Gold immobilized onto poly(ionic liquid) functionalized magnetic nanoparticles: A robust magnetically recoverable catalyst for the synthesis of propargylamine in water

Article abstract of DOI:10.1039/c5ra02974k

Supported gold(III) on poly(ionic liquid) coated on magnetic nanoparticles produced a highly active, stable, recoverable and high loading for the synthesis of propargylamines (A³ coupling reaction) under green conditions. The reaction of aldehy

Full text of DOI:10.1039/c5ra02974k

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Gold immobilized onto poly(ionic liquid)
functionalized magnetic nanoparticles: a robust
magnetically recoverable catalyst for the synthesis
of propargylamine in water†
Cite this: RSC Adv., 2015, 5, 34502
a
a
b
Firouz Matloubi Moghaddam,* Seyed Ebrahim Ayati, Seyed Hassan Hosseini
and Ali Pourjavadi
b
Supported gold(III) on poly(ionic liquid) coated on magnetic nanoparticles produced a highly active, stable,
3
recoverable and high loading for the synthesis of propargylamines (A coupling reaction) under green
conditions. The reaction of aldehyde, secondary amine and alkyne were followed in aqueous media. The
catalyst was characterized by TEM, TGA, AAS, FT-IR, XRD and EDX. A broad diversity of aldehydes,
secondary amines, and alkynes, and a good to excellent yield of corresponding propargylamines were
synthesized using 1.0% Au. The catalyst was easily recovered and reused 10 times without significant loss
of activity.
Received 16th February 2015
Accepted 9th April 2015
DOI: 10.1039/c5ra02974k
www.rsc.org/advances
16
mesoporous organosilicas, nanocrystalline magnesium oxi-
de. However, most of them suffer from some disadvantages
Introduction
9c
Since the rst use of gold in organic reactions as a catalyst by such as low stability in aqueous media, signicant leaching
Hayashi and co-workers in 1986, there have been many reports aer several cycles of use and difficult separation. So it is still
1
in which gold was used as a catalyst. Although Bulk gold is necessary to develop new supports for heterogeneous catalytic
+
+3
inactive, its ions (Au , Au ) and nanoparticles have extraordi- systems. Magnetic nanoparticles are one of the most attractive
2
nary catalytic properties in organic synthesis. Due to its low supports for immobilization of gold. Low toxicity, high thermal
3
toxicity in biological systems, stable oxidation state, high regio- stability, easy separation, good loading, high surface area to
and chemo-selectivities and easy recovery, gold has served as an volume, easy access to the catalytic active sites, readily
efficient catalyst in a wide range of reactions such as aerobic dispersible in organic solvents, stable under harsh shaking
4
5
17
oxidation of alcohols, hydration of alkynes, C–C coupling conditions and simple modication are brief reasons of
6
7
reactions, cyclization reactions carbon-heteroatom bond- extensive use of magnetic nanoparticles.
forming reactions, reduction of nitro compounds and
Poly(ionic liquid) coated magnetic nanoparticles have
synthesis of propargylamine derivatives via C–H bond activa- attracted much attention in recent years. Since poly(ionic
tion in the past decade. Despite the fact that the homogeneous liquids) are environmental friendly, they can be used as support
catalysts have excellent activity in chemical reactions, their for catalytic purpose in green conditions. High loading, low
separation is one the most challenges. Having inappropriate leaching and high surface area are other advantages of
effects on biological systems, long separation time and using magnetic poly(ionic liquids).
toxic organic solvents are a brief of vast homogeneous catalysts
On the other hand propargylamines are versatile organic
problems. In order to overcome the mentioned problems, using compounds that have been known as building block in organic
8
9
18
10
19
20
21
of heterogeneous catalysts is a versatile approach. Many synthesis, framework of some pharmaceutical systems and
different materials have been used as supports for immobili- natural products. The traditional method for the synthesis of
22
zation of gold ions and nanoparticles such as nanocrystalline propargylamines is the reaction of lithium acetylides or
11
9a,12
13
2,14
15
23
CeO
2
,
TiO
2
,
polymers,
ZrO
2
,
Cs
2
CO
3
,
periodic Grignard reagents with imine derivatives. Because the
mentioned method requires super dry solvent, inert atmo-
sphere and stoichiometric amounts of organometallic reagents,
a
Laboratory of Organic Synthesis and Natural Products, Department of Chemistry,
Sharif University of Technology, Azadi Street, PO Box 111559516, Tehran, Iran.
it is not a good and applicable method in quantitative scales.
Since the formation of imines are fast, three components
E-mail: matloubi@sharif.edu
b
10d
24
Polymer Research Laboratory, Department of Chemistry, Sharif University of reaction catalyzed by some noble metals like gold, silver,
25
26
27
28
Technology, Azadi Street, PO Box 111559516, Tehran, Iran
iridium, rhenium, copper and cobalt were suggested as
†
Electronic supplementary information (ESI) available. See DOI:
0.1039/c5ra02974k
new strategy to prepare propargylamines. The C–H activation of
1
34502 | RSC Adv., 2015, 5, 34502–34510
This journal is © The Royal Society of Chemistry 2015

View Article Online
Paper
RSC Advances
3
A reactions catalyzed by gold salts or other metal salts, not only ether. The semi-transparent mixture was cooled for 5 h at
ꢀ
could be done in water but also can be used quantitatively in ꢁ10 C. The white solid was collected by ltration and washed
ꢀ
large scales.
three times with diethyl ether and dried under vacuum at 50 C.
Here, we report the synthesis of new Au(III)-immobilized The same procedure was used for the synthesis of 1,4-butane-
0
magnetic poly imidazole/imidazolium bromide nanoparticles diyl-3,3 -bis-1-vinylimidazolium bromide.
as an efficient and reusable catalyst for the synthesis of prop-
argylamines under green media. Having a brief comparison
Synthesis of the catalyst
29
between the reported works and our work shows that a high
loading of Au(III) on magnetic nano-particels, excellent thermal
stability of magnetic poly imidazole/imidazolium bromide and
easy dispersion of catalyst in water are the reasons to use it as an
efficient and applicable catalyst for the synthesis of propargyl-
amines under mild conditions. The survey of catalyst properties
and optimization of reaction conditions have detailed in results
and discussion.
1
9
The catalyst was previously synthesized by our research group.
A 50 mL round bottom ask was charged with a mixture of
MNP@MPS (0.4 g), 1-vinylimidazole (Vim, 1 g), IL monomer
([EVim][Br], 0.4 g) and cross-linker ([BBVim][Br]
2
, 0.2 g) and
3
0 mL of dry methanol. Aerwards, the reaction mixture was
sonicated for 20 min and then, degassed by argon for 10 min. A
certain amount of AIBN (0.1 g) was added to the mixture of
reaction and then the ask was equipped with a condenser and
ꢀ
placed in an oil bath for 18 h at 70 C. The produced poly
Experimental section
Reagents and analysis
imidazole/imidazolium bromide magnetic nanoparticles
(MNP@PIL) were collected by an external magnetic eld and
washed three times with methanol and dried under vacuum at
Ferric chloride hexahydrate (FeCl
tetrahydrate (FeCl $4H O), tetrachloroauric(III) acid trihydrate
HAuCl ), ammonia (30%), and 3-methacryloxypropyl-
3 2
$6H O), ferrous chloride
ꢀ
5
0 C (MNP@PIL, 1.37 g).
2
2
In a 50 mL round bottom, tetrachloroauric(III) acid trihydrate
(
4
(0.1 g) was dissolved in 30 mL deionized water and then the
trimethoxy silane (MPS, 98%) were purchased from Merck. 1-
Vinylimidazole was obtained from Aldrich and was distilled
before use. 1,4-Dibromobutane was obtained from Aldrich,
powdered magnetic PIL (0.5 g) was added to the solution. The
mixture was stirred for 5 h at room temperature. The catalyst
(MNP@PILAu) was magnetically separated, washed four times
0
while 2,2 -azobisisobutyronitrile (AIBN, Kanto, 97%) was
with methanol (4 ꢂ 10 mL) and then dried under vacuum at
recrystallized from ethanol.
FTIR spectra of samples were taken using an ABB Bomem
MB-100 FTIR spectrophotometer. Thermogravimetric analysis
ꢀ
4
0 C for 10 h.
General procedure for the synthesis of propargylamines
(TGA) was performed under a nitrogen atmosphere using a TA
Instruments TGA Q 50 thermogravimetric analyzer. Trans- A glass tube was charged with deionized water (2 mL), aldehyde
mission electron microscopy (TEM) images were taken using a (1 mmol), amine (1.2 mmol), phenyl acetylene (1.1 mmol) and
1
13
Philips CM30 electron microscope. H NMR and C NMR catalyst (MNP@PILAu) (0.01 g). Then the mixture was stirred at
ꢀ
spectra were recorded on a Bruker (Avance DRX-400) spec- 60 C until completion of the reaction. The reaction completion
trometer using CDCl as solvent at room temperature.
was followed by thin layer chromatography (TLC) (EtOAc/n-
hexane, 20 : 80). In each case, aer completion, the product was
worked up and puried according to the following procedure:
The reaction mixture was diluted with ethyl acetate and then
washed with brine solution three times and dried over MgSO4.
3
Synthesis of vinyl functionalized magnetic nanoparticles
The magnetic nano-particle of Fe
3 4
O (denoted as MNPs) was
prepared by co-precipitation method and coated by silica
More purication was done by SiO column chromatography. In
2
30
according to previous work. A suspension of MNPs was
prepared by dispersion of 1 g Fe @SiO in dry ethanol and
order to reuse the catalyst, the catalyst (MNP@PILAu) was
3
O
4
2
collected using an external magnetic eld, washed with meth-
then 2 mL of ammonia solution was added to the ask. An
excess amount (10 mmol) of the 3-(trimethoxysilyl)propyl-
methacrylate (MPS) solution was gradually added to the ask
ꢀ
anol and dried under vacuum at 50 C for 10 h for the next run.
ꢀ
Results and discussion
and then, the reaction was stirred for 48 h at 60 C. Aerwards,
the MPS coated magnetic nanoparticles (denoted as
MNP@MPS) were collected by an external magnetic eld and
In this work the gold-immobilized catalyst was synthesized in a
few steps. The magnetic nano-particles Fe O were prepared by
3 4
co-precipitation method. The benets of this method are easy
preparation and good magnetism properties of nano-particles.
In order to stabilize magnetic nano-particles in acidic
washed 5 times with methanol and dried under vacuum oven at
ꢀ
5
0 C for 24 h.
Synthesis of IL monomer and cross-linker
medium and oxidation of Fe
3 4 2 3 2
O to Fe O , a thin layer of SiO
For the synthesis of ionic liquid (IL) as a common method, a was coated on Fe O by hydrolysis of TEOS under alkaline
3
4
mixture of 1-vinylimidazole (2.82 g, 30 mmol) and ethyl condition (pH ¼ 10). Since the surface of MNPs is not good for
bromide (3.27 g, 30 mmol) was stirred in 10 mL methanol at polymerization, MNPs were functionalized with MPS before
ꢀ
60
C for 20 h. The reaction mixture was cooled to room polymerization. The presence of C]C in MPS not only makes
temperature and gradually was added to 250 mL of diethyl MPS active in polymerization reaction, but also increase the
This journal is © The Royal Society of Chemistry 2015
RSC Adv., 2015, 5, 34502–34510 | 34503

View Article Online
RSC Advances
Paper
active surface area of MNPs. Ionic liquid monomer 3-ethyl-1-
vinylimidazolium bromide ([EVim][Br]) and cross-linker 1,4-
0
butanediyl-3,3 -bis-1-vinylimidazolium bisbromide ([BBVim]-
[
Br] ) were synthesized by the reaction of 1-vinylimidazole with
2
ethyl bromide. In order to immobilize poly(ionic liquid) on
MNPs, copolymerization of monomer and MNP@MPS was
performed in the presence of BVD as cross linker and AIBN as
initiator (Scheme 1). This approach efficiently increases the
surface to volume ratio and active site of the catalyst. Finally
Au(III) was loaded on MNPs@MPS by dispersion of the
MNPs@MPS in a solution of tetrachloroauric(III) acid (HAuCl4).
Due to the absorption of gold ion on support surface the yellow
color of solution disappeared aer treatment of MNPs@MPS
with tetrachloroauric(III) acid. Due to high loading of imidazole
groups onto the poly ionic liquid, a high absorption of gold ion
observed in comparison with traditional heterogeneous cata-
lysts. Because the co-polymer on MNPs produces a hydrophobic
media, the substrates can be easily adsorbed on the catalyst
surface in aqueous media and then catalyzed by gold ion on
surface (Scheme 1).
Fig. 1 FT-IR spectra of MNP@SiO
and MNP@PILAu catalyst (d).
2
(a), MNP@MPS (b), MNP@PIL (c),
The thermal stability and organic content calculation of
catalyst were done by thermal gravimetric analysis (TGA)
FT-IR spectroscopy was used for investigation the structure (Fig. 2). The rst weight losses of all samples were observed
ꢀ
of MNP@SiO
2
(Fig. 1a), MNP@MPS (Fig. 1b), MNP@PIL around 150 C which is attributed to the removal of adsorbed
(
Fig. 1c), and MNP@PILAu catalyst (Fig. 1d). The stretching water molecules. Evaluation of maximum weight loss of MNP
mode vibration peaks of Fe–O and Si–O appeared at 640 and (Fig. 2a) and MNP@MPS (Fig. 2b) revealed that loading of MPS
ꢁ
1
ꢁ1
1
3 4 2
100 cm conrm the formation of Fe O @SiO
(Fig. 1a). Bond on the surface of MNP is 0.78 mmol g . According to the TGA
formation between MPS and MNPs surface have been proved by curve of MNP@PIL, it can be concluded that the copolymer
stretching mode vibrations of C]C and steric C]O at 1420 and content of the catalyst is about 55 wt%. It should be noted that
ꢁ
1
1
720 cm , respectively (Fig. 1b). Aer co-polymerization and calculation of catalyst loading is not applicable by TGA due to
synthesis of MNP@PIL, the strong bands at 3100, 1610 and 1530 the identical nature of monomers and cross-linker in the cata-
ꢁ
1
cm are a strong reason for the presence of C–H band and lyst structure.
imidazole groups (Fig. 1c). Aer absorption of Au(III) onto the
DTG investigation of catalyst showed three degradation
MNP@PIL, FT-IR study of MNP@PILAu showed no signicant points at 100, 320 and 380. These points were attributed to
change in IR spectrum.
weight losses for losing adsorbed water molecules, imidazolium
Scheme 1 Preparation of MNP@PILAu(III) catalyst.
34504 | RSC Adv., 2015, 5, 34502–34510
This journal is © The Royal Society of Chemistry 2015

View Article Online
Paper
RSC Advances
Fig. 2 TGA and DTG curves of MNP (a), MNP@MPS (b) and MNP@PIL (c).
and imidazole parts of the catalyst structure, respectively.
According to data obtained from TGA and DTG analysis, it could
be argued that the catalyst has an excellent stability at high
temperature and harsh conditions.
Fig. 3 displays the powder X-ray diffraction pattern of
MNP@PILAu collected over the two-theta range 5 to 80 degrees.
The study of diffraction peak positions and intensities and its
comparison with standard Fe O sample (red lines) indicates
3
4
that the modications did not affect on crystalline structure of
ꢀ
Fe
3
O
4
particles. The broad peak at 20 was attributed to the
amorphous silica shell around the magnetic nanoparticles.
The study of magnetization of MNP and MNP@PILAu shows
a reasonable decrease in magnetism intensity of MNP@PILAu
due to entrapment of MNP into the poly(ionic liquid). However
it is still enough to respond to an external magnetic eld
Fig. 4 Magnetization curves of MNP (a) and MNP@PILAu (b).
(Fig. 4).
The TEM image of MNP@PILAu catalyst (Fig. 5) shows a
good dispersion of the MNPs into the poly(ionic liquid) matrix.
A narrow size distribution of the MNPs around 2–4 nm in
polymeric network can be clearly seen.
The EDX analysis of MNP@PILAu is shown in Fig. 6 clearly
conrmed that a high level of gold has loaded onto the polymer.
The iron peaks of catalyst that is attributed to Fe O clearly prove
3
4
the presence of magnetic nanoparticles into the catalyst matrix.
The loading amount of gold on catalyst was calculated by
atomic absorption spectroscopy (AAS). The analysis results
Fig. 5 TEM images of MNP@PILAu.
ꢁ1
showed the loading of gold onto the catalyst was 1.63 mmol g
.
AAs is in complete agreement with EDX analysis and conrms a
high level of absorption of gold onto the MNP@PIL.
In order to investigate the catalytic activity of MNP@PILAu,
the catalyst was used in the synthesis of propargylamine. To
afford the best condition for the reaction, benzaldehyde (0.5
mmol), piperidine (0.6 mmol), phenyl acetylene (0.65 mmol)
and catalyst were used for this reaction and the effect of
different experimental condition on the reaction was investi-
gated (Scheme 1). The completion of the reaction was followed
by thin layer chromatography (TLC). As an environmentally
friendly solvent, water was used as medium of the reaction
Fig. 3 The XRD pattern of MNP@PILAu.
This journal is © The Royal Society of Chemistry 2015
RSC Adv., 2015, 5, 34502–34510 | 34505

View Article Online
RSC Advances
Paper
0.5 and 0.25 mol%, (entry 9–11). By using support without gold
and in the absence of catalyst, no corresponding propargyl-
amine was detected even aer 30 h (entry 1 and 2). The
minimum catalyst amount for the case described in Scheme 1
without any signicant reaction times and the yields was
1.0 mol%. As can be seen from Table 1 the best condition for
the synthesis of propargylamine catalyzed by MNP@PILAu is
entry 9.
Our investigation of the reaction conditions proved a high
level of gold ion was loaded onto the MNP@PIL. Having iden-
tied the optimized reaction conditions, the substrate scope
was investigated by a variety of crude materials (alkynes, amines
and aldehydes). The results have been shown in Table 2. In
order to afford the best yields, the reactions were followed
regardless of the optimized time. In the rst strategy the
amount of alkyne (phenyl acetylene) and amine (piperidine)
Fig. 6 EDX analysis of MNP@PILAu.
3
were kept constant and the A reaction was followed with the
different aromatic and aliphatic aldehydes. As can be seen,
benzaldehyde reacts easily with phenylacetylene and piperidine
(
Table 1). Interestingly, the reaction was performed in water
ꢀ
aer 16 h at 40 C (entry 3).
To investigate the optimum temperature, the following
temperatures were examined: 50, 60, 70, 80 and 100 C (entry 4–
(entry 1). In order to investigation the activity of aldehydes
ꢀ
containing electron-donating and electron-withdrawing groups,
the different aldehydes were applied.
8). To our delight, a good yield of propargylamine was obtained
ꢀ
aer 16 h, when the reaction was performed at 50 C (entry 4).
When the temperature was raised to 60 C the yield of the
corresponding propargylamine increased to 94%. There is no
signicant change in time for completion of the reaction, when
Gratifyingly, the aromatic aldehydes with electron-donating
group reacted well (entry 12, 13 and 16); however, as shown in
Table 2, the reaction time for 4-methyl benzaldehyde has been
longer than benzaldehyde. As we expected, the aromatic alde-
hydes containing electron-withdrawing group such as Cl, Br and
CN on the 4-position of the aldehyde group resulted excellent
yield of the corresponding propargylamins at shorter times than
benzaldehyde (entry 2, 4, 7, 9, 14 and 15). Interestingly, when
the morpholine was engaged as a secondary amine for this
reaction, the good to excellent yields of corresponding products
ꢀ
ꢀ
the reaction temperature further increased up to 70 C. The gold
ions of catalyst were immediately reduced to gold nanoparticles
and yield of the reaction decreased when the reaction was
ꢀ
ꢀ
conducted at 80 C and higher temperatures. Therefore, 60 C
was chosen as temperature for further experiments. Using the
optimized catalyst amount, the following mol% was used: 1.0,
a
Table 1 Three-component coupling of benzaldehyde, piperidine, and phenylacetylene with MNP@PILAu
ꢀ
Entry
Solvent
Gold (mol%)
T ( C)
Time (h)
Conv. (%)
Yield (%)
b
1
H
H
H
H
H
H
H
H
H
H
H
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
—
—
60
60
40
50
60
70
80
100
60
60
60
30
30
16
16
16
16
16
16
16
20
20
0
0
n.d
n.d
60
85
94
93
89
91
92
85
76
c
2
3
4
5
6
7
8
9
1.5
1.5
1.5
1.5
1.5
1.5
1.0
0.5
0.25
70
90
97
97
85
90
96
95
90
1
1
0
1
a
b
Reaction conditions: benzaldehyde (0.5 mmol), piperidine (0.6 mmol), and phenylacetylene (0.65 mmol), H
2
O (1.5 mL) and MNP@PILAu. The
c
reaction in the absence of catalyst. The reaction in the presence of MNP@PIL.
34506 | RSC Adv., 2015, 5, 34502–34510
This journal is © The Royal Society of Chemistry 2015

View Article Online
Paper
RSC Advances
a
Table 2 Coupling of an aldehyde, alkyne, and amine catalyzed by MNP@PILAu in water
Entry
1
Aldehyde
PhCHO
Amine
Alkyne
Propargylamine
Time (h)
16
Yield (%)
92
Piperidine
Phenylacetylene
2
3
4
4-ClC
6
H
4
CHO
Piperidine
Piperidine
Piperidine
Phenylacetylene
Phenylacetylene
Phenylacetylene
12
13
11
97
92
98
6 4
3-BrC H CHO
6 4
4-CNC H CHO
5
6
OHCC
6
H
4
CHO
Piperidine
Piperidine
Phenylacetylene
Phenylacetylene
15
20
88
86
Furfural
7
8
9
4-CNC
6
H
4
CHO
Morpholine
Morpholine
Morpholine
Morpholine
Phenylacetylene
Phenylacetylene
Phenylacetylene
Phenylacetylene
15
15
10
16
94
94
98
89
4-FC
6
3
4
H CHO
4-CF
6 4
C H CHO
1
0
6 4
3-OHC H CHO
This journal is © The Royal Society of Chemistry 2015
RSC Adv., 2015, 5, 34502–34510 | 34507

View Article Online
RSC Advances
Paper
Table 2 (Contd.)
Entry
Aldehyde
Amine
Alkyne
Propargylamine
Time (h)
18
Yield (%)
92
11
12
13
14
Butanal
Piperidine
Phenylacetylene
4-CH
3
C
6
H
4
CHO
CHO
Piperidine
Morpholine
Piperidine
Morpholine
Phenylacetylene
Phenylacetylene
Phenylacetylene
Phenylacetylene
18
20
12
14
95
93
96
94
4-CH
3
C
6
H
4
2-ClC
6
H
H
4
CHO
1
1
5
6
2-ClC
6
4
CHO
4-CH
3
C
6
H
4
CHO
Piperidine
Piperidine
4-Ethynylanisole
4-Ethynylanisole
18
18
93
94
1
7
8
PhCHO
PhCHO
1
Morpholine
4-Ethynylanisole
19
92
a
ꢀ
2
Condition: aldehyde (0.5 eq.), amine (0.6 eq.), alkyne (0.65 eq.) and MNP@PILAu (5 mg, 1.0 mol% Au) in 1.5 mLs H O at 60 C.
were obtained (entry 7–10, 13, 15 and 18). To verify the activity of experimental conditions. As can be seen from Table 2, entry 16,
electron-donor group-containing alkynes, 4-ethynylanisole was the reaction was conducted to high yielding of propargylamin
reacted with benzaldehyde and piperidine under optimized that contains electron-donor alkyne unit. With this promising
34508 | RSC Adv., 2015, 5, 34502–34510
This journal is © The Royal Society of Chemistry 2015

View Article Online
Paper
RSC Advances
2
3
4
B. S. Takale, M. Bao and Y. Yamamoto, Org. Biomol. Chem.,
2014, 12, 2005.
E. C. Dreaden, A. M. Alkilany, X. Huang, C. J. Murphy and
M. A. El-Sayed, Chem. Soc. Rev., 2012, 41, 2740.
(a) A. Abad, P. Concepci ´o n, A. Corma and H. Garcia, Angew.
Chem., Int. Ed., 2005, 44, 4066; (b) D. I. Enache, J. K. Edwards,
P. Landon, B. Solsona-Espriu, A. F. Carley, A. A. Herzing,
M. Watanabe, C. J. Kiely, D. W. Knight and
G. J. Hutchings, Science, 2006, 311, 362; (c) H. Miyamura,
R. Matsubara, Y. Miyazaki and S. Kobayashi, Angew. Chem.,
Int. Ed., 2007, 46, 4151.
3
Fig. 7 Reuse of MNP@PILAu in the A coupling reaction of phenyl
acetylene, 4-chlorobenzaldehyde and piperidine.
5
(a) C. M. Krauter, A. S. K. Hashmi and M. Pernpointner,
ChemCatChem, 2010, 2, 1226; (b) G. Mazzone, N. Russo
and E. Sicilia, Organometallics, 2012, 31, 3074; (c)
J. Cord ´o n, G. Jim ´e nez-Os ´e s, J. M. L ´o pez-de-Luzuriaga,
M. Monge, M. E. Olmos and D. Pascual, Organometallics,
observation, morpholine and the other aromatic aldehydes
were applied for the three component coupling reactions. As
depicted in Table 2, entry(16–18) aliphatic electron-donor give
3
good to excellent yield to corresponding products. The A
2
014, 33, 3823.
H. A. Wegner and M. Auzias, Angew. Chem., Int. Ed., 2011, 50,
236.
(a) Z. Li, C. Brouwer and C. He, Chem. Rev., 2008, 108, 3239;
b) W. Rao, M. J. Koh, D. Li, H. Hirao and P. W. H. Chan, J.
coupling reaction was investigated with aliphatic aldehydes and
secondary aliphatic amines. As expected the reaction of
aliphatic aldehydes or secondary aliphatic amines proceeded
smoothly to propagylamine products (Table 2, entry 11).
The reusability of MNP@PILAu was investigated by using
phenyl acetylene, 4-chlorobenzaldehyde and piperidine as a
6
7
8
(
Am. Chem. Soc., 2013, 135, 7926; (c) C. Shu, C. B. Chen,
W. X. Chen and L. W. Ye, Org. Lett., 2013, 15, 5542.
A. Corma, A. Leyva-P ´e rez and M. J. Sabater, Chem. Rev., 2011,
3
sample for A reaction under aforementioned optimized
8
9
condition. The yields of products were measured aer 12 h in
each cycle and the separated catalyst was washed, dried for the
next cycle. The recycling process was followed for 10 times
without any signicant diminish at the yields of propargylamine
1
11, 1657.
(a) L. Tang, X. Guo, Y. Yang, Z. Zha and Z. Wang, Chem.
Commun., 2014, 50, 6145; (b) T. Mitsudomea and
K. Kaneda, Green Chem., 2013, 15, 2636; (c) K. Layek,
M. L. Kantam, M. Shirai, D. Nishio-Hamane, T. Sasakid
and H. Maheswaran, Green Chem., 2012, 14, 3164.
0 (a) G. Villaverde, A. Corma, M. Iglesias and F. S ´a nchez, ACS
Catal., 2012, 2, 399; (b) A. Corma, J. Navas and M. J. Sabater,
Chem.–Eur. J., 2012, 18, 14150; (c) X. Zhang and A. Corma,
Angew. Chem., Int. Ed., 2008, 47, 4358; (d) C. Wei and
C. J. Li, J. Am. Chem. Soc., 2003, 125, 9584.
(
Fig. 7). In order to investigate metal leaching, AAS analysis was
used. AAS analysis indicated that there is no signicant gold
leaching aer 10 times. According to these observations, the
proposed catalyst not only can be used for three component
coupling reaction but also can be easily separated and reused
for several times without any signicant loss of activity.
1
Conclusion
11 S. Carrettin, P. Concepci ´o n, A. Corma, J. M. L ´o pez Nieto and
V. F. Puntes, Angew. Chem., Int. Ed., 2004, 43, 2538.
In conclusion, we have introduced a new heterogeneous catalyst
based on gold ions immobilized on magnetic poly(imidazole/
imidazolium) for the synthesis of propargylamines. The cata-
lyst is stable under air atmosphere and can readily be recovered
by an external magnetic eld. In order to use vinyl imidazole as
a monomer of polymer, a high level of gold ion was loaded on
MNP@PIL leading to the use of a small quantity (0.005 g) of
catalyst in each reaction. The reaction is simple and followed
under green and mild conditions. This reaction is applicable to
both aromatic/aliphatic alkynes and aldehydes and generates
propargylamine derivatives in good to excellent yields. The
simple synthesis, easy magnetic recovery, excellent reusability
1
2 (a) S. S. Liu, X. Liu, L. Yu, Y. M. Liu, H. Y. He and Y. Cao,
Green Chem., 2014, 16, 4162; (b) M. Boominathan,
N. Pugazhenthiran, M. Nagaraj, S. Muthusubramanian,
S. Murugesan and N. Bhuvanesh, ACS Sustainable Chem.
Eng., 2013, 1, 1405.
1
1
3 (a) H. J. Cho, S. Jung, S. Kong, S. J. Park, S. M. Lee and
Y. S. Lee, Adv. Synth. Catal., 2014, 356, 1056; (b) F. Shi,
Q. Zhang, Y. Ma, Y. He and Y. Deng, J. Am. Chem. Soc.,
2005, 127, 4182.
4 (a) Q. Y. Bi, X. L. Du, Y. M. Liu, Y. Cao, H. Y. He and
K. N. Fan, J. Am. Chem. Soc., 2012, 134, 8926; (b)
X. Zhang, H. Shi and B. X. Xu, Angew. Chem., Int. Ed.,
(up to 10 runs) and high loading of gold ion onto the catalyst
2
005, 44, 7132; (c) J. E. Bailie and G. J. Hutchings, Chem.
surface are some of advantage of the present catalyst which
make it useful in large scale application.
Commun., 1999, 2151.
1
1
5 B. Karimi and F. K. Esfahani, Chem. Commun., 2009, 5555.
6 (a) B. Karimi and F. K. Esfahani, Adv. Synth. Catal., 2012, 354,
1
2
319; (b) B. Karimi and F. K. Esfahani, Chem. Commun.,
011, 47, 10452.
References
1
Y. Ito, M. Sawamura and T. Hayashi, J. Am. Chem. Soc., 1986, 17 X. Shen, X. Fang, H. Zhou and H. Liang, Chem. Lett., 2004,
08, 6405. 33, 1468.
1
This journal is © The Royal Society of Chemistry 2015
RSC Adv., 2015, 5, 34502–34510 | 34509

View Article Online
RSC Advances
Paper
1
1
2
8 Q. Zhao, P. Zhang, M. Antonietti and J. Yuan, J. Am. Chem.
Soc., 2012, 134, 11852.
9 A. Pourjavadi, S. H. Hosseini, N. Zohreh and C. Bennett, RSC 24 (a)
Adv., 2014, 4, 46418.
0 (a) A. A. Boulton, B. A. Davis, D. A. Durden, L. E. Dyck,
Chem. Commun., 2002, 2440; (c) H. Miyabe, M. Ueda,
A. Nishimura and T. Naito, Org. Lett., 2002, 4, 131.
M.
Jeganathan,
A.
Dhakshinamoorthy
and
K. Pitchumani, ACS Sustainable Chem. Eng., 2014, 2, 781;
(b) C. Wei, Z. Li and C. J. Li, Org. Lett., 2003, 5, 4473.
A. V. Juorio, X. M. Li, I. A. Paterson and P. H. Yu, Drug Dev. 25 (a) C. Fischer and E. M. Carreira, Org. Lett., 2001, 3, 4319; (b)
Res., 1997, 42, 150; (b) M. Miura, M. Enna, K. Okuro and
M. Nomura, J. Org. Chem., 1995, 60, 4999; (c) I. Naota,
H. Takaya and S. I. Murahashi, Chem. Rev., 1998, 98, 2599.
S. Sakaguchi, T. Kubo and Y. Ishii, Angew. Chem., Int. Ed.,
2001, 40, 2534; (c) S. Sakaguchi, T. Mizuta, M. Furuwan,
T. Kubo and Y. Ishii, Chem. Commun., 2004, 1638.
2
1 (a) T. S. Hu, R. Tannert, H. D. Arndt and H. Waldmann, 26 Y. Kuninobu, Y. Inoue and K. Takai, Chem. Lett., 2006, 35,
Chem. Commun., 2007, 3942; (b) H. B. Jeon, Y. Lee, C. Qiao, 1376.
H. Huang and L. M. Sayre, Bioorg. Med. Chem., 2003, 11, 27 (a) C. Wei and C. J. Li, J. Am. Chem. Soc., 2002, 124, 5638; (b)
4
631; (c) J. L. Wright, T. F. Gregory, S. P. Kesten,
N. Gommermann, C. Koradin, K. Polborn and P. Kn ¨o chel,
Angew. Chem., Int. Ed., 2003, 42, 5763; (c) S. B. Park and
H. Alper, Chem. Commun., 2005, 1315.
P. A. Boxer, K. A. Serpa, L. T. Meltzer, L. D. Wise,
S. A. Espitia, C. S. Konkoy, E. R. Whittemore and
R. M. Woodward, J. Med. Chem., 2000, 43, 3408.
28 W. W. Chen, H. P. Bi and C. J. Li, Synlett, 2010, 475.
2
2 B. J. Wakeeld, Organomagnesium Methods in Organic 29 B. Karimi, M. Gholinejad and M. Khorasani, Chem.
Synthesis, Academic Press, London, 1995, p. 3. Commun., 2012, 48, 8961.
3 (a) C. C. K. Keh, C. M. Wei and C. J. Li, J. Am. Chem. Soc., 30 A. Pourjavadi, S. H. Hosseini, S. T. Hosseini and
2
2003, 125, 4062; (b) T. S. Huang, C. C. K. Keh and C. J. Li,
S. A. Aghayeemeibody, Catal. Commun., 2012, 28, 86.
34510 | RSC Adv., 2015, 5, 34502–34510
This journal is © The Royal Society of Chemistry 2015