Synthesis of 4-substituted styrene compounds via palladium-catalyzed suzuki coupling reaction using free phosphine ligand in air

Article abstract of DOI:10.1080/00397910902883611

The air-stable and easy to prepare nonsymmetric Schiff base ligands have been synthesized and proven to be efficient ligands for Suzuki cross-coupling reaction between aryl bromides and arylboronic acids using PdCl ₂(CH₃CN)₂ as palladium source under aerobic conditions. The coupling reaction proceeded smoothly using N-[(3,4- dimethoxyphenyl)methylene]-1,2-benzenediamine (L₃) as ligand under mild conditions to provide 4-substituted styrene compounds in good yields.

Full text of DOI:10.1080/00397910902883611

This article was downloaded by: [State University NY Binghamton]
On: 13 June 2013, At: 18:52
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/lsyc20
Synthesis of 4-Substituted Styrene
Compounds via Palladium-Catalyzed
Suzuki Coupling Reaction Using Free
Phosphine Ligand in Air
Yan Liu a & Jinqu Wang a
a State Key Laboratory of Fine Chemicals, Institute of Adsorption
and Inorganic Membrane, Dalian University of Technology, Dalian,
China
Published online: 29 Dec 2009.
To cite this article: Yan Liu & Jinqu Wang (2009): Synthesis of 4-Substituted Styrene Compounds
via Palladium-Catalyzed Suzuki Coupling Reaction Using Free Phosphine Ligand in Air, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
40:2, 196-205
To link to this article: http://dx.doi.org/10.1080/00397910902883611
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation
that the contents will be complete or accurate or up to date. The accuracy of any
instructions, formulae, and drug doses should be independently verified with primary
sources. The publisher shall not be liable for any loss, actions, claims, proceedings,
demand, or costs or damages whatsoever or howsoever caused arising directly or
indirectly in connection with or arising out of the use of this material.

Synthetic Communications1, 40: 196–205, 2010
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910902883611
SYNTHESIS OF 4-SUBSTITUTED STYRENE COMPOUNDS
VIA PALLADIUM-CATALYZED SUZUKI COUPLING
REACTION USING FREE PHOSPHINE LIGAND IN AIR
Yan Liu and Jinqu Wang
State Key Laboratory of Fine Chemicals, Institute of Adsorption and Inorganic
Membrane, Dalian University of Technology, Dalian, China
The air-stable and easy to prepare nonsymmetric Schiff base ligands have been synthesized
and proven to be efficient ligands for Suzuki cross-coupling reaction between aryl bromides
and arylboronic acids using PdCl2(CH3CN)2 as palladium source under aerobic conditions.
The coupling reaction proceeded smoothly using N-[(3,4-dimethoxyphenyl)methylene]-
1,2-benzenediamine (L3) as ligand under mild conditions to provide 4-substituted styrene
compounds in good yields.
Keywords: 4-Substituted styrene compounds; Schiff base ligands; Suzuki; synthesis
Substituted styrene starting materials have been extensively used in both specialty
chemical and polymer syntheses. Not only can styrenes be used in transformations
such as olefin metathesis[1] or Heck-type reactions[2] but also the alkene can be
employed as a platform on which to introduce a variety of functionalities.[3–8] In
regard to polymer synthesis, a multitude of transformations exist for polymerizing
styrenes.[9–13] The utility of such transformations has dramatically increased the
demand for facile routes to substituted styrenes. Transition-metal-mediated cross-
coupling reactions provide efficient routes to functionalized styrenes that complement
traditional methods such as dehydration,[14,15] Grignard reaction,[16] or Hoffman
elimination, all of which are incompatible with sensitive functional groups. Although
the palladium-catalyzed Heck reaction of aryl halides with ethylene provides access to
substituted styrenes,[17] the high pressures required for the reaction and the tendency
for further reaction to give stilbenes make it undesirable.[18]
Palladium-catalyzed Suzuki coupling reaction is one of the most attractive
methods for preparing biaryl compounds thanks to the advantages of wide functional
group tolerance and use of stable and nontoxic organoborane reagents.[19,20] Since the
general procedures were discovered, efforts have been made to increase the substrate
scope and efficiency. Although the use of alternative bases or solvents can be
Received October 31, 2008.
Address correspondence to Yan Liu and Jinqu Wang, State Key Laboratory of Fine Chemicals,
Institute of Adsorption and Inorganic Membrane, Dalian University of Technology, Dalian 116012,
China. E-mail: liuyan1979810@yahoo.com.cn; wangjinqu@hotmail.cn
196

4-SUBSTITUTED STYRENE COMPOUNDS
197
Scheme 1. Syntheses of ligands L1–L3.
beneficial, electronic and steric tuning of the supporting ligand has the most impact
on increasing efficacy and reactivity in these processes.[21–24] It has been widely
recognized that ligands employed in these processes have a significant impact on
the outcome of the reactions. Therefore, designing ligands with appropriate features
and great diversity is crucial in dealing with the challenging substrates in this area.
For many years, phosphines have been the most commonly employed ligands for
the reaction. However, these types of ligands are generally either air=moisture sensi-
tive or expensive, which places significant limits on their synthetic applications.
Therefore, most N-ligands that are inexpensive, easy to access, and stable have gained
a lot of attention.[25–61] Thus, as a part of our ongoing efforts to develop efficient
methods for the synthesis of substituted styrene compounds, we investigated the syn-
thesis and coupling reaction of an air-stable, nonsymmetric Schiff base (Scheme 1).
The reaction setup is experimentally simple and does not require the use of a glovebox
for these reactions. Here, we report the results of palladium-catalyzed coupling
reaction between aryl bromides and arylboronic acids to prepare 4-substituted
styrene compounds by using a nonsymmetric Schiff base as ligands in air.
Table 1. Effect of the ratio of Pd source, solvent, base, and liganda
Entry
Pd source
Ligand=(% mmol)
Solvent
Base
Yield (%)b
1
2
Pd(OAc)2
L1=0.75
L1=0.75
L1=0.50
L1=1.00
0
Toluene
Toluene
Toluene
Toluene
Toluene
Water
K3PO4
K3PO4
K3PO4
44
50
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
PdCl2(CH3CN)2
3
45
31
4
K3PO4
K3PO4
5
5
6
L1=0.75
L1=0.75
L1=0.75
L1=0.75
L1=0.75
L1=0.75
L1=0.75
L1=0.75
L2=0.75
L3=0.75
K3PO4
K3PO4
trace
11
7
EtOH
DMF
8
K3PO4
NaOH
32
9
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
trace
33
10
11
12
13
14
15
K2CO3
K3PO4 ꢀ 3H2O
CsCO3
70
27
MeONa
K3PO4 ꢀ 3H2O
K3PO4 ꢀ 3H2O
37
29
80
aReaction conditions: p-bromostyrene (0.50 mmol), phenylboronic acids (0.75 mmol), PdCl2(CH3CN)2
(0.5% mmol), base (1.5 mmol), solution (2.0 mL), temperature 80ꢁC, reaction time 10 h.
bIsolated yield.

198
Y. LIU AND J. WANG
Table 2. Pd-catalyzed Suzuki coupling of aryl bromides and arylboronic acidsa
Entry
1
R1
R2
Product
Yield (%)b
80
4-OMe
4-ethenyl (1a)
2
3
4
4-Me
4-Ethenyl
4-CHO
1a
1a
1a
88
90
55
5
6
4-COCH3
4-F
1a
1a
80
84
7
8
3,4-Difluoro
1a
1a
84
87
2,4,5-Trifluoro
9
3,4,5-Trifluoro
1a
91
10
11
12
13
4-Ethenyl (1b)
4-H
4-Me
4-F
77
41
49
1b
1b
4,40-Propyl-cyclohexyl
1a
60
(Continued )

4-SUBSTITUTED STYRENE COMPOUNDS
199
Table 2. Continued
Entry
R1
R2
Product
Yield (%)b
14
15
4,40-Pentyl-cyclohexyl
4,40-Pentyl-bicyclohexyl
1a
1a
75
64
aReaction conditions: aryl bromides (0.50 mmol), arylboronic acids (0.75 mmol), L3 (0.75 mmol%),
PdCl2 (CH3CN)2 (0.50 mmol%), base (1.50 mmol), toluene (2.0 mL), 80ꢁC, reaction time 10 h.
bIsolated yield.
Ligands 1–3 were prepared by reaction of substituted benzaldehyde with 1.0
equiv of 1,2-diaminobenzene in ethanol. These ligands in the Suzuki coupling
reaction were used without further purification; their structures were established
1
by H NMR.
To test the feasibility of the ideas described, a model coupling reaction of
p-bromostyrene with phenylboronic acid was initially tested (Table 1). First, we inves-
tigated the effect of a variety of palladium sources for this coupling reaction. We used
0.5 mmol% of PdCl2(CH3CN)2 in combination with 0.5–1.0 mmol% of L1. This reac-
tion proceeded to afford the desired product in 31–50% isolated yield after 10 h
(Table 1, entries 2–4). Pd(OAc)2 showed the lowest result (44%; Table 1, entry 1).
The yield of this reaction was as low as 5% in the absence of L1 under the same con-
dition (Table 1, entry 5). Many commonly used solvents were also tested. The nonpo-
lar solvent toluene was better than the polar solvents, such as H2O, ethanol (EtOH),
and dimethylformamide (DMF); the latter afforded none or very little of the coupling
product (Table 1, entries 6–8). The base usually plays an important role in the Suzuki
coupling reaction. K3PO4ꢀ3H2O was the best among these bases (Table 1, entry 11),
giving 4-vinylbiphenyl in 70% yield. The contrast in yield for simple changes in base is
more profound for K3PO4ꢀ3H2O and K3PO4 (70% vs. 50%). When K2CO3, CsCO3,
and CH3ONa were used as base, the yield of product was reduced to 27–37%
(Table 1, entries 10, 12, 13). NaOH was not efficient (Table 1, entry 9). With this
encouraging result, we evaluated the efficiency of other ligands 2 and 3 in the same
screening. When ligand 2 was used, the product gave only 29% yield (Table 1, entry
14). L3 was the best one, giving the coupling product in 80% yield.
Thus, the optimized reaction conditions for the Suzuki coupling reaction were
PdCl2(CH3CN)2 (0.50% mmol), L3 (0.75% mmol), and K3PO4 ꢀ 3H2O (1.50 mmol) in
toluene at 80ꢁC. We evaluated the scope of the coupling of various aryl bromides
with arylboronic acids, and representative results are summarized in Table 1. The
electron-poor aryl bromides, such as 4-bromoacetophenone, reacted with (4-
vinylphenyl)boronic acid to also give excellent yield for 10 h (Table 2, entries
4–10). The electron-rich aryl bromides, such as 4-bromoanisole, reacted with (4-
vinylphenyl)boronic acid to give good yields at the same condition (80% and 88%;
Table 2, entries 1 and 2), but electron-poor or electron-rich arylboronic acids reacted
with p-bromostyrene to give lower yields (41% and 49%; Table 2, entries 11 and 12).
Noteworthy is that we used the catalyst system to synthesize liquid crystal

200
Y. LIU AND J. WANG
compounds and obtained satisfactory yields at the optimized reaction condition
(60–75%; Table 2, entries 13–15).
In conclusion, nonsymmetric Schiff base compounds (L1–L3) were easily
prepared from commercially available reagents and shows high air-, moisture-,
and thermostability, and we successfully synthesized 4-substituted styrene com-
pounds by Pd-catalyzed Suzuki coupling of various aryl bromides with arylboronic
acids using L3 as ligand in air and provided a practical procedure for the synthesis of
liquid crystal compounds.
EXPERIMENTAL
1H and 13C NMR spectra were recorded on a 400 MHz spectrometer with the
chemical shift values reported in d units (ppm) relative to an internal standard
(tetramethylsilane, TMS). The open-bed chromatography was carried out on silica
gel (200–300 mesh, Qingdao Haiyang) using gravity flow. The column was packed
with slurries made from the elution solvent.
Typical Preparation of Ligands 1–3
The solution of 0.10 mol benzenediamine in 25 mL ethanol was slowly added to
a solution composed of 0.10 mol substituted benzaldehyde and 25 mL ethanol under
stirring conditions. The resultant solution was further refluxed for 1 h, resulting in
the precipitation of a yellow solid. Ligands in the coupling reaction were used
without further purification.
N-[(Pentafluorophenyl)methylene]-1,2-benzenediamine (L1). Yield: 92%.
Yellow solid; 1H NMR (400 MHz, CDCl3): 8.68 (s, 1 H), 7.13 (m, 1 H), 6.78 (m, 3 H),
4.23 (br, 2 H).
1
4-[(2-Aminophenylimino)methyl]phenol (L2). Yield: 93%. White solid; H
NMR (400 MHz, CDCl3): d 8.45 (s, 1 H), 7.81 (d, J ¼ 8.4 Hz, 2 H), 7.07–7.02 (m,
2 H), 6.91 (d, J ¼ 8.4 Hz, 2 H), 6.77 (t, J ¼ 7.2, 5.2 Hz, 1 H), 6.73 (d, J ¼ 8.4 Hz,
1 H), 1.56 (s, 2 H).
N-[(3,4-Dimethoxyphenyl)methylene]-1,2-benzenediamine (L3). Yield:
1
95%. White solid; H NMR (400 MHz, CDCl3): d 8.44 (s, 1 H), 7.61 (s, 1 H), 7.34
(d, J ¼ 8.4 Hz, 1 H), 7.07–7.01 (m, 2 H), 6.94 (d, J ¼ 8.0 Hz, 1 H), 6.77 (t, J ¼ 7.2,
5.6 Hz, 1 H), 6.74 (d, J ¼ 8.4 Hz, 1 H), 4.21 (s, 2 H), 3.98 (s, 3 H), 3.93 (s, 3 H).
Typical Suzuki Coupling of Aryl Bromides and Arylboronic Acids
Aryl bromide (0.50 mmol), arylboronic acid (0.75 mmol), and K3PO4 ꢀ 3H2O
(1.5 mmol) were added to the solution of L3 (0.75% mmol) and PdCl2(CH3CN)2
(0.50% mmol) in toluene (2.0 mL). The mixture was stirred at 80ꢁC for 10 h, cooled
to room temperature, and then shaken with a mixture of water (4 mL) and EtOAc
(4 mL). The organic layer was separated, and the rest was extracted with EtOAc
(2 ꢂ 5 mL). The combined organic extracts were concentrated in vacuum, and the
product was purified by flash column chromatography on silica gel.

4-SUBSTITUTED STYRENE COMPOUNDS
201
4-Methoxy-40-vinylbiphenyl (2a). White solid. Mp 145–146ꢁC.1H NMR
(400 MHz, CDCl3): d 7.48 (d, J ¼ 8.8 Hz, 2 H), 7.44 (d, J ¼ 8.4 Hz, 2 H), 7.24 (d,
J ¼ 8.4 Hz, 2 H), 7.18 (d, J ¼ 8.0 Hz, 2 H), 6.66 (dd, J ¼ 10.8, 17.6 Hz, 1 H), 5.68 (d,
J ¼ 18.0 Hz, 1 H), 5.18 (d, J ¼ 11.2 Hz, 1 H), 3.74 (s, 3 H). 13C NMR (100 MHz,
CDCl3): d 55.3, 113.5, 114.2, 126.6, 126.7, 127.9, 133.2, 136.0, 136.4, 140.2, 159.2.
4-Methyl-40-vinylbiphenyl (2b). White solid. Mp 119–120ꢁC. 1H NMR
(400 MHz, CDCl3): d 7.49–7.45 (m, 8 H), 6.75 (dd, J ¼ 10.8, 17.6 Hz, 1 H), 5.79 (d,
J ¼ 17.6 Hz, 1 H), 5.27 (d, J ¼ 10.8 Hz, 1 H), 2.39 (s, 3 H). 13C NMR (100 MHz,
CDCl3): d 21.3, 113.8, 126.8, 127.0, 127.6, 129.7, 136.5, 136.6, 136.8, 138.02, 140.7.
4,40-Diethenyl-1,10-biphenyl (2c). White solid. Mp 153ꢁC. 1H NMR
(400 MHz, CDCl3): d 7.57 (d, J ¼ 8.4 Hz, 2 H), 7.48 (d, J ¼ 8.4 Hz, 2 H), 6.75 (dd,
J ¼ 10.8, 17.6 Hz, 1 H), 5.80 (d, J ¼ 17.6 Hz, 1 H), 5.28 (d, J ¼ 11.2 Hz, 1 H). 13C
NMR (100 MHz, CDCl3): d 114.1, 126.8, 127.2, 136.5, 136.8, 140.2.
40-Ethenyl-[1,10-biphenyl]-4-carboxaldehyde (2d). White solid. Mp
131–133ꢁC. 1H NMR (400 MHz, CDCl3): d 10.06 (s, 1 H), 7.95 (d, J ¼ 8.4 Hz,
2 H), 7.76 (d, J ¼ 8.4 Hz, 2 H), 7.62 (d, J ¼ 8.4 Hz, 2 H), 7.52 (d, J ¼ 8.4 Hz, 2 H),
6.77 (dd, J ¼ 10.8, 17.6 Hz, 1 H), 5.83 (d, J ¼ 17.6 Hz, 1 H), 5.33 (d, J ¼ 10.8 Hz,
1 H). 13C NMR (100 MHz, CDCl3) d 114.9, 127.0, 127.6, 127.7, 130.5, 135.4,
136.3, 138.0, 139.1, 146.8, 192.0.
1-[40-Ethenyl-(1,10-biphenyl)-4-yl]-ethanone (2e). White solid. Mp
134–136ꢁC. 1H NMR (400 MHz, CDCl3): d 10.06 (s, 1 H), 8.03 (d, J ¼ 6.8 Hz,
2 H), 7.70 (d, J ¼ 6.8 Hz, 2 H), 7.61 (d, J ¼ 6.8 Hz, 2 H), 7.52 (d, J ¼ 8.0 Hz, 2 H),
6.77 (dd, J ¼ 10.4, 18.4 Hz, 1 H), 5.83 (d, J ¼ 18.0 Hz, 1 H), 5.32 (d, J ¼ 10.8 Hz,
1 H), 2.64 (s, 3 H). 13C NMR (100 MHz, CDCl3): d 26.8, 114.7, 126.9, 127.1,
127.5, 129.1, 136.0, 136.3, 137.7, 139.3, 145.4, 197.8.
4-Fluoro-40-vinylbiphenyl (2f). White solid. Mp 125–126ꢁC. 1H NMR
(400 MHz, CDCl3): d 7.53–7.47 (m, 6 H), 7.15–7.10 (m, 2 H), 6.75 (dd, J ¼ 10.8,
17.6 Hz, 1 H), 5.80 (d, J ¼ 17.6 Hz, 1 H), 5.28 (d, J ¼ 11.6 Hz, 1 H). 13C NMR
(100 MHz, CDCl3): d 114.2, 115.7, 115.9, 126.9, 127.3, 128.6, 128.7, 136.5, 136.8,
161.4.
3,4-Difluoro-40-vinylbiphenyl (2g). White solid. Mp 39–40ꢁC.1H NMR
(400 MHz, CDCl3): d 7.31–7.12 (m, 7 H), 6.75 (dd, J ¼ 12.8, 17.8 Hz, 1 H), 5.80 (d,
J ¼ 18.4 Hz, 1 H), 5.30 (d, J ¼ 11.6 Hz, 1 H). 13C NMR (100 MHz, CDCl3): d
114.6, 115.9, 116.0, 117.6, 117.8, 127.0, 127.2, 136.3, 137.3, 138.6, 149.0, 149.6,
151.3, 152.0.
2,4,5-Trifluoro-40-vinylbiphenyl (2h). White solid. Mp 130–132ꢁC. 1H
NMR (400 MHz, CDCl3): d 7.50–7.44 (m, 4 H), 7.29–7.22 (m, 1 H), 7.05–6.98 (m,
1 H), 6.75 (dd, J ¼ 10.8, 17.6Hz, 1 H), 5.81 (d, J ¼ 17.6 Hz, 1 H), 5.31 (d, J ¼ 10.8 Hz,
1 H). 13C NMR (100MHz, CDCl3): d 106.3, 106.6, 114.9, 118.0, 118.3, 126.4, 129.2,
133.4, 136.3, 137.7, 148.2, 151.0.
1
3,4,5-Trifluoro-40-vinylbiphenyl (2i). White solid. Mp 30–31ꢁC. H NMR
(400 MHz, CDCl3): d 7.49–7.45 (m, 4 H), 7.21–7.17 (m, 2 H), 6.75 (dd, J ¼ 10.8,
17.6 Hz, 1 H), 5.81 (d, J ¼ 17.6 Hz, 1 H), 5.32 (d, J ¼ 10.8 Hz, 1 H). 13C NMR

202
Y. LIU AND J. WANG
(100 MHz, CDCl3): d 110.9, 111.1, 115.0, 127.1, 127.2, 136.2, 137.6, 138.0,
140.7, 150.5, 153.0.
4-Vinylbiphenyl (2j). White solid. Mp 115ꢁC. 1H NMR (400 MHz, CDCl3): d
7.61–7.22 (m, 9 H), 6.76 (dd, J1 ¼ 10.8, 17.6 Hz, 1 H), 5.79 (d, J ¼ 17.6 Hz, 1 H), 5.27
(d, J ¼ 10.8 Hz, 1 H). 13C NMR (100 MHz, CDCl3): d 114.0, 126.8, 127.1, 127.36,
127.4, 128.9, 136.6, 136.7, 140.7, 140.9.
4-Ethenyl-40-(4-pentylcyclohexyl)-1,10-biphenyl (2k). White solid. Mp
1
140–142ꢁC. H NMR (400 MHz, CDCl3): d 7.59–7.07 (m, 8 H), 6.75 (dd, J ¼ 10.8,
17.6 Hz, 1 H), 5.78 (d, J ¼ 17.6 Hz, 1 H), 5.26 (d, J ¼ 10.8 Hz, 1 H), 2.54–0.84 (m,
15 H). 13C NMR (100 MHz, CDCl3): d 14.3, 22.9, 26.9, 32.4, 33.8, 34.5, 37.5, 44.5,
113.8, 126.8, 127.0, 127.2, 127.5, 128.8, 131.5, 136.5, 138.4, 140.8, 147.4.
4-Ethenyl-40-(4-propylcyclohexyl)-1,10-biphenyl (2l). White solid. Mp
1
60–62ꢁC. H NMR (400 MHz, CDCl3): d 7.59–7.46 (m, 6 H), 7.28 (d, J ¼ 8.0 Hz,
2 H), 6.75 (dd, J ¼ 10.8, 17.6 Hz, 1 H), 5.78 (d, J ¼ 17.6 Hz, 1 H), 5.26 (d, J ¼ 10.8Hz,
1 H), 2.49 (m, 1 H), 1.94–0.89 (m, 16H). 13C NMR (100MHz, CDCl3): d 14.6, 20.2,
33.8, 34.6, 37.3, 40.0, 44.5, 113.8, 126.8, 127.0, 127.3, 127.5, 136.5, 136.7, 138.5,
140.8, 147.4.
4-Ethenyl-40-[40-pentyl(1,10-bicyclohexyl)-4-yl]-1,10-biphenyl (2m). White
1
solid. Mp 170–172ꢁC. H NMR (400 MHz, CDCl3): d 7.59–7.27 (m, 8 H), 6.75 (dd,
J ¼ 11.2, 17.6 Hz, 1 H), 5.80 (d, J ¼ 18.0 Hz, 1 H), 5.28 (d, J ¼ 10.8 Hz, 1 H), 2.47 (m,
1 H), 1.97–0.82 (m, 29 H). 13C NMR (100 MHz, CDCl3): d 14.3, 22.9, 26.9, 30.4,
30.6, 32.5, 33.9, 34.8, 37.7, 38.2, 43.2, 43.7, 44.6, 113.8, 126.8, 127.0, 127.2, 127.5,
136.5, 136.7, 138.4, 140.8, 147.4.
REFERENCES
1. Grubbs, R. H. Olefin metathesis. Tetrahedron 2004, 60, 7117–7140.
2. Heck, R. F. Acylation, methylation, and carboxyalkylation of olefins by group VIII metal
derivatives. J. Am. Chem. Soc. 1968, 90, 5518–5526.
3. Rodriguez, A. L.; Bunlaksananusorn, T.; Knochel, P. Potassium tert-butoxide catalyzed
addition of carbonyl derivatives to styrenes. Org. Lett. 2000, 2, 3285–3287.
4. Ikeda, Y.; Nakamaru, T. Cobalt-catalyzed Heck-type reaction of alkyl halides with
styrenes. J. Am. Chem. Soc. 2002, 124, 6514–6515.
5. Terao, J.; Saito, K.; Nii, S.; Kambe, N.; Sonoda, N. Regioselective double alkylation of
styrenes with alkyl halides using a titanocene catalyst. J. Am. Chem. Soc. 1998, 120,
11822–11823.
6. Crudden, C. M.; Hleba, Y. B.; Chen, A. C. Regio- and enantiocontrol in the
room-temperature hydroboration of vinyl arenes with pinacol borane. J. Am. Chem.
Soc. 2004, 126, 9200–9201.
7. Rajan Babu, T. V.; Nomura, N.; Jin, J.; Nandi, M.; Park, H.; Sun, X. Heterodimerization
of olefins, 1: Hydrovinylation reactions of olefins that are amenable to asymmetric cataly-
sis. J. Org. Chem. 2003, 68, 8431–8446.
8. Yoshino, N.; Sato, T. Synthesis of novel highly heat-resistant fluorinated silane coupling
agents. J. Fluor. Chem. 2006, 127, 1058–1065.
9. Lou, Y.; Baldamus, J.; Huo, Z. Scandium half-metallocene-catalyzed syndiospecific styr-
ene polymerization and styrene–ethylene copolymerization: Unprecedented incorporation

4-SUBSTITUTED STYRENE COMPOUNDS
203
of syndiotactic styrene–styrene sequences in styrene–ethylene copolymers. J. Am. Chem.
Soc. 2004, 126, 13910–13911.
10. Guo, N.; Li, L.; Marks, T. J. Bimetallic catalysis for styrene homopolymerization and
ethylene–styrene copolymerization: Exceptional comonomer selectivity and insertion
regiochemistry. J. Am. Chem. Soc. 2004, 126, 6542–6543.
11. Schlick, H.; Stelzer, F. Highly luminescent poly[(m-phenylenevinylene)-co-
(p-phenylenevinylene)] derivatives synthesized via metathesis condensation (ADMET).
J. Mol. Catal. A: Chem. 2000, 160, 71–84.
12. Ide, N.; Fukuda, T. Nitroxide-controlled free-radical copolymerization of vinyl and
divinyl monomers: Evaluation of pendant-vinyl reactivity. Macromolecules 1997, 30,
4268–4271.
13. Valyi, I.; Janssen, A. G. Molecular-size distribution of cross-linked polystyrene. J. Phys.
Chem. 1945, 49, 461–471.
14. Ohnishi, N.; Miyazaki, A. Polymer and cured polymer for liquid crystal layer of liquid
crystal display device. Jpn. Kokai Tokkyo Koho, 1999.
15. Takeda, M.; Uchide, M.; Iwane, H. Aryl-substituted propionic acids. Ge. Offen., 1977.
16. Nakamura, E.; Yoshikai, N. Method for producing aryl compounds through coupling.
PCT Int. Appl., 2006.
17. Plevyak, J. E.; Heck, R. F. Palladium-catalyzed arylation of ethylene. J. Org. Chem. 1978,
43, 2454–2456.
18. Spencer, A. A highly efficient version of the palladium-catalyzed arylation of alkenes with
aryl bromides. J. Organomet. Chem. 1983, 258, 101–108.
19. Hassan, J.; Sevignon, M. Aryl–aryl bond formation one century after the discovery of the
Ullmann reaction. Chem. Rev. 2002, 102, 1359–1469.
20. Kotha, S.; Lahin, K.; Kashinath, D. Recent applications of the Suzuki–Miyaura
cross-coupling reaction in organic synthesis. Tetrahedron 2002, 58, 9633–9695.
21. Kataoka, N.; Shelby, Q. Air stable, sterically hindered ferrocenyl dialkylphosphines for
palladium–catalyzed CꢃC, CꢃN, and CꢃO bond-forming cross-couplings. J. Org. Chem.
2002, 67, 5553–5556.
22. Li, G. Y. Highly active, air–stable palladium catalysts for the CꢃC and CꢃS
bond-forming reactions of vinyl and aryl chlorides: Use of commercially available
[(t-Bu)2P(OH)]2PdCl2, [(t-Bu)2P(OH)PdCl2]2, and [[(t-Bu)2POHOP(t-Bu)2]PdCl]2 as cata-
lysts. J. Org. Chem. 2002, 67, 3643–3650.
23. Colacot, T. L.; Shea, H. A. Cp2Fe(PR2)2PdCl2 (R ¼ i-Pr, t-Bu) Complexes as air-stable
catalysts for challenging Suzuki coupling reactions. Org. Lett. 2004, 6, 3731–3734.
24. Arvela, R. K.; Leadbeater, N. E. A reassessment of the transition-metal-free Suzuki-type
coupling methodology. J. Org. Chem. 2005, 70, 161–168.
25. Navarro, O.; Marion, N.; Oonishi, Y.; Kelly, R. A.; Nolan, S. P. Suzuki–Miyaura,
a-ketone arylation, and dehalogenation reactions catalyzed by a versatile N-heterocyclic
carbene–palladacycle complex. J. Org. Chem. 2006, 71, 685–692.
26. Moncada, A. I.; Manne, S.; Tanski, J. M.; Slaughter, L. M. Modular chelated palladium
diaminocarbene complexes: Synthesis, characterization, and optimization of catalytic
Suzuki–Miyaura cross-coupling activity by ligand modification. Organometallics 2006,
25, 491–505.
27. Zeng, F.-L.; Yu, Z.-K. Pyridyl-supported pyrazolyl-N-heterocyclic carbene ligands and
the catalytic activity of their palladium complexes in Suzuki–Miyaura reactions. J. Org.
Chem. 2006, 71, 5274–5281.
28. Kim, J.-W.; Kim, J.-H.; Lee, D.-H.; Lee, Y.-S. Amphiphilic polymer supported N-
heterocyclic carbene palladium complex for Suzuki cross-coupling reaction in water.
Tetrahedron Lett. 2006, 47, 4745–4748.

204
Y. LIU AND J. WANG
29. Kang, T.-R.; Feng, Q.; Luo, M.-M. An active and recyclable polystyrene-supported
N-heterocyclic carbine-palladium catalyst for the Suzuki reaction of arylbromides with
arylboronic acids under mild conditions. Synlett 2005, 2305–2308.
30. Shi, M.; Qian, H.-X.
A new dimeric bidentated NHC-Pd(II) complex from
trans-cyclohexane-1,2-diamine for Suzuki reaction and Heck reaction. Tetrahedron
2005, 61, 4949–4955.
31. Kim, J. H.; Kim, J. W.; Shokouhimehr, M.; Lee, Y. S. Polymer-supported N-heterocyclic
carbene–palladium complex for heterogeneous Suzuki cross-coupling reaction. J. Org.
Chem. 2005, 70, 6714–6720.
32. Wang, A.-E.; Zhong, J.; Xie, J.-H.; Li, K.; Zhou, Q.-L. Highly efficient Suzuki
cross-coupling catalyzed by palladium=phosphine-imidazolium carbene system. Adv.
Synth. Catal. 2004, 346, 595–598.
33. Altenhoff, G.; Goddard, R.; Lehmann, C. W.; Glorius, F. An N-heterocyclic carbene
ligand with flexible steric bulk allows Suzuki cross-coupling of sterically hindered aryl
chlorides at room temperature. Angew. Chem. Int. Ed. 2003, 42, 3690–3693.
ˆ
ˆ
34. Gstottmayr, C. W. K.; Bohm, V. P. W.; Herdtweck, E.; Grosche, M.; Herrmann, W. A. A
defined N-heterocyclic carbene complex for the palladium-catalyzed Suzuki cross-
coupling of aryl chlorides at ambient temperatures. Angew. Chem. Int. Ed. 2002, 41,
1363–1365.
35. Herrmann, W. A. N-Heterocyclic carbenes: A new concept in organometallic catalysis.
Angew. Chem. Int. Ed. 2002, 41, 1290–1309.
36. Miyaura, N.; Suzuki, A. Palladium-catalyzed cross-coupling reactions of organoboron
compounds. Chem. Rev. 1995, 95, 2457–2483.
37. Suzuki, A. Recent advances in the cross-coupling reactions of organoboron derivatives
with organic electrophiles. J. Organomet. Chem. 1999, 576, 147–168.
38. Herrmann, W. A.; Reisinger, C.-P.; Spiegler, M. Chelating N-heterocyclic carbene ligands
in palladium-catalyzed Heck-type reactions. J. Organomet. Chem. 1998, 557, 93–96.
39. Phan, N. T. S.; Van Der Sluys, M.; Jones, C. W. On the nature of the active species in
palladium-catalyzed Mizoroki–Heck and Suzuki–Miyaura couplings—Homogeneous or
heterogeneous catalysis: A critical review. Adv. Synth. Catal. 2006, 348, 609–679.
40. Wu, W.-Y.; Chen, S.-N.; Tsai, F.-Y. Recyclable and highly active cationic 2,20-bipyridyl
palladium(II) catalyst for Suzuki cross-coupling reaction in water. Tetrahedron Lett. 2006,
47, 9267–9270.
41. Lai, Y.-C.; Chen, H.-Y.; Hung, W.-C.; Lin, C.-C.; Hong, F.-E. Palladium-catalyzed Suzuki
cross-coupling reactions using N,O-bidentate ligands. Tetrahedron 2005, 61, 9484–9489.
´
42. Domin, D.; Benito-Garagorri, D.; Mereiter, K.; Frohlich, J.; Kirchner, K. Synthesis and
reactivity of palladium and nickel-diimine complexes: Application as catalysts for Heck,
Suzuki, and Hiyama coupling reactions. Organometallics 2005, 24, 3957–3965.
43. Mino, T.; Shirae, Y.; Sakamoto, M.; Fujita, T. Phosphine-free hydrazone-Pd complex
as the catalyst precursor for a Suzuki–Miyaura reaction under mild aerobic conditions.
J. Org. Chem. 2005, 70, 2191–2194.
44. Weng, Z.; Teo, S.; Koh, L. L.; Hor, T. S. A. Crystallographic characterization of a palla-
dium(II) metallamacrocycle supported by an amino-functionalized ferrocene and its use as
an efficient Suzuki-coupling catalyst. Organometallics 2004, 23, 3603–3609.
45. Najera, C.; Gil-Molto, J.; Karlstrom, S.; Falvello, L. R. Di-2-pyridylmethylamine-based
palladium complexes as new catalysts for Heck, Suzuki, and Sonogashira reactions in
organic and aqueous solvents. Org. Lett. 2003, 5, 1451–1454.
46. Mazet, C.; Gade, L. H. A bis(oxazolinyl)pyrrole as a new monoanionic tridentate
supporting ligand: Synthesis of a highly active palladium catalyst for Suzuki-type CꢃC
coupling. Organometallics 2001, 20, 4144–4146.

4-SUBSTITUTED STYRENE COMPOUNDS
205
47. Botella, L.; Najera, C. A convenient oxime-carbapalladacycle-catalyzed Suzuki cross-
coupling of aryl chlorides in water. Angew. Chem. Int. Ed. 2002, 41, 179–181.
48. Alonso, D. A.; Najera, C.; Pacheco, M. C. Oxime palladacycles: Stable and efficient
catalysts for carbon–carbon coupling reactions. Org. Lett. 2000, 2, 1823–1826.
49. Huang, R.; Shaughnessy, K. H. Water-soluble palladacycles as precursors to highly
recyclable catalysts for the Suzuki coupling of aryl bromides in aqueous solvents. Organo-
metallics 2006, 25, 4105–4112.
50. Rocaboy, C.; Gladysz, J. A. Thermomorphic fluorous imine and thioether palladacycles
as precursors for highly active Heck and Suzuki catalysts: Evidence for palladium nano-
particle pathways. New J. Chem. 2003, 27, 39–49.
51. Bedford, R. B.; Cazin, C. S. J. Highly active catalysts for the Suzuki coupling of aryl
chlorides. Chem. Commun. 2001, 1540–1541.
52. Bedford, R. B.; Cazin, C. S. J.; Hursthouse, M. B.; Light, M. E.; Pike, K. J.; Wimperis, S.
Silica-supported imine palladacycles—recyclable catalysts for the Suzuki reaction. J.
Organomet. Chem. 2001, 633, 173–181.
53. Weissman, H.; Milstein, D. Highly active Pd(II) cyclometallated imine catalyst for the
Suzuki reaction. Chem. Commun. 1999, 1901–1902.
54. Eberhardt, J. K.; Fro¨hlich, R.; Wurthwein, E.-U. N-Acylamidine palladium(II) com-
¨
plexes: Synthesis, structures, and catalytic activity for Suzuki–Miyaura cross-coupling
reactions: Experiments and DFT calculations. J. Org. Chem. 2003, 68, 6690–6694.
55. Li, S.; Lin, Y.; Cao, J.; Zhang, S. Guanidine=Pd(OAc)2-catalyzed room temperature
Suzuki cross-coupling reaction in aqueous media under aerobic conditions. J. Org. Chem.
2007, 72, 4067–4072.
56. Li, J.-H.; Hu, X.-C.; Liang, Y.; Xie, Y.-X. PEG-400 promoted Pd(OAc)2=DABCO-
catalyzed cross-coupling reactions in aqueous media. Tetrahedron 2006, 62, 31–38.
57. Li, J.-H.; Hu, X.-C.; Xie, Y.-X. Polymer-supported DABCO-palladium complex as a
stable and reusable catalyst for room temperature Suzuki–Miyaura cross-couplings of aryl
bromides. Tetrahedron Lett. 2006, 47, 9239–9243.
58. Li, J.-H.; Liu, W.-J.; Xie, Y.-X. Recyclable and reusable Pd(OAc)2=DABCO=PEG-400
system for Suzuki–Miyaura cross-coupling reaction. J. Org. Chem. 2005, 70, 5409–5412.
59. Li, J.-H.; Liu, W.-J. DABCO as an inexpensive and highly efficient ligand for palladium-
catalyzed Suzuki–Miyaura cross-coupling reaction. Org. Lett. 2004, 6, 2809–2811.
60. Tao, B.; Boykin, D. W. Simple amine=Pd(OAc)2-catalyzed Suzuki coupling reactions of
aryl bromides under mild aerobic conditions. J. Org. Chem. 2004, 69, 4330–4335.
61. Tao, B.; Boykin, D. W. Trans-Pd(OAc)2(Cy2NH)2-catalyzed Suzuki coupling reactions
and its temperature-dependent activities toward aryl bromides. Tetrahedron Lett. 2003,
44, 7993–7996.