Stereoselective synthesis of (1Z,3E)-2-ethoxycarbonyl-substituted 1,3-lienes via stille coupling of (E)α-Stannyl-α,β-unsaturated esters with alkenyl halides

Article abstract of DOI:10.1080/00397910902906610

Palladium-catalyzed hydrostannylation of alkynyl esters in benzene at room temperature gives stereoselectively (E)-αstannyl-α,β- unsaturated esters 1 in good yields. (E)α-Stannyl-α,β- unsaturated esters 1 are difunctional group reagents that undergo Still

Full text of DOI:10.1080/00397910902906610

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Stereoselective Synthesis of
(1Z,3E)-2-Ethoxycarbonyl-
Substituted 1,3-Dienes via
Stille Coupling of (E)-α-
Stannyl-α,β-Unsaturated Esters
with Alkenyl Halides
Hong Zhao a b , Ruchun Dai a & Mingzhong Cai a
a Department of Chemistry , Jiangxi Normal
University , Nanchang, China
b Department of Pharmacy , Guangdong
Pharmaceutical College , Guangzhou, China
Published online: 12 Nov 2009.
To cite this article: Hong Zhao , Ruchun Dai & Mingzhong Cai (2009) Stereoselective
Synthesis of (1Z,3E)-2-Ethoxycarbonyl-Substituted 1,3-Dienes via Stille Coupling
of (E)-α-Stannyl-α,β-Unsaturated Esters with Alkenyl Halides, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic
Organic Chemistry, 39:24, 4454-4466, DOI: 10.1080/00397910902906610
To link to this article: http://dx.doi.org/10.1080/00397910902906610
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Synthetic Communications1, 39: 4454–4466, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910902906610
Stereoselective Synthesis of
(1Z,3E)-2-Ethoxycarbonyl-Substituted
1,3-Dienes via Stille Coupling of (E)-a-Stannyl-
a,b-Unsaturated Esters with Alkenyl Halides
Hong Zhao,1,2 Ruchun Dai,1 and Mingzhong Cai1
1Department of Chemistry, Jiangxi Normal University, Nanchang, China
2Department of Pharmacy, Guangdong Pharmaceutical College,
Guangzhou, China
Abstract: Palladium-catalyzed hydrostannylation of alkynyl esters in benzene at
room temperature gives stereoselectively (E)-a-stannyl-a,b-unsaturated esters 1
in good yields. (E)-a-Stannyl-a,b-unsaturated esters 1 are difunctional group
reagents that undergo Stille coupling reactions with alkenyl halides 2 in the
presence of Pd(PPh3)4 and CuI co-catalyst to afford stereoselectively (1Z,3E)-2-
ethoxycarbonyl-substituted 1,3-dienes 3 in good yields.
Keywords: Alkynyl ester, functionalized 1,3-diene, hydrostannylation, (E)-a-
stannyl-a,b-unsaturated ester, Stille coupling
INTRODUCTION
The stereocontrolled synthesis of conjugated dienes attracts considerable
interest in organic chemistry because of their appearance in a wide variety
of biologically active molecules and their key synthetic intermediates.[1]
The synthesis of 1,3-dienes for use in the Diels–Alder reaction is still
an important challenge in organic synthesis,[2] although other elegant
uses of these compounds have been developed.[3] Conjugated dienes are
usually prepared by utilizing either a Wittig-type approach[4] or the
Received December 27, 2008.
Address correspondence to Mingzhong Cai, Department of Chemistry, Jiangxi
Normal University, Nanchang 330022, China. E-mail: caimzhong@163.com
4454

Synthesis of 2-Ethoxycarbonyl-1,3-Dienes
4455
transition-metal-catalyzed coupling reactions of stereodefined vinyl
halides with vinyl organometallic compounds.[5] Recently, Kasatkin
and Whitby reported the insertion of 1-lithio-1-halobutadiene into orga-
nozirconocenes, providing a stereocontrolled synthesis of (1E,3Z)-1,3-
dienes.[6] Molander and Yokoyama reported a one-pot stereoselective
synthesis of trisubstituted 1,3-dienes via sequential Suzuki–Miyaura
cross-coupling with alkenyl- and alkyltrifluoroborates.[7]
The stereoselective synthesis of functionalized 1,3-dienes is also of
considerable interest in organic synthesis.[8] Heteroatom-substituted
1,3-dienes are also useful precursors for constructing highly functiona-
lized ring systems in Diels–Alder reactions.[9] The stereoselective synthesis
of 1,3-dienylsilanes,[10] 1,3-dienyl sulfides,[11] 1,3-dienyl selenides,[12]
1,3-dienyl sulfones,[13] and 1,3-dienylstannanes[14] has already been
described in the literature. 2-Alkoxycarbonyl-substituted 1,3-dienes have
been extensively studied in recent years as potential starting materials for
organic synthesis, in particular for various [4 þ 2] cycloadditions. A
number of these compounds have proven to be valuable precursors for
functionalized alkyl 1-cyclohexene-1-carboxylates,[15] naturally occurring
cyclopentanoid terpenic acids,[16] and biologically important litseno-
lides.[17] Many methods for the synthesis of 2-alkoxycarbonyl-substituted
1,3-dienes have been developed, including aldol-type condensation of
metalated alkene carboxylates,[16,17] Wittig olefination of aldehydes,[18]
titanium(IV) chloride–catalyzed reaction of 1-ethoxy-3-trimethylsilyl-
1-propyne with 1-haloketones,[19] Pd(0)-catalyzed coupling of lithium
(a-alkoxycarbonyl)alkenyl cuprates with vinyl halides,[20] and the
Horner–Emmons reaction of the allylphosphonates with aldehydes.[21]
Very recently, Palmelund et al. have reported the synthesis of
2-ethoxycarbonyl-substituted 1,3-dienes from aldehydes and ethyl
acrylate in the presence of a phosphine and a Lewis acid through a
modification of the Morita reaction.[22] Despite considerable methodolo-
gical differentiation, the majority of the reported procedures suffer from
some drawbacks such as limited scope,[16,17] scarce availability of sub-
strates,[19–21] moderate yields,[17,18] and poor stereoselectivity.[22] Herein,
we report that (1Z,3E)-2-ethoxycarbonyl-substituted 1,3-dienes can be
synthesized stereoselectively by palladium-catalyzed hydrostannylation
of alkynyl esters, followed by Stille coupling reaction with alkenyl halides
in the presence of Pd(PPh3)4 and CuI cocatalyst.
RESULTS AND DISCUSSION
The Stille coupling reactions of vinylstannanes with alkenyl halides
provide a convenient route to stereoselective synthesis of 1,3-dienes.[23]

4456
H. Zhao, R. Dai, and M. Cai
Scheme 1. Synthesis of (E)-a-stannyl-a,b-unsaturated esters.
The interesting point of the method is a high tolerance for functional
groups such as allylic ether, vinylic thioethers, esters, ketones, or tri-
methylsilyl ether.[24] Palladium-catalyzed hydrostannylation of phe-
nylthioalkynes,[25] alkynyl selenides,[26] and alkynyl sulfoxides[27] have
been reported to be highly regio- and stereoselective, providing a direct
route for the stereoselective synthesis of 1,1-difunctional group reagents
containing heteroatom and tin. Rossi et al.[28] reported palladium-
catalyzed hydrostannylation of alkynyl esters in tetrahydrofuran
(THF). To prepare highly selectively (E)-a-stannyl-a,b-unsaturated
esters, we investigated palladium-catalyzed hydrostannylation of alkynyl
esters with Bu3SnH in benzene at room temperature and found that
benzene was a better solvent than THF. (E)-a-Stannyl-a,b-unsaturated
esters 1 were obtained with good regio- and stereoselectivity in good
yields (Scheme 1).
1
Investigations of the crude products 1 by H NMR spectroscopy
(400 MHz) showed their isomeric purities of more than 98%. One olefinic
proton signal of compounds 1a and 1b splits characteristically into one
triplet at d ¼ 6.04 with coupling constant J ¼ 6.8–7.2 Hz, which indicated
that the hydrostannylation to the alkynyl esters had taken place with
strong preference for the addition of the tin atom at the carbon adjacent
to the ester group. The stereochemistry of the addition was readily appar-
ent from the H NMR spectra of compounds 1, which showed a (3JSn-H
1
)
coupling constant of 64 Hz, fully in accord with an E geometry and
overall cis addition of tin hydride.[29]
(E)-a-Stannyl-a,b-unsaturated esters
1 are difunctional group
reagents in which two synthetically versatile groups are linked to the
same olefinic carbon atom and can be considered both as vinylstannanes
and as a,b-unsaturated esters. With a convenient route to the (E)-a-
stannyl-a,b-unsaturated esters 1, we decided to establish the feasibility
of using 1 in cross-coupling reactions with alkenyl halides 2. Gratifyingly,
when the cross-coupling reactions of 1 with a variety of alkenyl iodides 2
were conducted in dimethylformamide (DMF) at room temperature
using Pd(PPh3)4 and CuI as cocatalysts (Scheme 2), fairly rapid reactions

Synthesis of 2-Ethoxycarbonyl-1,3-Dienes
4457
Scheme 2. Synthesis of (1Z,3E)-2-ethoxycarbonyl-substituted 1,3-dienes.
occurred, affording stereoselectively the desired coupling products 3 in
good yields. The experimental results are summarized in Table 1. When
alkenyl bromides were used as the electrophiles, the cross-coupling reac-
tions of (E)-a-stannyl-a,b-unsaturated esters 1 also proceeded smoothly
under the same conditions to give (1Z,3E)-2-ethoxycarbonyl-substituted
1,3-dienes 3 in good yields (entries 10–13).
It is well documented that the cross-coupling reaction (Stille
coupling) of vinylstannanes with organic halides in the presence of a
palladium catalyst occurs with retention of configuration.[24] The 3E-
configuration of the compounds 3a–h has been proved by their 1H
NMR spectra, which show a doublet at d ¼ 6.00–6.88 with a coupling
constant of 15.6–16.4 Hz, and this is also the evidence of the retention
of the E-configuration of the starting compounds 2. In addition, the
1Z-configuration of the compound 3c was confirmed by nuclear overhau-
ser effect spectroscopy (NOESY) in the 1H NMR spectrum. An enhance-
ment of the allylic protons was observed as the vinylic proton (d ¼ 5.92)
of 3c was irradiated. There was no correlation between the allylic protons
Table 1. Synthesis of (1Z,3E)-2-ethoxycarbonyl-substituted 1,3-dienes (3a—i)
Entry
R
R1
R2
X
Product
Yielda (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
n-C4H9
n-C4H9
n-C4H9
n-C4H9
Ph
Ph
Ph
Ph
n-C4H9
n-C4H9
n-C4H9
Ph
H
H
H
H
H
H
H
H
n-C4H9
Ph
CH3OCH2
n-C6H13
CH3OCH2
Ph
n-C4H9
n-C6H13
ꢀ(CH2)4ꢀ
n-C4H9
Ph
I
I
I
I
I
I
I
I
I
Br
Br
Br
Br
3a
3b
3c
3d
3e
3f
81
86
78
79
75
82
86
84
80
78
81
74
80
3g
3h
3i
H
H
H
H
3a
3b
3e
3f
CH3OCH2
Ph
Ph
aIsolated yield based on (E)-a-stannyl-a,b-unsaturated ester 1.

4458
H. Zhao, R. Dai, and M. Cai
(d ¼ 2.26–2.32) and the vinylic proton (d ¼ 6.24). The correlation between
the vinylic proton (d ¼ 5.92) and another vinylic proton (d ¼ 6.24) was
observed. The NOE results indicate that 3c had the expected 1Z-config-
uration and that the cross-coupling reaction of (E)-a-stannyl-a,b-unsatu-
rated esters with alkenyl halides occured with the configuration retention
of both the starting compounds 1 and the compounds 2.
EXPERIMENTAL
General
1H NMR spectra were recorded on a Bruker AC-P400 (400-MHz) spec-
trometer with tetramethylsilane (TMS) as an internal standard using
CDCl3 as the solvent. 13C NMR (100-MHz) spectra were recorded on
a Bruker AC-P400 (400-MHz) spectrometer using CDCl3 as the solvent.
Infrared (IR) spectra were determined on an FTS-185 instrument as neat
films. Mass spectra (MS) were obtained on a Finnigan 8239 mass spectro-
meter. Microanalyses were measured using a Yanaco MT-3 CHN micro-
elemental analyzer. All reactions were carried out in predried glassware
(150ꢁC, 4 h) and cooled under a stream of dry Ar. Benzene was distilled
from sodium prior to use. DMF was dried by distillation over calcium
hydride.
Synthesis of (E)-a-Stannyl-a,b-unsaturated Esters (1a–c)
General Procedure
A 25-mL, two-necked, round-bottomed flask equipped with a magnetic stir
bar and argon was charged sequentially with alkynyl ester (1mmol),
benzene (4mL), Pd(PPh3)4(0.02 mmol), and Bu3SnH (1.05 mmol). The mix-
ture was stirred at room temperature for 4 h. After removal of the solvent
under reduced pressure, the residue was diluted with light petroleum ether
(20 mL) and filtered to remove the palladium catalyst. The resulting solution
was concentrated under vacuum, and the residue was purified by flash
chromatography on silica gel (eluent: light petroleum ether=EtOAc, 19:1).
(E)-1-Tributylstannyl-1-ethoxycarbonyl-1-hexene (1a)
1
3
Oil. H NMR (400 MHz, CDCl3): d 6.04 (t, J ¼ 6.8 Hz, JSn-H ¼ 64 Hz,
1H), 4.14 (q, J ¼ 7.2 Hz, 2H), 2.44–2.40 (m, 2H), 1.58–1.26 (m, 19H),

Synthesis of 2-Ethoxycarbonyl-1,3-Dienes
4459
0.95–0.84 (m, 18H); 13C NMR (100 MHz, CDCl3): d 171.3, 153.6, 135.6,
59.9, 31.8, 31.4, 29.9, 27.3, 22.3, 14.4, 13.9, 13.7, 10.3; IR (neat): n (cmꢀ1
)
2958, 2929, 1709, 1603, 1464, 1182, 1038; MS (EI, 70 eV): m=z 446 (Mþ,
2.3), 389 (69), 387 (48), 205 (50), 105 (100), 73 (75). Anal. calc. for
C21H42O2Sn: C, 56.64; H, 9.50. Found: C, 56.34; H, 9.25%.
(E)-1-Tributylstannyl-1-ethoxycarbonyl-1-octene (1b)
1
3
Oil. H NMR (400 MHz, CDCl3): d 6.04 (t, J ¼ 7.2 Hz, JSn-H ¼ 64 Hz,
1H), 4.14 (q, J ¼ 7.2 Hz, 2H), 2.45–2.39 (m, 2H), 1.53–1.26 (m, 23H),
0.96–0.84 (m, 18H); 13C NMR (100 MHz, CDCl3): d 171.3, 153.7,
135.5, 59.9, 32.1, 31.7, 29.2, 29.0, 28.9, 27.3, 22.6, 14.4, 14.1, 13.7, 10.3;
IR (neat): n (cmꢀ1) 2957, 2927, 1709, 1603, 1464, 1377, 1180; MS (EI,
70 eV): m=z 417 (Mþ-Bu, 100), 371 (21), 291 (19), 235 (28), 179 (38). Anal.
calc. for C23H46O2Sn: C, 58.36; H, 9.79. Found: C, 58.08; H, 9.62%.
(E)-1-Tributylstannyl-1-ethoxycarbonyl-2-phenylethene (1c)
1
3
Oil. H NMR (400 MHz, CDCl3): d 7.32–7.29 (m, 5H), 6.70 (s, JSn-
¼ 64 Hz, 1H), 4.17 (q, J ¼ 7.2 Hz, 2H), 1.58–1.52 (m, 6H), 1.37–1.32
H
(m, 6H), 1.22 (t, J ¼ 7.2 Hz, 3H), 1.07 (t, J ¼ 8.0 Hz, 6H), 0.91 (t,
J ¼ 7.2 Hz, 9H); 13C NMR (100 MHz, CDCl3): d 173.2, 142.1, 139.8,
137.0, 128.3, 128.1, 128.0, 60.3, 28.9, 27.3, 14.2, 13.7, 10.6; IR (neat): n
(cmꢀ1) 3059, 2958, 2923, 1700, 1596, 1463, 1183, 1034, 788, 695; MS
(EI, 70 eV): m=z 466 (Mþ, 1.5), 409 (100), 407 (87), 179 (54), 177 (46).
Anal. calc. for C23H38O2Sn: C, 59.37; H 8.23. Found: C, 59.57; H, 8.35%.
Synthesis of (1Z,3E)-2-Ethoxycarbonyl-substituted 1,3-Dienes (3a–i)
General Procedure
(E)-a-Stannyl-a,b-unsaturated ester 1 (1.0 mmol) and alkenyl halide 2
(1.1 mmol) were dissolved in DMF (8 mL) under Ar at room tempera-
ture. Pd(PPh3)4 (0.05 mmol) and CuI (0.75 mmol) were then added. The
mixture was stirred for 20–24 h at room temperature and monitored by
thin-layer chromatography (TLC) (SiO2) for the disappearance of the
starting (E)-a-stannyl-a,b-unsaturated ester 1. The reaction mixture
was diluted with diethyl ether (30 mL), filtered, and then treated with
20% aqueous KF (10 ml) for 30 min before being dried and concentrated.
The residue was purified by column chromatography on silica gel (eluent:
light petroleum ether=EtOAc, 19:1).

4460
H. Zhao, R. Dai, and M. Cai
(5Z,7E)-6-(Ethoxycarbonyl)-5,7-dodecadiene (3a)
1
Oil. H NMR (400 MHz, CDCl3): d 6.00 (d, J ¼ 15.6 Hz, 1H), 5.75 (t,
J ¼ 7.6 Hz, 1H), 5.68 (dt, J ¼ 15.6, 7.2 Hz, 1H), 4.27 (q, J ¼ 7.2 Hz, 2H),
2.25–2.20 (m, 2H), 2.10–2.06 (m, 2H), 1.43–1.25 (m, 11H), 0.92–0.85
(m, 6H); 13C NMR (100 MHz, CDCl3): d 168.2, 136.2, 133.4, 131.8,
127.8, 60.5, 32.6, 31.4, 31.3, 29.3, 22.3, 22.2, 14.3, 13.9; IR (neat): n
(cmꢀ1) 2959, 2931, 2873, 1717, 1650, 1465, 1226, 1120, 696; MS (EI,
70 eV): m=z 238 (Mþ, 6.4), 209 (22), 149 (100), 85 (61), 57 (82). Anal. calc.
for C15H26O2: C, 75.58; H, 10.99. Found: C, 75.31; H, 10.76%.
(1E,3Z)-1-Phenyl-3-(ethoxycarbonyl)-1,3-octadiene (3b)
Oil. 1H NMR (400 MHz, CDCl3): d 7.40–7.20 (m, 5H), 6.74 (d,
J ¼ 16.4 Hz, 1H), 6.58 (d, J ¼ 16.4 Hz, 1H), 6.02 (t, J ¼ 7.6 Hz, 1H),
4.34 (q, J ¼ 7.2 Hz, 2H), 2.35–2.29 (m, 2H), 1.49–1.22 (m, 7H), 0.92 (t,
J ¼ 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 165.9, 135.4, 134.6,
132.7, 131.3, 129.0, 128.6, 128.2, 127.4, 60.5, 31.5, 29.2, 22.4, 14.3,
13.8; IR (neat): n (cmꢀ1) 3131, 2958, 2929, 2871, 1718, 1619, 1452,
1227, 1096, 698; MS (EI, 70 eV): m=z 258 (Mþ, 33), 229 (15), 201 (28),
105 (100), 77 (61). Anal. calc. for C17H22O2: C, 79.03; H, 8.58. Found:
C, 78.85; H, 8.31%.
(2E,4Z)-1-Methoxy-4-(ethoxycarbonyl)-2,4-nonadiene (3c)
1
Oil. H NMR (400 MHz, CDCl3): d 6.24 (d, J ¼ 16.0 Hz, 1H), 5.92 (t,
J ¼ 7.6 Hz, 1H), 5.80 (dt, J ¼ 16.0, 5.2 Hz, 1H), 4.27 (q, J ¼ 7.2 Hz, 2H),
3.97 (d, J ¼ 5.2 Hz, 2H), 3.34 (s, 3H), 2.32–2.26 (m, 2H), 1.43–1.25 (m,
7H), 0.92 (t, J ¼ 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 167.6,
139.7, 132.4, 130.3, 126.6, 72.8, 60.6, 58.0, 31.3, 29.4, 22.3, 14.3, 13.8;
IR (neat): n (cmꢀ1) 3064, 2929, 1713, 1450, 1402, 1198, 1095, 698; MS
(EI, 70 eV): m=z 226 (Mþ, 17), 197 (65), 73 (100), 57 (95). Anal. calc.
for C13H22O3: C, 68.99; H, 9.80. Found: C, 68.71; H, 9.68%.
(5Z,7E)-6-(Ethoxycarbonyl)-5,7-tetradecadiene (3d)
1
Oil. H NMR (400 MHz, CDCl3): d 6.02 (d, J ¼ 16.0 Hz, 1H), 5.77 (t,
J ¼ 7.6 Hz, 1H), 5.69 (dt, J ¼ 16.0, 7.6 Hz, 1H), 4.30 (q, J ¼ 7.2 Hz, 2H),
2.27–2.20 (m, 2H), 2.13–2.06 (m, 2H), 1.45–1.21 (m, 15H), 0.91–0.85
(m, 6H); 13C NMR (100 MHz, CDCl3): d 168.3, 136.1, 133.6, 131.9,
127.7, 60.5, 32.9, 31.7, 31.4, 29.3, 29.1, 28.9, 22.6, 22.3, 14.3, 14.1, 13.9;

Synthesis of 2-Ethoxycarbonyl-1,3-Dienes
4461
IR (neat): n (cmꢀ1) 2928, 1727, 1606, 1464, 1378, 1156, 962, 862; MS (EI,
70 eV): m=z 266 (Mþ, 100), 221 (45), 177 (20). Anal. calc. for C17H30O2:
C, 76.64; H, 11.35. Found: C, 76.37; H, 11.09%.
(1Z,3E)-1-Phenyl-2-(ethoxycarbonyl)-5-methoxy-1,3-pentadiene (3e)
Oil. 1H NMR (400 MHz, CDCl3): d 7.35–7.28 (m, 5H), 6.63 (s, 1H), 6.38
(d, J ¼ 16.0 Hz, 1H), 5.86 (dt, J ¼ 16.0, 5.6 Hz, 1H), 4.25 (q, J ¼ 7.2 Hz,
2H), 4.04 (d, J ¼ 5.6 Hz, 2H), 3.37 (s, 3H), 1.21 (t, J ¼ 7.2 Hz, 3H); 13C
NMR (100 MHz, CDCl3): d 168.7, 135.4, 133.5, 132.7, 130.5, 130.0,
128.8, 128.4, 128.2, 72.6, 61.3, 58.2, 13.9; IR (neat): n (cmꢀ1) 3065,
2959, 2873, 1717, 1619, 1466, 1380, 1153, 1096, 965, 893, 792; MS (EI,
70 eV): m=z 246 (Mþ, 12), 202 (48), 115 (64), 105 (100), 77 (63). Anal.
calc. for C15H18O3: C, 73.15; H, 7.37. Found: C, 72.87; H, 7.22%.
(1Z,3E)-1,4-Diphenyl-2-(ethoxycarbonyl)-1,3-butadiene (3f)
Oil. 1H NMR (400 MHz, CDCl3): d 7.45–7.24 (m, 10H), 6.88 (d,
J ¼ 16.4 Hz, 1H), 6.75 (s, 1H), 6.64 (d, J ¼ 16.4 Hz, 1H), 4.34 (q,
J ¼ 7.2 Hz, 2H), 1.25 (t, J ¼ 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3):
d 168.9, 135.6, 134.5, 134.3, 132.7, 131.1, 130.4, 128.9, 128.7, 128.5,
128.0, 127.4, 121.7, 61.1, 14.0; IR (neat): n (cmꢀ1) 3073, 2934, 2863,
1721, 1565, 1201, 1095, 967, 804; MS (EI, 70 eV): m=z 278 (Mþ, 24),
205 (100), 202 (37), 105 (82), 77 (25). Anal. calc. for C19H18O2: C,
81.99; H, 6.52. Found: C, 81.72; H, 6.38%.
(1Z,3E)-1-Phenyl-2-(ethoxycarbonyl)-1,3-octadiene (3g)
Oil. 1H NMR (400 MHz, CDCl3): d 7.37–7.22 (m, 5H), 6.51 (s, 1H), 6.16
(d, J ¼ 16.0 Hz, 1H), 5.80 (dt, J ¼ 16.0, 7.2 Hz, 1H), 4.26 (q, J ¼ 7.2 Hz,
2H), 2.20–2.13 (m, 2H), 1.45–1.25 (m, 4H), 1.23 (t, J ¼ 7.2 Hz, 3H),
0.94 (t, J ¼ 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 169.2, 135.7,
134.5, 134.2, 130.1, 128.7, 128.4, 128.1, 127.9, 61.2, 32.7, 31.2, 22.3,
14.0, 13.9; IR (neat): n (cmꢀ1) 3067, 2927, 2854, 1716, 1494, 1451,
1094, 1027, 963, 756, 697; MS (EI, 70 eV): m=z 258 (Mþ, 2.4), 229 (15),
205 (35), 105 (100), 77 (44). Anal. calc. for C17H22O2: C, 79.03; H,
8.58. Found: C, 79.26; H, 8.35%.
(1Z,3E)-1-Phenyl-2-(ethoxycarbonyl)-1,3-decadiene (3h)
Oil. 1H NMR (400 MHz, CDCl3): d 7.30–7.23 (m, 5H), 6.51 (s, 1H), 6.16
(d, J ¼ 15.6 Hz, 1H), 5.80 (dt, J ¼ 15.6, 7.2 Hz, 1H), 4.26 (q, J ¼ 7.2 Hz,

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H. Zhao, R. Dai, and M. Cai
2H), 2.18–2.12 (m, 2H), 1.44–1.38 (m, 2H), 1.33–1.25 (m, 6H), 1.21 (t,
J ¼ 7.2 Hz, 3H), 0.89 (t, J ¼ 6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3):
d 169.2, 135.7, 134.5, 134.3, 130.1, 128.7, 128.4, 128.1, 127.9, 61.1, 33.0,
31.7, 29.0, 28.9, 22.6, 14.1, 13.9; IR (neat): n (cmꢀ1) 3059, 2924, 1728,
1637, 1598, 1574, 1447, 1149, 1022, 960, 696; MS (EI, 70 eV): m=z 286
(Mþ, 100), 241 (43), 159 (46), 143 (82), 129 (97). Anal. calc. for
C19H26O2: C, 79.68; H, 9.15. Found: C, 79.40; H, 9.29%.
(Z)-1-(Ethoxycarbonyl)-1-(1-cyclohexenyl)-1-hexene (3i)
Oil. 1H NMR (400 MHz, CDCl3): d 5.65–5.60 (m, 2H), 4.28 (q,
J ¼ 7.2 Hz, 2H), 2.14–2.02 (m, 6H), 1.69–1.56 (m, 4H), 1.42–1.25 (m,
7H), 0.91 (t, J ¼ 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 169.9,
137.7, 133.0, 128.4, 126.6, 60.6, 31.6, 29.5, 25.8, 25.2, 22.5, 22.3, 22.1,
14.4, 13.9; IR (neat): n (cmꢀ1) 2958, 2931, 2873, 1715, 1617, 1453,
1379, 1228, 1096, 1023; MS (EI, 70 eV): m=z 236 (Mþ, 14), 207 (61),
165 (97), 149 (92), 91 (93), 79 (83), 55 (100). Anal. calc. for C15H24O2:
C, 76.23; H, 10.24. Found: C, 76.11; H, 10.32%.
CONCLUSION
A convenient synthetic method for (1Z,3E)-2-ethoxycarbonyl-substituted
1,3-dienes has been developed by the palladium-catalyzed hydrostannyla-
tion of alkynyl esters, followed by a Stille coupling reaction with alkenyl
halides. The present method has the advantages of readily available
starting materials, straightforward and simple procedures, mild reaction
conditions, high stereoselectivity, and good yields.
ACKNOWLEDGMENTS
We thank the National Natural Science Foundation of China (Project
No. 20462002) and the Natural Science Foundation of Jiangxi Province
in China (Project No. 2007GZW0172) for financial support.
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