Nano-Fe3O4 encapsulated-silica particles bearing 3-aminopropyl group as a magnetically separable catalyst for efficient knoevenagel condensation of aromatic aldehydes with active methylene compounds

Article abstract of DOI:10.1002/cjoc.201400025

Knoevenagel condensation of aromatic aldehydes with active methylene compounds such as malononitrile, ethylcyanoacetate, benzimidazol-2-acetonitrile and benzothiazole-2-acetonitrile proceeded very smoothly, catalyzed by nano-Fe₃O₄ encapsulated-silica particles supported primary amine. Both reaction time and yield are satisfying. The advantages of this catalyst are ease of preparation, non-toxicity, low cost, ease of handling and recyclability. Copyright

Full text of DOI:10.1002/cjoc.201400025

FULL PAPER
DOI: 10.1002/cjoc.201400025
Nano-Fe O Encapsulated-Silica Particles Bearing 3-Amino-
3
4
propyl Group as a Magnetically Separable Catalyst for
Efficient Knoevenagel Condensation of Aromatic
Aldehydes with Active Methylene Compounds
b
b
a
a
,a
,b
Shuo Liu, Yuxiang Ni, Jianguo Yang, Huanan Hu, Anguo Ying,* and Songlin Xu*
a
School of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou, Zhejiang 318000, China
b
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
Knoevenagel condensation of aromatic aldehydes with active methylene compounds such as malononitrile,
ethylcyanoacetate, benzimidazol-2-acetonitrile and benzothiazole-2-acetonitrile proceeded very smoothly, catalyzed
by nano-Fe O encapsulated-silica particles supported primary amine. Both reaction time and yield are satisfying.
3 4
The advantages of this catalyst are ease of preparation, non-toxicity, low cost, ease of handling and recyclability.
Keywords magnetic nanoparticle, Knoevenagel condensation, recyclability, magnetic separation
[
17]
[18]
Introduction
lysts, such as zeolite catalyst,
Ni-SiO2,
fly ash
[19]
supported calcium oxide,
porous polybenzimida-
The Knoevenagel reaction involves the condensation
of aldehydes with a C-H acidic methylene group acti-
vated by one or two electron-withdrawing group, such
as nitrile, acyl, and nitro.
synthesis of important intermediates or products for
cosmetics, perfumes, pharmaceuticals, calcium antago-
nists and functional polymers.
evenagel condensation is performed under homogene-
ous conditions in the presence of bases or acids, such as
[20]
[21]
zoles,
supported titanium(IV) catalyst,
porous SBA-15 functionalized with imidazolium or
Carbon Nitride materials, polycarbosilane-
[22]
silica gel or meso-
[
1-3]
It has been used for the
[23,24]
pyridinium based ionic liquids,
of amine immobilized catalysts based on polyacryla-
and different types
[25-27]
[
4-7]
mide or silica gel.
Immobilization of the organo-
Traditionally, Kno-
catalysts to insoluble materials allows an easy separa-
tion by filtration, which is a conventional way to make
catalysts recovery and the work-up procedure simple.
However, many heterogeneous catalysts tend to need
harsh conditions to prepare.
Nowadays, magnetic nanoparticles (MNPs) have
appeared as a new kind of catalyst support because of
their good stability, easy synthesis and functionalization,
high surface area, facile separation by magnetic forces,
[
8,9]
primary or secondary amines and salts. Using these
catalysts, however, has numerous drawbacks such as the
use of toxic solvents, long reaction time and in some
reactions the catalysts are not efficient and cannot be
reused. Recently, ionic liquids (ILs) have become of
growing interest due to their unique chemical and
physical properties of nonvolatility, nonflammability,
thermal stability, and controlled miscibility. Conse-
quently, many kinds of ionic liquids have been used as
solvents and catalysts for Knoevenagel condensa-
[28]
low toxicity and cost.
MNP catalysts can be recov-
ered by an external magnetic field and their catalytic
efficiency remains after repeated reactions. However,
ultrafine magnetic nanoparticles always tend to undergo
agglomeration due to the large surface area-to-volume
ratio and the magnetic dipole-dipole attractions between
particles. It has been demonstrated that the formation of
a passive coating of inert materials such as silica on the
surfaces of iron oxide nanoparticles could help prevent
their aggregation in liquid and improve their chemical
[10-12]
tion.
Our group also synthesized several ionic liq-
uids to catalyze Knoevenagel condensation reaction
with wonderful effects.
[
13-16]
Although the ability of ILs
has been demonstrated successfully in many reactions,
the chemical industry still prefers to use heterogeneous
catalyst system due to its ease of handling and regener-
ability.
In recent years, many efforts have been made to
prepare heterogeneous catalysts based on solid materials.
Literature survey reports various heterogeneous cata-
[29,30]
stability.
Driven by the unique properties of magnetic
nanoparticles and the interest in the preparation and use
*
E-mail: agying@tzc.edu.cn (A. Ying), slxu@tju.edu.cn (S. Xu)
Received January 7, 2014; accepted March 6, 2014; published online XXXX, 2014.
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cjoc.201400025 or from the author.
Chin. J. Chem. 2014, XX, 1—6
© 2014 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1

Liu et al.
FULL PAPER
of solid catalysts, herein, we report a novel silica-coated
Fe O nanoparticle bearing 3-aminopropyl group and its
3 4
solved in 250 mL deionized water under nitrogen with
mechanical stirring at 85 ℃. A solution of concentrated
aqueous ammonia (10 mL, 25 wt%) was added to the
solution in a drop-wise manner using a dropping funnel.
After continuous stirring for 4 h, the magnetite precipi-
tates were washed using deionized water. The black
precipitate (Fe O ) was collected by a permanent mag-
3 4
net. Sonicating a dispersion of the above black precipi-
tate (1.0 g) with ethanol (50 mL) for 30 min at room
application as a highly efficient and magnetically re-
coverable catalyst for Knoevenagel condensation be-
tween aromatic aldehydes and active methylene com-
pounds in water under mild conditions. The experiments
result in high yields. The water stable catalyst can be
easily recycled from the reaction system using external
magnet and can be reused several times without loss of
activity, which provides a green route for Knoevenagel
reactions.
temperature, then conc. NH
(2.0 mL) was added successively. After mechanical stir-
ring for 24 h, the black precipitate (SiO @Fe ) was
3 2
•H O (6 mL) and TEOS
2
3 4
O
collected using a permanent magnet, followed by wash-
ing with ethanol several times and drying in a vacuum.
Experimental
Reagents
Procedure for the synthesis of AP-SiO
2 3 4
@Fe O
All aldehydes, active methylene compounds,
1
.0 g of SiO @Fe was dispersed in 50 mL etha-
2
3 4
O
(
(
(
3-aminopropyl)triethoxysilane, tetraethyl orathosilicate
TEOS), FeCl •4H O, FeCl •6H O, NH OH solution
25%) and the other reagents used were analytical grade
nol by sonication for 1 h. 2.0 g of (3-aminopropyl)tri-
ethoxysilane was then added, and the reaction mixture
was refluxed for 2 d under nitrogen. After cooling to
room temperature, the catalyst AP-SiO @Fe O was
2 3 4
collected by a permanent magnet and rinsed with etha-
nol, then dried under vacuum. The loading amount of
2
2
3
2
4
and employed without further purification. Water was
deionized.
Apparatus and instruments
1
13
H NMR and C NMR spectra were recorded on a
2 3 4
the 3-aminopropyl group on SiO @Fe O was deter-
1
Bruker 400 MHz spectrometer. FT-IR spectra were reg-
istered with a Nicolet 5700 Fourier infrared spectro-
photometer. Magnetization curves were performed by
using a SQUID magnetometer. X-ray diffraction (XRD)
was detected by Bruker D8 X-ray diffractometer, trans-
mission electron microscope (TEM) was examined by
Tecnai G2 F20 transmission electron microscope.
Thermogravimetric analysis (TGA) was examined by
SDT Q600 simultaneous thermal analyzer.
mined to be 0.64 mmol•g by elemental analysis.
General procedure for Knoevenagel condensation
A mixture of aldehyde (1 mmol), active methylene
compound (1 mmol) and catalyst in water (2 mL) was
stirred at room temperature. The reaction progress was
monitored by TLC. After completion of the reaction, the
catalyst was collected by a permanent magnet and
washed with ethyl acetate (10 mL×3). The reaction
mixture was extracted three times with ethyl acetate.
The combined organic phases were concentrated and
purified by column chromatography (petroleum ether-
ethyl acetate). All of the products generated in this way
Synthesis of the catalyst
The magnetic nanoparticle supported catalyst was
prepared following the procedure shown in Scheme 1.
1
were characterized by comparison of their spectral ( H
1
3
Scheme 1 Synthesis of the magnetic nanoparticle supported
catalyst
NMR, C NMR) and melting point data with those of
the authentic samples.
TEOS
(EtO) Si
NH2
Results and Discussion
3
Fe O
3
4
Fe O
3
4
EtOH, reflux
Characterization of the catalyst
SiO2
The magnetic properties of the AP-SiO
2 3 4
@Fe O and
SiO @Fe O
2
3
4
SiO @Fe O were investigated at room temperature and
2
3
4
up to external field of 20 kOe. As shown in Figure 1, the
hysteresis loop for the samples was completely reversi-
ble, showing that the nanoparticles exhibit super-para-
magnetic characteristics. The hysteresis loops of them
reached saturation up to the maximum applied magnetic
field. The saturation magnetization of samples changed
O
Fe O
O Si
O
NH2
3
4
SiO2
AP-SiO @Fe O
3 4
2
1
from 15 to 6 emu•g , due to the functionalization of
-aminopropyl group. Both particles showed high per-
Synthesis of silica-coated Fe
3
O
4
nanoparticles
3
(
SiO @Fe O )
2
3
4
meability in magnetization and their magnetization was
sufficient for magnetic separation with a conventional
magnet.
Fe
3 4
O was prepared via a coprecipitation method
according to the procedures reported in the literature.
[31]
FeCl
3
•6H
2
O (11.0 g) and FeCl
2
•4H
2
O (4.0 g) were dis-
In order to demonstrate the successful functionaliza-
2
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© 2014 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2014, XX, 1—6

3 4
Nano-Fe O Encapsulated-Silica Particles Bearing 3-Aminopropyl Group
tion of SiO
employed to give detailed investigation of the AP-
SiO @Fe and SiO @Fe (Figure S1). In com-
parison with SiO @Fe , Si－OH band (3447 cm ),
Fe－O band (579 cm ) and Si－O bonds (964 and 1099
2
@Fe
3
O
4
with 3-aminopropyl group, IR was
occurred below 150 ℃, which is due to the loss of
adsorbed solvent or trapped water from the catalyst. A
mass loss of approximately 20% weight is seen between
150 and 500 ℃, which is the loss of 3-aminopropyl
group. What’s more, the DTG curve shows that the de-
composition of the organic structure mainly occurred
from 250 to 500 ℃, which is related to main weight loss
of 17.5%. The peak in the DTG curve shows that the
fastest loss of the 3-aminopropyl group occurred at
270 ℃. Therefore, the catalyst is stable around or be-
low 200 ℃.
2
3
O
4
2
3 4
O
1
2
3 4
O
1
1
cm ) are the same, demonstrating the existence of SiO
2
1
components. In addition, at 2949 and 2872 cm (CH
2
stretching vibration), 1211 and 1153 cm1 (NH
stretch-
2
ing vibration) the new bands are observed, indicating
the definite graft of 3-aminopropyl group.
Optimization of the Knoevenagel reaction conditions
To optimize the reaction conditions, the conden-
sation of benzaldehyde and ethyl cyanoacetate was used
as a model reaction as depicted in Table 1. Initially, the
reaction was carried out without catalyst using
benzaldehyde (1 mmol) and ethyl cyanoacetate (1 mmol)
in H O (2 mL) at room temperature. The reaction yield
2
was 42% after 1.5 h. Then the reaction was carried out
with various amounts of catalyst from 1 to 6 mol% in
1
.5 h. As can be seen in Table 1 (Entries 2－6), there
was a sharp increase in the yield from 76% to 90%
when the catalyst loading increased from 1 to 5 mol%.
When the amount of catalyst was increased from 5 to 6
mol%, no further increase in yield was observed.
Therefore, a dosage of 5 mol% catalyst was selected for
all subsequent reactions. Then the influence of solvent
on the Knoevenagel condensation catalyzed by
Figure 1 Magnetic curves of SiO
2 3 4 2
@Fe O and AP-SiO @
Fe
3
4
O .
2
The crystalline structure of SiO @MNP was charac-
terized by X-ray diffraction (XRD). The diffraction
pattern shows characteristic peaks and relative intensity
AP-SiO @Fe O was investigated (Entries 8－13, Table
matched well with the standard Fe
JCPDS file No. 19-0629, Figure 2). The broad peak
from 2θ＝20° to 30° shows the typical properties of
3
O
4
nanoparticles
2
3
4
1
). The reaction proceeded smoothly in the absence of
(
[
32]
amorphous silica shell on the surface of the MNPs.
Moreover, transmission electron microscope (TEM)
analysis displays that the particle size of the catalyst
Table 1 Optimization of catalyst/organic solvent in Knoevena-
a
gel condensation reaction
CHO
CN
CN
r. t.
+
H O
2
AP-SiO
SiO @MNP (Figure S2), with the average size range of
0－30 nm for dark Fe core which is surrounded by
a grey silica shell of about 4－6 nm in thickness.
2
3 4
@Fe O is similar to that of blank carrier
+
COOEt
COOEt
2
b
c
2
3
O
4
Entry
Solvent
Catalyst /mol%
Yield /%
42
1
2
3
4
5
6
7
8
9
H
2
2
O
O
0
1
2
3
4
5
6
5
5
5
5
5
5
H
76
H O
2
79
H O
2
85
H O
2
89
H
2
O
90
H O
2
90
—
81
CH CN
78
3
10
11
12
13
CHCl3
THF
82
81
ethanol
acetone
83
80
2
Figure 2 XRD pattern of SiO @MNP.
a
Reaction conditions: benzaldehyde (1.0 mmol) and ethyl
cyanoacetate (1.0 mmol), AP-SiO @Fe O , room temperature,
TGA was used to study the thermal stability of
AP-SiO @Fe . The TG curve indicates several
different mass loss (Figure S3). The first mass loss is
2
3
4
b
2
3
O
4
reaction time＝90 min. Based on the loading of 3-aminopropyl
group. Isolated yields.
c
Chin. J. Chem. 2014, XX, 1—6
© 2014 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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3

Liu et al.
FULL PAPER
solvent with moderate yield. For solvents such as
acetonitrile, CHCl , THF, ethanol, and acetone,
3
dehyde with active methylene compounds also under-
went favourably (Entries 15, 16, Table 2).
moderate to good yield was obtained. When the reaction
underwent in water, the reaction yield was more than
Encouraged by the results above, we continued to
study the reaction of aromatic aldehydes with complex
active methylene compounds, such as benzimidazol-
2-acetonitrile, benzothiazole-2-acetonitrile. The reaction
smoothly proceeded to afford the corresponding
products with moderate to good yield. From Table 2 and
Table 3, we found that the acidity of methylene was the
key factor influencing the reaction (Entries 1, 8, Table 2,
Entries 1, 4, Table 3). Especially, the acidity of malono-
nitrile methylene is apparently stronger than others and
results in good effect.
9
0%. Hence 5% catalyst in water is the most effective
combination.
Knoevenagel condensation of various aromatic
aldehydes with active methylene compounds
Various functionalized aromatic aldehydes including
heterocyclic systems were reacted with active
methylene compounds (malononitrile, ethyl cyanacetate)
2 3 4
in water catalyzed by AP-SiO @Fe O (Table 2). The
method gave good results in terms of yield as well as
time compared with many of the reported methods.
Compared to ethyl cyanoacetate, malonontrile was more
reactive. The effects of substituents at the aromatic ring
on the Knoevenagel reaction were studied. The electron-
withdrawing group (such as nitro, chloro group)
substituted aromatic aldehydes with active methylene
compounds converted smoothly to the corresponding
products in high yields (Entries 2－4, 9－11, Table 2).
Electron-donating group (such as methoxyl group)
substituted aromatic aldehydes underwent Knoevenagel
condensation smoothly and in good yield (Entries 5－7,
Table 3 Knoevenagel condensation reaction of other active
methylene compounds with functionalized aromatic aldehydes
a
CHO
N
cat. 5 mol%
water, r.t.
R
+
CN
X
CN
N
X
R
Entry
R
H
X Time/h Yield/% m.p./℃ Reported m.p./℃
[
42]
1
2－14, Table 2). In addition, Knoevenagel conden-
1
2
3
4
5
6
S
S
S
3
4
3
3
3
4
86
89
93
89
92
83
145－147 147－148
140－142 143－144
[
42]
sation of hetero aromatic aldehydes such as 2-thenal-
4-OCH3
2-Cl
241－242
－
Table 2 Knoevenagel condensation reaction of active methyl-
[
[
43]
44]
C H NH
6
219－221 217－218
140－142 136－138
230－232 218－220
a
5
ene compounds with functionalized aromatic aldehydes
2-Cl NH
O
R
[45]
cat. 5 mol%
water, r.t.
R
4-OCH NH
3
+
Ar
a
Ar
H
Reaction conditions: benzaldehyde (1.0 mmol) and ethyl cyano-
acetate (1.0 mmol), AP-SiO @Fe O (5 mol%), water (2 mL),
CN
CN
2
3
4
Time/ Yield/ m.p./ Reported m.p./
room temperature.
Entry
Ar
R
min
60
30
30
20
60
60
60
%
℃
℃
[
33]
1
2
3
4
5
6
7
8
9
C
6
H
5
CN
CN
CN
CN
CN
CN
CN
93
79－81
80－82
Recyclability studies
[
34]
3-NO
2-ClC
4-NO
2
C
6
H
4
96 103－104 102－103
Considering that the key feature of our catalyst was
magnetic response, we investigated the reusability and
the recycling use of the catalyst by carrying out repeated
runs on the same batch of the used magnetic catalyst in
Knoevenagel reaction of benzaldehyde and ethyl cyano-
acetate. After each run, the catalyst can be easily col-
lected by a magnet (Figure S4). The recovered catalyst
was used directly for the next run after simply washing
with ethyl acetate and removing the residue solvent
under vacuum. The recovered catalyst still maintained
similar activity after 4 cycles (Figure 3).
[
35]
6
H
4
94
92－93
92－94
[
36]
2
C
6
H
4
98 158－160 159－160
[
35]
2-OCH
3-OCH
4-OCH
3
3
3
C
C
C
6
6
6
H
H
H
4
4
4
92
79－80
79－80
[
35]
95 105－107 102－104
[
1]
94 113－115
90 49－50
115
[
1]
C
6
H
5
COOEt 90
COOEt 60
COOEt 60
COOEt 45
COOEt 90
COOEt 90
COOEt 90
47－48
[
37]
3-NO
2-ClC
4- NO
2
C
6
H
4
94 130－131 132－134
[
[
[
[
[
[
[
38]
36]
35]
35]
39]
40]
41]
1
1
1
1
1
1
1
0
6
H
4
96
96
86
88
83
52－53
79－80
75－76
53－54
79－81
95－96
88－90
54－55
80－81
72－74
52－54
80－81
97－98
94－98
1
2
6 4
C H
To demonstrate the stability of AP-SiO @Fe O , the
2
3
4
2 2-OCH
3 3-OCH
4 4-OCH
3
C
6
H
H
H
4
4
4
FT-IR spectra of fresh catalyst and reused catalyst (5
times) were provided (Figure S5). No significant change
in the catalyst occurred even after five times of reuse.
TEM images (Figure S2b vs. S2c), also showed that the
catalyst still maintained its nanostructure after repeated
reuse. These observations suggested that the catalyst
was perfectly stable during the Knoevenagel reaction
and was readily recyclable from the reaction system.
3
3
C
6
6
C
5
6
2-thienyl
CN 120 89
2-thienyl COOEt 120 81
a
Reaction conditions: benzaldehyde (1.0 mmol) and ethyl cyano-
acetate (1.0 mmol), AP-SiO @Fe O (5 mol%), water (2 mL),
2
3
4
room temperature.
4
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© 2014 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2014, XX, 1—6

Nano-Fe
3 4
O Encapsulated-Silica Particles Bearing 3-Aminopropyl Group
Scheme 2 Proposed mechanism for the Knoevenagel condensation reaction
R
R
OH
O
H
O
HO
H
H
O
OH
E1
E1
Fe O
O Si
O
NH2
3
4
R
R
E1
E2
E2
E2
SiO2
E1
H
H
H
E2
OH
O
OH
OH
H
H
O
OH
NH2
O
NH2
O
O
Fe O
O Si
O
3
4
Fe O
O Si
O
Fe O
O Si
O
NH2
3
4
3
4
SiO2
SiO2
SiO2
Carbon Fatty Amine Engineering Research Center of
Zhejiang Province (No. 2012E10033).
References
[
[
1] Aharma, Y. O.; Degani, M. S. Green Chem. 2009, 11, 526.
2] Ebitani, K.; Motokura, K.; Mori, K.; Mizugaki, T.; Kaneda, K. J.
Org. Chem. 2006, 71, 5440.
[
[
[
[
3] Freeman, F. Chem. Rev. 1980, 80, 329.
4] Tietze, L. F.; Rackelmann, N. Pure Appl. Chem. 2004, 76, 1967.
5] Kwak, G.; Fujiki, M. Macromolecules 2004, 37, 2021.
6] Liang, F.; Pu, Y. J.; Kurata, T.; Kido, J.; Nishide, H. Polymer 2005,
Figure 3 Reuse of catalyst for Knoevenagel condensation be-
tween benzaldehyde and ethyl cyanoacetate within 2 h.
4
6, 3767.
[
[
7] Kraus, G. A.; Krolski, M. E. J. Org. Chem. 1986, 51, 3347.
8] Cardillo, G.; Fabbroni, S.; Gentilucci, L.; Gianotti, M.; Tolomelli, A.
Synth. Commun. 2003, 33, 1587.
Proposed mechanism
We proposed the mechanism reported in Scheme 2.
The immobilized amino group extracts a proton from
the active methylene compound, while the silanol group
promotes the nucleophilic addition on the carbonyl
compound via a hydrogen bond. The carbanion of active
methylene attacks the carbocation to form the aldol
intermediate. The aldol intermediate dehydrates and
obtains the final product. The silica oxygen regenerates
the amino function through hydrogen bonds.
[9] Narsaiah, A. V.; Basak, A. K.; Visali, N. B. K. Synth. Commun.
004, 34, 2893.
10] Ranu, B. C.; Jana, R. Eur. J. Org. Chem. 2006, 16, 3767.
2
[
[
11] David, C. F.; Amanda, M. L.; Doug, W. M. Tetrahedron Lett. 2006,
4
7, 1699.
[
12] Forsyth, S. A.; Frohlich, U.; Goodrich, P.; Gunaratne, H. Q. N.;
Hardacre, C.; McKeown, A.; Seddon, K. R. New J. Chem. 2010, 34,
723.
[13] Ying, A. G.; Liang, H. D.; Zheng, R. H.; Ge, C. H.; Jiang, H. J.; Wu,
C. L. Res. Chem. Intermed. 2011, 37, 579.
[
[
14] Ying, A. G.; Liu, L.; Wu, G. F.; Chen, X. Z.; Ye, W. D.; Chen, J. H.;
Zhang, K. Y. Chem. Res. Chin. U. 2009, 25, 876.
15] Ying, A. G.; Wang, L. M.; Wang, L. L.; Chen, X. Z.; Ye, W. D. J.
Chem. Res. 2010, 34, 30.
Conclusions
2 3 4
AP-SiO @Fe O is a good recyclable catalyst for the
Knoevenagel condensation between active methylene
compounds and aromatic aldehydes in water at room
temperature. Compared with the reported methods, this
method offers marked improvements in terms of sim-
plicity, decreased reaction time, general applicability,
low cost and no need for hazardous organic solvents and
toxic catalysts. Thus, it provides a better and practical
alternative to existing procedures.
[
[
16] Ying, A. G.; Wu, C. L.; He, G. F. Asian J. Chem. 2012, 24, 653.
17] Zhang, X. F.; Lai, E. S. M.; Martin-Aranda, R.; Yeung, K. L. Appl.
Catal. A: Gen. 2004, 261, 109.
18] Rajasekhar, P. V. S. R.; Rahman, A.; Jonnalagadda, S. B. Catal.
Commun. 2009, 10, 365.
[
[19] Jain, D.; Khatri, C.; Rani, A. Fuel Process. Technol. 2010, 91, 1015.
[
[
[
[
20] Zhang, X. J.; Bian, N.; Mao, L. J.; Chen, Q.; Fang, L.; Qi, A. D.;
Han, B. H. Chem. Phys. 2012, 213, 1575.
21] Xu, J.; Shen, K.; Xue, B.; Li, Y. X.; Cao, Y. Catal. Lett. 2013, 143,
6
00.
22] Mangala, K.; Sreekumar, K. Appl. Organometal. Chem. 2013, 27,
3.
Acknowledgement
7
We are grateful to the financial supports for this re-
search by the National Natural Science Foundation of
China (Grant No. 21106090), Postdoctoral Foundation
of China (No. 2012M511352) and Foundation of Low
23] Lai, G. Q.; Peng, J. J.; Li, J. Y.; Qiu, H. Y.; Jiang, J. X.; Jiang, K. Z.;
Shen, Y. J. Tetrahedron Lett. 2006, 47, 6951.
[24] Liu, Y.; Peng, J.; Zhai, S.; Li, J.; Mao, J.; Li, M.; Qiu, H.; Lai, G.
Eur. J. Inorg. Chem. 2006, 15, 2947.
Chin. J. Chem. 2014, XX, 1—6
© 2014 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
5

Liu et al.
FULL PAPER
[
25] Angeletti, E.; Canepa, C.; Martinetti, G.; Venturello, P. J. Chem.
Soc., Perkin Trans. 1 1989, 105.
11, 1815.
[34] Kalbasi, R. J.; Mosaddegh, N. Catal. Commun. 2011, 12, 1231.
[35] Li, G. W.; Xiao, J.; Zhang, W. Q. Green Chem. 2011, 13, 1828.
[36] Dong, F.; Li, Y. Q.; Dai, R. F. Chin. Chem. Lett. 2007, 18, 266.
[37] Mukhopadhyay, C.; Datta, A. Synth. Commun. 2008, 38, 2103.
[38] Popp, F. D. J. Org. Chem. 1960, 25, 646.
[
[
26] Wang, S. G. Catal. Commun. 2003, 4, 469.
27] Zienkiewicz, Z.; Calvino-Casilda, V.; Sobczak, I.; Ziolek, M.; Mar-
tin-Aranda, R. M.; Lopez-Peinado, A. J. Catal. Today 2009, 142,
3
03.
[
[
[
28] Polshettiwar, V.; Luque, R.; Fihri, A.; Zhu, H.; Bouhrara, M.; Basset,
J. M. Chem. Rev. 2011, 111, 3036.
29] Lu, Y.; Yin, Y. D.; Mayers, B. T.; Xia, Y. N. Nano Lett. 2002, 2,
[39] Krishnan, G. R.; Sreekumar, K. Eur. J. Org. Chem. 2008, 28, 4763.
[40] Emerson, W. S.; Patrick, T. M. J. J. Org. Chem. 1949, 14, 790.
[41] Pettersson, K. Arkiv foer Kemi 1954, 7, 39.
[42] Saito, K.; Kambe, S.; Nakano, Y.; Sakurai, A.; Midorikawa, H. Syn-
thesis 1983, 210.
[43] Hranjec, M.; Karminski-Zamola, G. Molecules 2007, 12, 1817.
[44] Dubey, P. K.; Reddy, P. V. V. P. Indian J. Heterocyclic Chem. 2007,
16, 395.
[45] Regaila, H. A. A.; El-Bayouki, K.; Hammad, M. Egyptian J. Chem.
1977, 20, 157.
1
83.
30] Zhang, Y.; Zhao, Y. W.; Xia, C. G. J. Mol. Catal. A: Chem. 2009,
06, 107.
3
[
[
31] Zhang, Q.; Su, H.; Luo, J.; Wei, Y. Y. Green Chem. 2012, 14, 201.
32] Wang, X.; Dou, P. P.; Zhao, P.; Zhao, C. M.; Ding, Y.; Xu, P.
ChemSusChem 2009, 2 , 947.
[
33] Trilla, M.; Pleixats, R.; Man, M. W. C.; Bied, C. Green Chem. 2009,
(Zhao, X.)
6
www.cjc.wiley-vch.de
© 2014 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2014, XX, 1—6