Highly stable magnetically separable copper nanocatalyst as an efficient catalyst for C(sp2)–C(sp) and C(sp2)–C(sp2) cross-coupling reactions

Article abstract of DOI:10.1002/aoc.3691

A copper catalyst has been explored as an efficient and recyclable catalyst to effect Sonogashira and Suzuki cross-coupling reactions. After modification of 2-(((piperazin-1-ylmethyl)imino)methyl)phenol (PP) on the surface of amorphous silica-coated iron oxide (Fe₃O₄@SiO₂@Cl) magnetic core–shell nanocomposite, copper(II) chloride was employed to synthesize the Fe₃O₄@SiO₂@PP-Cu catalyst, affording a copper loading of 1.52?mmol?g^?1. High yield, low reaction times, non-toxicity and recyclability of the catalyst are the main merits of this protocol. The catalyst was characterized using Fourier transform infrared, X-ray photoelectron, energy-dispersive X-ray and inductively coupled plasma optical emission spectroscopies, X-ray diffraction, scanning and transmission electron microscopies, and vibrating sample magnetometry.

Full text of DOI:10.1002/aoc.3691

Received: 1 October 2016
DOI 10.1002/aoc.3691
Accepted: 25 October 2016
F U L L PA P E R
Highly stable magnetically separable copper nanocatalyst as an
2
2
2
efficient catalyst for C(sp )–C(sp) and C(sp )–C(sp ) cross‐
coupling reactions
1
1
2
3
Hassan Keypour | Masomeh Balali | Razieh Nejat | Mojtaba Bagherzadeh
1
Faculty of Chemistry, Bu‐Ali Sina University,
A copper catalyst has been explored as an efficient and recyclable catalyst to
effect Sonogashira and Suzuki cross‐coupling reactions. After modification of
2‐(((piperazin‐1‐ylmethyl)imino)methyl)phenol (PP) on the surface of amorphous
silica‐coated iron oxide (Fe O @SiO @Cl) magnetic core–shell nanocomposite,
Hamedan 65174, Iran
2
Faculty of science, Department of Chemistry,
Kosar University of Bojnord, Iran
3
Chemistry Department, Sharif University of
3
4
2
Technology, PO Box 11155–3615, Tehran, Iran
copper(II) chloride was employed to synthesize the Fe O @SiO @PP‐Cu catalyst,
3
4
2
Correspondence
Mojtaba Bagherzadeh, Chemistry Department,
Sharif University of Technology, PO Box
−1
affording a copper loading of 1.52 mmol g . High yield, low reaction times, non‐
toxicity and recyclability of the catalyst are the main merits of this protocol. The
catalyst was characterized using Fourier transform infrared, X‐ray photoelectron,
energy‐dispersive X‐ray and inductively coupled plasma optical emission
spectroscopies, X‐ray diffraction, scanning and transmission electron microscopies,
and vibrating sample magnetometry.
1
1155–3615, Tehran, Iran.
Email: bagherzadeh@sharif.edu
Funding information
Faculty of Chemistry of Bu‐Ali Sina University;
Research Council of Sharif University of
Technology
KEYWORDS
magnetic nanocatalyst, magnetite Cu nanoparticle‐supported catalyst, Sonogashira and
Suzuki cross‐coupling reactions
[
11–14]
1
|
INTRODUCTION
activity,
but their difficult separation leads to the con-
clusion that they cannot be reused in subsequent reactions.
Metal catalysts have been studied widely as versatile
catalysts in modern organic synthesis for the formation
of carbon–carbon bonds, such as in hydrogenation, Heck,
Suzuki, Stille and Sonogashira cross‐coupling reactions.
Therefore from a ‘green’ chemistry point of view, homoge-
[
15]
neous catalysts are not acceptable.
Hence, immobilization
of metal complexes as recyclable heterogeneous catalysts has
attracted much attention and made great advances. However,
most supported metal catalysts have a lower activity in com-
parison with similar homogeneous systems. An important
strategy for overcoming this problem is the fixing of a homo-
geneous metal catalytic system into a carrier in which the
active centres are supported on a large surface area in order
to achieve a high dispersion of the catalytic active sites.
Providing a high surface to volume ratio which can
increase the contact between catalysts and reactants is one
of the appealing advantages of nanoparticles as carriers.
Small size, high activity and easy separation via magnetic
[1–7]
However, since most of these reactions need a noble
metal catalyst, investigators have focused their attention
on reducing the cost of the reactions either by replacing
[8]
noble metals with cheaper metals or by using noble
[
9,10]
metal nanoparticles immobilized on solid supports.
Hence, much recent attention has been focused on
employing less expensive transition metal catalyst com-
plexes, like those of copper, to replace palladium. In this
context, the Suzuki and Sonogashira reactions are useful
2
2
couplings for the efficient formation of C(sp )─C(sp )
2
[16–18]
and C(sp )─C(sp) bonds with good functional group
concentration are the ideal specifications of a catalyst.
tolerance.
Such properties are achievable by employing nanochemistry
technology.
[
19,20]
Two important parameters in the design of new catalysts,
activity and recyclability, have to be considered. A large
number of homogeneous catalysts show excellent catalytic
In this paper, we report the production of a copper cata-
lyst based on Schiff base‐functionalized magnetic Fe O4
3
Appl Organometal Chem 2016; 1–7
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
1

2
KEYPOUR ET AL.
nanoparticles as an efficient and recyclable catalyst for C─C
coupling reactions including the Suzuki and Sonogashira
reactions. The reactions were performed in an environmen-
tally friendly solvent with high efficiency and excellent
yields. The catalyst can be easily separated from the reaction
medium using an external magnet and reused in subsequent
reactions.
2
2
|
RESULTS AND DISCUSSION
.1 | Characterization of novel catalyst
As illustrated in Scheme 1, the synthesis of
Fe O @SiO @PP‐Cu catalyst is a multistep procedure.
3
4
2
First, superparamagnetic Fe O nanoparticles were prepared
3
4
[21]
by the co‐precipitation method.
Next, the surface of
Fe O was encapsulated by silica in order to increase the
3
4
functionality and stability of the nanoparticles. For this pur-
pose, silica‐coated magnetic nanoparticles (Fe O @SiO )
3
4
2
were synthesized by basic hydrolysis and condensation of
tetraethyl orthosilicate (TEOS) on the surface of the
[22]
Fe O nanoparticles.
The Fe O @SiO nanoparticles
3 4 2
3
4
FIGURE 1 FT‐IR spectra of (a) Fe
3 4 2 3 4 2
O @SiO @Cl, (b) Fe O @SiO @PP
were surface‐modified with 3‐chloropropyltriethoxysilane
and (c) Fe @SiO @PP‐Cu catalyst
3
O
4
2
(
CPTES) which introduced ─Cl groups on to the surface
[
23]
of the support.
For preparation of Fe O @SiO @PP
3 4 2
1
nanoparticles, Fe O @SiO @Cl nanoparticles were reacted
assigned to the C═N bonds from 1642 cm− in the spectrum
3
4
2
−1
with 2‐(((piperazin‐1‐ylmethyl)imino)methyl)phenol (PP).
Undoubtedly, the Schiff base ligand on the surface of the
Fe O @SiO @PP nanoparticles has a good ability to
of Fe O @SiO @PP to 1633 cm
in that of
3
4
2
Fe O @SiO @PP‐Cu (Figure 1c) confirms the coordination
3
4
2
[
25]
of Schiff base ligand.
3
4
2
form complexes with many transition metal centres which
makes the Fe O @SiO @PP nanoparticles a suitable candi-
X‐ray diffraction (XRD) patterns allow the determination
of the crystal structures of the synthesized nanoparticles
(Fe O , Fe O @SiO , Fe O @SiO @Cl, Fe O @SiO @PP
3
4
2
date for immobilization applications. With respect to this,
Fe O @SiO @PP was reacted with copper(II) chloride in
3
4
3
4
2
3
4
2
3
4
2
and Fe O @SiO @PP‐Cu). Sharp peaks confirm the good
3
4
2
3
4
2
ethanol to synthesize Fe O @SiO @PP‐Cu.
crystallinity of Fe O4 (Figure 2). The XRD pattern of
3
4
2
3
The Fourier transform infrared (FT‐IR) spectrum of
Fe O exhibits six diffraction peaks at 2θ of about 30.2°,
3
4
Fe O @SiO @Cl shows absorption bands at 2910 and
35.5°, 43.1°, 53.2°, 57.1° and 63.8° which correspond to
3
4
2
−1
2
850 cm (Figure 1a) which are ascribed to C─H stretching
indices (220), (311), (400), (422), (511) and (440), respec-
[
21]
[26]
of the propyl group. In addition, the presence of magnetite
tively.
Fe O @SiO exhibits a broadened XRD pattern
3 4 2
−
1 [24]
.
is evident from the band at 620 cm
The broad band at
110 cm− is the characteristic peak of the Si─O─Si group.
The spectrum of Fe O @SiO @PP exhibits a ν(C═N) stretch
due to its non‐crystalline nature at 2θ = 20–29°. The results
for Fe O @SiO @PP‐Cu are in agreement with standard
1
1
3
4
2
patterns of inverse cubic spinel magnetite (Fe O ). The peak
3
4
2
3
4
at 1642 cm− (Figure 1b). The shift of the absorption band
1
FIGURE
2
XRD patterns of Fe
@PP and Fe @SiO
2
3
O
4
, Fe
@PP‐Cu
3
O
4
@SiO
2
3 4 2
, Fe O @SiO @Cl,
SCHEME 1 Step‐by‐step synthesis of Fe
3
O
4
@SiO
2
@PP‐Cu
Fe @SiO
3
O
4
2
3
O
4

KEYPOUR ET AL.
3
intensity is weakened and its width is broadened gradually in
size is estimated at between 20 and 30 nm (Figure 4). The
dark spots within the microspheres are magnetic Fe O nano-
the pattern of Fe O @SiO @PP‐Cu (Figure 2).
3
4
2
3 4
Scanning electron microscopy (SEM) images of the
particles, while SiO appears as a lighter colour.
2
products Fe O and Fe O @SiO @PP‐Cu are shown in
The thermal behaviour of Fe O @SiO @PP‐Cu was
3
4
3
4
2
3
4
2
Figure 3(a) and (b), respectively. It is found that the nanopar-
ticles are present as uniform particles with spherical morphol-
ogy. SEM images reveal that the Fe O particles are
studied using thermogravimetric analysis (TGA). TGA exper-
iments were performed under a nitrogen atmosphere with a
heating rate of 10 °C min− in the range 25–600 °C.
Figure 5 indicates the occurrence of three distinct weight loss
stages during nanoparticle pyrolysis. At 600 °C, the residual
mass percent of Fe O @SiO @PP‐Cu is about 77.9%. The
1
3
4
aggregated having rough external surfaces (Figure 3a). Silica
coating makes the particles exhibit smooth and spongy
surfaces (Figure 3b) which indicates the successful coating
of silica over the magnetic nanoparticles. However, the
nanocatalyst particles still fall in the nanometric size
3
4
2
weight loss of 3.2% from 50 to 150 °C is mainly due to the
loss of physically adsorbed water, while the second and third
weight loss peaks in the range 150–600 °C are ascribed to the
[
27,28]
range.
[
29]
Figure 4 shows a typical transmission electron micros-
loss of organic Schiff base and propyl linkage.
copy (TEM) image of as‐synthesized Fe O @SiO @PP‐Cu
X‐ray photoelectron spectroscopy (XPS) was applied to
determine the oxidation state of the copper content (Figure 6).
XPS analysis of the Fe O @SiO @PP‐Cu nanoparticles
3
4
2
[
28]
nanoparticles.
Particles have a spherical morphology
(Figure 4). From the TEM micrographs the average particle
3
4
2
(Figure 6a) shows expected elements on the surface of the
nanocatalyst, such oxygen, carbon, nitrogen and copper. In
addition, the absence of Fe in the XPS analysis (Figure 6a)
3 4 2
FIGURE 5 TGA analysis of Fe O @SiO @PP‐Cu catalyst
FIGURE
3
3 4 3 4 2
SEM images of (a) Fe O and (b) Fe O @SiO @PP‐Cu
catalyst
3 4 2
FIGURE 6 XPS spectra for Fe O @SiO @PP‐Cu catalyst: (a) survey scan;
FIGURE 4 TEM image of Fe
3
O
4
@SiO
2
@PP‐Cu catalyst
(b) Cu 2p

4
KEYPOUR ET AL.
confirms the Fe O cores are completely coated with silica
Furthermore, inductively coupled plasma optical emission
3
4
layer.
spectroscopy (ICP‐OES) analysis of Fe O @SiO @PP‐Cu
shows 9.667 wt% (1.51 mmol g ) of Cu content.
3
4
2
−
1
The XPS spectrum of Cu 2p (Figure 6b) can be fitted to
two peaks at binding energies of 934.68 eV (Cu 2p3/2) and
9
54.68 eV (Cu 2p1/2). The presence of a satellite band nearby
2
.2 | Suzuki cross‐coupling reaction catalysed by
the peak at binding energy of 954.68 eV may represent the
oxidation state (+2) of Cu in 2p1/2 orbital. The results sug-
gest the accumulation of Cu(II) on the sorbent.
Magnetic measurements of the samples were conducted
using vibrating sample magnetometry (VSM) at room tem-
perature (Figure 7). According to the magnetization curves,
the saturation magnetization of the nanoparticles decreases
Fe O @SiO @PP‐Cu
[30]
3
4
2
In order to investigate the catalytic performance of the
Fe O @SiO @PP‐Cu catalyst and the effect of media, the
3
4
2
coupling reaction of iodobenzene with phenylboronic acid
was initially examined as a model reaction. The effects of
solvents, bases, catalyst loading and reaction temperature on
the yield were studied using non‐solvent condition and with
various solvents such dimethylformamide (DMF), DMF–
water and ethanol (Table 1). As evident from Table 1, the best
yields are observed with DMF–water (1:1). Also, maximum
of activity and selectivity of the catalyst are observed in the
−1
from 60 emu g for the initial Fe O sample to 13 emu g
3
4
−
1
for the final Fe O @SiO @PP‐Cu nanoparticles. This
3
4
2
decrease in saturation magnetization is due to the presence
of non‐magnetic silica phase, organic Schiff base group and
copper complex around the Fe O magnetic core. It is note-
3
4
presence of Cs CO as base.
worthy the most significant decrease in magnetization occurs
2
3
[
31]
The reactions were also investigated with various aryl
halides and arylboronic acids to determine the optimal condi-
tions, the results of which are summarized in Table 2. The
time of reaction with aryl iodides was shorter than with aryl
in the coating of Fe O nanoparticles with silica layer.
3
4
The chemical identity of the Fe O , Fe O @SiO ,
3
4
3
4
2
Fe O @SiO @Cl and Fe O @SiO @PP nanoparticles was
3
4
2
3
4
2
confirmed using energy‐dispersive X‐ray (EDX) analysis
Figures S1–S4, respectively). EDX analysis of the
Fe O @SiO @PP‐Cu nanoparticles (Figure 8) shows the
[
33]
bromides with yields being very good to excellent.
It
(
should be noted that the yield of the reaction with aryl iodides
and aryl bromides having an electron‐withdrawing group was
a little greater than for those with an electron‐releasing group
3
4
2
expected elements like iron, oxygen, silicon, carbon, nitrogen
[
32]
and copper.
(Table 2, entries 2–4 and 8–10). We utilized this catalyst in
coupling 2‐naphthylboronic acid as a larger ring and the reac-
[
34]
tion was successful (entry 6).
2
.3 | Sonogashira–Hagihara reaction catalysed by
Fe O @SiO @PP‐Cu
3
4
2
The Cu nanoparticle catalyst was also used for the
Sonogashira–Hagihara reaction in which iodobenzene and
TABLE 1 Optimization conditions in Suzuki reaction between iodobenzene
and phenylboronic acid in the presence of Fe O @SiO @PP‐Cu
3 4 2
a
Solvent
Base
Catalyst (g) T (°C) Time (h) Yield (%)
FIGURE
7
VSM analysis of (a) Fe
@PP‐Cu
3
O
4
, (b) Fe
3
O
4
@SiO
2
and (c)
DMF–H O
—
0.01
0.01
0.01
0.01
0.01
0.01
0.005
0.01
0.03
0.01
0.01
0.01
0.01
100
100
100
80
12
1
3
3
3
3
5
2
2
2
5
4
4
—
90
53
65
78
83
86
90
90
55
45
82
87
2
Fe @SiO
3
O
4
2
DMF
Cs
Cs
Cs
Cs
Cs
Cs
Cs
Cs
2
CO
2
CO
2
CO
2
CO
2
CO
2
CO
2
CO
2
CO
3
3
3
3
3
3
3
3
2
H O
EtOH
—
100
80
DMF–H
DMF–H
DMF–H
DMF–H
DMF–H
DMF–H
DMF–H
DMF–H
2
2
2
2
2
2
2
2
O
O
O
O
O
O
O
O
100
100
100
100
100
100
100
DABCO
n‐Pr
KOAc
CO
3
N
K
2
3
a
FIGURE 8 EDX analysis of the Fe
3
O
4
@SiO
2
@PP‐Cu catalyst
Isolated yield.

KEYPOUR ET AL.
5
a
a
TABLE 2 Suzuki reaction of arylboronic acids with aryl halides
TABLE 4 Sonogashira reaction of aryl halides with phenylacetylene
1
b
1
b
Entry
Ar X
Time (min)
Yield (%)
Entry
Ar X
Boronic acid
Time (h)
Yield (%)
1
PhB(OH)
2
2
90
1
30
91
2
PhB(OH)
2
3
85
2
3
4
5
6
7
8
80
45
45
30
45
60
45
80
75
80
80
75
72
78
3
4
PhB(OH)
PhB(OH)
2
2
1.3
2
80
85
5
6
7
4‐NO
C
2 6
H
4
B(OH)
2
1
4
3
89
86
85
2‐NaphthylB(OH)
2
PhB(OH)
2
8
9
PhB(OH)
PhB(OH)
2
2
3
4
80
83
a
Reaction conditions: catalyst (0.02 g), aryl halide (1 mmol), phenylacetylene
2 mmol) and DABCO (2 mmol).
(
b
1
0
PhB(OH)
2
2.3
84
Isolated yield.
the optimization of reaction conditions are presented in
Table 3.
The reaction was then examined with various aryl halides
and phenylacetylene under the determined optimized condi-
tions. The results are summarized in Table 4.
a
Reaction conditions: Fe
3
O
4
@SiO
2
@PP‐Cu (0.01 g), aryl halide (1 mmol),
CO (2 mmol).
arylboronic acid (1.5 mmol) and Cs
b
2
3
Isolated yield.
phenylacetylene were used as model substrates. Various
solvents, bases, temperatures and catalyst loadings were
[35]
3 | CONCLUSIONS
examined in this reaction.
The results obtained for
In summary, a copper complex was immobilized on Schiff
TABLE 3 Optimization conditions in Sonogashira reaction between
base‐modified magnetic Fe O @SiO nanoparticles by
3
4
2
iodobenzene and phenylacetylene in the presence of Fe
3
O
4
@SiO
2
@PP‐Cu
covalent linkage.
The obtained nanoparticles were identified with various
a
characterization methods. The Fe O @SiO @PP‐Cu
3
4
2
Solvent
Base
Catalyst (g)
T (°C)
Time (h)
Yield (%)
nanocatalyst shows good activity towards Sonogashira and
Suzuki cross‐coupling reactions in an environmentally
friendly solvent (water–DMF) under mild conditions. The
catalyst shows not only high catalytic activity, but also offers
many practical advantages such recyclability and air stability.
Potentially, the nanocatalyst could be applied in large‐scale
industrial synthesis.
DMF–H
2
O
—
0.02
0.02
0.02
0.02
0.02
0.01
0.02
0.03
0.02
0.02
0.02
0.02
100
100
100
100
80
12
0.5
5
—
91
47
73
78
78
91
91
88
54
80
82
DMF
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
2
H O
—
2
DMF–H
DMF–H
DMF–H
DMF–H
DMF–H
DMF–H
DMF–H
DMF–H
2
2
2
2
2
2
2
2
O
O
O
O
O
O
O
O
1
100
100
100
100
100
100
100
0.5
0.5
0.5
1
4
| EXPERIMENTAL
Cs
n‐Pr
KOAc
CO
2
CO
3
3
N
3
2
4.1 | Materials
K
2
3
2
TEOS, 1,4‐bis(bromomethyl)benzene, CPTES and 2‐
hydroxybenzaldehyde were purchased from Aldrich. All
a
Isolated yield.

6
KEYPOUR ET AL.
commercially available solvents and tested compounds were
of analytical reagent grade and used without further
purification.
separated magnetically, then washed with methanol several
times to remove the unreacted residue of the PP and dried
under vacuum at 303 K.
4
.3.4 | Preparation of Fe O @SiO @PP‐Cu catalyst
3
4
2
4
1
.2 | Characterization methods
For the preparation of the nanocatalyst, CuCl (1.0 mmol)
2
13
H NMR and C NMR spectra were measured in DMSO‐d6
using a Bruker Avance 300 MHz instrument (DRX). Melting
points were determined with an SMPI apparatus. The struc-
ture of the new magnetite nanocatalyst was characterized
using FT‐IR spectroscopy, XRD, SEM, EDX, TEM, TGA/
DTA, XPS and VSM. FT‐IR spectra were recorded as KBr
pellets using a PerkinElmer Spectrum Version 10.01.00 spec-
trophotometer. SEM was carried out with a Philips XL30.
TGA/DTA curves were determined using a Mettler Toledo
was dissolved in ethanol (50 ml). Next, 1.0 g of
Fe O @SiO @PP was added to this solution and refluxed
for 24 h under a nitrogen atmosphere. After separation with
an external magnet, the product was washed with ethanol to
remove unreacted CuCl2.
3
4
2
4
.4 | Application of catalyst for suzuki reaction
In a conical flask, a mixture of aryl halide (1.0 mmol),
arylboronic acid (1.5 mmol), Cs CO (2.0 mmol) and
Fe @SiO @PP‐Cu catalyst (0.01 g) was stirred at
851 apparatus. XPS was carried out with a dual anode
2
3
(Mg and Al Kα) achromatic X‐ray source. Magnetic mea-
3
O
4
2
surements of materials were conducted with a VSM instru-
ment (4 inch, Daghigh Meghnatis Kashan Co., Kashan,
Iran) at room temperature. XRD was performed using an X‐
ray diffractometer (ITAL Structures model APD2000) with
Cu Kα radiation, in the 2θ range of 5° to 90°. TEM images
were obtained with an EM10C (Zeiss) transmission electron
microscope at an accelerating voltage of 80 kV. Samples
dispersed in solution were cast onto a carbon‐coated cop-
per grid. Cu content of the catalyst was determined using
ICP‐OES.
100 °C under aerobic conditions. After completion of the
reaction (monitored by TLC), EtOAc (10 ml) was added to
the mixture, stirred for 5 min and filtered to separate the
catalyst. Water (15 ml) was added and the products were
extracted with ethyl acetate (3 × 50 ml). The combined
extracts were dried over anhydrous Na SO , filtered and then
2 4
dried by rotary evaporation. The purification of the resulting
crude products by column chromatography (hexane–ethyl
acetate) afforded the pure products in excellent yields.
4
.5 | Application of catalyst for Sonogashira–Hagihara
reaction
In a conical flask, a mixture of Fe O @SiO @PP‐Cu catalyst
4
.3 | Preparation of catalyst
4
.3.1
|
Preparation of Fe O , Fe O @SiO and
3
4
2
3
4
3
4
2
(0.02 g), aryl halide (1.0 mmol), phenylacetylene (2 mmol),
Fe O @SiO @Cl
3
4
2
1
,4‐diazabicyclo[2.2.2]octane (DABCO; 2 mmol) and H O–
2
At first, Fe O4 and Fe O @SiO magnetic nanoparticles
3
3
4
2
DMF (5 ml) was stirred at 100 °C under aerobic conditions.
After completion of the reaction (monitored by TLC), extrac-
tion of products was carried out as described in Section 3.4,
which were purified by column chromatography. Finally,
evaporation of the solvent afforded the desired pure products
in good yields.
were synthesized according to a procedure previously
[21,22]
reported in the literature.
The obtained Fe O @SiO
3 4 2
nanoparticles were dried under vacuum and then modified
[
23]
with CPTES.
4
.3.2
| Preparation of 2‐(((piperazin‐1‐ylmethyl)imino)
methyl)phenol (PP)
ACKNOWLEDGMENTS
2‐Hydroxybenzaldehyde (0.122 g, 1.00 mmol) in ethanol was
We are grateful to the Faculty of Chemistry of Bu‐Ali Sina
University for financial support. We also acknowledge the
Research Council of Sharif University of Technology for
research funding of this project.
added dropwise with stirring to a solution of 2‐(piperazin‐1‐
yl)ethan‐1‐amine (0.129 g, 1.00 mmol) in ethanol (50 ml),
over a period of 30 min. The mixture was stirred and refluxed
for 2 h. A yellow precipitate was obtained that was filtered off
[
36]
and washed with cold ethanol and dried in vacuum.
Yield
−1
REFERENCES
0
.220 g (88%); m.p. 118 °C. FT‐IR (KBr, cm ): 1640
1
[1] Á. Molnár (Ed), Palladium‐Catalyzed Coupling Reactions, Wiley‐VCH,
Weinheim 2013.
(
ν(C═N)) 1596, 1484 (ν(C═C)ar). H NMR (90 MHz,
CDCl , δ , ppm): 3.766 (s, 10H, CH ), 8.149 (s, H, CH═N),
3
H
2
[
[
[
2] V. Polshettiwar, C. Len, A. Fihri, Coord. Chem. Rev. 2009, 253, 2599.
6.352–7.988 (m, 4H, ArH), 13.233 (s, 1H, OH).
3] Á. Molnár, G. V. Smith, M. Bartók, J. Catal. 1986, 101, 67.
4] G. Szöllősi, T. Hanaoka, S. Niwa, F. Mizukami, M. Bartók. J. Catal. 2005,
4
.3.3 | Preparation of Fe O @SiO @PP
3 4 2
231, 480.
Fe O @SiO @Cl was suspended in 100 ml of methanol with
sonication. PP (0.8 mmol) was then added. The resulting
mixture was refluxed for 24 h. The resultant solid was
3
4
2
[5] G. Szollosi, B. Herman, K. Felfoldi, F. Fulop, M. Bartok, Adv. Synth. Catal.
2008, 350, 2804.
[6] F. Alonso, I. P. Beletskaya, M. Yus, Tetrahedron 2005, 61, 11771.

KEYPOUR ET AL.
7
[
[
[
7] F. Alonso, I. P. Beletskaya, M. Yus, Tetrahedron 2008, 64, 3047.
8] R. Loska, C. M. R. Volla, P. Vogel, Adv. Synth. Catal. 2008, 350, 2859.
9] Q. Du, W. Zhang, H. Ma, J. Zheng, B. Zhou, Y. Li, Tetrahedron 2012, 68,
[27] C. I. Fernandes, M. D. Carvalho, L. P. Ferreira, C. D. Nunes, P. D. Vaz,
J. Organometal. Chem. 2014, 760, 2.
[
28] S. Shylesh, J. Schweizer, S. Demeshko, V. Schnemann, S. Ernst, W. R. Thiel.
Adv. Synth. Catal. 2009, 351, 1789.
3577.
[
29] M. Jafarzadeh, I. A. Rahman, C. S. Sipaut, Synth. Met. 2012, 162, 466.
30] Z.‐C. Wu, Z.‐Z. Wang, J. Liu, J.‐H. Yin, S.‐P. Kuang, Int. J. Biol. Macromol.
[
[
[
[
10] H. Firouzabadi, N. Iranpoor, A. Ghaderi, J. Mol. Catal. A 2011, 347, 38.
11] K. W. Anderson, S. L. Buchwald, Angew. Chem. Int. Ed. 2005, 44, 6173.
12] B. Saito, G. C. Fu, J. Am. Chem. Soc. 2007, 129, 9602.
[
2015, 81, 838.
[
31] M. Masteri‐Farahani, N. Tayyebi, J. Mol. Catal. A 2011, 348, 83.
13] Z. Zhao, Y. L. Fang, P. J. J. Alvarez, M. S. Wong, Appl. Catal. B 2013,
[
32] H. Keypour, M. Balali, M. M. Haghdoost, M. Bagherzadeh, RSC Adv. 2015,
140–141, 468.
5
, 53349.
33] R. Nejat, A. R. Mahjoub, Z. Hekmatian, T. Azadbakht, RSC Adv. 2015, 5,
6029.
[
[
[
[
[
14] K. L. Billingsley, S. L. Buchwald, Angew. Chem. Int. Ed. 2008, 120, 4773.
[
[
15] F. Cozzi, Adv. Synth. Catal. 2006, 348, 1367.
1
16] F. Matloubi‐Moghaddam, S. E. Ayati, RSC Adv. 2015, 5, 3894.
17] J. Safari, L. Javadian, RSC Adv. 2014, 4, 48973.
34] Y.‐Y. Sun, J. Yi, X. Lu, Z.‐Q. Zhang, B. Xiao, Y. Fu, Chem. Commun. 2014,
50, 11060.
18] N. Zohreh, S. H. Hosseini, A. Pourjavadi, C. Bennett, RSC Adv. 2014, 4,
[35] H.‐J. Chen, Z.‐Y. Lin, M.‐Y. Li, R.‐J. Lian, Q.‐W. Xue, J.‐L. Chung, S.‐C.
Chen, Y.‐J. Chen, Tetrahedron 2010, 66, 7755.
5
0047.
19] S. Shylesh, V. Schunemann, W. R. Thiel, Angew. Chem. Int. Ed. Engl. 2010,
9, 3428.
20] T. Zeng, L. Yang, R. Hudson, G. Song, A. R. Moores, C.‐J. Li, Org. Lett.
011, 13, 442.
[
[
[
[
[36] H. Keypour, P. Arzhangi, N. Rahpeyma, M. Rezaeivala, Y. Elerman, O.
4
Büyükgüngör, L. Valencia, H. R. Khavasi, J. Mol. Struct. 2010, 977, 6.
2
How to cite this article: Keypour, H., Balali, M.,
Nejat, R., and Bagherzadeh, M. (2016), Highly stable
magnetically separable copper nanocatalyst as an effi-
cient catalyst for C(sp2)–C(sp) and C(sp2)–C(sp2)
cross‐coupling reactions, Appl Organometal Chem,
doi: 10.1002/aoc.3691
21] M. Bagherzadeh, M. M. Haghdoost, F. Matlobi‐Moghaddam, B. Koushki‐
Foroushani, S. Sarazdi, E. Payab, J. Coord. Chem. 2013, 66, 3025.
22] M. Bagherzadeh, M. M. Haghdoost, A. Shahbazirad, J. Coord. Chem. 2012,
65, 591.
[23] A. Rostami, B. Atashkar, D. Moradi, Appl. Catal. A 2013, 467, 7.
[24] M. Z. Kassaee, H. Masrouri, F. Movahedi, Appl. Catal. A 2011, 395, 28.
[25] M. Esmaeilpour, A. R. Sardariana, J. Javidi, Appl. Catal. A 2012, 445, 359.
[26] X. Du, J. He, J. Zhu, L. Sun, S. An, Appl. Surf. Sci. 2012, 258, 2717.