Synthesis of 5Z,9E-tridecadien-1-ylacetate, an attractant of Trichoplusia ni

Article abstract of DOI:10.1007/s10600-011-9838-z

A new synthetic scheme for 5Z,9E-tridecadien-1-ylacetate, an attractant of the cabbage looper Trichoplusia ni (Huebner) was developed using a highly stereoselective Claisen rearrangement.

Full text of DOI:10.1007/s10600-011-9838-z

Chemistry of Natural Compounds, Vol. 47, No. 1, March, 2011 [Russian original No. 1, January–February, 2011]
SYNTHESIS OF 5Z,9E-TRIDECADIEN-1-YLACETATE,
AN ATTRACTANT OF Trichoplusia ni
*
R. R. Vakhidov and S. B. Alekseev
UDC 542.91+547.473+639.936.2
A new synthetic scheme for 5Z,9E-tridecadien-1-ylacetate, an attractant of the cabbage looper Trichoplusia
ni (Huebner) was developed using a highly stereoselective Claisen rearrangement.
Keywords: insect pheromones, cabbage looper (Trichoplusia ni), 5Z,9E-tridecadien-1-ylacetate, Claisen rearrangement, Wittig
reaction.
5Z,9E-Tridecadien-1-ylacetate (1) is an attractant of the male cabbage looper (Trichoplusia ni Huebner) that affects
their mating behavior [1]. Only one synthetic method for this compound that uses the so-called acetylene method has been
reported [1].
We developed a new synthetic scheme for 1 that uses as the key step the construction of a double bond with the
E-configuration via the orthoester version of the Claisen rearrangement.
OH
O
COOEt
O
OH
2
4
3
5
OAc
OTHP
6
1
The starting material in the proposed scheme was 1-hexen-3-ol (2), which was readily obtained from reaction of
propylmagnesium bromide and acrolein. The Claisen rearrangement occurred easily upon heating allylic alcohol 2 with
triethylorthoacetate in the presence of a catalytic amount of propionic acid. This produced the ethyl ester of 4E-octenoic acid
(3). The stereochemical purity of 3 was confirmed by GC and IR and PMR spectral data. In particular, the IR spectrum of 3
–1
exhibited a single absorption band with ꢀ = 965 cm in the region of double bond bending vibrations. This was characteristic
–1
of trans compounds. A band with ꢀ = 780 cm , characteristic of cis compounds, was not observed. Next, 3 was converted to
the target molecule using a Wittig reaction through the two intermediates 4E-octen-1-ol (4) and 4E-octenal (5). The reaction
of 5 with the ylide generated from 1-bromo-5-(tetrahydropyran-2-yl)oxypentane produced 5Z,9E-tridecadien-1-ol
tetrahydropyranyl ether (6), which was converted in one step to the target compound 1 upon reaction with AcCl–AcOH. The
overall yield of 1 was 15.5% calculated per starting acrolein.
EXPERIMENTAL
IR spectra were recorded in thin layers on a Beckman Microlab 620 MX instrument. PMR spectra were taken in
(CD ) CO solution with HMDS internal standard on a Tesla BS-587A spectrometer (operating frequency 80 MHz). Chemical
3 2
shifts are given on the ꢁ scale. GC was performed on a Chrom-5 instrument with a flame-ionization detector, column
(3500 ꢂ 3 mm), silicone liquid SE-30 (5%) stationary phase on chromaton N-AW-DMCS (0.16–0.20 mm), operating temperature
50–250°C, and He carrier gas (30 mL/min). TLC was performed on Silufol UV-254 plates with a fixed layer of SiO .
2
1-Hexen-3-ol (2). The Grignard reagent obtained from propylbromide (24.6 g, 0.2 mol), Mg (4.86 g, 0.2 mol), and
anhydrous Et O (300 mL) was stirred vigorously, cooled (–10° to –15°C), treated dropwise with acrolein (11.2 g, 0.2 mol) in
2
Ufa State Petroleum Technology University, Salavat Filial, Russia, Salavat, e-mail: vrr2007@mail.ru. Translated
from Khimiya Prirodnykh Soedinenii, No. 1, pp. 84–85, January–February, 2011. Original article submitted June 16, 2010.
©
94
0009-3130/11/4701-0094 2011 Springer Science+Business Media, Inc.

anhydrous Et O (40 mL) over 1 h, stirred for 1 h, refluxed for 0.5 h, cooled to 0°C, and decomposed with icewater (70 mL).
2
The aqueous layer was separated and extracted with Et O (2 ꢂ 50 mL). The combined organic layers were washed with a small
2
quantity of saturated NaCl solution (30 mL), dried over Na SO , and evaporated. The residue was distilled to afford 2
2
4
(14.2 g, 71%), bp 135–136°C [2]. The IR and PMR spectra were analogous to those published [3].
4E-Octenoic Acid Ethyl Ester (3). A mixture of 2 (8.42 g, 84.2 mmol), triethylorthoacetate (50.6 g, 289 mmol), and
propionic acid (0.2 g) was stirred at 135–137°C for 2 h, collecting the released EtOH through a fractionating column equipped
with a condenser. The mixture was cooled to room temperature, treated with Et O (150 mL), washed successively with
2
saturated NaHCO and NaCl solutions, dried over MgSO , and evaporated. The residue was vacuum distilled to afford 3
3
4
–1
(10.88 g, 76%), bp 104°C (10 mm Hg). IR spectrum (ꢀ, cm ): 1745 (C=O), 1645, 965 (E-CH=CH). PMR spectrum (ꢁ, ppm,
J/Hz): 0.86 (3H, t, J = 6, CH ), 1.13 (3H, t, J = 6, CH CH O), 1.3–1.5 (2H, m, CH ), 1.7–2.0 (4H, m, H CC=CCH ), 2.24 (2H,
3
3
2
2
2
2
t, J = 2, CH COO), 4.02 (2H, q, J = 6, CH O), 5.4–5.8 (2H, m, HC=CH) [4].
2
2
4E-Octen-1-ol (4). A suspension of LiAlH (1.45 g, 39.6 mmol) in anhydrous Et O (100 mL) was stirred (under Ar),
4
2
cooled (0–5°C), treated dropwise over 1 h with 3 (6.44 g, 37.9 mmol), heated to room temperature, stirred for another 2 h,
cooled to 0°C, and treated dropwise over 0.5 h with H O (20 mL). The solution was decanted. The residue was washed with
2
Et O (20 mL). The combined Et O layers were washed with saturated NaCl solution (3 ꢂ 50 mL), dried over Na SO , and
2
2
2
4
evaporated. The residue was vacuum distilled to afford 4 (3.59 g, 74%), bp 108°C (13 mm) [5]. The IR and PMR spectra were
analogous to those published [6].
4E-Octenal (5). A suspension of pyridinium chlorochromate (10.74 g, 4.96 mmol) in dry CHCl (100 mL) was
3
treated dropwise over 2 h with 4 (2.54 g, 19.8 mmol), diluted with Et O (100 mL), and passed over a column of silica gel
2
(15 cm). The resulting solution was washed successively with saturated NaHCO and NaCl solutions, dried over Na SO , and
3
2
4
evaporated. The residue was chromatographed over a column of silica gel (eluent hexane:Et O, 8:2) to afford aldehyde 5
2
(2.02 g, 81%). The IR and PMR spectra were analogous to those published [6, 7].
1-(Tetrahydropyran-2-yl)oxy-5Z,9E-tridecadiene (6). 1-(Tetrahydropyran-2-yl)oxy-5-bromopentane (1.62 g,
6.45 mmol) (prepared as before [8]) and PPh (1.69 g, 6.45 mmol) were heated at 160°C for 8 h in an ampul under Ar. The
3
contents were cooled, transferred to a flask, treated with anhydrous THF (50 mL), treated carefully under Ar at –30°C with
t-BuOK (0.72 g, 6.45 mmol), stirred for 0.5 h, cooled to –70°C, treated with 5 (0.83 g, 6.45 mmol), stirred for 3 h, heated to
room temperature, left overnight, diluted with hexane (50 mL), filtered through a fritted-glass filter, and evaporated. The
residue was chromatographed over a column of silica gel (eluent hexane then hexane:Et O, 8:2) to afford 6 (1.08 g, 60%).
2
–1
IR spectrum (ꢀ, cm ): 1640, 970 (E-CH=CH), 780 (Z-CH=CH). PMR spectrum (ꢁ, ppm, J/Hz): 0.88 (3H, t, J = 6, CH ),
3
1.2–1.6 (12H, m, 6 ꢂ CH ), 1.8–2.1 (8H, m, CH C=C), 3.6–3.9 (4H, m, CH O), 4.83 (1H, m, CH), 5.1–5.6 (4H, m, HC=CH).
2
2
2
5Z,9E-Tridecadien-1-ylacetate (1). A mixture of 6 (0.62 g, 2.21 mmol), AcOH (1.5 mL), and AcCl (0.35 mL) was
refluxed for 5 h (TLC monitoring), cooled, treated with icewater, and extracted with Et O (3 ꢂ 20 mL). The extract was
2
washed successively with saturated NaHCO and NaCl solutions, dried over Na SO , and evaporated. The residue was
3
2
4
–1
chromatographed over a column of silica gel (eluent hexane:Et O, 8:2) to afford 1 (0.42 g, 80%). IR spectrum (ꢀ, cm ): 1750
2
(C=O), 1640, 970 (E-CH=CH), 780 (Z-CH=CH). PMR spectrum (ꢁ, ppm, J/Hz): 0.88 (3H, t, J = 6, CH ), 1.2–1.6 (6H, m,
3
3 ꢂ CH ), 1.8–2.1 (11H, m, CH COO, 4 ꢂ CH C=C), 3.6–3.9 (2H, m, CH O), 5.1–5.6 (4H, m, 2 ꢂ HC=CH) [1].
2
3
2
2
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