Highly regioselective and stereoselective hydrostannylation of (z)-2-ethoxycarbonyl-1,3-enynes leading to (1e,3e)-2- ethoxycarbonyl-3-stannyl-1,3-dienes

Article abstract of DOI:10.3184/174751915X14447407625303

The Stille coupling of (E)-stannyl-unsaturated esters with alkynyl bromides in DMF in the presence of Pd(PPh₃)₄ and CuI gave (Z)- 2-ethoxycarbonyl-1,3-enynes in good yields. The latter underwent the palladium-catalysed hydrostannylation with tributyltin hydride in THF at room temperature to afford (1E,3E)-2-ethoxycarbonyl-3- stannyl-1,3-dienes in good yields with high regio- and stereoselectivities.

Full text of DOI:10.3184/174751915X14447407625303

JOURNAL OF CHEMICAL RESEARCH 2015
VOL. 39 NOVEMBER, 627–630
RESEARCH PAPER 627
Highly regioselective and stereoselective hydrostannylation of
(Z)-2-ethoxycarbonyl-1,3-enynes leading to
(1E,3E)-2- ethoxycarbonyl-3-stannyl-1,3-dienes
Pingping Wanga,b, Bin Huanga, Shiyun Xiea, Yuxin Tuoa and Mingzhong Caia*
aKey Laboratory of Functional Small Organic Molecule, Ministry of Education and Department of Chemistry, Jiangxi Normal University, Nanchang 330022,
P. R. China
bDepartment of Chemistry, Jiujiang University, Jiujiang 330022, P. R. China
The Stille coupling of (E)-α-stannyl-α,β-unsaturated esters with alkynyl bromides in DMF in the presence of Pd(PPh3) and CuI gave (Z)-
2-ethoxycarbonyl-1,3-enynes in good yields. The latter underwent the palladium-catalysed hydrostannylation with tri4butyltin hydride in
THF at room temperature to afford (1E,3E)-2-ethoxycarbonyl-3- stannyl-1,3-dienes in good yields with high regio- and stereoselectivities.
Keywords: difunctionalised 1,3-diene, palladium, hydrostannylation, (E)-α-stannyl- α,β-unsaturated ester, stereoselective synthesis
The stereoselective synthesis of 1,3-dienes containing metal or
heteroatom functional groups has attracted considerable interest
in organic synthesis because many useful functional group
transformations can be achieved by the introduction and removal
of metal or heteroatom functions. The stereoselective synthesis of
1,3-dienyl sulfides,1-3 1,3-dienyl selenides,4-6 1,3-dienylsilanes7-9
and 1,3-dienylstannanes10-12 has been reported previously.
Recently, the stereocontrolled synthesis of difunctionalised
1,3-dienes has also received much attention in organic
synthesis since such dienes may find use as versatile synthetic
building blocks.13-18 In addition, difunctionalised 1,3-dienes
containing heteroatoms can control both regioselectivity and
stereoselectivity and play a key role in cycloadditions.19-22
Jin and co-workers described the stereoselective synthesis of
2-alkoxy-3-alkyl(aryl)thiobuta-1,3-dienes by a Negishi coupling
reaction between α-alkyl(aryl)thio vinyl zinc chlorides and
α-bromo vinyl ethers.23 Coleman and Walczak reported24 the
stereoselective synthesis of (E,E)-1-tributylstannyl-4-borylbuta-
1,3-diene and its use as an orthogonal Stille and Suzuki–
Miyaura coupling partner. Recently, we have described the
stereoselective synthesis of (Z,Z)-2-silyl-3-stannyl-substituted
1,3-dienes by the hydromagnesiation of alkynylsilanes, followed
by a cross-coupling reaction with (E)-α-iodovinylstannanes in
the presence of Pd(PPh3)4 catalyst.25 However, to the best of
our knowledge, no well-established method is used to prepare
both as vinylstannanes and α,β-unsaturated esters. With a
convenient route to the (E)-α-stannyl-α,β-unsaturated esters
1, we decided to explore the Stille coupling reaction of 1 with
alkynyl bromides 2 to prepare (Z)-2-ethoxy-carbonyl-1,3-
enynes 3. We were pleased to find that when the cross-coupling
reactions of 1 with a variety of alkynyl bromides 2 were carried
out in DMF at room temperature using Pd(PPh3)4 and CuI as
co-catalyst (Scheme 1), the desired (Z)-2- ethoxycarbonyl-1,3-
enynes 3 were obtained stereoselectively in good yields. The
experimental results are listed in Table 1.
Palladium-catalysed hydrostannylation of alkynes provides a
simple, general route for the synthesis of vinylstannanes.27 The
palladium-catalysed hydrostannylation of substituted enynes
generally leads to the α-addition product, providing a convenient
route for the synthesis of 1,3-dienylstannanes. The Pd-catalysed
hydrostannylation of 1-methoxycarbonyl-substituted enynes,28
chloroenynes and alkyl-substituted enynes,29 enediynes30 and
eneynols12havebeenreported.However,tothebestofourknowledge,
no Pd-catalysed hydrostannylation of 2-ethoxycarbonyl-substituted
1,3-enynes has been reported until now. In order to prepare highly
regioselectivity and stereoselectively (1E,3E)-2-ethoxycarbonyl-
3-stannyl-substituted 1,3-dienes, we investigated the palladium-
Table 1 Synthesis of (Z)-2-ethoxycarbonyl-substituted 1,3-enynes 3a–ga
stereoselectively
(1E,3E)-2-ethoxycarbonyl-3-stannyl-1,3-
Entry
R
R1
Product
Yield/%b
dienes. We now wish to report that (1E,3E)-2-ethoxycarbonyl-3-
stannyl-1,3-dienes could be easily synthesised by Stille coupling
of (E)-α-stannyl-α,β-unsaturated esters with alkynyl bromides,
followed by hydrostannylation with tributyltin hydride in the
presence of Pd(PPh3)4.
The starting (E)-α-stannyl-α,β-unsaturated esters were
easily prepared by the palladium-catalysed hydrostannylation
of alkynyl esters according to a literature procedure.26 (E)-
α-Stannyl-α,β-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
1
2
3
4
5
6
7
n-C H
n-C44H99
Ph
Ph
Ph
Ph
n-C6H13
CH OCH2CH2
Cy3clopropyl
CH OCH2CH2
Cy3clopropyl
n-C H13
3a
3b
3c
3d
3e
3f
85
81
78
75
79
73
83
P6h
CH3OCH2CH2
3g
aReaction was performed with (E)-α-stannyl-α,β-unsaturated ester 1 (1 mmol), alkynyl
bromide 2 (1.1 mmol), Pd(PPh3)4 (0.05 mmol), CuI (0.75 mmol) in DMF (8 mL) at room
temperature under Ar for 24 h.
bIsolated yield based on the (E)-α-stannyl-α,β-unsaturated ester 1 used.
R
H
CO2Et
R
H
Et
CO2
Pd(PPh3)4/CuI
DMF, r.t. 24 h
R1
+
Br
SnBu3
R1
3
1
2
Scheme 1
* Correspondent. E-mail: caimzhong@163.com

628 JOURNAL OF CHEMICAL RESEARCH 2015
R
H
R
CO2Et
CO2Et
R1
H
Pd(PPh3)4
+
HSnBu3
H
THF, rt, 2 h
R1
SnBu3
4
3
Scheme 2
catalysed hydrostannylation of (Z)-2-ethoxycarbonyl-substituted
1,3-enynes 3 with tributyltin hydride (Scheme 2).
triplet at δ = 5.56–5.78 with coupling constant J = 7.0–7.6 Hz,
and one olefinic proton signal of compounds 4b and 4d splits
characteristically into one doublet at δ = 5.02–5.93 with coupling
constant J = 9.2 Hz, which indicated that the hydrostannylation of
the compounds 3 had taken place with strong preference for the
addition of the hydride at the more electron-deficient terminus
of the acetylene. A reasonable explanation lies in the electronic
polarisation of the acetylene due to the electron-withdrawing
nature of the ester group. The stereochemistry of the addition was
readily apparent from the 1H NMR spectra of compounds 4, which
showed a (3JSn117-H) coupling constant of 56–64 Hz, fully in accord
with an E geometry and overall cis addition of tin hydride.31
We also performed the Stille coupling reaction of (1E,3E)-
1-hexyl-2-ethoxycarbonyl-3-tributylstannyl-6-methoxy-1,3-
hexadiene (4g) with iodobenzene in DMF at room temperature in
the presence of Pd(PPh3)4 and CuI affording the desired (1Z,3Z)-
1-hexyl-2-ethoxycarbonyl-3-phenyl-6-methoxy-1,3-hexadiene (5a)
in 73% yield (Scheme 3).
In conclusion, we have developed a highly efficient method
for the stereoselective synthesis of (1E,3E)-2-ethoxycarbonyl-3-
stannyl-substituted 1,3-dienes by Stille coupling of (E)-α-stannyl-
α,β-unsaturated esters with alkynyl bromides, followed by the
palladium-catalysed hydrostannylation reaction with tributyltin
hydride. The present method has some attractive advantages of
readily available starting materials, mild reaction conditions, high
regioselectivity and stereoselectivity and good yields.
Our initial efforts were devoted to optimise the reaction
conditions using the hydrostannylation of (Z)-1-butyl-2-
ethoxycarbonyl-6-methoxyhex-1-en-3-yne 3a (1 mmol) and
Bu3SnH (1.1 mmol) as the model reaction. The influences of
the catalyst and solvent on the reaction were examined and the
results are listed in Table 2. For the palladium catalysts evaluated
[Pd(OAc)2, PdCl2(PPh3)2, Pd(PPh3)4, and PdCl2], both Pd(OAc)2
and PdCl2 were inefficient, and Pd(PPh3)4 was found to be more
efficient than PdCl2(PPh3)2. Both THF and benzene could be used
as solvent, but THF gave the best result. Increasing the quantity
of Pd(PPh3)4 could shorten the reaction time, but did not increase
the yield of (1E,3E)-1-butyl-2-ethoxycarbonyl-3-tributylstannyl-
6-methoxy-1,3-hexadiene (4a). Taken together, a good result was
obtained when the hydrostannylation reaction was carried out with
2 mol% Pd(PPh3)4 in THF at room temperature for 4 h under Ar
(entry 5).
To examine the scope for this reaction, the hydrostannylation
reactions of
a variety of (Z)-2-ethoxycarbonyl-substituted
1,3-enynes 3 with Bu3SnH were investigated under the optimised
conditions and the experimental results are listed in Table 3. The
palladium-catalysed hydrostannylation reactions of a variety of (Z)-
2-ethoxycarbonyl-substituted 1,3-enynes 3 with Bu3SnH proceeded
smoothly in the presence of 2 mol% Pd(PPh3)4 in THF at room
temperature to afford regioselectively and stereoselectively the
desired (1E,3E)-2-ethoxycarbonyl-3-stannyl-substituted 1,3-dienes
4 in good yields. In all cases, a single regio- and geometric isomer
was formed according to Scheme 2 and the isolation of products
only involved direct flash chromatography.
Experimental
THF was distilled from sodium before use, all other reagents were used
as-received without further purification. All reactions were carried
out under an atmosphere of Ar in oven-dried glassware with magnetic
stirring. IR spectra were determined on an FTS-185 instrument as neat
The regioselectivity is easily assessed by the appropriate
coupling patterns of the vinylic proton. One olefinic proton signal
of compounds 4a, 4c, 4e and 4g splits characteristically into one
1
films. H NMR spectra were recorded on a Bruker Avance 400 (400
Table 2 Influences of catalyst and solvent in the hydrostannylation
Table 3 Synthesis of (1E,3E)-2-ethoxycarbonyl-3-stannyl-substituted
1,3-dienes 4a
reactiona
Entry
Catalyst/mol%
Solvent
Time/h
Yield/%b of 4a
Entry
R
R1
Product
Yield/%b
1
2
3
4
5
6
7
8
9
Pd(OAc) (2)
Pd(OAc)2 (2)
PdCl (PPh2) (2)
PdCl2(PPh3)22 (2)
Pd(2PPh )3 (2)
Pd(PPh3)4 (2)
Pd(PPh3)44 (5)
PdCl 3(2)
THF
Benzene
THF
Benzene
THF
Benzene
THF
THF
24
24
6
8
4
6
2
24
24
0
0
1
2
3
4
5
6
7
n-C H
n-C44H99
Ph
Ph
Ph
Ph
n-C6H13
CH OCH2CH2
Cy3clopropyl
CH OCH2CH2
Cy3clopropyl
n-C H13
4a
4b
4c
4d
4e
4f
81
73
79
75
82
79
84
52
44
81
66
82
0
P6h
CH3OCH2CH2
4g
aReaction was performed with 3 (1 mmol), Bu3SnH (1.1 mmol), Pd(PPh3)4 (0.02 mmol),
THF (2 mL) at room temperature under Ar for 4 h.
bIsolated yield
PdCl22 (2)
Benzene
0
a Reaction was performed with 3a (1 mmol), Bu3SnH (1.1 mmol), solvent (2 mL) at room
temperature under Ar.
bIsolated yield.
n-C6H13
CO2Et
n-C6H13
CO2Et
5 mol% Pd(PPh3)4
75 mol% CuI
CH2CH2OCH3
CH2CH2OCH3
H
+
I
H
H
DMF, r.t., 8 h
Bu3Sn
Ph
H
5a
4g
Scheme 3

JOURNAL OF CHEMICAL RESEARCH 2015 629
MHz) spectrometer with TMS as an internal standard using CDCl3 as
the solvent. 13C NMR spectra were recorded on a Bruker Avance 400
(100 MHz) spectrometer using CDCl3 as the solvent with TMS as an
internal standard. Microanalyses were obtained using a PerkinElmer
240 elemental analyser.
(m, 2H), 2.55 (t, J = 7.2 Hz, 2H), 1.58–1.28 (m, 11H), 0.89 (t, J = 7.2
Hz, 3H); 13C NMR (CDCl3): δ 165.0, 153.7, 116.2, 86.0, 78.6, 70.7,
60.9, 58.6, 31.6, 29.9, 28.9, 28.8, 22.5, 20.5, 14.2, 14.1. Anal. calcd for
C16H26O3: C, 72.14; H, 9.84; found: C, 71.85; H, 9.58%.
Synthesis of (1E,3E)-2-ethoxycarbonyl-3-stannyl- substituted 1,3-dienes
Synthesis of (Z)-2-ethoxycarbonyl-substituted 1,3-enynes (3a–g);
(4a–g); general procedure
general procedure
(Z)-2-Ethoxycarbonyl-substituted 1,3-enyne 3 (1.0 mmol) was added
dropwise to a solution prepared by adding tributylstannane (1.1 mmol)
to Pd(PPh3)4 (0.02 mmol) in THF (2 mL) at room temperature under an
argon atmosphere. After 4 h, the reaction mixture was evaporated at
60 ºC under reduced pressure and the residue was purified by column
chromatography (light petroleum ether (30–60 ºC)/ethyl acetate, 19:1)
on silica gel.
The (E)-α-stannyl-α,β-unsaturated ester 1 (1.0 mmol) and the alkynyl
bromide 2 (1.1 mmol) were dissolved in DMF (8 mL) under Ar at room
temperature. 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 TLC (SiO2) for the disappearance of the starting (E)-α-
stannyl-α,β-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 over MgSO4 and concentrated
at 40 ºC under reduced pressure. The residue was purified by column
chromatography on silica gel (eluent: light petroleum ether (30–60 ºC)/
EtOAc, 19:1).
(Z)-1-Butyl-2-ethoxycarbonyl-6-methoxyhex-1-en-3-yne (3a): Colour-
less oil. IR (film): ν (cm-1) 2927, 2859, 2218, 1722, 1468, 1374, 1115;
1H NMR (CDCl3): δ 6.51 (t, J = 7.6 Hz, 1H), 4.23 (q, J = 7.2 Hz, 2H),
3.54 (t, J = 7.2 Hz, 2H), 3.36 (s, 3H), 2.61–2.58 (m, 2H), 2.53 (t, J = 7.2
Hz, 2H), 1.47–1.26 (m, 7H), 0.89 (t, J = 7.2 Hz, 3H); 13C NMR (CDCl3):
δ 165.1, 153.8, 116.2, 86.1, 78.6, 70.8, 61.0, 58.7, 31.4, 25.6, 22.7, 20.7,
14.2, 14.0. Anal. calcd for C14H22O3: C, 70.56; H, 9.30; found: C, 70.29;
H, 9.11%.
(Z)-1-Butyl-2-ethoxycarbonyl-4-cyclopropylbut-1-en-3-yne (3b):
Colourless oil. IR (film): ν (cm-1) 2929, 2854, 2221, 1719, 1464, 1378,
1120; 1H NMR (CDCl3): δ 6.53 (t, J = 7.6 Hz, 1H), 4.25 (q, J = 7.2 Hz,
2H), 2.59–2.53 (m, 2H), 1.46–1.25 (m, 8H), 0.90 (t, J = 7.2 Hz, 3H),
0.68–0.46 (m, 4H); 13C NMR (CDCl3): δ 165.6, 157.8, 118.5, 87.2, 77.3,
60.9, 31.3, 25.5, 22.7, 14.2, 14.1, 11.3, 0.3. Anal. calcd for C14H20O2: C,
76.33; H, 9.15; found: C, 76.08; H, 8.87%.
(Z)-1-Phenyl-2-ethoxycarbonyl-6-methoxyhex-1-en-3-yne
Colourless oil. IR (film): ν (cm-1) 2930, 2222, 1728, 1598, 1447, 1374,
1174, 1116, 752, 695; H NMR (CDCl3): δ 7.39-7.26 (m, 5H), 7.14 (s,
(1E,3E)-1-Butyl-2-ethoxycarbonyl-3-tributylstannyl-6-methoxy-
1,3-hexadiene (4a): Colourless oil. IR (film): ν (cm-1) 2956, 2925,
1
2854, 1716, 1464, 1376, 1342, 1197, 1120; H NMR (CDCl3): δ 5.63
3
(t, J = 7.0 Hz, 1H), 5.56 (t, J = 7.6 Hz, JSn-H = 56 Hz, 1H), 4.16 (q,
J = 7.2 Hz, 2H), 3.37 (t, J = 7.4 Hz, 2H), 3.32 (s, 3H), 2.47–2.36 (m,
4H), 1.48–1.18 (m, 19H), 0.93–0.78 (m, 18H); 13C NMR (CDCl3): δ
167.5, 145.0, 139.7, 138.1, 134.7, 72.4, 60.1, 58.5, 31.8, 30.4, 29.7, 29.1,
27.4, 22.5, 14.3, 14.2, 14.0, 11.6. Anal. calcd for C26H50O3Sn: C, 58.99;
H, 9.52; found: C, 58.73; H, 9.31%.
(1E,3E)-1-Butyl-2-ethoxycarbonyl-3-tributylstannyl-4-cyclopropyl-
1,3-butadiene (4b): Colourless oil. IR (film): ν (cm-1) 2954, 2923,
1
2854, 1720, 1613, 1464, 1377, 1204, 1153, 1045, 937, 723; H NMR
(CDCl3): δ 6.11 (t, J = 7.2 Hz, 1H), 5.93 (d, J = 9.2 Hz, 3JSn-H = 56 Hz,
1H), 4.21 (q, J = 7.2 Hz, 2H), 2.47–2.38 (m, 2H), 1.60–1.17 (m, 19H),
0.98–0.55 (m, 23H); 13C NMR (CDCl3): δ 168.3, 142.9, 136.3, 130.0,
124.7, 60.5, 31.9, 29.1, 27.8, 26.9, 22.5, 17.5, 13.9, 13.8, 13.6, 11.1, 7.1.
Anal. calcd for C26H48O2Sn: C, 61.07; H, 9.46; found: C, 60.82; H,
9.59%.
(1E,3E)-1-Phenyl-2-ethoxycarbonyl-3-tributylstannyl-6-methoxy-
1,3-hexadiene (4c): Colourless oil. IR (film): ν (cm-1) 3059, 2957,
2926, 2871, 1719, 1599, 1464, 1375, 1204, 1117, 909, 734, 696; 1H NMR
(3c):
3
(CDCl3): δ 7.33–7.20 (m, 5H), 6.29 (s, 1H), 5.78 (t, J = 7.0 Hz, JSn-H
1
= 56 Hz, 1H), 4.12 (q, J = 7.2 Hz, 2H), 3.43 (t, J = 6.8 Hz, 2H), 3.34
(s, 3H), 2.61–2.52 (m, 2H), 1.58–1.42 (m, 6H), 1.39–1.31 (m, 6H), 1.28
(t, J = 7.2 Hz, 3H), 0.97–0.83 (m, 15H); 13C NMR (CDCl3): δ 169.0,
144.7, 139.8, 138.0, 136.3, 130.0, 128.1, 128.0, 127.4, 72.4, 60.7, 58.5,
30.7, 29.0, 27.4, 13.9, 13.7, 10.5. Anal. calcd for C28H46O3Sn: C, 61.22;
H, 8.44; found: C, 60.97; H, 8.18%.
1H), 4.21 (q, J = 7.2 Hz, 2H), 3.57 (t, J = 7.2 Hz, 2H), 3.39 (s, 3H), 2.67
(t, J = 7.2 Hz, 2H), 1.19 (t, J = 7.2 Hz, 3H); 13C NMR (CDCl3): δ 166.0,
142.6, 134.8, 128.8, 128.5, 128.2, 117.0, 89.4, 79.0, 70.5, 61.5, 58.7, 20.8,
13.7. Anal. calcd for C16H18O3: C, 74.39; H, 7.02; found: C, 74.13; H,
6.87%.
(Z)-1-Phenyl-2-ethoxycarbonyl-4-cyclopropylbut-1-en-3-yne
(3d): Colourless oil. IR (film): ν (cm-1) 2957, 2874, 2214, 1717, 1447,
1324, 1148, 751, 688; 1H NMR (CDCl3): δ 7.32–7.24 (m, 5H), 7.11 (s,
1H), 4.22 (q, J = 7.2 Hz, 2H), 1.33–1.24 (m, 4H), 0.69–0.45 (m, 4H);
13C NMR (CDCl3): δ 165.7, 141.9, 134.7, 128.6, 128.4, 128.1, 117.5, 87.9,
77.6, 60.9, 14.1, 11.4, 0.3. Anal. calcd for C16H16O2: C, 79.97; H, 6.71;
found: C, 79.75; H, 6.54%.
(1E,3E) -1-Phenyl-2-ethoxycarbonyl-3-tributylstannyl-4-
cyclopropyl-1,3-butadiene (4d): Colourless oil. IR (film): ν (cm-1)
2956, 2926, 2871, 1717, 1593, 1464, 1374, 1203, 1094, 1070, 695;
1H NMR (CDCl3): δ 7.30–7.18 (m, 5H), 6.45 (s, 1H), 5.02 (d, J = 9.2
3
Hz, JSn-H = 56 Hz, 1H), 4.15 (q, J = 7.0 Hz, 2H), 1.57–1.48 (m, 6H),
1.37–1.22 (m, 6H), 1.17 (t, J = 7.0 Hz, 3H), 0.98–0.75 (m, 18H),
0.45–0.42 (m, 2H); 13C NMR (CDCl3): δ 169.5, 148.2, 139.4, 138.5,
136.5, 130.4, 128.2, 128.0, 127.3, 60.72, 29.0, 27.4, 13.9, 13.8, 12.7, 10.5,
7.7. Anal. calcd for C28H44O2Sn: C, 63.29; H, 8.35; found: C, 63.07; H,
8.12%.
(Z)-1-Phenyl-2-ethoxycarbonyl-4-hexylbut-1-en-3-yne (3e): Colour-
less oil. IR (film): ν (cm-1) 3060, 2930, 2858, 2218, 1728, 1598, 1493,
1
1373, 1248, 1025, 753, 694; H NMR (CDCl3): δ 7.37–7.29 (m, 5H),
7.10 (s, 1H), 4.21 (q, J = 7.2 Hz, 2H), 2.39 (t, J = 7.2 Hz, 2H), 1.45–1.25
(m, 8H), 1.20 (t, J = 7.2 Hz, 3H), 0.92 (t, J = 7.2 Hz, 3H); 13C NMR
(CDCl3): δ 166.2, 141.8, 134.9, 128.7, 128.5, 128.2, 117.4, 93.4, 78.1,
61.5, 31.3, 28.6, 28.4, 22.5, 19.6, 14.1, 13.8. Anal. calcd for C19H24O2: C,
80.24; H, 8.51; found: C, 79.98; H, 8.22%.
(Z)-1,4-Diphenyl-2-ethoxycarbonylbut-1-en-3-yne (3f): Colourless
oil. IR (film): ν (cm-1) 2958, 2225, 1726, 1622, 1489, 1374, 1214, 1094,
1019, 755, 690; 1H NMR (CDCl3): δ 7.52–7.49 (m, 2H), 7.39–7.31 (m,
8H), 7.27 (s, 1H), 4.27 (q, J = 7.2 Hz, 2H), 1.25 (t, J = 7.2 Hz, 3H);
13C NMR (CDCl3): δ 165.7, 143.2, 134.7, 131.7, 129.1, 128.8, 128.6,
128.3, 128.2, 122.7, 116.8, 91.6, 87.0, 61.6, 13.8. Anal. calcd for
C19H16O2: C, 82.58; H, 5.84; found: C, 82.39; H, 5.57%.
(1E,3E)-1-Phenyl-2-ethoxycarbonyl-3-tributylstannyl-4-hexyl-1,3-
butadiene (4e): Colourless oil. IR (film): ν (cm-1) 3060, 2957, 2926,
1
2854, 1713, 1595, 1464, 1375, 1203, 1096, 908, 735, 695; H NMR
(CDCl3): δ 7.33–7.22 (m, 5H), 6.25 (s, 1H), 5.71 (t, J = 7.0 Hz, 3JSn-H
=
56 Hz, 1H), 4.11 (q, J = 7.2 Hz, 2H), 2.31–2.20 (m, 2H), 1.52–1.20 (m,
20H), 1.14 (t, J = 7.2 Hz, 3H), 1.02–0.81 (m, 18H); 13C NMR (CDCl3):
δ 169.1, 144.6, 142.2, 138.3, 136.5, 129.9, 128.1, 128.0, 127.3, 60.6, 31.8,
30.4, 29.6, 29.1, 28.9, 27.4, 22.6, 14.0, 13.9, 13.7, 10.5. Anal. calcd for
C31H52O2Sn: C, 64.70; H, 9.11; found: C, 64.43; H, 8.89%.
(1E,3E)-1,4-Diphenyl-2-ethoxycarbonyl-3-tributylstannyl-1,3-
butadiene (4f): Colourless oil. IR (film): ν (cm-1) 3059, 2956, 2925,
2853, 1714, 1598, 1492, 1464, 1446, 1375, 1205, 1096, 751, 694;
1H NMR (CDCl3): δ 7.51 (d, J = 7.6 Hz, 2H), 7.29–7.15 (m, 8H), 6.66 (s,
1H), 6.35 (s, 3JSn-H = 64 Hz, 1H), 4.07 (t, J = 7.2 Hz, 2H), 1.60–1.52 (m,
6H), 1.39–1.31 (m, 6H), 1.09 (t, J = 7.2 Hz, 3H), 1.05 (t, J = 8.0 Hz, 6H),
0.89 (t, J = 7.2 Hz, 9H); 13C NMR (CDCl3): δ 168.8, 157.4, 147.0, 140.6,
(Z)-1-Hexyl-2-ethoxycarbonyl-6-methoxyhex-1-en-3-yne
(3g):
Colourless oil. IR (film): ν (cm-1) 2928, 2858, 2215, 1723, 1463, 1371,
1
1194, 1118, 1027; H NMR (CDCl3): δ 6.52 (t, J = 7.6 Hz, 1H), 4.24
(q, J = 7.2 Hz, 2H), 3.53 (t, J = 7.2 Hz, 2H), 3.37 (s, 3H), 2.63–2.59

630 JOURNAL OF CHEMICAL RESEARCH 2015
138.4, 130.6, 129.1, 128.4, 128.1, 128.0, 127.4, 127.1, 60.7, 29.0, 27.4,
13.8, 13.7, 10.8. Anal. calcd for C31H44O2Sn: C, 65.62; H, 7.82; found:
C, 65.35; H, 7.53%.
Received 23 August 2015; accepted 27 September 2015
Paper 1503560 doi: 10.3184/174751915X14447407625303
Published online: 1 November 2015
(1E,3E)-1-Hexyl-2-ethoxycarbonyl-3-tributylstannyl-6-methoxy-
1,3-hexadiene (4g): Colourless oil. IR (film): ν (cm-1) 2956, 2925,
2855, 1716, 1522, 1458, 1419, 1376, 1340, 1186, 1120, 1071, 865;
1H NMR (CDCl3): δ 5.63 (t, J = 7.0 Hz, 1H), 5.56 (t, J = 7.2 Hz, 3JSn-H
= 56 Hz, 1H), 4.15 (q, J = 6.8 Hz, 2H), 3.37 (t, J = 6.8 Hz, 2H), 3.32
(s, 3H), 2.46–2.34 (m, 4H), 1.48–1.17 (m, 23H), 1.02–0.76 (m, 18H);
13C NMR (CDCl3): δ 167.5, 145.0, 139.7, 138.1, 134.7, 72.4, 60.1, 58.5,
31.7, 30.4, 29.7, 29.5, 29.1, 29.0, 27.4, 22.7, 14.3, 14.1, 13.8, 10.2. Anal.
calcd for C28H54O3Sn: C, 60.33; H, 9.76; found: C, 60.05; H, 9.54%.
References
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(1E,3E)-1-Hexyl-2-ethoxycarbonyl-3-tributylstannyl-6-methoxy-1,3-
hexadiene (4g) (1.0 mmol) and iodobenzene (1.1 mmol) were dissolved
in DMF (8 mL) under Ar at room temperature. Pd(PPh3)4 (0.05 mmol)
and CuI (0.75 mmol) were then added. The mixture was stirred for
8 h at room temperature. 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 over MgSO4 and concentrated
at 40 ºC under reduced pressure. The residue was purified by column
chromatography on silica gel (eluent: light petroleum ether (30–60 ºC)/
EtOAc, 19:1) to give 5a as a Colourless oil. IR (film): ν (cm-1) 2924,
1
2854, 1718, 1459, 1377, 1210, 1120, 908, 736; H NMR (CDCl3): δ
7.35–7.18 (m, 5H), 6.07 (t, J = 7.0 Hz, 1H), 5.99 (t, J = 7.2 Hz, 1H), 4.05
(q, J = 7.2 Hz, 2H), 3.47 (t, J = 6.8 Hz, 2H), 3.36 (s, 3H), 2.65–2.55
(m, 2H), 2.52–2.40 (m, 2H), 1.58–1.16 (m, 11H), 0.89 (t, J = 7.2 Hz,
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Anal. calcd for C22H32O3: C, 76.70; H, 9.36; found: C, 76.43; H, 9.44%.
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We thank the National Natural Science Foundation of China
(21462021) for financial support.