Application of highly efficient, recyclable organic-inorganic hybrid material immobilized palladium catalyst in amine- and phosphine-free Suzuki-Miyaura reaction

Article abstract of DOI:10.1080/00397910801928509

Palladium immobilized on organic-inorganic (silica-gel) hybrid materials behaves as a very efficient heterogeneous catalyst in the Suzuki-Miyaura coupling reaction. Aryl iodides, bromides, and activated chlorides, coupled with organoboronic acids (Suzuki-Miyaura reaction), smoothly afford the corresponding cross-coupling products in excellent yields under phosphine-free and amine-free reaction conditions in the presence of 3-aminopropyl functionalized silica-gel immobilized palladium (silica-APTS-Pd) as catalyst. Furthermore, the silica-supported palladium catalyst could be recovered and recycled by simple filtration of the reaction solution. It could be reused for more than 15 consecutive trials without significant loss of its catalytic activity. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910801928509

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Application of Highly Efficient, Recyclable
Organic–Inorganic Hybrid Material
Immobilized Palladium Catalyst in Amine‐ and
Phosphine‐Free Suzuki–Miyaura Reaction
Liyuan Zhang a , Lei Wang a b , Hongji Li a & Pinhua Li a
a Department of Chemistry, Huaibei Coal Teachers College, Huaibei, Anhui,
China
b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of
Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
Available online: 24 Apr 2008
To cite this article: Liyuan Zhang, Lei Wang, Hongji Li & Pinhua Li (2008): Application of Highly Efficient,
Recyclable Organic–Inorganic Hybrid Material Immobilized Palladium Catalyst in Amine‐ and Phosphine‐Free
Suzuki–Miyaura Reaction, Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 38:10, 1498-1511
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Synthetic Communicationsw, 38: 1498–1511, 2008
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910801928509
Application of Highly Efficient, Recyclable
Organic–Inorganic Hybrid Material
Immobilized Palladium Catalyst in
Amine- and Phosphine-Free
Suzuki–Miyaura Reaction
Liyuan Zhang,1 Lei Wang,1,2 Hongji Li,1 and Pinhua Li1
1Department of Chemistry, Huaibei Coal Teachers College, Huaibei,
Anhui, China
2State Key Laboratory of Organometallic Chemistry, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
Abstract: Palladium immobilized on organic–inorganic (silica-gel) hybrid materials
behaves as a very efficient heterogeneous catalyst in the Suzuki–Miyaura coupling
reaction. Aryl iodides, bromides, and activated chlorides, coupled with organoboronic
acids (Suzuki–Miyaura reaction), smoothly afford the corresponding cross-coupling
products in excellent yields under phosphine-free and amine-free reaction conditions in
the presence of 3-aminopropyl functionalized silica-gel immobilized palladium (silica-
APTS-Pd) as catalyst. Furthermore, the silica-supported palladium catalyst could be
recovered and recycled by simple filtration of the reaction solution. It could be reused
for more than 15 consecutive trials without significant loss of its catalytic activity.
Keywords: Heterogeneous catalyst, immobilization of palladium, organic–inorganic
hybrid material, Suzuki–Miyaura reaction
The palladium-catalyzed cross-coupling of arylboronic acids with aryl halides
(Suzuki–Miyaura reaction) is one of the most versatile and commonly utilized
Received in the USA December 10, 2007
Address correspondence to L. Wang, Department of Chemistry, Huaibei Coal
Teachers College, Huaibei, Anhui 235000, China. E-mail: leiwang@hbcnc.edu.cn
1498

Synthesis of Organic–Inorganic Hybrid Materials
1499
reactions for the construction of carbon–carbon bonds, particularly for the
formation of biaryl.[1–4] As the biaryl motif was found in a range of pharmaceu-
ticals, herbicides, and natural products as well as in conducting polymers and
liquid-crystalline materials, development of improved reaction conditions for
the Suzuki–Miyaura reaction has received much attention in recent years.[5–9]
The Suzuki–Miyaura reaction is generally performed in either organic
solvents such as toluene, N,N-dimethylformamide (DMF), and tetrahydrofuran
(THF) or aqueous bisolvent systems in the presence of bases and homogeneous
3
.
palladium catalysts, such as Pd(PPh3)4, Pd2(dba)3 C6H6, [(h -C3H5)-PdCl]2, or
Pd(PPh3)2Cl2.[10–14] One of the major problems in homogeneous Pd catalysis is
separation of the reaction products from the catalyst. A number of modifications
that can simplify this separation procedure have been reported. Marck and
LeBlond investigated a heterogeneous Pd/C-catalyzed Suzuki–Miyaura
reaction,[15–17] and Kabalka explored the submicron palladium powder on a
KF/Al2O3-catalyzedSuzuki–Miyaura couplingreaction under solvent-freecon-
ditions, as well as in methanol.[18,19] Meanwhile, a layered double-hydroxide-
supported heterogeneous nanopalladium catalyst for a Suzuki–Miyaura-type
coupling reaction was demonstrated.[20]
The high costs of transition-metal catalysts coupled with the toxic effects
associated with many transition metals has led to an increased interest in
immobilizing catalysts onto a support. This class of supported reagent can
facilitate both the isolation and recycling of the catalyst by filtration, thus
providing environmentally cleaner processes.[21,22] Recent examples have
immobilized palladium complexes onto amphiphilic polystyrene supports
for effecting Suzuki coupling reaction in an aqueous medium as well as a
modified aminomethyl polystyrene–supported palladium reagent for use as
a catalyst in a range of Sonogashira coupling reactions.[23–26] The develop-
ment of organic reagents grafted onto silica-gel has attracted increasing
attention in recent years because industry seeks more environmentally
friendly chemical manufacturing processes.[27–34] Most recently, we have
developed silica-immobilized palladium- and copper-catalyzed Sonogashira
reaction and Ullmann diaryl etherification.[35–37]
In this article, we present the synthesis of 3-aminopropyl functionalized
silica-gel-immobilized palladium (silica-APTS-Pd) catalyst (Scheme 1), and
it was subsequently used for Suzuki–Miyaura coupling reactions. As a
highly effective catalyst for the Suzuki–Miyaura reactions of aryl iodides,
Scheme 1.

1500
L. Zhang et al.
Scheme 2.
aryl bromides, and activated aryl chlorides with organoboronic acids, the
reactions generated the corresponding coupling products in high yields only
in the presence of silica-APTS-Pd and potassium carbonate in N,N-dimethyl-
acetamide (DMA) under ligand-free and amine-free reaction conditions.
Moreover, silica-APTS-Pd could be recovered and recycled by simple fil-
tration of the reaction solution. It could be reused for 15 consecutive trials
without significant loss of its reactivity.
The synthesis of the organic–inorganic hybrid materials immobilized
palladium catalyst is illustrated in Scheme 2. It was readily prepared
through a two-step procedure. The silica-gel (100–200 mesh) was reacted
with 3-aminopropyltriethyoxysilane (APTS) in dry toluene at 120 8C for
24 h to afford 3-aminopropyl-functionalized silica-gel (silica-APTS). The
organic–inorganic hybrid materials subsequently reacted with palladium
acetate in ethanol at room temperature for 4 h to generate the corresponding
silica-supported palladium catalyst silica-APTS-Pd.
The assignments of infrared (IR) absorption bands for the sample,
3-aminopropyl-functionalized silica-gel (silica-APTS), were made in com-
parison with the IR spectra of related palladium complex, silica-APTS-Pd. The
results are listed in Table 1. The magnitude of Dn [vSi-O(silica-APTS) 2 vSi-O
(silica-APTS-Pd)] was found to be 48 cm21, indicating the coordination effect of
CH2CH2CH2NH2 as monodentate ligand with palladium.
The silica-gel (100–200 mesh) as support was commercially available
from Aldrich, and its surface area was found to be 554 m2/g according to
the Brunner-Emmett-Teller (BET) method used in N2 sorption. Table 2 sum-
marizes the results of analytical studies for the modified silica. The CHN
analytical data confirmed that the organic functionalization took place with
Table 1. IR of functionalized silica and its immobilized
palladium catalyst
FT-IR (KBr, n cm21
)
Sample
nSi-O
nC-H
Silica-APTS
Silica-APTS-Pd
1074
1026
2926
2912

Synthesis of Organic–Inorganic Hybrid Materials
1501
Table 2. Surface area, pore volume, and elemental analysis results of samples
Elemental analysis (wt%)
Surface areaa
S(m2/g)
Pore volumea
V(cm3/g)
Sample
Cb
Nb
Pdc
Silica
Silica-APTS
Silica-APTS-Pd
554
439
277
0.75
0.53
0.41
N/A
3.85
3.72
N/A
1.31
1.24
N/A
N/A
2.30
aBET method used in N2 sorption.
bCHN microanalysis results.
cICP analysis results.
the intended ligands. (Analysis of the pure silica prior to modification showed
only negligible amounts of carbon and nitrogen.) Upon functionalization of
the silica, silica-APTS, the total surface area of the sample dropped from
the initial value of 554 to 439 m2/g. On the other hand, the pore volume of
the samples also decreased from the initial value 0.75 to 0.53 cm3/g for
silica-APTS. Similar changes were also obtained in the silica-supported
palladium catalyst, silica-APTS-Pd. The elemental analytical data in
Table 2 showed that for silica-APTS, the loading was readily quantified via
CHN microanalysis and was 0.935 mmol/g of CH2CH2CH2NH2 based on
the nitrogen percentage. The palladium metal amount of silica-APTS-Pd
was 2.30 wt% based on inductively coupled plasma (ICP) analysis. The
nitrogen contents of silica-APTS and silica-APTS-Pd were observed to be
in only small amounts decreases.
Transmission electron microscope (TEM) images of silica, silica-APTS,
and silica-APTS-Pd catalyst are presented in Fig. 1. It is characteristic of
catalysts with 2.30 wt% loading of palladium. These reveal the presence of
palladium nanoparticles in the solid host. The palladium particles have
typical diameters of ca. 3 nm, and these particles are located in the surfaces
of silica and showed good distribution. The pores of silica are maintained
even after silylation and Pd-complex loading.
Figure 1. TEM images of silica (A), silica-APTS (B), and silica-APTS-Pd catalyst (C).

1502
L. Zhang et al.
In our initial experiments, we attempted to test the Suzuki–Miyaura
model coupling reaction of iodobenzene with phenylboronic acid in the
presence of a silica-APTS-Pd catalyst, potassium carbonate in DMA under
a ligand-free and amine-free reaction condition. To our surprise and delight,
a high yield of expected product was observed. Using silica-APTS-Pd
complex as the catalyst, the coupling reaction of iodobenzene with phenyl-
boronic acid was carried out under different systems to optimize the
reaction conditions (Table 3). It was found that DMA and K2CO3 are
suitable solvent and base for the reaction at 100 8C, respectively. Under the
stated conditions, only K2CO3 prompted the arylhalide to reach complete con-
version. When 1% mol loading of palladium in silica-APTS-Pd was used, the
reaction proceeded slowly at a temperature less than 90 8C, and a reaction
temperature of 100 8C was found to be optimal. Thus, the optimized
reaction conditions for this Suzuki–Miyaura reaction were silica-APTS-Pd
(1% mol Pd) and K2CO3 (2 equiv.) in DMA at 100 8C.
In the presence of silica-APTS-Pd catalyst and K2CO3 as the base, the
coupling reactions of aryl iodides, bromides, and chlorides with aryl and
vinylboronic acids were carried out in DMA at 100 8C, and the
results listed in Table 4. With 1 mol% of the Pd-catalyst, electron-neutral,
Table 3. Effect of solvent and base on the Suzuki–Miyaura reactiona
Silica-APTS-Pd
Phl þ PhB(OH)2 ꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀ! Ph-Ph
Base Solvent
Entry
Solvent/temp. (8C)
Base
Yieldb (%)
1
2
CH3OH/65
C2H5OH/78
Dioxane/80
DMF/100
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K3PO4
81
90
62
95
99
86
45
52
92
89
85
75
67
43
36
3
4
5
DMA/100
DMSO/100
Toluene/100
Xylene/100
DMA/100
DMA/100
DMA/100
DMA/100
DMA/100
DMA/100
DMA/100
6
7
8
9
10
11
12
13
14
15
Na2CO3
KOH
KF
Cs2CO3
Triethylamine
Piperidine
aPhenylboronic acid (1.00 mmol), iodobenzene (1.00 mmol), silica-APTS-Pd
(46 mg, contains 0.01 mmol of Pd), and base (2.00 mmol) in solvent (3 mL) at the
temperature indicated for 2 h.
bIsolated yields.

Synthesis of Organic–Inorganic Hybrid Materials
1503
electron-rich, and electron-poor aryl iodides reacted easily with phenylboronic
acid to generate the desired products in ꢁ98% isolated yields within 2 h
(Table 4, entries 1–5). In a similar fashion, the reactions of activated aryl
bromides and bromobenzene with phenylboronic acid were completed
within 4 h to afford the expected products in ꢁ95% yields (Table 4, entries
6–10). On the other hand, reactions of relatively unreactive bromides
bearing an alkyl or alkoxy as the substituent with phenylboronic acid, also
went smoothly to generate the corresponding diaryl products in 90 2 94%
yields over a period of 6 h (Table 4, entries 7–14). In most cases, no
obvious reactivity difference was found between the reaction of phenylboronic
Table 4. Silica-supported palladium-catalyzed Suzuki–Miyaura coupling reactiona
Entry
Organic halide
Organoboronic acid
Time (h)
Yieldb (%)
1
2
C6H5I
p-CH3C6H4I
p-CH3OC6H4I
p-CH3COC6H4I
p-NO2C6H4I
C6H5Br
C6H5B(OH)2
C6H5B(OH)2
C6H5B(OH)2
2
2
99
99
98
99
99
95
97
99
98
97
90
92
91
94
99
99
98
96
99
85
56
88c
66
90c
61d
53d
3
2
4
C6H5B(OH)2
C6H5B(OH)2
2
5
2
6
C6H5B(OH)2
C6H5B(OH)2
4
7
p-CH3COC6H4Br
p-CNC6H4Br
p-NO2C6H4Br
m-NO2C6H4Br
p-CH3C6H4Br
m-CH3C6H4Br
o-CH3C6H4Br
p-CH3OC6H4Br
C6H5I
4
8
C6H5B(OH)2
C6H5B(OH)2
4
9
4
10
11
12
13
14
15
16
17
18
19
20
21
C6H5B(OH)2
C6H5B(OH)2
4
6
C6H5B(OH)2
C6H5B(OH)2
C6H5B(OH)2
6
6
6
p-CH3C6H4B(OH)2
p-FC6H4B(OH)2
p-ClC6H4B(OH)2
o-CH3C6H4B(OH)2
a-C10H9B(OH)2
2
C6H5I
C6H5I
2
2
C6H5I
C6H5I
C6H5I
2
2
2
p-CNC6H4Cl
C6H5B(OH)2
C6H5B(OH)2
4
10
4
22
p-NO2C6H4Cl
10
10
10
23
24
C6H5Cl
p-CH3C6H4Cl
C6H5B(OH)2
C6H5B(OH)2
aOrganoboronic acid (1.00 mmol), aryl halide (1.00 mmol), silica-APTS-Pd
(contains 0.01 mmol of Pd), and K2CO3 (2.00 mmol) in DMA (3 mL) at 100 8C for
the time indicated.
bIsolated yields.
cSilica-APTS-Pd (2% mol Pd) was used.
dSilica-APTS-Pd (2% mol Pd) was used at 120 8C.

1504
L. Zhang et al.
acid, p-tolylboronic acid, o-tolylboronic acid, p-fluorophenylboronic acid,
p-chlorophenylboronic acid or a-naphathleneboronic acid with iodobenzene
except in the case of entry 20 (Table 4, entries 15–20). Vinylboronic acid
also reacted with iodobenzene to generate the cross-coupling product in
85% yield under the optimized reaction conditions (Table 4, entry 20). It is
noteworthy that the relatively hindered substrates (i.e., 2-methyl-bromoben-
zene and 2-tolylboronic acid) also exhibited a high activity toward the
Suzuki–Miyaura cross-coupling reaction under present reaction conditions
(Table 4, entries 13 and 18). The chloride substrates exhibited much lower
reactivity than their iodo and bromo analogs. For activated aryl chlorides,
moderate yields were obtained under the current reaction conditions
(Table 4, entries 21 and 22). Fortunately, good to excellent yields were
observed when the reactions were carried out with 2.0% mol of palladium
catalyst over a longer period (10 h) (Table 4, entries 21 and 22). However,
unreactive aryl chlorides such as chlorobenzene and 4-methyl-chlorobenzene
underwent the coupling reactions with phenylboronic acid very slowly under
the stated conditions, and moderate yields were gained for the reactions in the
presence of 2.0% mol of palladium catalyst at 120 8C for 10 h (Table 4, entries
23 and 24). Unfortunately, no expectant compound was obtained when 3-(2-
aminoethylamino)propyl functionalized silica-gel-immobilized palladium
(silica-AAPTS-Pd)[10] was used instead of silica-APTS-Pd as catalyst for
the Suzuki–Miyaura reaction even for 24 h, and starting materials remained
unchanged. Further investigation is currently under way in our laboratory.
The recyclability of silica-APTS-Pd catalyst was also examined using the
standard procedure of the reaction of iodobenzene and phenylboronic acid.
The results revealed that silica-APTS-Pd could be recovered, recycled, and
reused for 15 consecutive trials without loss of activity (Fig. 2). Moreover,
palladium leaching in silica-APTS-Pd was also determined, and ICP
analyses of the clear filtrates indicated that Pd content is less than 0.17 ppm.
In conclusion, we present a highly efficient and recyclable organic–
inorganic hybrid material immobilized palladium catalyst in the Suzuki–
Miyaura reaction. Iodoarenes, bromoarenes, and activated chloroarenes
coupled with organoboronic acids (Suzuki–Miyaura reaction) afforded the cor-
responding cross-coupling products in good to excellent yields under phosphine-
free and amine-free reaction conditions only in the presence of 3-aminopropyl
functionalized silica-gel immobilized palladium (silica-APTS-Pd) catalyst. Fur-
thermore, the silica-supported palladium catalysts could be recovered and
recycled by simple filtration of the reaction solution. It could be reused for
more than 15 consecutive trials without significant loss of catalytic activity.
EXPERIMENTAL
Melting points were recorded on a WRS-2B melting-point apparatus and
1
are uncorrected. All H NMR spectra were recorded at 300 MHz by Bruker

Synthesis of Organic–Inorganic Hybrid Materials
1505
Figure 2. Yields obtained with recycled silica-APTS-Pd catalyst.
FT-NMR spectrometers. Chemical shift are given as d value with reference to
tetramethylsilane (TMS) as internal standard. IR spectra were obtained using a
Nicolet Nexus 470 spectrophotometer. The CHN analysis was performed on a
Vario El III. The palladium content was determined by Jarrell-Ash 1100 ICP
analysis. Specific surface areas and pore volumes of the samples were deter-
mined in a Micromeritics ASAP-2000 automated nitrogen physisorption
apparatus and calculated according to the BET method. Products were
purified by flash chromatography on 230- to 400-mesh silica-gel, SiO2.
The chemicals were purchased from commercial suppliers (Aldrich,
USA, and Shanghai Chemical Company, China) and were used without puri-
fication prior to use.
Preparation and Characterization of Silica-APTS-Pd Catalyst
This catalyst was prepared in the following steps from commercial silica-gel.
Silica (10.00 g) (100–200 mesh, Aldrich) was introduced in a round-
bottom flask equipped with a reflux condenser; 80 mL of concentrated
H2SO4 and 15 mL of HNO3 were added. The mixture was heated in an oil
bath at 140 8C for 24 h. The solution was filtered, and the white powder
was washed with distilled water until neutral pH was attained. The solid
was again washed with acetone, methanol, and dichloromethane and dried
under vacuum at 150 8C for 48 h.
In a 50-mL round-bottom flask, 20 mL of anhydrous toluene, 3.00 g
of activated silica (obtained from the previous procedure), and 10 mL of
3-aminopropyltriethyoxysilane (APTS) were introduced successively. The
solution was refluxed for 24 h. The solution was filtered, and the solid was
washed with acetone and dichloromethane respectively and dried under reduced
pressure at 60 8C. A yield of 3.26 g of silica-APTS material was obtained.
In a small Schlenk tube, 1.00 g (0.935 meq. CH2CH2CH2NH2/g) of
silica-APTS was mixed with 0.112 g (0.5 mmol) of Pd(CH3CO2)2 in 5 mL

1506
L. Zhang et al.
of dry ethanol. The mixture was stirred for 4 h under a nitrogen atmosphere at
room temperature. The solution was filtered, and the solid was washed with
acetone and methanol respectively. The solid was dried under reduced
pressure at room temperature for 16 h, leading to a yellow powder (1.03 g).
Representative Procedure for Suzuki–Miyaura Reaction
Under an atmosphere of nitrogen, an oven-dried round-bottomed flask was
charged with silica-APTS-Pd (46 mg, contains 0.01 mmol of Pd), K2CO3
(276 mg, 2.0 mmol), organoboronic acid (1.0 mmol), organic halide
(1.0 mmol), and DMA (3 mL). The reaction solution was stirred at 100 8C
for 2 2 10 h according to the activity of the substrates. After completing the
reaction and cooling to the room temperature, the reaction mixture was
vacuum filtered using a sintered glass funnel and washed with CH2Cl2
(2 ꢂ 5 mL). The combined organic materials were dried over Na2SO4,
filtered, and concentrated, and the residue was purified by flash chromato-
graphy on silica-gel to give the desired cross-coupling product.
Recyclability of the Silica-Supported Palladium Catalyst
After carrying out the reaction, the mixture was vacuum filtered using a
sintered glass funnel and washed with CH2Cl2 (3 mL), Et2O (3 mL),
C2H5OH (3 mL), and hexane (3 mL), respectively. After drying in an oven,
they can be reused directly without further purification.
Data
4-Methylbiphenyl: mp 46–48 8C (lit.[38] mp 46–47 8C). 1H NMR (300 MHz,
CDCl3) d: 7.58–7.21 (m, 9H), 2.37 (s, 3H); 13C NMR (75 MHz, CDCl3) d:
141.2, 138.4, 137.0, 129.5, 128.7, 127.0, 20.1; IR (cm21, KBr) n: 2793,
2662, 1631, 1351.
1
4-Acetylbiphenyl: mp 120–121 8C (lit.[39] mp 119–120 8C). H NMR (300
MHz, CDCl3) d: 8.05 (d, 2H, J ¼ 8.4 Hz), 7.71–7.62 (m, 4H), 7.50–7.40
(m, 3H), 2.64 (s, 3H); 13C NMR (75 MHz, CDCl3) d: 197.5, 145.7, 139.8,
135.9, 128.9, 128.8, 128.2, 127.2, 127.1, 26.5; IR (cm21, KBr) n: 2999,
2789, 2660, 1679, 1604, 1501, 1351, 764.
1
4-Nitrobiphenyl: mp 110–111 8C (lit.[40] mp 112–113 8C). H NMR (300
MHz, CDCl3) d: 8.30 (d, 2H, J ¼ 9.0 Hz), 7.74 (d, 2H, J ¼ 9.0 Hz), 7.63
(d, 2H, J ¼ 8.0 Hz), 7.53–7.42 (m, 3H); 13C NMR (75 MHz, CDCl3) d:

Synthesis of Organic–Inorganic Hybrid Materials
1507
147.6, 147.0, 138.7, 129.1, 128.9, 127.8, 127.3, 124.1; IR (cm21, KBr) n:
2672, 1594, 1513, 1447, 1351, 1104, 1077.
4-Cyanobiphenyl: mp 83–85 8C (lit.[41] mp 82–84 8C). 1H NMR (300 MHz,
CDCl3) d: 7.75–7.66 (m, 4H), 7.60–7.56 (m, 2H), 7.50–7.41 (m, 3H); 13C
NMR (75 MHz, CDCl3) d: 145.6, 139.1, 132.5, 129.0, 128.6, 127.6, 127.4,
118.9, 110.8; IR (cm21, KBr) n: 2661, 2227, 1605, 1485, 768.
1
3-Nitrobiphenyl: mp 60–62 8C (lit.[42] mp 59 8C). H NMR (300 MHz,
CDCl3) d: 8.42 (dd, 1H, J ¼ 2.4, 1.8 Hz), 8.14 (dd, 1H, J ¼ 8.1, 2.4 Hz),
7.86 (d, 1H, J ¼ 7.8 Hz), 7.54 (dd, 3H, J ¼ 8.7, 8.1 Hz), 7.49–7.37
(m, 3H); 13C NMR (75 MHz, CDCl3) d: 148.7, 142.9, 138.6, 133.0, 129.7,
129.1, 128.5, 127.1, 122.0, 121.9; IR (cm21, KBr) n: 2675, 1601, 1523,
1457, 1345, 1106.
2-Methylbiphenyl: Oil.[43] 1H NMR (300 MHz, CDCl3) d: 7.37–7.22
(m, 9H), 2.27 (s, 3H); 13C NMR (75 MHz, CDCl3) d: 141.9, 135.3, 130.3,
129.8, 129.2, 128.0, 127.2, 126.7, 125.7, 20.4; IR (cm21, film) n: 3059,
3020, 2802, 1631, 1479, 1438, 1351.
Biphenyl: mp 69–70 8C (lit.[44] mp 69–70 8C). 1H NMR (300 MHz, CDCl3)
d: 7.58–7.28 (m, 10H); 13C NMR (75 MHz, CDCl3) d: 141.2, 128.7, 127.2,
127.1; IR (cm21, KBr) n: 2682, 1630, 1600, 1474, 1350.
4-Chlorobiphenyl: mp 77–79 8C (lit.[45] mp 76–78 8C). 1H NMR (300 MHz,
CDCl3) d: 7.50–7.30 (m, 9H); 13C NMR (75 MHz, CDCl3) d: 139.9, 139.6,
133.3, 128.8, 128.3, 127.5, 126.9; IR (cm21, KBr) n: 2786, 2666, 1631,
1477, 1362.
1
4-Fluorobiphenyl: mp 73–74 8C (lit.[46] mp 73 8C). H NMR (300 MHz,
CDCl3) d: 7.51–7.03 (m, 9H); 13C NMR (75 MHz, CDCl3) d: 162.4
(d, J ¼ 244.6 Hz), 140.2, 137.3, 128.8, 128.6 (d, J ¼ 8.0 Hz), 127.2, 127.0,
115.6 (d, J ¼ 21.1 Hz); IR (cm21, KBr): n ¼ 2788, 2664, 1631, 1478, 1361.
1
4-Methoxybiphenyl: mp 86–87 8C (lit.[47] mp 86 8C). H NMR (300 MHz,
CDCl3) d: 7.54–7.23 (m, 7H), 6.96–6.91 (m, 2H), 3.77 (s, 3H); 13C NMR
(75 MHz, CDCl3) d: 159.1, 140.7, 133.7, 128.7, 128.1, 126.6, 126.6, 114.2,
55.2; IR (cm21, KBr) n: 2832, 1632, 1523, 1488, 1350.
(E)-1-Phenyl-5-chloro-1-pentene: Oil.[48] 1H NMR (300 MHz, CDCl3) d:
7.34–7.17 (m, 5H), 6.40 (d, 1H, J ¼ 15.9 Hz), 6.18–6.07 (m, 1H), 3.53
(t, 2H, J ¼ 6.6 Hz), 2.37–2.28 (m, 2H), 1.95–1.84 (m, 2H); 13C NMR (75
MHz, CDCl3) d: 137.4, 131.1, 128.5, 128.4, 127.0, 125.9, 44.2, 32.0, 30.0;

1508
L. Zhang et al.
MS (70 eV): m/z (%) ¼ 182, 180 (Mþ, 34, 98), 144 (5), 128 (12), 117 (100),
91 (21).
1
1-Phenylnaphthalene: mp 41–43 8C (lit.[49] mp 40–42 8C). H NMR (300
MHz, CDCl3) d: 7.91–7.82 (m, 3H), 7.52–7.37 (m, 9H); 13C NMR (75
MHz, CDCl3) d: 130.1, 128.9, 128.4, 128.2, 128.1, 127.6, 127.4, 127.3,
127.2, 126.9, 126.0, 125.9, 125.8, 125.4; IR (cm21, KBr) n: 2732, 1632,
1659, 1523, 1488, 1350.
3-Methylbiphenyl: mp 42–44 8C (lit.[50] mp 42–43 8C). 1H NMR (300 MHz,
CDCl3) d: 7.64–7.12 (m, 9H), 2.41 (s, 3H); 13C NMR (75 MHz, CDCl3) d:
141.5, 138.7, 137.3, 129.8, 129.0, 127.31, 127.29, 21.4; IR (cm21, KBr) n:
2920, 2856, 1629, 1461, 820, 756, 695.
ACKNOWLEDGMENTS
We gratefully acknowledge financial support by the National Natural Science
Foundation of China (Nos. 20572031, 20772043), the Excellent Scientist
Foundation of Anhui Province, China (No. 04046080), the Scientific
Research Foundation for the Returned Overseas Chinese Scholars, State
Education Ministry, China (No. 2002247), and the Key Project of Science
and Technology of State Education Ministry, China (No. 0204069).
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