSO (17 ml) at 15–
20 8C within 2 h a solution of 3 (4.9 g, 15.27 mmol) in dry
DMSO) (17 ml) was slowly added and stirring was
continued for 12 h. The reaction was quenched by the
addition of water (15 ml), hexane (15 ml) and again water
(15 ml). The aq. layer was extracted with hexane
(3£100 ml), the combined organic phases washed with
brine (3£25 ml), dried (Na2SO4), the solvents were
removed under diminished pressure and the residue purified
by chromatography (silica gel, hexane/ethyl acetate 98:2) to
yield 4 (3.19 g, 79%) as a colourless liquid. Rf (hexane/ethyl
acetate 9:1)¼0.5; IR (film): n¼3312m, 2929s, 2855s,
2118w, 1465s, 1455s, 1441m, 1384m, 1136s, 1121s,
1079s, 1034s, 990s, 906m, 869m, 844w, 815m, 722m,
Scheme 1. (a) DHP, PPTA, CH2Cl2; (b) LiCl, CuCl2, THF; (c) lithium-
acetylide, DMSO; (d) n-BuLi, THF/HMPT; (e) Amberlyst15 (Hþ-form),
methanol; (f) Ac2O/pyridine; (g) Lindlar-catalyst, H2, hexane.
3. Experimental
3.1. General
1
628m cm21; H NMR (400 MHz, CDCl3): d¼1.20–1.40
(m, 13H, CH2), 1.55 (m, 8H, CH2), 1.75 (m, 1H, CH2), 1.90
(dd, 4JH,H¼2.69 Hz, 4JH,H¼2.49 Hz, 1H, CH), 2.15 (m, 2H,
CH2–CvC), 3.35 (m, 1H, CH2–O), 3.45 (m, 1H, CH2–O,
Melting points are uncorrected (Leica hot stage micro-
scope), optical rotations were obtained using a Perkin–
Elmer 341 polarimeter (1 cm micro cell), NMR spectra were
recorded using the Varian spectrometers Gemini 200,
Gemini 2000 or Unity 500 (d given in ppm, J in Hz,
internal Me4Si or internal CCl3F), IR spectra (film or KBr
pellet) on a Perkin–Elmer FT-IR spectrometer Spectrum
1000, MS spectra were taken on a Intectra GmbH AMD 402
(electron impact, 70 eV) or on a Finnigan MAT TSQ 7000
(electrospray, voltage 4.5 kV, sheath gas nitrogen) instru-
ment; for elemental analysis a Foss-Heraeus Vario EL
instrument was used; TLC was performed on silica gel
(Merck 5554, detection by UV absorption or by treatment
with a solution of 10% sulfuric acid, ammonium molybdate
and cerium(IV)) sulfate followed by gentle heating. The
solvents were dried according to usual procedures.
2
3
3
THP), 3.70 (ddd, JH,H¼9.53 Hz, JH,H¼6.84 Hz, JH,H
¼
6.84 Hz, 1H, CH2–O), 3.85 (m, 1H, CH2, THP), 4.55 (dd,
3JH,H¼4.57 Hz, JH,H¼2.49 Hz, 1H, O–CH–O, THP); 13C
3
NMR (100 MHz, CDCl3): d¼18.5 (CH2–CuC), 19.8
(CH2, THP), 25.6 (CH2, THP), 26.3 (CH2), 28.6 (CH2),
28.8 (CH2), 29.1 (CH2), 29.5 (CH2), 29.5 (CH2), 29.6 (CH2),
29.8 (CH2), 30.9 (CH2, THP), 62.3 (CH2–O, THP), 67.7
(CH2–O), 68.0 (CHuC), 84.7 (CuC), 98.8 (O–CH–O,
THP); MS (GC-MS, e.i., 70 eV): m/z (%)¼85 (100), 101
(28), 115 (4), 135 (1), 165 (1), 195 (1), 225 (1), 265 (1), 266
(1); HRMS for C17H30O2: calcd 266.22458; found:
266.22459. Anal. calcd for C17H30O2 (266.42): C, 76.64;
H, 11.35; found: C, 76.52; H, 11.51.

R. Csuk et al. / Tetrahedron 60 (2004) 6001–6004
6003
3.1.3. 8-Chloro-1-octene (5). A mixture of CuCl2 (1.9 g,
14.06 mmol) and LiCl (1.2 g, 28.04 mmol) was stirred in
abs. THF (100 ml) at room temperature overnight.
1,5-dichloropentane (10.0 g, 70.98 mmol) in dry THF
(30 ml) was added to this deep red solution at 215 8C and
stirred at this temperature for another 3 h. Then a solution
of allylmagnesium chloride (106 mmol, 2 M in THF) was
added, the mixture was allowed to warm to room
temperature and stirred overnight. Then aq. hydrochloric
acid (1 M, 100 ml) was added, the aq. phase extracted with
ether (3£100 ml) and the combined organic phases were
dried (Na2SO4), die solvents removed and the residue was
subjected to chromatography (silica gel, hexane) to afford 5
(3.0 g, 29%) as a colourless liquid. Rf (hexane)¼0.69; IR
(film): n¼3077m, 2931s, 2857s, 1641m, 1445m, 1308m,
(100), 101 (25), 109 (7), 135 (7), 149 (2), 163 (1), 177 (1),
189 (1), 219 (1), 221 (1%), 247 (1), 265 (2), 279 (1), 303 (2),
305 (1); HRMS for C25H44O2: calcd 376.3341; found:
376.3342. Anal. calcd for C25H44O2 (376.62): C, 79.73; H,
11.78; found: C, 79.56; H, 11.85.
3.1.5. 19-Icosen-11-yn-1-ol (8). A solution of 6 (0.55 g,
1.46 mmol) in methanol (15 ml) was stirred with ion
exchange resin (Amberlyst 15, Hþ-form, 0.5 g) for 2 days.
The resin was filtered off and the filtrate was evaporated
followed by a chromatographic purification (silica gel,
hexane/ethyl acetate 9:1) to afford 8 (0.39 g, 91%) as a
greasy solid. Rf (hexane/ethyl acetate 9:1)¼0.1; IR (film):
n¼3331s, 3078m, 2927s, 2854s, 1829w, 1642m, 1461m,
1436m, 1335m, 1288m, 1262m, 1224w, 1190w, 1133m,
1060m, 1042m, 1024m, 994m, 969m, 910s cm21; 1H NMR
(400 MHz, CDCl3): d¼1.20–1.40 (m, 19H, CH2), 1.45 (m,
1
994m, 911m, 728m cm21; H NMR (400 MHz, CDCl3):
d¼1.30–1.50 (m, 6H, CH2), 1.75 (m, 2H, CH2), 2.05 (m,
3
3
2H, CH2), 3.50 (t, JH,H¼6.7 Hz, 2H, CH2–Cl), 4.90 (m,
4H, CH2), 1.55 (m, 2H, CH2), 2.0 (dd, JH,H¼6.84 Hz,
1H, CH2vC), 4.95 (m, 1H, CH2vC), 5.80 (m, 1H,
CHvC); 13C NMR (100 MHz, CDCl3): d¼26.8 (CH2),
28.4 (CH2), 28.8 (CH2), 32.6 (CH2), 33.7 (CH2), 45.1
(CH2–Cl), 114.3 (CH2vC), 138.8 (CHvC); MS (GC-MS,
e.i., 70 eV): m/z (%)¼41 (100), 54 (16), 55 (56), 68 (39), 82
(9), 83 (5), 95 (2), 104 (20), 118 (3), 146 (1); HRMS for
C9H15Cl: calcd 146.08623; found: 146.08625. Anal. calcd
for C9H15Cl (146.66): C, 65.52; H, 10.31; found: C, 65.47;
H, 10.55.
3JH,H¼6.84 Hz, 2H, CH2–CvC), 2.15 (m, 4H, CH2–
3
CuC), 3.60 (t, JH,H¼6.63 Hz, 2H, CH2–OH), 4.90 (m,
1H, CH2vC), 4.95 (m, 1H, CH2vC), 5.8 (m, 1H, CHvC);
13C NMR (100 MHz, CDCl3): d¼18.8 (CH2, 2C), 25.8
(CH2), 28.6 (CH2), 28.7 (CH2), 28.8 (CH2), 28.9 (CH2), 29.2
(3£CH2), 29.5 (2£CH2), 29.6 (CH2), 32.9 (CH2), 33.8
(CH2), 63.1 (CH2–OH), 80.2 (CuC), 80.3 (CuC), 114.1
(CH2vC), 139.0 (CHvC); MS (GC-MS, e.i., 70 eV): m/z
(%)¼67 (100), 95 (63), 121 (39), 135 (60), 150 (15), 163
(4), 191 (1), 210 (1), 235 (1), 249 (1), 263 (1), 292 (1);
HRMS for C20H36O: calcd 292.2766; found: 292.2766.
Anal. calcd for C20H36O (292.50): C, 82.12; H, 12.41; C,
81.93; H, 12.55.
3.1.4. 19-Icosen-11-ynyltetrahydro-2H-2-pyranyl ether
(6). To a 210 8C cold solution of 4 (0.8 g, 3.0 mmol) in abs.
THF (15 ml) a solution of butyllithium (3.15 mmol, 1.6 M
in hexane) was slowly added, stirring at that temperature
was continued for 1 h and a solution of 5 (3.5 g, 3.15 mmol)
in HMPT (8 ml) was slowly added at 218 8C. The mixture
was allowed to warm to room temperature and stirring was
continued for another 12 h, then the reaction was stopped by
the addition of water (11 ml). The phases were separated,
the aq. phase was extracted with hexane (3£100 ml), the
combined organic layers were washed with water (2£20 ml)
and brine (15 ml) and dried (Na2SO4). After evaporation of
the solvents the residue was purified by chromatography
(silica gel, hexane/ethyl acetate 98:2) to yield 6 (0.64 g,
57%) as a colourless liquid. Rf (hexane/ethyl acetate
9:1)¼0.6; IR (film): n¼3333w, 3076w, 2926s, 2855s,
2360w, 1737w, 1676w, 1640m, 1465m, 1440m, 1352m,
1323m, 1284w, 1260m, 1200s, 1184m, 1137s, 1079s,
3.1.6. 19-Icosen-11-ynyl acetate (9). To a solution of 8
(1.3 g, 4.45 mmol) in dry pyridine (8.2 ml) acetic anhydride
(4.3 ml) was added and the mixture was stirred for 3.5 h,
then the volatiles were removed under diminished pressure.
The residue was suspended in hexane (100 ml) and washed
with water (3£100 ml) and the solvents were evaporated to
afford 9 (1.45 g, 98%) as a colourless liquid. Rf (hexane/
ethyl acetate 9:1)¼0.65; IR (film): n¼3076w, 2929s, 2856s,
1743s, 1641w, 1465m, 1437m, 1387m, 1365m, 1332w,
1
1238s, 1039m, 995w, 910m cm21; H NMR (400 MHz,
CDCl3): d¼1.20–1.40 (m, 19H, CH2), 1.45 (m, 4H, CH2),
1.60 (m, 2H, CH2), 2.0 (m, 5H, CH2–CvC, CH3), 2.15 (m,
3
4H, CH2–CuC), 4.05 (t, JH,H¼6.84 Hz, 2H, CH2–O),
4.90 (m, 1H, CH2vC), 4.95 (m, 1H, CH2vC), 5.80 (m, 1H,
CHvC); 13C NMR (100 MHz, CDCl3): d¼18.8 (2£CH2),
21.0 (CH2), 26.0 (CH2), 28.7 (2£CH2), 28.9 (2£CH2), 29.1
(CH2), 29.2 (2£CH2), 29.3 (CH2), 29.5 (CH2), 29.6 (CH2),
33.8 (CH2), 64.6 (CH2–O), 80.2 (2£CuC), 114.2
(CH2vC), 139.0 (CH2vC), 171.1 (CvO); MS (GC-MS,
e.i., 70 eV): m/z (%)¼63 (100), 178 (65), 192 (76), 203 (7),
217 (7), 231 (6), 238 (7), 252 (18), 263 (7), 277 (9), 291
(19), 305 (28), 319 (9), 320 (3), 334 (3); HRMS for
C22H38O2: calcd 334.2872; found: 334.2872. Anal. calcd for
C22H38O2 (334.54): C, 78.99; H, 11.45; found: C, 78.77; H,
11.54.
1034s, 992m, 908s, 869m, 815m cm21
;
1H NMR
(400 MHz, CDCl3): d¼1.20–1.60 (m, 28H, CH2), 1.70
3
(m, 1H, CH2), 1.80 (m, 1H, CH2), 2.0 (dd, JH,H¼6.84 Hz,
3JH,H¼6.84 Hz, 2H, CH2–CvC), 2.15 (m, 4H, CH2–
2
3
3
CuC), 3.35 (ddd, JH,H¼9.53 Hz, JH,H¼6.63 Hz, JH,H
¼
6.63 Hz, 1H, CH2–O), 3.45 (m, 1H, CH2–O, THP), 3.70
(ddd, JH,H¼9.51 Hz, JH,H¼6.83 Hz, JH,H¼6.84 Hz, 1H,
2
3
3
CH2–O), 3.85 (m, 1H, CH2–O, THP), 4.55 (dd, THP,
3
3JH,H¼4.35 Hz, JH,H¼2.69 Hz, 1H, O–CH–O), 4.90 (m,
1H, CH2vC), 4.95 (m, 1H, CH2vC) 5.80 (m, 1H, CHvC);
13C NMR (100 MHz, CDCl3): d¼18.8 (CH2), 18.9 (CH2),
19.8 (CH2), 25.6 (CH2), 26.3 (CH2), 28.7 (CH2), 28.7 (CH2),
28.8 (CH2), 28.9 (CH2), 29.1 (CH2), 29.2 (CH2), 29.3 (CH2),
29.4 (CH2), 29.5 (CH2), 29.6 (CH2), 29.8 (CH2), 30.8 (CH2),
33.8 (CH2), 62.3 (CH2–O, THP), 67.7 (CH2–O), 80.1
(CuC), 80.3 (CuC), 98.8 (CH, THP), 114.1 (CH2vC),
139.0 (CHvC); MS (GC-MS, e.i., 70 eV): m/z (%)¼85
3.1.7. (11Z)-11,19-Icosadienyl acetate (1). A solution of 9
(0.27 g, 0.81 mmol) in hexane (10 ml) containing quinoline
(0.125 ml) and Lindlar-catalyst (42 mg) was stirred under
hydrogen (1 atm) for 1 h, then the catalyst was removed and
the solvents were evaporated. Chromatographic purification

6004
R. Csuk et al. / Tetrahedron 60 (2004) 6001–6004
(silica gel, hexane/ethyl acetate 95:5) gave 1 (0.25 g, 92%)
as a colourless liquid. Rf (hexane/ethyl acetate 9:1)¼0.57;
IR (film): n¼3467w, 3077m, 3004s, 2924s, 2853s, 1744s,
1641s, 1464s, 1387s, 1365s, 1237s, 1039s, 994s, 909s,
References and notes
1. Naumov, Y. A. Khim. Promyshl. 2002, 32–51.
2. Qui, H.; Jun, H. W.; McCall, J. W. J. Am. Mosquito Contr.
Assoc. 1998, 14, 12–27.
810w, 723s, 634m, 606m cm21 1H NMR (400 MHz,
;
CDCl3): d¼1.20–1.40 (m, 22H, CH2), 1.60 (m, 2H, CH2),
3. Osimitz, T.; Murphy, J. V. J. Toxicol. Clin. Toxicol. 1997, 35,
435–441.
3
2.0 (m, 9H, CH2–CvC, CH3), 4.05 (t, JH,H¼6.7 Hz, 2H,
CH2–O), 4.90 (m, 1H, CH2vC), 4.95 (m, 1H, CH2vC),
4. Abov-Donia, M. B.; Dechkovskaia, A. M.; Goldstein, L. B.;
Abdel-Rahman, A.; Bullman, S. L.; Khan, W. A. Pharmacol.
Biochem. Behav. 2004, 77, 253–262.
3
3
3
5.35 (ddd, JH,H¼9.6 Hz, JH,H¼6.02 Hz, JH,H¼5.81 Hz,
2H, C–CHvCH–C), 5.80 (m, 1H, CHvC); 13C NMR
(100 MHz, CDCl3): d¼21.0 (CH3), 26.0 (CH2, 2C), 27.2
(CH2), 27.3 (CH2), 28.7 (CH2), 29.0 (CH2), 29.1 (CH2), 29.2
(CH2), 29.3 (2£CH2), 29.6 (2£CH2), 29.7 (CH2), 29.8
(CH2), 33.8 (CH2), 64.7 (CH2–O), 114.1 (CH2vC), 129.8
(–CHvCH–), 129.9 (–CHvCH–), 139.1 (CHvC), 194.4
(CvO); MS (GC-MS, e.i., 70 eV): m/z (%)¼43 (100), 55
(83), 81 (53), 95 (40), 121 (12), 149 (4), 164 (2), 191 (1),
219 (1), 247 (1), 276 (1), 293 (1), 308 (1), 336 (2); HRMS
for C22H40O6: calcd 336.3028; found: 336.3028. Anal. calcd
for C22H40O6 (336.55): C, 78.51; H, 11.98; found: C, 78.43;
H, 12.07.
5. Sakawsegawa, M.; Yatagai, M. Aroma Res. 2002, 3, 213–221.
6. Vollmer, J. H.; Gordon, S. A. Chemistry 1975, 48, 6–11.
7. Moore, J. S.; Lenglet, A.; Hill, N. J. Am. Mosquito Contr.
Assoc. 2002, 18, 107–110.
8. Tschuch, G.; Lindemann, P.; Niesen, A.; Csuk, R.; Moritz, G.,
submitted for publication.
9. Mound, L. A.; Marullo, R. Entomol. Mon. Mag. 1994, 130,
95–98.
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3.2. Bio-assay
Two colonies of M. rubra (about 25 individuals each,
Antstore, Berlin) were reared separately in glass tanks.
During the assay the ants were allowed to choose between
two pieces of prey (ca 75 mg turkey meat) that were placed
on a sheet of paper at a distance of ca. 50 mm. Each piece
was surrounded by a circle (20 mm radius) soaked (50 ml)
either with pure methanol (for reference) or a solution of 1
(0.5 ml in 50 ml methanol). Statistical evaluation of the test
results was made using the x2 test for pairwise comparison
of the number of ants (p,0.05).
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