The geometric isomers of methyl-2,4,6-decatrienoate, including pheromones of at least two species of stink bugs

Article abstract of DOI:10.1016/j.tet.2005.02.032

All eight geometric isomers of methyl 2,4,6-decatrienoate were synthesized from readily accessible starting materials by fully exploiting Wittig-type olefinations, and taking advantage of an easy separation of 2E and 2Z unsaturated esters. The aggregation pheromone of the brown-winged green bug, Plautia stali, methyl (E,E,Z)-2,4,6-decatrienoate (also a cross-attractant for the brown marmorated stink bug, Halyomorpha halys), was expediently produced in two easy steps from (E)-4,4-dimethoxy-2-butenal in 55% yield. The sex pheromone of the red-shouldered stink bug, Thyanta pallidovirens, methyl (E,Z,Z)-2,4,6-decatrienoate, was conveniently synthesized from 2,4-octadiyn-1-ol in 32% yield using in situ manganese dioxide oxidation-Wittig condensation in a key step.

Full text of DOI:10.1016/j.tet.2005.02.032

Tetrahedron 61 (2005) 3651–3657
The geometric isomers of methyl-2,4,6-decatrienoate, including
pheromones of at least two species of stink bugs
*
Ashot Khrimian
USDA-ARS, Beltsville Agricultural Research Center, PSI, CAIBL, Building 007, Room 301, Beltsville, MD 20705, USA
Received 17 December 2004; revised 10 February 2005; accepted 11 February 2005
Abstract—All eight geometric isomers of methyl 2,4,6-decatrienoate were synthesized from readily accessible starting materials by fully
exploiting Wittig-type olefinations, and taking advantage of an easy separation of 2E and 2Z unsaturated esters. The aggregation pheromone
of the brown-winged green bug, Plautia stali, methyl (E,E,Z)-2,4,6-decatrienoate (also a cross-attractant for the brown marmorated stink
bug, Halyomorpha halys), was expediently produced in two easy steps from (E)-4,4-dimethoxy-2-butenal in 55% yield. The sex pheromone
of the red-shouldered stink bug, Thyanta pallidovirens, methyl (E,Z,Z)-2,4,6-decatrienoate, was conveniently synthesized from 2,4-octadiyn-
1-ol in 32% yield using in situ manganese dioxide oxidation–Wittig condensation in a key step.
Published by Elsevier Ltd.
1. Introduction
ester 10, and, importantly, that both esters readily
isomerized under daylight to produce primarily mixtures
of geometric isomers. The most attractive blend of esters for
H. halys is yet to be found, so easy access to ester 3 and
other isomers is a prerequisite for our future biological
studies. Synthesis of ester 3 as an attractant for P. stali was
patented in Japan9 and used a partial hydrogenation of
methyl (E,E)-2,4-decadien-6-ynoate with Lindlar catalyst in
a key step. Not only was the starting material not readily
available, the yield of 3 from the reduction step was only
12%. To our knowledge, the only other reported preparation
of ester 3 produced it as a by-product in an unspecified
yield.10 The existing synthesis of ester 10 featured a one-
pot double-carbocupration of acetylene with subsequent
additon of methylpropiolate and provided the desired com-
pound in 13% yield after reverse phase HPLC purification.3
2,4,6-Decatrienoic acid does not appear to commonly occur
in nature. Mixtures of several geometric isomers esterified
with diterpenols and triterpenols have been found in the
lattices of several Euphorbia plant species,1–3 with the
E,E,Z isomer being perhaps the most abundant. Methyl
(E,Z,Z)-2,4,6-decatrienoate (10) was identified as a
thermally unstable male-produced sex pheromone of the
red-shouldered stink bug, Thyanta pallidovirens.3,4 Methyl
(E,E,Z)-2,4,6-decatrienoate (3) was isolated from males of
the brown-winged green bug, Plautia stali, and was
demonstrated to be responsible for the aggregation of
conspecific males and females in orchards.5 Reports
indicated that yet another bug, the brown marmorated
stink bug, Halyomorpha halys, was cross-attracted to ester 3
in field trials.6,7 Although the explanation of this cross-
attraction is still unknown, the trapping of H. halys with
ester 3 was of particular interest to us because this invasive
bug has recently become established in the Northeast U.S.
and poses a potential threat to many commercial crops and
ornamental plants.8 The availability of an attractant for
monitoring the spread of H. halys in the U.S. would be
invaluable to extension and pest management programs.
In this paper, we report syntheses of all geometric isomers
of methyl 2,4,6-decatrienoate by fully exploiting Wittig-
type olefinations. Two stink bug pheromones, 3 and 10,
were conveniently prepared in 55 and 32% yields from
easily accessible starting materials, (E)-4,4-dimethoxy-2-
butenal and 2,4-octadiyn-1-ol, respectively.
2. Results and discussion
Our preliminary studies showed that H. halys was cross-
attracted to not only the E,E,Z ester 3 but also to the E,Z,Z
2.1. Synthesis of 4E isomers
Keywords: Methyl 2,4,6-decatrienoate; Geometric isomers; Wittig reac-
tion; Pheromone; Plautia stali; Thyanta pallidovirens; Halyomorpha halys.
All four isomers with a 4E configuration were easily
synthesized from the same precursor, (E)-4,4-dimethoxy-2-
butenal (1). The starting material for the preparation of 1,
*
Corresponding author. Tel.: C1 301 504 6138; fax: C1 301 504 6580;
e-mail: khrimiaa@ba.ars.usda.gov
0040–4020/$ - see front matter Published by Elsevier Ltd.
doi:10.1016/j.tet.2005.02.032

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A. Khrimian / Tetrahedron 61 (2005) 3651–3657
Scheme 1. Reagents and conditions: (a) (Ph3PC4H9)Br/[(CH3)3Si]2NNa, K70 8C; (b) PTSA, acetone–H2O, 0–5 8C; (c) (CH3O)2P(O)CH2CO2CH3, K2CO3–
H2O; (d) (CF3CH2O)2P(O)CH2CO2CH3/[(CH3)3Si]2NK, 18-crown-6, K70 8C; (e) (Ph3PC4H9)Br/2BuLi, THF.
fumaraldehyde bis(dimethylacetal), is commercially avail-
able, or can be straightforwardly prepared from furan.11
Earlier, we used this compound in the syntheses of
conjugated dienic insect pheromones using stereoselective
Wittig olefination.12 In fact, this approach has already been
applied to make the acetals 2 and 5,13 key intermediates
in this synthesis. For cis-olefination of 1, we deprotonated
n-butyltriphenylphosphonium bromide with bis(trimethyl-
silyl)amide; condensation with 1 provided a 70% yield
and a 96:4 ratio of 2 and 5. Trans-olefination of 1 was
accomplished by using 2 equiv of butyllithium as the base14
and gave a 54% yield with a 94:6 ratio of 5:2. Acetals 2 and
5 were deprotected under mild conditions (p-TSA, acetone-
water, 0–5 8C) to avoid cis-trans isomerizations12,13 and the
unsaturatred aldehydes were used in the next steps without
purification. A Horner–Wadsworth–Emmons trans-olefina-
tion with trimethyl phosphonoacetate was employed to
convert 2 and 5, respectively, to esters 3 and 6. We selected
the most straightforward, solvent-free protocol using
potassium carbonate in water15 and obtained a 79% yield
for ester 3 (3:6, 96:4) and 76% yield for 6 (6:3, 95:5). The
condensations were not entirely trans-stereoselective, but
the minor cis-olefination products were successfully sepa-
rated by flash chromatography on SiO2. Importantly, the
configurations of the existing double bonds in 2 and 5
essentially did not change during the course of the reaction,
though we did find it useful to protect the reaction vessels
from light to avoid photo-induced isomerizations. Whereas
2E olefinic esters could be easily prepared from aldehydes,
there are not many procedures to reliably make 2Z olefinic
esters. We were pleased to find that dienic aldehydes made
from acetals 2 and 5 could be converted to esters 4 and 7
with cis-stereoselectivity under the modified Horner–
Wadsworth–Emmons olefination16 conditions utilizing
electrophilic (CF3CH2O)2P(O)CH2COOCH3 and a strongly
dissociated base system, KN(TMS)2/18-crown-6. The
yields of the esters 4 and 7, after purification from trace
amounts of 2E esters by flash chromatography, were 88 and
87%, respectively, and the stereochemical purities (% of 7
in 4 and vice versa) 93 and 95%, respectively. Some loss of
the geometry (from 96 to 93%) of the 6Z double bond in 4
was perhaps due to using a fairly large amount of 18-crown-
6 (5 equiv). This could significantly increase the polarity of
the medium and promote cis-trans isomerizations of the
existing double bonds in the aldehyde.17 Despite this minor
limitation, the cis-olefination method seems viable for
syntheses of 4 and 7 because of high yields and availability
of all components (Scheme 1).
2.2. Synthesis of 4Z isomers
For syntheses of the isomers with 4Z double bonds, we
intended to utilize the same strategy that had been
successful for 4E isomers: that is, to assemble the sensitive
trienoic esters in the last step by capitalizing on high
yielding stereoselective cis and trans Horner-Wadsworth–
Emmons olefinations. The main challenge of this pathway
was the instability of the intermediate 2Z dienals, which
were expected to be even more labile than Z-enals, which
are themselves known to undergo rapid isomerizations18
(Scheme 2).
Octadiyn-1-ol (8) was converted to a THP–ether and
hydroborated with dicyclohexylborane19 to furnish, after
protonolysis and deprotection, dienol 9 in 62% yield and
99% selectivity. First, we examined a sequential one-pot
Swern oxidation–Wittig reaction protocol that has proved
useful for unstable aldehydes.20 The oxidation of dienol 9
was conducted under standard Swern oxidation conditions
(see Section 3), followed by the addition of methyl
(triphenylphosphoranylidene)acetate to provide esters 10
and 11 which were separated by flash chromatography.
Whereas the by-product all-cis isomer 11 was sufficiently
pure to be fully characterized by 1H and 13C NMR spectra,
ester 10 was significantly (w15%) contaminated with
1
isomer 3, judged by H NMR (d 6.84 and 7.35).
We next explored an in situ alcohol oxidation–olefination
reaction utilizing manganese dioxide and a stabilized Wittig
reagent, which reportedly proceeded without a change of
the geometry of a pre-existing Z double bond in starting
allylic alcohols.21 Oxidation of 9 with activated MnO2 was

A. Khrimian / Tetrahedron 61 (2005) 3651–3657
3653
Scheme 2. Reagents and conditions: (a) DHP, PPTS/dicyclohexylborane/AcOH/MeOH, PPTS; (b) MnO2, CH2Cl2, (Ph)3P]CHCO2Me; (c) Zn(Cu/Ag),
MeOH–H2O.
conducted in the presence of methyl (triphenylphosphor-
anylidene)acetate in methylene chloride21 and gave a
mixture of esters (70% yield) separated by flash chroma-
tography into individual stereoisomers 10 (51%) and 11
(4%). 1H and 13C NMR spectra of 10 were in close
agreement with literature values.3 Ester 10 was unstable
under GC conditions3,22 to asses its purity but the 1H NMR
spectrum revealed only traces (total 3–5%) of esters 3 and
14 (d 6.27). A slight isomerization of 4Z or 6Z double bonds
may have occurred during the course of olefination of the
intermediate (Z,Z)-2,4-octadienal, which appeared to be a
limiting step and required a 12 h reaction time at room
temperature with 20% excess of the Wittig reagent.
(Attempts to invigorate the olefination by increasing the
temperature to 40 8C, or using THF instead of CH2Cl2,
resulted in lower yields and decreased stereochemical purity
of ester 10). Thus, the in situ version of alcohol 9 oxidation–
Wittig reaction proved efficient for synthesis of ester 10, the
pheromone of T. pallidovirens, because of its simplicity and
reasonably good overall yield (32%) from the known diyne
alcohol 8.
target molecules and will be required as reference
compounds in our bioassays, we did not pursue more
economical synthetic routes. (An attempted synthesis of 15
by oxidation of 13 with MnO2 and cis-olefination of the
crude aldehyde with a fluorinated Horner–Wadsworth–
Emmons reagent, as described above, resulted in a product
of 88% stereochemical purity).
The structure assignments of the geometric isomers of
1
methyl 2,4,6-decatrienoate were based on the expected H
chemical shifts, 1H–1H coupling constants, and specifically
1H–1H COSY NMR recordings. In general, interactions of
vicinal protons across double bonds were of expected
values, with JcisZ11.0–12.1 Hz, and JtransZ14.7–15.5 Hz.
Yet, in the E,Z,Z isomer 10, cis coupling constants J4–5 and
J6–7 were anomalously low, 9.4 and 9.1 Hz, respectively.
All stereoisomeric methyl 2,4,6-decatrienoates but one
(103) survived GC conditions, as judged by the integrity
and sharpness of their peaks and a close similarity of their
mass spectra in the GC-MS analyses. Besides a strong
molecular ion at m/z 180 (39–71%), they display a notable
peak at 149 m/z (11–26%) apparently due to (M-OCH3)C
ion. However, the GC and GC–MS analyses of ester 14
performed at the injection temperature 260 8C showed an
additional peak with a significantly shorter retention time
but the same molecular ion (180 m/z) as the main
compound, and thus could be misleading in the determi-
nation of its purity. However, at lower injection tempera-
tures (e.g., 130 8C) the extra peak (apparently arising from
an intramolecular Diels–Alder reaction) was absent.
Although we did not pursue methodical photochemical
studies, all geometric isomers of methyl 2,4,6-decatrieno-
ates seemed unstable under daylight, not surprising given a
strong UV absorption at w300 nm (see Section 3). Thus, the
attractant of H. halys, E,E,Z-ester 3, left unprotected under
The second part of Scheme 2 depicts the syntheses of the
remaining two 4Z esters 14 and 15. A CuI/[(Ph)3P]4Pd
catalyzed condensation23 of (E)-1-iodo-1-pentene24 with
propargyl alcohol provided enynol 12 in 69% yield. Partial
cis-hydrogenation of 12 was accomplished in 80% yield and
O98% stereoselectivity using a Zn(Cu/Ag) reagent that
proved handy in the reduction of enynols.25 Dienol 13
underwent in situ MnO2 oxidation–Wittig reaction similar
to 9 and furnished esters 14 and 15 in 59 and 3% yields,
respectively. Ester 15 was 93% pure and was contaminated
with esters 7 and 14, and ester 14 was 96% pure by GC.
Despite appearing as a by-product, isomer 15 was
sufficiently pure (as was ester 11) to be fully characterized
1
by H and 13C NMR. Because esters 11 and 15 were not

3654
A. Khrimian / Tetrahedron 61 (2005) 3651–3657
room conditions as a hexane solution (1 mg/mL) in a Pyrex
vial for two days decreased in purity from 95 to 78%, with
Z,E,Z-ester 4 and E,E,E-ester 6 being the main by-products.
A similar trend was noticed when rubber septa impregnated
with ester 3 were exposed to sunlight. The pheromone of
T. pallidovirens, E,Z,Z-ester 10, both in a hexane solution
and rubber septa formulations, isomerized in sunlight
producing a mixture of geometric isomers, among which
esters 3 and 6 were most abundant. The role of esters 3 and
10, or their combinations with other isomers, in trapping
H. halys stink bug is under investigation.
when chromatography was conducted on neutral alumina
(Brockman Activity I, 60–325 mesh, Fisher Scientific) as
described.12 MS (m/z): 170 (MC, 35), 141 (34), 139 (100),
127 (81), 109 (40), 97 (57), 88 (59), 79 (63), 67 (46), 45
1
(52). H NMR: 0.91 (t, JZ7.3 Hz, H-8), 1.41 (sextet, JZ
7.3 Hz, H-7), 2.17 (dtd, JZ7.3, 7.3, 1.1 Hz, H-6), 3.32 (s,
6H, OCH3), 4.85 (br d, JZ4.9 Hz, H-1), 5.50 (dt, JZ10.5,
7.5 Hz, H-5), 5.59 (dd, JZ15.6, 4.9 Hz, H-2), 6.00 (br dd,
JZ11.0, 11.0 Hz, H-4), 6.63 (dd, JZ15.5, 11.0 Hz, H-3).
The data are a close match with reported values.13
3.1.2. (E,E)-2,4-Octadienal dimethyl acetal (5). To a
suspension of butyltriphenylphosphonium bromide
(1.197 g, 3 mmol) in dry THF (10 mL) was added
butyllithium (1.2 mL, 2.5 M in hexanes, 3 mmol) at
K40 8C. The mixture was stirred 2 h at K20 to (K30) 8C,
cooled to K65 8C, and treated with a solution of aldehyde 1
(390 mg, 3 mmol) in THF (3 mL). After decolorization, the
second equivalent of BuLi (1.2 mL) was added at K65 8C,
and the dark-brown mixture was allowed to warm to
K40 8C. After stirring 1 h, methanol (200 mL) was added
and the mixture was poured into water and extracted with
hexanes/ether, 1:1. The organic extracts were washed with
NH4Cl solution, water, dried, and concentrated. Flash
chromatography on neutral alumina with 2% ethyl acetate
in hexanes afforded 5 (276 mg, 54%) of 98% chemical
purity and 5:2 ratio 94:6. 1H NMR: 0.89 (t, JZ7.5 Hz, H-8),
1.41 (sextet, JZ7.3 Hz, H-7), 2.06 (br dt, JZ6.8, 7.2 Hz,
H-6), 3.31 (s, 6H, OCH3), 4.80 (br d, JZ4.9 Hz, H-1), 5.50
(dd, JZ15.5, 5.0 Hz, H-2), 5.75 (dt, JZ15.1, 6.8 Hz, H-5),
6.04 (br dd, JZ15.1, 10.2 Hz, H-4), 6.31 (dd, JZ15.5,
10.2 Hz, H-3). The data are in close agreement with those
reported.13
3. Experimental
3.1. General
1
Boiling points are uncorrected. H NMR (300 MHz) and
13C NMR (75 MHz) spectra were recorded in CDCl3 with
TMS as an internal standard on a Bruker QE-300
spectrometer. Chemical shifts are reported in d, and J
coupling constants in Hz. 1H–1H COSY was used to assign
signals of trienoates. GC analyses were performed on a
Shimadzu 17A gas chromatograph with a flame ionization
detector using a 60 m!0.25 mm RTX-1701 column
(Restek Corporation), or a 15 m!0.25 mm DB-5 column
(J&W Scientific), and H2 as carrier gas. Electron impact
ionization mass spectra (70 eV) were obtained with an
Agilent Technologies 5973 GC-MS equipped with a 30 m!
0.25 mm HP-5MS column. High resolution electron impact
mass spectra were measured on a Shimadzu GC-17A
coupled with JEOL JMS-SX102A mass spectrometer using
a 15 m!0.25 mm OV-5 capillary column (Ohio Valley
Specialty Chemicals, Marietta, OH). UV spectra were
recorded in hexane on a Shimadzu UV-160 spectrophoto-
meter. Flash chromatography was carried out with 230–400
mesh silica gel (Whatman), and neutral alumina (Brockman
Activity I, 60–325 mesh, Fisher Scientific, acetals 2 and 5).
The reagents were purchased from Aldrich Chemical Co.
unless otherwise specified. THF was freshly distilled from
sodium-benzophenone ketyl under N2. Methylene chloride
and benzene were distilled from P2O5. (E)-4,4-dimethoxy-
2-butenal (1) was prepared from (E)-1,1,4,4-tetramethoxy-
2-butene.11 Mention of a proprietary company or product
does not imply endorsement by the U.S. Department of
Agriculture.
3.1.3. Methyl (E,E,Z)-2,4,6-decatrienoate (3). Acetal 2
(2.125 g, 12.5 mmol) was stirred with p-toluenesulphonic
acid monohydrate (47 mg, 0.25 mmol) in a water–acetone
(5 mLC13 mL) solution at 0–5 8C. After 0.5 h, dry
potassium carbonate (w500 mg) was added to bring the
pH to w9–10. The mixture was evaporated on a rotary
evaporator, extracted with hexane/ether, 3:1, dried
(Na2SO4) for 0.5 h, and concentrated to give crude (Z,E)-
2,4-octadienal (1.570 g). This was added to a mixture of
trimethyl phosphonoacetate (3.035 mL, 18.75 mmol),
potassium carbonate (4.174 g, 30.2 mmol) and water
(3 mL). The mixture was stirred at rt overnight protected
from light by wrapping the flask in an aluminum foil. The
mixture was diluted with water, extracted with hexanes/
ether, 1:1, the organic extract was washed with brine and
dried. After evaporation of the solvent, the crude product
was purified by flash chromatography with hexanes/ethyl
acetate, 95:5. A low-polar fraction (27 mg, 92% Z,E,Z-ester
4, 6% 7, and 2% 3) was isolated followed by the main
fraction (1.784 g, 79%), 3:6, 96:4. MS (m/z): 180 (MC, 53),
151 (9), 149 (19), 138 (18), 121 (22), 120 (16), 119 (44), 111
(20), 107 (27), 106 (15), 105 (19), 91 (83), 79 (100), 77 (38).
1H NMR: 0.92 (t, JZ7.2 Hz, H-10), 1.43 (sextet, JZ7.3 Hz,
H-9), 2.21 (qd, JZ7.4, 1.3 Hz, H-8), 3.73 (s, OCH3), 5.68
(dt, JZ10.6, 8.0 Hz, H-7), 5.86 (d, JZ15.5 Hz, H-2), 6.09
(br dd, J1wJ2Z11.0 Hz, H-6), 6.28 (dd, JZ14.7, 11.4 Hz,
H-4), 6.84 (dd, JZ14.7, 11.3 Hz, H-5), 7.35 (dd, JZ15.1,
11.3 Hz, H-3). 13C NMR: 13.7 (C-10), 22.7 (C-9), 30.1
(C-8), 51.4 (OCH3), 120.0, 128.1, 129.6, 136.1, 137.6, 145.0
3.1.1. (Z,E)-2,4-Octadienal dimethyl acetal (2). To a
suspension of butyltriphenylphosphonium bromide (7.98 g,
20 mmol) in dry THF (30 mL) was added a THF solution
of sodium bis(trimethylsilyl)amide (20 mL of 1.0 M,
20 mmol) at K40 8C. The mixture was allowed to warm
to room temperature, stirred for 2 h, and then cooled to
K75 8C. Aldehyde 1 (2.860 g, 22 mmol) dissolved in dry
THF (10 mL) was slowly added while maintaining the
temperature between K75 and K65 8C. The resulting
mixture was stirred at this temperature for 2 h and warmed
to rt. The mixture was poured into ice-water, extracted with
hexane/ether, 1:1, and dried (Na2SO4). Evaporation of the
solvent and flash chromatography with hexanes/ethyl
acetate, 95:5, afforded 2 (2.370 g, 70%) consisting of 92%
2, 3% E,E-acetal 5 and 3% of the deacetalization product,
(Z,E)-2,4-octadienal. No deacetalization was observed

A. Khrimian / Tetrahedron 61 (2005) 3651–3657
3655
(C-2–C-7), 167.5 (CO2CH3). UV: lmax 295 nm (3 45716).
1H NMR and mass-spectrum of 3 were in a close agreement
with reported.5
1.56 mmol) as described in the previous experiment, was
dissolved in 5 mL THF and added to a Horner–Wadsworth–
Emmons reagent prepared from bis(2,2,2-trifluoroethyl)
(methoxycarbonylmethyl)phosphonate (332 mL, 1.57 mmol),
18-crown-6 (2.068 g, 7.83 mmol), potassium bis(trimethyl-
silyl)amide (3.13 mL 0.5 M in toluene, 1.57 mmol), and dry
THF (40 mL) as described for ester 4. The mixture was
stirred for 1 h, then worked-up, and flash chromatographed
with hexanes/ethyl acetate, 97:3, to provide (Z,E,E)-ester 7
(245 mg, 87%) containing 5% ester 4. MS (m/z): 180 (MC,
39), 151 (7), 149 (17), 138 (18), 121 (19), 119 (44), 107
3.1.4. Methyl (Z,E,Z)-2,4,6-decatrienoate (4). Bis(2,2,2-
trifluoroethyl) (methoxycarbonylmethyl)phosphonate
(954 mg, 3 mmol), 18-crown-6 (3.96 g, 15 mmol) and dry
THF (40 mL) were loaded into the flask, and the mixture
was cooled to K70 8C. Potassium bis(trimethylsilyl)amide
(6.0 mL, 0.5 M in toluene, 3 mmol) was added, and the
pale-yellow suspension was stirred for 15 min at this
temperature. Crude (Z,E)-2,4-octadienal, prepared from
acetal 2 (510 mg, 3 mmol) as described in the previous
experiment, was dissolved in 5 mL THF and added to the
reaction mixture at K75 8C. The mixture was stirred for 1 h
(or until GC analysis showed completion of the reaction) at
that temperature, poured into saturated NH4Cl solution,
extracted with ether/hexanes, 1:1, then the organic layer
was washed with water, dried, concentrated, and flash
chromatographed with hexanes/ethyl acetate, 97:3. (Z,E,Z)-
ester 4 (473 mg, 88%) containing 7% (Z,E,E)-ester 7 was
isolated from a low-polar fraction. MS (m/z): 180 (MC, 60),
151 (13), 149 (26), 138 (30), 121 (29), 120 (20), 119 (61),
111 (25), 107 (30), 106 (17), 105 (22), 91 (88), 79 (100), 77
(38). 1H NMR: 0.92 (t, JZ7.3 Hz, H-10), 1.43 (sextet, JZ
7.2 Hz, H-9), 2.22 (br q, JZ7.3 Hz, H-8), 3.72 (s, OCH3),
5.63 (d, JZ11.0 Hz, H-2), 5.68 (dt, JZ11.0, 7.5 Hz, H-7),
6.18 (br dd, J1wJ2Z11.0 Hz, H-6), 6.64 (dd, J1wJ2Z
11.3 Hz, H-3), 6.78 (dd, JZ15.1, 11.4 Hz, H-5), 7.47 (dd,
JZ15.0, 11.5 Hz, H-4). 13C NMR: 13.7 (C-10), 22.7 (C-9),
30.1 (C-8), 51.1 (OCH3), 116.3, 128.3, 128.6, 136.9,
137.5, 145.0 (C-2–C-7), 166.9 (CO2CH3). UV: lmax
299 nm (3 37656). HRMS for C11H12O calcd 180.1150,
found 180.1153.
1
(28), 91 (82), 79 (100), 77 (37). H NMR: 0.91 (t, JZ7.4,
H-10), 1.43 (sextet, JZ7.3 Hz, H-9), 2.12 (br q, JZ7.2 Hz,
H-8), 3.72 (s, OCH3), 5.60 (d, JZ11.3 Hz, H-2), 5.92 (dt,
JZ14.8, 7.2 Hz, H-7), 6.21 (dd, JZ14.9, 10.8 Hz, H-6),
6.46 (dd, JZ14.8, 10.8 Hz, H-5), 6.58 (dd, J1wJ2Z
11.3 Hz, H-3), 7.40 (dd, JZ15.0, 11.8 Hz, H-4). 13C
NMR: 13.7 (C-10), 22.1 (C-9), 35.0 (C-8), 51.0 (OCH3),
115.7, 126.5, 130.4, 140.4, 142.2, 145.2 (C-2–C-7), 167.0
(CO2CH3). UV: lmax 297 nm (3 35521). HRMS for
C11H12O calcd 180.1150, found 180.1154.
3.1.7. 2,4-Octadiyn-1-ol (8). 3-Bromo-1-propyn-1-ol was
prepared from propargyl alcohol (11.20 g, 0.20 mol) and
sodium hypobromide.26 The crude product was extracted
with ether, dried (Na2SO4), concentrated under reduced
pressure and used in Cadiot–Chodkiewicz27 condensation
without further purification. The reaction flask was charged
under N2 atmosphere with a 30% solution of n-BuNH2
(167 mL), cooled to 0–5 8C and CuCl (1.00 g, 10.1 mmol)
and NH2OH hydrochloride (3–4 g) were added. 1-Pentyne
(16.32 g, 0.24 mol) was added at once followed by slow
addition of 3-bromo-1-propyn-1-ol at 5–15 8C. More
NH2OH hydrochloride was added (total 16.68 g, 0.24 mol)
throughout the addition of bromopropynol to prevent the
solution from turning blue. The reaction mixture was stirred
another 45 min after the addition of bromopropynol, then
the layers were separated, and the aqueous phase was
extracted with ether. The combined ethereal extracts were
washed with NH4Cl, 3% HCl, brine and dried (Na2SO4).
After evaporation of the solvent, the crude material was
filtered through silica gel aided with hexane/ethyl acetate,
10:1, to give pure 2,4-octadiyn-1-ol (12.51 g, 51% from
propargyl alcohol). MS (m/z): 122 (MC, 46), 107 (18), 91
(25), 79 (44), 77 (100), 65 (30), 63 (26), 51 (15), 39 (32). 1H
NMR: 0.98 (t, JZ7.4 Hz, H-8), 1.55 (sextet, JZ7.3 Hz,
H-7), 1.83 (OH), 2.25 (t, JZ7.2 Hz, H-6), 4.30 (br s, H-1).
The data are in close agreement with those reported.28
3.1.5. Methyl (E,E,E)-2,4,6-decatrienoate (6). Acetal 5
(215 mg, 1.26 mmol) was deprotected with p-toluene-
sulphonic acid monohydrate (5 mg) in a mixture of water
(2.5 mL) and acetone (6 mL) at 0–5 8C as described for
acetal 2. Crude (E,E)-2,4-octadienal (143 mg) was added to
a mixture of trimethyl phosphonoacetate (306 mL,
1.9 mmol), potassium carbonate (435 mg, 3.15 mmol) and
water (315 mL). The mixture was stirred overnight protected
from light, diluted with water, and extracted with hexanes/
ether, 1:1. The organic extracts were washed with brine and
dried with Na2SO4. After evaporation of the solvent, the
crude product was purified by flash chromatography with
hexanes/ethyl acetate, 95:5, to afford ester 6 (172 mg, 76%)
containing 5% 3. MS (m/z): 180 (MC, 57), 151 (10), 149
(19), 138 (19), 121 (24), 120 (17), 119 (49), 111 (20), 107
3.1.8. (Z,Z)-2,4-Octadien-1-ol (9). Compound 8 (2.44 g,
20.0 mmol) was stirred with 3,4-dihydro-2H-pyran (2.52 g,
30.0 mmol) in the presence of pyridinium p-toluenesulfo-
nate (503 mg, 2.0 mmol) in a methylene chloride solution
(50 mL) at 25 8C for 4 h. Evaporation of the volatiles
and subsequent flash chromatography with hexanes/ethyl
acetate, 12:1, gave tetrahydro-2-[(2,4-octadiynyl)oxy]-2H-
pyran (3.74 g, 18.1 mmol, 91% yield). This was dissolved in
dry THF (10 mL) and added at K20 8C to a suspension of
dicyclohexylborane in THF prepared as follows: Borane–
methyl sulfide complex (4.03 mL of 10 M in THF,
40.3 mmol) was added under N2 atmosphere to dry THF
(55 mL) at 0 8C, followed by addition of cyclohexene
(8.2 mL, 81 mmol) and stirring for 0.5 h at 5–10 8C and 2 h
1
(31), 106 (15), 105 (19), 91 (84), 79 (100), 77 (38). H
NMR: 0.91 (t, JZ7.2 Hz, H-10), 1.44 (sextet, JZ7.3 Hz,
H-9), 2.12 (br q, JZ7.1 Hz, H-8), 3.73 (s, OCH3), 5.83 (d,
JZ15.5 Hz, H-2), 5.93 (dt, JZ15.1, 6.8, H-7), 6.13 (br dd,
JZ10.6, 15.1 Hz, H-6), 6.20 (dd, JZ14.8, 11.3 Hz, H-4),
6.53 (dd, JZ14.8, 10.5 Hz, H-5), 7.29 (dd, JZ15.5,
11.4 Hz, H-3). 13C NMR: 13.7 (C-10), 22.1 (C-9), 35.0
(C-8), 51.4 (OCH3), 119.5, 127.7, 129.9, 140.5, 141.3, 145.1
(C-2–C-7), 167.6 (CO2CH3). UV: lmax 292 nm (3 45216).
HRMS for C11H12O calcd 180.1150, found 180.1159.
3.1.6. Methyl (Z,E,E)-2,4,6-decatrienoate (7). Crude
(E,E)-2,4-octadienal, prepared from acetal 5 (266 mg,

3656
A. Khrimian / Tetrahedron 61 (2005) 3651–3657
at rt. After the addition of the THP ether, the mixture was
warmed to rt, stirred for 22 h, quenched with glacial acetic
acid (20 mL) at 0 8C, and stirred at rt for 20 h. The solution
was cooled to 0 8C and treated with 5 M NaOH (82 mL),
then 30% H2O2 (10 mL) upon which the temperature went
up and was maintained at w30 8C for 1 h. The mixture was
poured into water (100 mL), extracted with hexanes/ether,
1:1, then the combined organic extracts were washed with
NH4Cl solution and dried (Na2SO4). Evaporation of the
solvent and flash chromatography with hexanes/ethyl
acetate, 20:1, afforded (2Z,4Z)-tetrahydro-2-[(2,4-octa-
dienyl)oxy]-2H-pyran (2.889 g, 76%), which was depro-
tected by heating with pyridinium p-toluenesulfonate
(340 mg) in methanol (20 mL) at 50–55 8C. The solution
was concentrated, dissolved in ether/hexanes, 1:1, washed
with brine, dried, and flash chromatographed with pentane/
ethyl acetate, 5:2, to yield (Z, Z)-2,4-octadien-1-ol (1.560 g,
90%; 62% yield from 2,4-octadiyn-1-ol, 99% purity by GC).
MS (EI, m/z): 126 (MC, 23), 108 (19), 93 (21), 82 (36), 83
(100), 84 (60), 79 (87), 77 (42), 70 (39), 69 (30), 67 (84), 55
(89). 1H NMR (CDCl3): 0.90 (t, JZ7.3 Hz, H-8), 1.40
(sextet, Jw7.4 Hz, H-7), 2.15 (br q, JZ7.4 Hz, H-6), 4.31
(br d, JZ6.8 Hz, H-1), 5.49–5.64 (m, 2H, H-2, H-5), 6.23
(dd, J1wJ2Z11.3 Hz, H-3), 6.37 (dd, JZ11.7, 10.6 Hz,
H-4). 13C NMR (76 MHz, CDCl3): 13.7 (C-8), 22.7 (C-7),
29.4 (C-6), 58.6 (C-1), 122.9, 125.8, 129.1, 134.4 (C-2–
C-5). HRMS for C8H14O calcd 126.1045, found 126.1043.
H-5, H-6), 7.77 (dd, JZ15.2, 11.7 Hz, H-3). 13C NMR
(CDCl3): 13.7 (C-10), 22.6 (C-9), 29.7 (C-8), 51.5 (OCH3),
121.1, 123.3, 125.9, 132.1, 137.4, 139.3 (C-2–C-7), 167.5
(CO2CH3). 1H and 13C NMR data matched those reported.3
UV: lmax 299 nm (3 29214).
3.1.10. Swern oxidation–Wittig reaction of 9. To a stirred
solution of oxalyl chloride (214 mL, 2.45 mmol) in CH2Cl2
(15 mL) was added methyl sulfoxide (348 mL, 4.95 mmol)
at K60 8C. After stirring for 20 min, a solution of alcohol 9
(252 mg, 2 mmol) in CH2Cl2 (10 mL) was added. After
20 min, triethylamine (1.393 mL, 10 mmol) was added at
K60 8C, and the mixture was allowed to warm to 0 8C.
Methyl (triphenylphosphoranylidene)acetate (2.00 g,
6.0 mmol) was added at once and the mixture was stirred
at room temperature for 3 h, or until TLC (CH2Cl2) showed
essentially no intermediate aldehyde present. The mixture
was poured into ice-water (30 mL) and extracted with
CH2Cl2 (3!30 mL). The combined organic extracts were
washed with water, dried (Na2SO4), concentrated, and
chromatographed using hexanes/CH2Cl2, 1:1. Z,Z,Z-Isomer
11 (19 mg) was isolated in the first fraction and E,Z,Z-
isomer 10 (196 mg) in the most polar fraction. 1H NMR did
not reveal any significant impurities in 11, but it showed
15% contamination of 10 with E,E,Z isomer 3.
3.1.11. (E)-4-Octen-2-yn-1-ol (12). Tetrakis(triphenyl-
phosphine)palladium (3.11 g, 2.0 mmol) was added under
N2 to a solution of (E)-1-iodo-1-pentene23 (7.84 g,
40.0 mmol) in benzene (100 mL). After 45–50 min, a
solution of cuprous iodide (1.52 g, 8.0 mmol) and propargyl
alcohol (3.36 g, 60.0 mmol) in n-butylamine (40 mL) was
added over 15–20 min maintaining the temperature 20–
25 8C by cooling. The resulting dark-brown mixture was
stirred for 2.5 h and poured into sat. NH4Cl (400 mL) then
extracted with ether (200 mL). The organic layer was
separated and the aqueous phase was extracted with
ether:hexane, 1:1 (3!100 mL). The combined extracts
were washed with sat. NH4Cl, ammonium hydroxide, brine,
and dried with sodium sulfate. After evaporation of the
solvent, the residue was distilled under vacuum (bp 69–
70 8C/0.05 mmHg) to give 4E-octen-2-yn-1-ol containing
4–5% of the homo-coupling product, 4,6-decadiene (MS:
138 (MC, 45), 109 (25), 95 (28), 82 (19), 81 (30), 67 (100),
55 (13), 54 (14). The product was further purified by flash
chromatography with hexane/ethyl acetate, 3:1, to give 98%
pure 12 (3.482 g, 69%). MS (m/z): 124 (MC, 100), 95 (39),
91 (43), 81 (96), 79 (50), 77 (41), 67 (30), 65 (56), 55 (35).
1H NMR: 0.89 (t, JZ7.2 Hz, H-8), 1.41 (sextet, JZ7.2 Hz,
H-7), 2.07 (br q, JZ7.2 Hz, H-6), 4.35 (br s, H-1), 5.48 (dm,
H-4), 6.15 (dt, JZ15.5, 7.2 Hz, H-5). HRMS for C8H12O
calcd 124.0888, found 124.0888. 12 was described in the
literature29 as a mixture with Z isomer.
3.1.9. Methyl (E,Z,Z)-2,4,6-decatrienoate (10) and
methyl (Z,Z,Z)-2,4,6-decatrienoate (11). Activated
manganese dioxide (Alfa Aesar, technical grade, Ward
Hill, MA, 1.74 g, 20 mmol) was added under N2 to a
solution of dienol 9 (252 mg, 2 mmol) and methyl
(triphenylphosphoranylidene)acetate (803 mg, 2.4 mmol)
in dry methylene chloride (30 mL). The flask was protected
from light by wrapping in aluminum foil, and the mixture
was stirred for 12 h at 25 8C, or until TLC showed no
intermediate aldehyde present. The mixture was filtered
through a short pad of Celite under N2 pressure aided with
an additional amount of CH2Cl2 (3!10 mL). The filtrate
was then concentrated and flash chromatographed with
hexanes/CH2Cl2, 1:1. A mixture of 10 and 11 (253 mg,
70%) was isolated and carefully re-chromatographed using
hexanes/ethyl acetate, 19:1, to first afford ester 11 (13 mg).
MS (m/z): 180 (MC, 63), 151 (10), 149 (11), 138 (20), 137
(11), 121 (25), 120 (18), 119 (44), 111 (18), 107 (28), 105
1
(30), 93 (21), 91 (100), 79 (87), 77 (38). H NMR: 0.92 (t,
JZ7.3 Hz, H-10), 1.43 (sextet, JZ7.3 Hz, H-9), 2.22 (br q,
H-8), 3.72 (s, OCH3), 5.69 (d, JZ11.2 Hz, H-2), 5.72 (m,
H-7), 6.55 (dd, J1wJ2Z11.3 Hz, H-3), 6.67 (dd, J1wJ2Z
11.5 Hz, H-5), 7.10 (dd, JZ12.1, 11.3 Hz, H-6), 7.27 (br dd,
J1wJ2Z11.5 Hz, H-4). 13C NMR: 13.7 (C-10), 22.6 (C-9),
29.7 (C-8), 51.1 (OCH3), 117.2, 122.7, 123.8, 132.1,
137.5, 138.6 (C-2-C-7), 166.8 (CO2CH3). UV: lmax
303 nm (3 26674). HRMS for C11H12O calcd 180.1150,
found 180.1146. Further elution provided a mixture of esters
11 and 10 (25 mg), and finally pure 10 (182 mg, 51%). MS
(m/z): 180 (MC, 68), 151 (7), 149 (7), 138 (8), 121 (21), 120
(16), 119 (26), 107 (24), 106 (30), 105 (36), 93 (27), 91
(100), 79 (73), 77 (35). 1H NMR: 0.91 (t, JZ7.4 Hz, H-10),
1.43 (sextet, JZ7.3 Hz, H-9), 2.21 (br q, JZ7.6 Hz, H-8),
3.75 (s, OCH3), 5.73 (dt, JZ9.1, 8.0 Hz, H-7), 5.88 (d, JZ
15.2 Hz, H-2), 6.08 (dd, JZ11.2, 9.4 Hz, H-4), 6.60 (m, 2H,
3.1.12. (Z,E)-2,4-Octadien-1-ol (13). Alcohol 12 (1.84 g,
14.8 mmol) was reduced with Zn(Cu/Ag) prepared from
zinc (29.25 g, 0.447 mol), copper(II) acetate hydrate
(2.925 g) and silver nitrate (2.925 g) in methanol at 40–
43 8C for 8 h as described.24 The crude product (1.695 g)
was distilled under vacuum to provide O98% pure 2Z,4E-
octadien-1-ol (1.495 g, 80%). Bp 53 8C/0.05 mmHg. MS
(m/z): 126 (MC, 32), 108 (16), 93 (14) 91 (14), 84 (51), 83
(100), 82 (29), 79 (65), 77 (33), 70 (36), 69 (28), 67 (72), 55

A. Khrimian / Tetrahedron 61 (2005) 3651–3657
3657
1
(83). H NMR: 0.90 (t, JZ7.4 Hz, H-8), 1.41 (sextet, JZ
7.3 Hz, H-7), 2.08 (q, H-6), 4.29 (br d, JZ6.9 Hz, H-1), 5.48
(dt, JZ10.6, 7.1 Hz, H-2), 5.74 (dt, JZ14.4, 7.2 Hz, H-5),
6.06 (dd, J1ZJ2Z10.7 Hz, H-3), 6.30 (dd, JZ14.7,
11.0 Hz, H-4). HRMS for C8H14O calcd 126.1045, found
126.1041. 13 was described in the literature as a mixture
with Z,Z isomer and characterized by 13C NMR.29
References and notes
1. Warnaar, F. Lipids 1977, 12, 707–710.
2. (a) Warnaar, F. Phytochemistry 1981, 20, 89–91. (b)
Furstenberger, G.; Hecker, E. Tetrahedron Lett. 1977,
925–928.
3. Millar, J. G. Tetrahedron Lett. 1997, 38, 7971–7972.
4. McBrien, H. L.; Millar, J. G.; Rice, R. E.; McElfresh, J. S.;
Cullen, E.; Zalom, F. G. J. Chem. Ecol. 2002, 28, 1797–1818.
5. Sugie, H.; Yoshida, M.; Kawasaki, K.; Noguchi, H.; Moriya,
S.; Takagi, K.; Fukuda, H.; Fujiie, A.; Yamanaka, M.; Ohira,
Y.; Tsutsumi, T.; Tsuda, K.; Fukumoto, K.; Yamashita, M.;
Suzuki, H. Appl. Entomol. Zool. 1996, 31, 427–431.
6. Tada, N.; Yoshida, M.; Sato, Y. Ann. Rept. Plant Prot. North
Japan 2001, 52, 224–226.
3.1.13. Methyl (E,Z,E)-2,4,6-decatrienoate (14) and
methyl (Z,Z,E)-2,4,6-decatrienoate (15). Manganese diox-
ide (3.82 g, 43.9 mmol) was added under N2 in five portions
over 5 h to a solution of dienol 13 (553 mg, 4.39 mmol) and
methyl (triphenylphosphoranylidene)acetate (1.91 g,
5.71 mmol) in dry methylene chloride (60 mL). The mixture
was stirred for another 16 h at 25 8C and filtered through a
short pad of Celite. The filtrate was concentrated and flash
chromatographed with hexanes/CH2Cl2, 1:1 to afford: Z,Z,E
ester 15 (24 mg, 3%), a mixture of 15 and 14 (164 mg) and
E,Z,E ester 14 (467 mg, 59%).
7. Lee, K.-C.; Kang, C.-H.; Lee, D. W.; Lee, S. M.; Park, C.-G.;
Choo, H. Y. Korean J. Appl. Entomol. 2002, 41, 233–238.
8. http://www.rce.rutgers.edu/stinkbug/.
9. Yamashita, M.; Fukumoto, T.; Suzuki, H. Japanese Patent No.
09176089, 1997.
10. Bohlmann, F.; Zdero, C. Chem. Ber. 1973, 106, 3779–3787.
11. Gree, R.; Tourbah, H.; Carrie, R. Tetrahedron Lett. 1986, 27,
4983–4986.
Ester 15 was 93% pure by GC and was contaminated with
isomers 14 and 7. Spectral data for 15: MS (m/z): 180 (MC,
71), 151 (13), 149 (14), 138 (27), 137 (15), 121 (29), 119
1
12. Khrimian, A. P.; Ovanesyan, A. L.; Strienz, L.; Svatos, A.;
Khrimyan, E. P.; Makaryan, G. M.; Badanyan, Sh. O. Soviet
J. Bioorg. Chem. 1992, 18, 532–539.
(70), 111 (25), 107 (37), 91 (100), 79 (87), 77 (36). H
NMR: 0.91 (t, JZ7.3 Hz, H-10), 1.45 (sextet, JZ7.4 Hz,
H-9), 2.14 (br q, JZ6.9 Hz, H-8), 3.72 (s, OCH3), 5.66 (br d,
JZ11.7 Hz, H-2), 5.97 (dt, JZ15.0, 7.2 Hz, H-7), 6.33 (dd,
J1wJ2Z11.3 Hz, H-5), 6.58 (dd, JZ14.8, 11.3 Hz, H-6),
7.09 (dd, H-3), 7.15 (br dd, H-4). 13C NMR: 13.7 (C-10),
22.2 (C-9), 35.1 (C-8), 51.1 (OCH3), 116.5, 122.3, 124.9,
137.9, 138.9, 140.7 (C-2–C-7), 166.9 (CO2CH3). UV: lmax
298 nm (3 35197). HRMS for C11H12O calcd 180.1150,
found 180.1145.
13. Badanyan, Sh. O.; Makaryan, G. M.; Ovanesyan, A. L.;
Panosyan, G. A. Russ. J. Org. Chem. 2001, 37, 633–639.
14. Schlosser, M.; Christmann, K. F. Ann. Chem. 708 1967, 1–35.
15. Villieras, J.; Rambaud, M. Synthesis 1983, 300–303.
16. Still, W. C.; Gennari, S. Tetrahedron Lett. 1983, 24,
4405–4408.
17. Ideses, R.; Shani, A. Tetrahedron 1989, 45, 3523–3534.
18. Thomas, D. A.; Warburton, W. K. J. Chem. Soc. 1965,
2988–2990. Xiao, X.-Y.; Prestwich, G. D. Synth. Commun.
1990, 20, 3125–3130.
Isomer 14 was thermally unstable at GC injection
temperature 260 8C but at 130 8C showed purity of 96%.
MS (m/z): 180 (MC, 68), 151 (12), 149 (14), 138 (18), 137
(15), 121 (27), 119 (49), 111 (20), 107 (32), 91 (100), 79
19. Zweifel, G.; Polston, N. L. J. Am. Chem. Soc. 1970, 92,
4068–4071.
1
20. Ireland, R. E.; Norbeck, D. W. J. Org. Chem. 1985, 50,
2198–2200.
(95), 77 (36). H NMR: 0.91 (t, JZ7.4 Hz, H-10), 1.44
(sextet, JZ7.3 Hz, H-9), 2.16 (br q, JZ6.9 Hz, H-8), 3.74
(s, OCH3), 5.84 (d, JZ15.1 Hz, H-2), 5.90 (dt, H-7), 5.96
(dd, H-4), 6.27 (dd, J1wJ2Z11.2 Hz, H-5), 6.62 (ddm, JZ
14.7, 11.5 Hz, H-3), 7.74 (ddd, JZ15.1, 11.7, 0.8 Hz, H-3).
13C NMR (CDCl3): 13.7 (C-10), 22.2 (C-9), 35.1 (C-8), 51.5
(OCH3), 120.3, 124.2, 125.5, 137.8, 139.6, 140.6 (C-2–
C-7), 167.6 (CO2CH3). UV: lmax 296 nm (3 32984). HRMS
for C11H12O calcd 180.1150, found 180.1144.
21. Wei, X.; Taylor, R. J. K. J. Org. Chem. 2000, 65, 616–620.
Wei, X.; Taylor, R. J. K. Tetrahedron Lett. 1998, 39,
3815–3818.
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Perkin Trans. 1 1986, 1809–1815.
23. Ratovelomana, V.; Linstrumelle, G. Synth. Commun. 1981, 11,
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Acknowledgements
I wish to thank Dr. J. R. Aldrich, USDA-ARS, CAIBL,
Beltsville, MD, for bringing the importance of this project to
my attention, Dr. J. G. Millar, University of California,
Riverside, CA, for supplying a sample of E2,Z4,Z6–
10:COOMe, and Shin-Etsu Chemical Co., Japan for sample
of E2,E4,Z6–10:COOMe. Assistance of N. H. Dees in
syntheses and analyses is much appreciated.
26. Chodkiewicz, W. Ann. Chim. 1959, 2(13 Series), 819–869.
27. Marino, J. P.; Nguyen, H. N. Org. Chem. 2002, 67, 6841–6844.
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5023–5026.
¨
¨
¨
29. (a) Maeorg, U.; Valimae, T. Proc. Acad. Sci. Estonian SSR
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