An imidazolium-based phosphinite ionic liquid (IL-OPPh2) as a reusable reaction medium and PdII ligand in Heck reactions of aryl halides with styrene and n-butyl acrylate

Article abstract of DOI:10.1002/ejoc.200601021

A new imidazolium-based phosphinite ionic liquid (IL-OPPh₂) is reported as an effective reusable medium and suitable Pd^II ligand for C-C bond formation through Heck coupling reactions of aryl iodides, bromides and also chlorides with

Full text of DOI:10.1002/ejoc.200601021

FULL PAPER
DOI: 10.1002/ejoc.200601021
An Imidazolium-Based Phosphinite Ionic Liquid (IL-OPPh2) as a Reusable
Reaction Medium and PdII Ligand in Heck Reactions of Aryl Halides with
Styrene and n-Butyl Acrylate
Nasser Iranpoor,*[a] Habib Firouzabadi,*[a] and Roya Azadi[a]
Keywords: Ionic liquid / Heck reaction / Palladium / Aryl halide
A
new imidazolium-based phosphinite ionic liquid (IL-
taining its corresponding PdII complex, was easily recovered
and reused in several runs without losing its efficiency.
OPPh2) is reported as an effective reusable medium and suit-
able PdII ligand for C–C bond formation through Heck coup-
ling reactions of aryl iodides, bromides and also chlorides
with styrene and n-butyl acrylate. The ionic liquid, still con-
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
ionic liquid can play a dual role both as reaction medium
and also – through the phosphinite group that it bears –
as a potential complexing agent, we decided to apply it in
conjunction with PdII salts for Heck C–C bond-formation
reactions. This dual property offers the potential for recycl-
ing of the ionic liquid together with its corresponding cata-
lytic PdII complex, which should thus eliminate wastage
both of the ligand and also of the Pd compound. Here we
report on the successful application of this ionic liquid both
as solvent and as a ligand for efficient Heck coupling reac-
tions of aryl iodides and bromides at 80 °C, and also of
chlorides at 120 °C, with styrene and n-butyl acrylate in the
presence of catalytic amounts of PdCl2 and Et3N
(Scheme 1).
Introduction
Catalytic carbon–carbon bond-forming coupling reac-
tions have emerged as exceedingly important methodologies
for the preparation of unsaturated carbon skeletons of or-
ganic molecules. The use of phosphanes in Pd-catalysed
Heck reactions provides an efficient route for the synthesis
of substituted olefins through cross-coupling of aryl halides
and olefins.[1–6] In the case of the less reactive aryl bromides
and aryl chlorides, electron-rich bulky tertiary phosphanes
are usually used as ligands.[2] As well as recent develop-
ments in catalytic carbon–carbon coupling reactions involv-
ing new ligands[7–10] or bases,[11] alongside techniques such
as microwave irradiation[12] or the use of supported rea-
gents, complex matrices immobilized on silica,[13] polymers
and PEG,[14] ionic liquids have also been considered as po-
tential tools for this purpose.[15] As far as we know, imid-
azolium-based ionic liquids are either used as media[16] or
used as ligands in complexation with palladium compounds
in different C-C coupling bond formation reactions.[17–19]
Results and Discussion
We have recently reported the preparation of a new imid-
azolium-based phosphinite ionic liquid (Scheme 1, IL-
OPPh2) and its application as a reaction medium and rea-
gent for bromination and thiocyanation of alcohols and of
trimethylsilyl and tetrahydropyranyl ethers.[20] Since this
Scheme 1.
The desired products were isolated simply by diethyl
ether extraction. The use of this ionic liquid also allows the
use of solvents such as DMF or DMAc, otherwise widely
employed in Heck reactions, to be avoided. Of the PdII
compounds we have studied as catalysts, PdCl2 proved to be
the most effective under our reaction conditions (Table 1).
If the ionic liquid is used in an amount equimolar with
the PdII catalyst, a sticky mass is produced and the reaction
does not take place. In comparison with the reported metal
phosphane complexes, the complex produced between this
[a] Department of Chemistry, College of Sciences, Shiraz Univer-
sity,
Shiraz 71454, Iran
Fax: +98-711-2280926
E-mail: iranpoor@chem.susc.ac.ir
firouzabadi@chem.susc.ac.ir
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
Eur. J. Org. Chem. 2007, 2197–2201
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2197

N. Iranpoor, H. Firouzabadi, R. Azadi
FULL PAPER
Table 1. Effect of the catalyst on the Heck reaction between bromo-
benzene and styrene.[a]
Table 3. PdCl2/IL-OPPh2-catalysed Heck reactions between aryl
halides and styrene.
Entry
Catalyst
Yield (%)[b]
1
2
3
4
none
PdCl2
Pd(OAc)2
PdCl2(CH3CN)2
0
100
15
60
[a] Reaction conditions: 0.03 mmol of catalyst, 0.5 mmol of IL-
OPPh2, 1.0 mmol of bromobenzene, 2.0 mmol of styrene and
2.0 mmol of Et3N at 80 °C. [b] GC yields with n-octane as internal
standard.
phosphinite ionic liquid and PdII has high stability towards
oxygen and moisture. Little difference in the yields and
times of the reactions was observed when oxygen was ex-
cluded from the reaction system.
Of the bases studied in the reaction between bromoben-
zene and styrene in the presence of PdCl2 in this ionic li-
quid, Et3N and NaOAc were found to be more efficient,
probably thanks to their solubility in the reaction medium
(Table 2). We therefore selected Et3N as the most suitable
base under our reaction conditions.
Table 2. Effects of different bases on the reaction between bromo-
benzene and styrene.[a]
Entry
Base
Time [h]
Yield (%)[b]
1
2
3
4
5
none
12
12
12
5
0
Na2CO3
Cs2CO3
NaOAc
Et3N
10
70
100
100
1
[a] Reaction conditions: 0.5 mmol of IL-OPPh2, 0.03 mmol of
PdCl2, 1.0 mmol of bromobenzene, 2.0 mmol of styrene and
2.0 mmol of base. [b] GC yield with n-octane as an internal stan-
dard.
Under our optimized reaction conditions (0.5 mmol IL-
OPPh2, 0.03 mmol of PdCl2 and 2.0 mmol of Et3N), the
desired products were obtained in excellent yields both from
a wide array of aryl iodides and bromides with styrene at
80 °C and also from chlorides at 120 °C (Table 3). Iodo-
benzene and 4-iodoanisole, for example, had been com-
pletely converted into the coupled products after 0.5 and
1 h, respectively (Table 3, Entries 1, 2). Remarkably, the
catalytic system was equally efficient with the electron-neu-
tral bromides: complete conversion had been achieved in
[a] All products are known compounds and were identified by com-
parison of their physical or spectroscopic data with those for
known samples.[21–23] [b] Data in the brackets show the GC yields
with n-octane as an internal standard. [c] The reaction went to
completion at 120 °C.
The use of this system for the coupling of chlorobenzene
the reactions of bromobenzene and 4-bromotoluene with and styrene at 120 °C was also successful (Table 3, En-
styrene after 1 h (Table 3, Entries 3, 4). With electron-de- try 10). In these reactions, no formation of 1,1-diarylethy-
ficient bromides, elongations of the reaction times were ob- lene compounds as side products was observed.
served, along with the decrement of the yields of the prod-
In an additional series of experiments we also studied the
ucts. This is most probably due to the poorer solubilities of coupling reactions between aryl halides and n-butyl acry-
4-bromobenzonitrile, 4-bromoacetophenone and 1-bromo- late. A methodology similar to that described for styrene
4-nitrobenzene in this ionic liquid (Table 3, Entries 5–7).
As illustrated in Table 3, Entry 9, these Heck cross-coup- study are presented in Table 4.
ling reactions based on the PdCl2/IL-OPPh2 complex were The trans products, as confirmed by H NMR analysis,
was also employed for this purpose, and the results of this
1
also applicable to heteroaryl halides. Use of 3-bromopyri- were obtained exclusively in all the cases that we present in
dine and styrene as substrates gave a satisfactory result and this article. The remaining mixture of ionic liquid and its
the desired product was isolated in 65% yield.
corresponding PdII complex was washed with water to re-
2198
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Eur. J. Org. Chem. 2007, 2197–2201

Heck Reaction in Ionic Liquid as Reaction Medium and Ligand
FULL PAPER
Table 4. PdCl2/IL-OPPh2-catalysed Heck reactions between aryl
halides and n-butyl acrylate.
In order to gain insight into the nature of the catalyst,
the ionic liquid and PdII were mixed in the ratio of 2:1 in
two separate reaction mixtures, Et3N (2 equiv.) was added
to one of them, and both reaction mixtures were heated to
80 °C. The complexes obtained from these reactions showed
similar reactivities when they were used as catalysts in the
coupling reaction between styrene and bromobenzene at
80 °C. The 1H NMR spectra of these complexes each
showed the presence of the C(2)-H unit of the imidazolium
group, which indicates that the carbon (2) of the imid-
azolium group does not take part in the complex formation
and that two molecules of the phosphinite ionic liquid and
PdII form a ML2 complex. The absence of formation of a
carbene-type complex with this phosphinite ionic liquid is
probably due to the low probability of the formation of a
seven-membered ring in the ML complex. The use of the
mole ratio method[24] for the complex formation between
this IL and PdCl2 in the presence of triethylamine is in good
agreement with the ML2 structure for this complex (Fig-
ure 1).
Figure 1. Mole ratio plot for complex formation between PdCl2
and IL at 267 nm in relation to λmax of the ligand.
[a] All products are known compounds and were identified by com-
parison of their physical or spectroscopic data with those for
known samples.[21–23] [b] The data in the brackets are GC yields
with n-octane as internal standard. [c] The reaction went to com-
pletion at 120 °C.
Comparison of our results (Table 1, Table 2) with those
based on the use of ionic liquids in other reaction systems
show the advantages of the present method. The use of
10 mol% of Pd(OAc)2 and immobilized ionic liquid on SiO2
in n-dodecane at 150 °C, for example, allowed the coupling
only of aryl iodides and bromides with alkyl acrylates,[21]
the reaction between PhCl and n-butyl acrylate in the pres-
ence of 0.5 mol-% of Pd(dba)2 and equimolar amounts of
a phosphane-imidazolium salt system in DMAc at 120 °C
gave only a 13% yield of the coupled product,[17a] while
use of Pd nanoparticles dispersed in BMI·PF6 produced the
coupled products of ArX (X = I, Br) with n-butyl acrylate
at 130 °C after 14 h in 77–87% isolated yields.[16]
move the produced triethylammonium halide and could be
reused for six runs in the reaction between bromobenzene
and styrene without losing its efficiency, giving trans-stil-
bene (Table 5).
Table 5. Coupling of bromobenzene with styrene in the presence of
recycled ionic liquid and its Pd complex.[a]
Cycle
Conversion (%)
Yield (%)[b]
1
2
3
4
5
6
7
100
100
100
100
100
100
90
91
91
93
90
90
92
84
Conclusions
In summary, the use of this easily prepared phosphinite
ionic liquid (IL-OPPh2) both as the reaction medium and
as the ligand in PdII-catalysed Heck reactions provides a
useful method for the efficient coupling of ArX (X = Cl,
Br and I) with styrene and n-butyl acrylate. The reusability
[a] All the reactions were performed with Et3N as base at 80 °C
over 1 h. [b] Isolated yields.
Eur. J. Org. Chem. 2007, 2197–2201
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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2199

N. Iranpoor, H. Firouzabadi, R. Azadi
FULL PAPER
of this phosphinite ionic liquid and its IL/PdII complex in
a mixture can also be regarded as strong practical advan-
tages of this new Heck method.
(60 MHz, CDCl3): δ = 160.5, 138.8, 130.9, 129.5, 128.0, 127.5,
127.0, 126.5, 126.0, 116.5, 57.5 ppm.
trans-4-Cyanostilbene:[23] 1H NMR (250 MHz, CDCl3): δ = 7.45–
7.60 (m, 6 H), 7.49 (t, J = 7.5 Hz, 2 H), 7.40 (t, J = 7.45 Hz, 1 H),
7.20 (d, J = 16.5 Hz, 1 H), 7.02 (d, J = 16.5 Hz, 1 H) ppm.
trans-4-Acetylstilbene:[23] M.p. ref.[23] 138.7–144.8 °C; found 140–
144 °C. 1H NMR (250 MHz, CDCl3): δ = 7.90 (d, J = 8.0 Hz, 2
H), 7.70 (d, J = 8.0 Hz, 2 H), 7.40 (d, J = 8.0 Hz, 2 H), 7.30–7.35
(m, 3 H), 7.20 (d, J = 16.5 Hz, 1 H), 7.01 (d, J = 16.5 Hz, 1 H),
2.15 (s, 3 H) ppm. 13C NMR (60 MHz, CDCl3): δ = 194.5, 144.5,
137.9, 137.5, 130.7, 129.8, 129.8, 128.0, 127.8, 127.0, 125.0,
30.5 ppm.
trans-4-Nitrostilbene:[23] M.p. ref.[23] 156–157 °C; found 155–157 °C.
1H NMR (250 MHz, CDCl3): δ = 8.40 (d, J = 9.3 Hz, 2 H), 7.80
(d, J = 9.3 Hz, 2 H), 7.71 (d, J = 7.3 Hz, 2 H), 7.45–7.55 (m, 3 H),
7.37 (d, J = 16 Hz, 1 H), 7.23 (d, J = 16.5 Hz, 1 H) ppm. 13C NMR
(60 MHz, CDCl3): δ = 152.2, 149.9, 140.5, 135.5, 130.1, 129.0,
128.5, 128.0, 127.0, 125.5 ppm.
trans-4-Chlorostilbene:[23] 1H NMR (250 MHz, CDCl3): δ = 7.80
(d, J = 7.3 Hz, 2 H), 7.65 (d, J = 8.5 Hz, 2 H), 7.30–7.44 (m, 5 H),
7.20 (s, 2 H) ppm. 13C NMR (60MHz, CDCl3): δ = 140.0, 137.9,
135.5, 131.3, 129.9, 129.5, 128.2, 127.5, 127.0, 125.5 ppm.
trans-3-Styrylpyridine:[23] M.p. ref.[23] 78.6–81.6 °C; found 79–
81 °C. 1H NMR (250 MHz, CDCl3): δ = 8.70 (s, 1 H), 8.50 (d, J =
4.8 Hz, 1 H), 7.90 (d, J = 8.3 Hz, 1 H), 7.65 (d, J = 7.3 Hz, 2 H),
7.30 (t, J = 7.3 Hz, 2 H), 7.15–7.25 (m, 2 H), 7.08 (d, J = 16.5 Hz,
1 H), 6.90 (d, J = 16.0 Hz, 1 H) ppm. 13C NMR (60 MHz, CDCl3):
δ = 150.5, 149.5, 138.8, 135.0, 133.3, 130.0, 129.7, 127.6, 126.0,
125.0, 121.0 ppm.
Butyl trans-Cinnamate:[23] 1H NMR (250 MHz, CDCl3): δ = 7.80
(d, J = 16 Hz, 1 H), 7.66 (m, 2 H), 7.43 (m, 3 H), 6.75 (d, J =
16 Hz, 1 H), 4.45 (t, J = 6.8 Hz, 2 H), 2.65 (m, J = 7.3 Hz, 2 H),
1.80 (m, J = 7.3 Hz, 2 H), 1.05 (t, J = 7.3 Hz, 3 H) ppm. 13C NMR
(60 MHz, CDCl3): δ = 170.5, 151.5, 140.8, 135.6, 130.2, 129.5,
120.8, 71.6, 35.0, 22.2, 15.5 ppm.
Butyl trans-4-Methylcinnamate:[23] 1H NMR (250 MHz, CDCl3): δ
= 7.87 (d, J = 16 Hz, 1 H), 7.55 (d, J = 8.5 Hz, 2 H), 7.25 (d, J =
8.5 Hz, 2 H), 6.60 (d, J = 16 Hz, 1 H), 4.90 (t, J = 6.5 Hz, 2 H),
2.80 (s, 3 H), 1.99 (m, J = 6 Hz, 2 H), 1.20 (m, J = 7.3 Hz, 2 H),
0.88 (t, J = 7.5 Hz, 3 H) ppm. 13C NMR (60 MHz, CDCl3): δ =
175.5, 150.6, 144.5, 130.0, 129.0, 128.5, 119.0, 70.5, 41.3, 25.7, 17.5,
13.0 ppm.
Experimental Section
Chemicals were obtained from Fluka or Merck. The progress of
reactions was followed by TLC on silica gel SILG/UV 254 plates.
IR spectra were run on a Shimadzu FTIR-8300 spectrophotometer.
1
The H NMR and 13C NMR spectra were recorded on a Bruker
Avance DPX 250 FT-NMR spectrometer (δ in ppm). Melting
points were determined with a Büchi 510 instrument in open capil-
lary tubes and are uncorrected. All yields refer to the isolated prod-
ucts. Evaporation of solvents was performed at reduced pressure,
with a Büchi rotary evaporator. The absorbance measurements as
a function of time, at a fixed wavelength, were made with a Shim-
adzu UV-1601PC spectrophotometer interfaced with a Pentium
200 MHz computer.
Typical Procedure for the Heck Reaction between Bromobenzene and
Styrene: PdCl2 (0.03 mmol, 5.3 mg) and Et3N (2 mmol, 0.27 mL)
were placed in a flask containing the phosphinite ionic liquid
(0.5 mmol, 0.23 g). The flask was placed in an 80 °C oil bath, the
mixture was stirred for 15 min, and bromobenzene (1 mmol,
0.105 mL) and styrene (2 mmol, 0.22 mL) were then added to the
mixture. GC and TLC of the reaction mixture showed the comple-
tion of the reaction after 1 h. After completion of the reaction, the
mixture was allowed to cool to room temperature and trans-stil-
bene was extracted with diethyl ether (3ϫ5 mL). Evaporation of
the solvent, followed by chromatography on a short column of sil-
ica gel, gave trans-stilbene (0.162 g, 91%).
Typical Procedure for the Heck Reaction between Bromobenzene and
n-Butyl Acrylate: PdCl2 (0.03 mmol, 5.3 mg) and Et3N (2 mmol,
0.27 mL) were added at 80 °C to a flask containing phosphinite
ionic liquid (0.5 mmol, 0.23 g), the mixture was stirred for 15 min,
and bromobenzene (1 mmol, 0.105 mL) and n-butyl acrylate
(2 mmol, 0.28 mL) were then added. GC and TLC of the reaction
mixture showed the completion of the reaction after 3 h. After
completion of the reaction, the mixture was allowed to cool to
room temperature and butyl trans-cinnamate was extracted with
diethyl ether (3ϫ5 mL). Evaporation of the solvent, followed by
chromatography on a short column of silica gel, gave butyl trans-
cinnamate (90%).
Butyl trans-4-Methoxycinnamate:[23] 1H NMR (250 MHz, CDCl3):
δ = 1.07 (t, J = 7.5 Hz, 3 H), 1.30–1.42 (m, 2 H), 1.59–1.70 (m, 2
H), 3.67 (s, 3 H), 4.05 (t, J = 6.7 Hz, 2 H), 6.46 (d, J = 16.0 Hz, 1
H), 6.70–6.90 (m, 2 H), 7.35–7.50 (m, 2 H), 7.65 (d, J = 16.0 Hz,
1 H) ppm. 13C NMR (60 MHz, CDCl3): δ = 12.05, 21.20, 35.67,
44.34, 60.19, 110.05, 118.05, 125.08, 126.72, 150.21, 159.09,
162.43 ppm.
Butyl trans-4-Cyanocinnamate:[23] M.p. ref.[23] 43.5–46.9 °C; found
44–46 °C. 1H NMR (250 MHz, CDCl3): δ = 7.82–7.69 (m, 5 H),
6.90 (d, J = 16 Hz, 1 H), 5.45 (t, J = 6.6 Hz, 2 H), 2.23 (m, J =
7.3 Hz, 2 H), 1.99 (m, J = 7.3 Hz, 2 H), 1.07 (t, J = 7.3 Hz, 3
H) ppm. 13C NMR (60 MHz, CDCl3): δ = 184.5, 163.3, 151.2,
145.5, 133.7, 128.2, 121.9, 119.0, 86.5, 42.8, 25.5, 16.7 ppm.
Spectral Data for Products
trans-Stilbene:[22] M.p. ref.[22] 123–124 °C; found 122–123 °C. 1H
NMR (250 MHz, CDCl3): δ = 7.53 (d, J= 7.5 Hz, 4 H), 7.45 (t, J
= 7.5 Hz, 4 H), 7.35 (t, J = 7.5 Hz, 2 H), 7.26 (s, 2 H) ppm. 13C
NMR (60 MHz, CDCl3): δ = 139.5, 130.5, 128.5, 126.7, 128.5 ppm.
trans-4-Methylstilbene:[23] M.p. ref.[23] 117–118 °C; found 117.5–
118 °C. 1H NMR (250 MHz, CDCl3): δ = 7.42 (d, J = 8.5 Hz, 2
H), 7.31 (d, J = 8.0 Hz, 2 H), 7.20 (t, J = 7.5 Hz, 2 H), 7.15 (t, J
= 6.5 Hz, 1 H), 7.05 (d, J = 8.0 Hz, 2 H), 6.96 (d, J = 16.5 Hz, 1
H), 6.90 (d, J = 16.5 Hz, 1 H), 2.30 (s, 3 H) ppm. 13C NMR
(60 MHz, CDCl3): δ = 136.7, 136.3, 134.2, 130.5, 129.8, 128.7,
127.8, 127.2, 126.0, 126.0, 23.0 ppm.
trans-4-Methoxystilbene:[23] M.p. ref.[23] 135.4–137.1 °C; found 136–
137 °C. 1H NMR (250 MHz, CDCl3): δ = 7.42 (d, J = 7.5 Hz, 2
H), 7.37 (d, J = 8.5 Hz, 2 H), 7.28 (t, J = 7.5 Hz, 2 H), 7.18 (t, J
Butyl trans-4-Acetylcinnamate:[23] 1H NMR (250 MHz, CDCl3): δ
= 8.11 (d, J = 8.5 Hz, 2 H), 7.89 (d, J = 15.5 Hz, 1 H), 7.72 (d, J
= 8.5 Hz, 2 H), 6.92 (d, J = 16 Hz, 1 H), 5.35 (t, J = 7.5 Hz, 2 H),
= 6.5 Hz, 1 H), 6.99 (d, J = 16.0 Hz, 1 H), 6.89 (d, J = 16.5 Hz, 1 3.98 (s, 3 H), 2.56 (m, J = 7.5 Hz, 2 H), 1.98 (m, J = 7.5 Hz, 2 H),
H), 6.80 (d, J = 8.5 Hz, 2 H), 3.77 (s, 3 H) ppm. 13C NMR 1.06 (t, J = 7.3 Hz, 3 H) ppm. 13C NMR (60 MHz, CDCl3): δ =
2200
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Heck Reaction in Ionic Liquid as Reaction Medium and Ligand
FULL PAPER
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195.5, 172.5, 155.0, 146.5, 141.5, 132.6, 130.8, 125.5, 88.3, 45.0,
33.4, 23.4, 16.0 ppm.
Butyl trans-4-Nitrocinnamate:[23] M.p. ref.[23] 59.6–64.4 °C; found
1
60–63 °C. H NMR (250 MHz, CDCl3): δ = 8.65 (d, J = 8.7 Hz, 2
H), 7.98–7.88 (m, 3 H), 7.09 (d, J = 15.5 Hz, 1 H), 5.65 (t, J =
7 Hz, 2 H), 2.45 (m, J = 7.8 Hz, 2 H), 1.86 (m, J = 7.5 Hz, 2 H),
1.08 (t, J = 7.5 Hz, 3 H) ppm. 13C NMR (60 MHz, CDCl3): δ =
184.0, 166.5, 155.5, 138.7, 133.5, 129.5, 123.3, 87.7, 54.4, 28.8,
15.5 ppm.
Butyl trans-4-Chlorocinnamate:[23] 1H NMR (250 MHz, CDCl3): δ
= 1.09 (t, J = 7.4 Hz, 3 H), 1.44–1.51 (m, 2 H), 1.70–1.85 (m, 2
H), 3.99 (t, J = 6.7 Hz, 2 H), 5.87 (d, J = 16.0 Hz, 1 H), 7.43–7.50
(m, 2 H), 7.54–7.78 (m, 2 H), 7.89 (d, J = 16.0 Hz, 1 H) ppm. 13C
NMR (60 MHz, CDCl3): δ = 15.55, 25.15, 47.55, 74.66, 108.82,
125.50, 127.75, 130.14, 134.40, 152.13, 175.88 ppm.
Butyl trans-3-(Pyridin-3-yl)acrylate:[23] 1H NMR (250 MHz,
CDCl3): δ = 8.85 (s, 1 H), 8.72 (m, 1 H), 7.75 (d, J = 8.5 Hz, 1 H),
7.57 (d, J = 16 Hz, 1 H), 7.24 (m, 1 H), 6.79 (d, J = 16.5 Hz, 1 H),
5.09 (t, J = 6.5 Hz, 2 H), 2.23 (m, J = 7.3 Hz, 2 H), 1.78 (m, J =
7.3 Hz, 2 H), 1.04 (t, J = 7.3 Hz, 3 H) ppm. 13C NMR (60 MHz,
CDCl3): δ = 187.5, 172.2, 159.9, 138.8, 135.5, 128.5, 123.3, 111.4,
89.9, 56.6, 39.9, 28.4, 15 ppm.
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Acknowledgments
We are grateful for a grant for this work from the Organization of
Management and Planning of Iran and also to Shiraz University
Research Council.
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Received: November 27, 2006
Published Online: March 14, 2007
Eur. J. Org. Chem. 2007, 2197–2201
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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