Immobilized palladium nanoparticles on MNPs@A-N-AEB as an efficient catalyst for C-O bond formation in water as a green Solvent

Article abstract of DOI:10.1002/aoc.4463

Palladium nanoparticles immobilized on the magnetic nanoparticles@2-amino-N-(2-aminoethyl) benzamide (MNPs@A-N-AEB.Pd⁰) have been presented as an efficient, and reusable magnetically heterogeneous catalyst for the C-O coupling reaction, namely Ullmann condensation reactions in an aqueous medium. This heterogeneous catalyst shows superior reactivity for the C-O arylation of different aryl halide (chloride, bromide, and iodide) with phenol derivatives to afford the desired products in good to excellent yields within short reaction time. Moreover, the catalyst can be easily recovered and reused for seven runs without loss of catalytic activity. The catalyst was characterized by several techniques, such as FT-IR, SEM, TEM, EDS, XRD, TGA and ICP-OES.

Full text of DOI:10.1002/aoc.4463

Received: 27 January 2018
DOI: 10.1002/aoc.4463
Revised: 11 April 2018
Accepted: 6 May 2018
F U L L P A P E R
Immobilized palladium nanoparticles on MNPs@A‐N‐AEB
as an efficient catalyst for C‐O bond formation in water as a
green Solvent
Firouz Matloubi Moghaddam
| Mohammad Eslami
Laboratory of Organic Synthesis and
Natural Products, Department of
Chemistry, Sharif University of
Technology, Tehran, Iran
Palladium nanoparticles immobilized on the magnetic nanoparticles@2‐
amino‐N‐(2‐aminoethyl) benzamide (MNPs@A‐N‐AEB.Pd0) have been pre-
sented as an efficient, and reusable magnetically heterogeneous catalyst for
the C‐O coupling reaction, namely Ullmann condensation reactions in an
aqueous medium. This heterogeneous catalyst shows superior reactivity for
the C‐O arylation of different aryl halide (chloride, bromide, and iodide) with
phenol derivatives to afford the desired products in good to excellent yields
within short reaction time. Moreover, the catalyst can be easily recovered
and reused for seven runs without loss of catalytic activity. The catalyst was
characterized by several techniques, such as FT‐IR, SEM, TEM, EDS, XRD,
TGA and ICP‐OES.
Correspondence
Firouz Matloubi Moghaddam, Laboratory
of Organic Synthesis and Natural
Products, Department of Chemistry,
Sharif University of Technology, Azadi
Street, PO Box 111559516, Tehran, Iran.
Email: matloubi@sharif.edu
Funding information
Sharif University of Technology (SUT)
KEYWORDS
green chemistry, heterogeneous catalyst, magnetic nanoparticle, Ullmann reaction, unsymmetrical
diphenyl ether
1 | INTRODUCTION
large‐scale and total synthesis sequence, it often suffers
from some requirements including high temperatures
Diaryl ethers unit constitute a valuable class of organic
structures that represents important roles, such as anti-
fungal, anti‐inflammatory, antiviral, antibacterial, anti-
cancer agents, anti‐tumor, analgesic, and antipyretic
activities[1] in a variety of biologically interesting com-
pounds,[2] A wide range of diaryl ethers are key moieties
in a variety of naturally occurring medicinally active
(125–300 °C), longer reaction times, polar and hazardous
solvents (such as pyridine, collidine, DMF, …) and a stoi-
chiometric amount of the copper reagents.[10]
In recent years, the increased attention to Ullmann
synthesis of diaryl ethers has led to the presented several
innovative heterogeneous and homogeneous catalyst sys-
tems. In this regard, mainly copper and palladium com-
plexes containing electron‐rich ligands have been
developed as catalyst systems for the aryl ether synthesis
under various conditions.[11] although in 2012, Yang et al.
reported Metal‐ and ligand‐free Ullmann type C‐O cou-
pling reaction in harsh and humidity sensitive conditions,
such as potassium tert‐butoxide, DMSO, and 120 °C.[12]
Despite these improvements, the cost of precious
metal and metal residue in products are remaining
unsolved problems. Thus, development of a robust, eco‐
friendly and low‐cost protocol using a reusable and
compounds
K13,[4]
perrottetin,
piperazinomycin,[7] and gerfelin[8] (Figure 1).
including
tetramethylmagnolamine,[3]
obavatol,[5] B,[6]
riccardin
Owing to its applications in pharmaceutical science,
extensive studies for the synthesis of diaryl ether moieties
have been conducted.
The copper‐catalyzed Ullmann coupling of phenols
with aryl halides is one of the most straightforward syn-
thetic pathways for the formation of diaryl ethers.[9]
Although this strategy has the ability to use in the
Appl Organometal Chem. 2018;32:e4463.
wileyonlinelibrary.com/journal/aoc
© 2018 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4463

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MOGHADDAM AND ESLAMI
FIGURE 1 Examples of the pharmaceutical diaryl ether chemical structure in natural products
sustainable catalyst for the green synthesis of diaryl
ethers is an attractive subject for research.
Synthesized catalyst was characterized using several
techniques such as Fourier transform infrared (FT‐IR)
spectroscopy, transmission electron microscopy (TEM),
scanning electron microscopy (SEM), thermogravimetric
analysis (TGA), energy dispersive X‐ray spectroscopy
(EDX) and inductively coupled plasma atomic emission
spectroscopy (ICP‐OES).
From these studies and in connection with our earlier
studies on introducing novel methodologies, specifically,
the use of affordable magnetic nanoparticle[13] as an effi-
cient and clean heterogeneous support that would solve
the problems of separation and reusability of catalyst,
herein we wish to report the successful synthesis, charac-
terization and evaluation of Pd0‐nanoparticles loaded on
the MNPs@A‐N‐AEB as a more sustainable and efficient
catalyst for the Ullmann type C‐O coupling of substituted
aryl halides with various phenols in water medium as a
green solvent (Scheme 1).
Figure 2 shows FT‐IR spectra of MNPs@A‐N‐AEB.Pd0
that was utilized as an elementary analysis for confirming
the anchoring of organic substrates on the surface of mag-
netic nanoparticles. The prominent IR absorption peaks at
600 and 1100 cm−1 was attributed to Fe–O and Si–O, which
truly confirm the formation of Fe3O4 silica‐coated magnetic
nanoparticles (Figure 2a, 2b). The stretching vibration
peaks of Fe‐O‐Si at around 600 cm−1 cannot be seen
because of overlaps with the strong and wide Fe–O vibra-
tion of MNPs. It is noteworthy that the weak stretching
vibrations mode at ~2900 cm−1, attributed to C‐H (alkanes),
confirms the presence of N‐[3‐(Trimithoxysilyl)propyl]
ethylenediamine organosilanes groups as a linker onto the
surface of MPNs (Figure 2d). The presence of the anchored
2‐aminbenzamide was confirmed by vibrational frequency
of C=C, C=O, C‐N and –NH– groups. The two bands at
1579 and 1527 cm−1 can be ascribed to the C=O and C=C
2 | RESULTS AND DISCUSSION
2.1 | Catalyst synthesis
Due to the importance of the application of magnetic
nanoparticles in catalysis[14] and in continuation of our
goals to develop the metal complexes immobilized on
MNPs, MNPs@A‐N‐AEB.Pd0 was synthesized using a fac-
ile synthetic route presented in Scheme 2.
SCHEME 1 O‐arylation of substituted
aryl halides catalysed by Pd0‐nanoparticles
loaded on MNPs@A‐N‐AEB in aqueous
media as a green solvent

MOGHADDAM AND ESLAMI
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SCHEME 2 The schematic pathway for synthesis of MNPs@A‐N‐AEB.Pd0
FIGURE 2 FTIR spectra (Transmittance/wavenumber (cm−1) of (a) Fe3O4, (b) Fe3O4@SiO2, (c) Isatoic anhydride, and (d) MNPs@A‐N‐
AEB.Pd0
double band vibration modes, respectively. Also, the strong
band at 1100 cm−1 is attributable to the C‐N single band.
Again the weak peaks related to –NH– at around 3300–
3450 cm−1 cannot be seen in the spectrum because of the
overlaps with the broad ‐OH vibration originated from the
opening of epoxide and Si‐OH (Figure 2d).
Therefore, SEM, TEM, EDX, CHN and TGA analyses
were required to confirm the uniform distribution of final
MNPs@A‐N‐AEB.Pd0.
The crystallinity of the prepared MNPs@A‐N‐AEB.
Pd0 was investigated by XRD in the range 4 to 80° 2θ
(Figure 3). Six main diffraction peaks at 2θ equal to 30,
35.82, 43.41, 53, 57.46, and 63.01° clearly indicate that
the catalyst preparation does not show any change in
the crystallographic structure of Fe3O4 nanoparticles.
Moreover, the size of the crystalline nanoparticles deter-
mined to be below 25 nm from Scherrer's equation based
on the strongest intensity of 2θ =35.82.
The size, morphology and disparity of the nanoparti-
cles were investigated by the SEM and TEM analyses of
the synthesized MNPs@A‐N‐AEB.Pd0 (Figure 4a, 4b).
The SEM demonstrates the spherical nature of the nano-
particles. The particle size distribution of the catalyst is in
the range of 20–30 nm (Figure 4b). The presence of palla-
dium particles in the catalyst structure was approved by
EDX analysis (Figure 4c).

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MOGHADDAM AND ESLAMI
FIGURE 3 XRD pattern of MNPs@A‐N‐AEB
FIGURE 4 (a) SEM, (b) TEM and (c) EDX images of MNPs@A‐N‐AEB.Pd0
The thermogravimetric analysis (TGA) gives the ther-
mal stability of the catalyst. So that the main change in
mass of samples is monitored from 260 up to 550 °C. As
a result of TGA curves of MNPs@A‐N‐AEB a high
palladium shows the high performance of designed
ligands to keep metal.
2.2 | Catalytic activity
amount of organosilane (1.38 mmol. g−1
immobilized on the magnetic nanoparticles.
)
have
In continuation of our interest to develop mild and envi-
ronmentally friendly methods,[15] the activity of the mag-
netically separable catalyst was consequently investigated
upon characterization in the O‐arylation of phenols with
The successful anchoring of 2‐amino‐benzamide onto
the surface of magnetic nanoparticles was further con-
firmed by CHN analysis of MNPs@A‐N‐AEB and
MNPs@ N‐[3‐(Trimithoxysilyl)propyl] ethylenediamine
(Table 1). Accordingly, 1.45 mmol. g−1 of 2‐
aminobenzamide as well as 1.48 mmol. g−1 organosilane
group were loaded onto the MNPs@SiO2, which is in
complete accordance with TGA analysis.
TABLE 1 CHN (carbon, hydrogen, nitrogen) analysis of
MNPs@A‐N‐AEB and MNPs@ N‐[3‐(Trimithoxysilyl)propyl]
ethylenediamine
Contents
%C %H %N
Finally, the Pd0 content immobilized on the surface of
the support was calculated by ICP‐OES. The obtained
results revealed that the high loading of palladium
(0.72 mmol. g−1) was immobilized. The loading of
MNPs@A‐N‐AEB
23.08 3.13 6.2
10.87 2.4 4.22
MNPs@N‐[3‐(Trimithoxysilyl)propyl]
ethylenediamine

MOGHADDAM AND ESLAMI
5 of 13
aryl halides. Herein, we wish to improve and accelerate
the formation of C‐O bonds between aryl halides and
phenol derivatives using our pd0‐catalytic systems. In this
regard, the investigation was initiated by the reaction of
phenol (2a) with bromobenzene (1e) (less activated aryl
halide) in the presence of K2CO3 (3a) as a model reaction
and in different experimental conditions, namely the
loading of catalyst and base, temperature, ratios of reac-
tants, and reaction time were optimized. The results are
summarized in Table 2. No reaction occurs in the absence
of any transition metal catalysts, and the starting material
has been unreacted. Notably, the presence of a transition
metal catalyst is essential for planning and executing
reactions. Following this result, the reaction was per-
formed with 5 mg (0.036 mol% of Pd0) of desired catalyst
in the presence of K2CO3 (3a) as a base in polar aprotic
and protic solvents at 70 °C for 2 h (Table 2, entry 1–7).
The solvent screening results indicated that both of the
DMF and H2O gives the diphenyl ether product in an
approximately similar yield (83, 85 respectively). This
highlights that the polar solvents play an important role
in enhancing the rate of reaction. Therefore, water was
chosen as the reaction media due to its more green cre-
dentials, availability, and low price (Table 2, entry 5, 6).
In addition to, water has the important role in the closing
the catalytic cycle and recovering the Pd0 catalyst, that
makes it the good solvent to accelerate the coupling
reaction.
Additionally, to study the influence of different sol-
vents on the chemical reactivity of the model reaction,
we examined various kinds of organic and inorganic
bases (e.g. KOH (3b), K3PO4 (3c), NaOAc (3d), Et3N
(3e), DABCO (3f), and Cs2CO3 (3 g)) in comparison with
K2CO3 (3a) (Table 2, entry 8–13). Interestingly, no
TABLE 2 Optimazation of reaction conditions for o‐arylation of phenols under conventional heating conditionsa
Entry
Solvent
Base
Cat. (mg)
Temp. (°C)
Time (min)
Yield (%)b
1
THF
Toluene
CH3CN
EtOH
H2O
K2CO3 3a
K2CO3 3a
K2CO3 3a
K2CO3 3a
K2CO3 3a
K2CO3 3a
K2CO3 3a
KOH 3b
5
80
80
180
180
180
180
180
180
180
180
180
180
180
180
180
180
180
90
41
49
56
51
82
84
78
67
58
58
64
60
80
32
52
89
86
53
91
21
2
5
3
5
80
4
5
80
5
5
80
6
DMF
DMSO
H2O
5
80
7
5
80
8
5
80
9
H2O
K3PO4 3c
NaOAc 3d
NEt3 3e
5
80
10
11
12
13
14
15
16
17
18
19c
20d
H2O
5
80
H2O
5
80
H2O
DABCO 3f
Cs2CO3 3 g
K2CO3 3a
K2CO3 3a
K2CO3 3a
K2CO3 3a
K2CO3 3a
K2CO3 3a
K2CO3 3a
5
80
H2O
5
80
H2O
5
r.t
H2O
5
50
H2O
5
reflux
reflux
reflux
reflux
reflux
H2O
7.5
2.5
5
90
H2O
90
H2O
90
H2O
5
90
aphenol (1 mmol), bromobenzene (1 mmol), base (1.1 mmol), catalyst nanoparticles, solvent (2 ml) and temperature.
bIsolated yield.
cphenol (1 mmol), bromobenzene (1 mmol), base (1.5 mmol), catalyst nanoparticle, solvent (2 ml) and reflux.
dreaction was carried out in the presence of Magnetic catalyst without palladium.

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MOGHADDAM AND ESLAMI
TABLE 3 General scheme O‐arylation of substituted aryl halides catalysed by Pd0‐nanoparticles loaded on MNPs@A‐N‐AEB in aqueous
media as a green solventa
Entry
Aryl Halide
Phenol
Product
Time (min)
Melting Point (°C)
Yield (%)
1
120
27–28[16]
86
1a
2a
2a
4a
2
3
100
120
52–53[17]
51–53
91
89
4b
1b
2a
2a
1c
4c
4a
4
100
44–45[18]
88
4d
1d
5
6
7
90
27–28[16]
Oil
91
85
83
1e
1f
2a
2a
2a
140
130
4e
Oil
4f
1g
8
9
120
110
Oil
89
90
2a
2a
1i
4g
4a
49–51[19]
1j
4h
10
11
12
80
27–28[16]
Oil
93
90
94
1k
1a
2a
120
120
2b
4e
69–71[20]
2b
2b
4i
1b
13
120
51–53[21]
89
1c
4j
14
15
16
80
Oil
90
87
90
1e
1f
2b
2b
2b
4e
145
160
49–51[22]
50–51[22]
4k
1g
4l
17
18
80
Oil
Oil
95
1k
1a
2b
4e
135
85
(Continues)

MOGHADDAM AND ESLAMI
7 of 13
TABLE 3 (Continued)
Entry
Aryl Halide
Phenol
Product
Time (min)
Melting Point (°C)
Yield (%)
4f
2c
19
20
95
91–93[23]
96–98[23]
91
89
2c
2c
4m
1b
100
1c
4n
4f
21
22
23
130
130
130
oil
89
85
83
1e
1f
2c
2c
2c
50–51[22]
100–102[24]
4l
1g
1h
4o
4p
24
125
58–60[25]
88
2c
25
26
27
28
29
130
120
145
90
63–65[26]
oil
86
91
86
85
83
1i
1k
2c
2c
2d
2d
2d
4q
4f
52–53[17]
139–141[27]
103–105[28]
1a
4b
4r
1b
160
1c
4s
30
31
32
135
150
150
52–53[17]
69–71[20]
91–93[23]
88
85
84
1e
1f
2d
2d
2d
4b
4i
1g
4m
33
34
140
120
52–53[17]
51–53[29]
90
85
1k
1a
2d
4b
2e
4t
(Continues)

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MOGHADDAM AND ESLAMI
TABLE 3 (Continued)
Entry
Aryl Halide
Phenol
Product
Time (min)
Melting Point (°C)
Yield (%)
35
120
98–100[30]
89
1b
2e
4u
36
37
38
100
145
140
51–53[29]
40–41[21]
73–74[21]
89
88
84
1a
2e
2e
2e
4t
1f
4v
1g
4w
39
100
51–53[29]
85
1k
1a
2e
4t
40
41
100
90
47–49[18]
87
85
2f
2f
4x
98–100[31]
1b
4y
42
43
110
100
54–56[32]
85
93
2f
2f
1c
4z
4x
103–105[33]
1d
4aa
44
45
46
100
110
110
47–49[18]
53–55[34]
71–72[35]
88
85
86
1e
2f
2f
2f
1f
4ab
1g
4ac
47
90
47–49[18]
90
1k
2f
4x
aReaction condition: Aryl halide 1a‐k (1 mmol), Phenol 2a‐g (1 mmol), K2CO3 3a (1.5 mmol), MNPs@A‐N‐AEB.Pd0 (5 mg, 0.036 mol%) as catalyst and H2O
(2 mL).
bCompounds structures were established from their spectral data (Figures S1‐S39) and melting points as compared with authentic samples or literature values.
cIsolated yield.
alternative base to K2CO3 provide the better yields of the
expected product under the investigated conditions.
For the determination of the optimum temperature,
the model reaction was performed at r.t., 50 °C and reflux
condition and it was founded that reflux condition can
effectively improve the yield of the desired product in a
short reaction time (Table 2, entries 14–16).
Finally, the effect of both catalyst and base loading on
Pd0‐catalyzed C‐O bond formation were evaluated. Inter-
estingly, an increase in the catalyst amount to 7.5 mg

MOGHADDAM AND ESLAMI
9 of 13
gave the same results. In contrast when the amount of the
catalyst is 2.5 mg the yield of the reaction decreased
(Table 2, entry 17, 18). However, increase of the amount
of K2CO3 up to 1.5 mmol, hold a positive impact in the
yield of product (Table 2, entry 19). At the end, to demon-
strate the role of MNPs@A‐N‐AEB, as ligand the model
reaction examined in the presence of MNPs@A‐N‐AEB,
but acceptable result does not obtained (entry 20, 21).
It is very important to note that in contrast to most of
the homogeneous Pd‐catalyzed methods, decomposition
and Pd black form was not observed in optimization reac-
tion conditions.
Thus, the optimized reaction conditions utilized 5 mg
of MNPs@A‐N‐AEB.Pd0 (0.036 mol% of Pd(0)), aryl halide
(1a‐k, 1 equiv), and the mixture of appropriate phenol
(2a‐g, 1 equiv), and K2CO3 (1.5 equiv) in water (2 ml) as
a green media under reflux conditions (Table 3).
The different derivatives of diaryl ether (4a‐ac) were
prepared and the results have been summarized in
Table 3. In the light of these premises, we have performed
a systematic study with different types of aryl iodides,
bromides, chlorides (1a‐k), and phenols (2a‐g) with elec-
tron‐rich and deficient substrates (such as methoxy and
nitro) to clarify the factors that influence the reaction rate
and yield.
The results indicated that both aryl bromide and aryl
iodide were well performed the coupling reactions with
the phenol in excellent yields (Table 3, entry 5, 10 vs 1).
More importantly, less active aryl chlorides were also suc-
cessfully coupled with phenols under the catalysis of
MNPs@A‐N‐AEB.Pd0 (Table 3, entries 1).
The presence of methoxy groups on the phenol ring as
electron‐donating groups increased the yield of the diaryl
ethers in short times (Table 3, entries 11, 14, 17 vs 1, 5,
10), whereas a nitro group on the phenol ring as an elec-
tron‐withdrawing group somewhat decrease the yield
(entries 27, 30, 33 vs 1, 5, 10). This negative inductive
effect might be referring to the stronger decreased nucle-
ophilicity of phenols by the nitro group.
On the other hand the presence of an electron donat-
ing groups on aryl halide ring such as a methyl or
methoxy and as well as week electron‐withdrawing group
such as carbonyl did not affect the reactivity and yield of
product (entries 6, 7, 8, 9). Whereas the reactions success-
fully led to the formation of excellent yields of the
corresponding products in the presence of electron‐with-
drawing group on the aryl halide ring such as nitro and
nitrile at ortho and para position (entries 2, 3, 4 vs 1, 5,
10). In this case, the coupling reaction was performed in
the absence of MNPs@A‐N‐AEB.Pd0. As expected, the
cross‐coupling product was obtained in low yield (29%)
after 2 h, showing that direct nucleophilic aromatic sub-
stitution (SNAr) at the ipso‐carbon atom do not play an
efficient role in the cross‐coupling reaction.
In the following, the cross‐coupling reaction of 1&2‐
naphthol examined, fortunately the final products are
achieved in good yields (entries 1 vs 11 and 2 vs 12). In
this case excellent yields of the corresponding products
in the presence of electron‐withdrawing group on the aryl
halide ring such as nitro and nitrile were obtained.
At the end, to demonstrate the capabilities of the
designed new catalyst, product 4 h was synthesized on a
gram scale (Scheme 3). A slight increase in reaction time
and yield of the product had to be accepted.
The possible mechanism along with some recent liter-
ature review proposed for Pd0 catalytic routes of cou-
plings has been explained in Scheme 4. It is widely
accepted that the initially step is oxidative‐addition of
heterogeneous Pd0 nanoparticles into the C‐X bond to
produce aryl palladium intermediate A. This species
could then react with potassium phenoxide to render
intermediates B. Finally, in situ reductive elimination of
intermediates B gives the desired cross‐coupled product
together with the regenerated Pd0 catalyst in its original
form.
To evaluate the performance and efficiency of the
present protocol in the synthesis of diverse diaryl ether
derivatives, Table 4 compares some of the obtained
result in this strategy and other reports. As evident from
the results tabulated in Table 4, it is obvious that a
superior methodology in terms of the use of an environ-
mentally and green condition, reusable and efficient
magnetic catalyst, low catalyst loading, good to excel-
lent yields, and a short reaction time in most cases has
been developed.
2.3 | Reusability
To investigate the truly heterogeneous nature of the cata-
lyst, recyclability of the catalyst was investigated in the
SCHEME 3 Gram scale synthesis of product 1‐(4‐phenoxyphenyl) ethanone (4 h)

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MOGHADDAM AND ESLAMI
SCHEME 4 Plausible mechanism of the MNPs@A‐N‐AEB.Pd0 nanoparticle‐catalyzed cross‐coupling reactions
TABLE 4 Comparison of activity of different catalysts in the Ullmann type coupling reactions (Ullmann type reaction: phenol and phenyl
halides)
Time (h)
Yield (%)
Entry Catalyst (loading)
Reaction Conditions
X = Cl, Br, I
X = Cl, Br, I Ref.
[36]
1
2
3
4
5
6
AT‐Nano CP–Pd0 (0.06 mole% Pd0)
H2O, K2CO3, 60 °C
3/2.5/1
85/92/98
[37]
[(Cinnamyl)PdCl]2 (0.025 mol%)
CuO nanoparticles (10 mol%)
Fe3O4@PPh2‐Pd0 (1.5 mol%)
UiO‐66‐NH2‐Mlm/CuO NPs
Toluene/DME, K3PO4, r.t. −/16/−
Dry DMSO, KF/CP, 120 °C −/30/20
−/91/−
[38]
−/46/86
[39]
H2O, K2CO3, 80 °C
3.5/2/1.5
24/18/18
83/90/93
[40]
DMSO, KOH, 110 °C
30/93/95
[41]
CuFe2O4 (5 mol%) and
2,2,6,6‐tetramethylheptane‐
3,5‐dione (10 mol%)
NMP, Cs2CO3, N2, 135 °C 24/24/24
trace/34/91
[42]
[42]
7
CoFe2O4 (5 mol%)
NiFe2O4 (5 mol%)
Cu@MCTP‐1 (200 mg)
DMF, K2CO3, 80 °C
DMF, K2CO3, 80 °C
DMF, Cs2CO3, 130 °C
120 min/80 min/60 min 91/93/96
90 min/80 min/60 min 91/94/96
−/24/24 −/94/82
120 min/90 min/80 min 86/91/93
8
[43]
9
10
MNPs@A‐N‐AEB.Pd0 (5 mg, 0.036 mol% pd0) H2O, K2CO3, reflux
This Work
model reaction under optimized condition. After each
reaction cycle, the MNPs@A‐N‐AEB.Pd0 heterogeneous
catalyst was separated by an external magnet field, rinsed
with ethanol several times, dried, and reused in the
model reaction. As shown in Table 5, only an inconsider-
able decrease in the isolated yield of di phenyl ether was
observed after 7 successive runs, which confirmed the
high stability of the prepared catalyst and no significant
metal leaching was seen even after seven cycles of the
reaction. ICP analysis result after seven cycles confirmed
that there is no significant metal leaching, also almost all
metal easily separated and reused several times.
TABLE 5 The recycling capability of MNPs@A‐N‐AEB.Pd0 as a
catalyst in the synthesis of diphenyl ether (4a) under optimized
conditions
3 | CONCLUSION
In conclusion, we have introduced more effective, eco‐
friendly strategy for the synthesis of densely functional-
ized diaryl ethers, which often seen in biologically and
Run
1
2
3
4
5
6
7
Yield
91
91
89
87
88
86
84

MOGHADDAM AND ESLAMI
11 of 13
pharmacologically active compounds. Additionally, the
environmentally benign conditions, such as the use of
aqueous media, reusable and recoverable MNPs@A‐N‐
AEB.Pd0 metal catalyst, the high yields are the high
points of present protocol.
4.3 | Immobilization of N‐[3‐
(Trimithoxysilyl)propyl] ethylenediamine
on Fe3O4@SiO2
In a 50 ml round bottom flask equipped with condenser,
2 g of synthesized Fe3O4@SiO2 dispersed in 10 ml dry
Moreover, our attractive reported method can be
extended to scale up synthesis.
THF. Then,
2 ml of N‐[3‐(Trimithoxysilyl)propyl]
ethylenediamine was added to the mixture and refluxed
for 48 h. The resulting powdered material was separated
again by an external magnetic field. This product washed
with methanol (2 × 20) and dried in an oven at 60 °C.
4 | EXPERIMENTAL
4.1 | Reagents and analyses
All solvents and starting materials were purchased from
Merck and Sigma‐Aldrich used without any additional
purification. 1H NMR and 13C NMR spectra were
recorded on a Bruker Avance DRX‐500 machine using
CDCl3 as solvent and TMS as an internal standard at
4.4 | Synthesis of MNPs@2‐amino‐N‐(2‐
aminoethyl)benzamide. Pd0 (MNPs@A‐N‐
AEB.Pd0)
To the dispersed mixture of 1 g MNPs in THF (10 ml),
489.39 mg (3 mmol) of isatoic anhydride was added and
the mixture was stirred for 3 hr. The progress of the reac-
tion can be controlled by the release of carbon dioxide
gas. For the best result, MNPs@A‐N‐AEB were separated
from reaction mediate and dispersed again in THF
(10 ml) and the solution of 0.5 mmol K2PdCl4 in 2 ml
deionized water was added slowly under the vigorous
stirring condition to above mixture and the mixture was
stirred at ambient temperature for 24 hr to give the
MNPs@A‐N‐AEB.PdCl2. Finally, the mnps@a‐n‐aeb.
pdcl2 catalyst was dispersed in ethanol and then hydra-
zine hydrate was added to prepare mnps@a‐n‐aeb.pd0.
Stepwise preparation of MNPs@A‐N‐AEB.Pd0 as shown
in Scheme 2.
1
room temperature (CDCl3: H: δ = 7.26 ppm). Chemical
shifts were reported in ppm scale. FT‐IR spectra of sam-
ples were obtained on ABB Bomem MB100 spectrometer
with potassium bromide (KBr) pellets. Scanning electron
microscopy (SEM) was performed on VEGA\\TESCAN‐
LMU. An energy dispersive detector (EDS) coupled to
the microscope was used to identify chemical elements
of the prepared catalyst. X‐ray diffraction (XRD) pattern
was recorded on APD 2000, using Cu Kα radiation
(50 kV, 150 mA) in the range 2θ = 10–120°. Transmission
electron microscopy (TEM) was performed on Philips
CM30. CHN analysis was done by LECO Truspec.
4.2 | Synthesis of silica‐coated iron oxide
magnetic nanoparticles
4.5 | Ullmann cross‐coupling reactions;
General procedure
To synthesis of magnetic Fe3O4, the amount of 2 g
FeCl2.4H2O (10 mmol) and 5.4 g FeCl3.6H2O (20 mmol)
was entirely dissolved in 30 ml of deionized water. To
attain pH = 10, aqueous ammonia (28% v/v) was added
drop wise into mixture under the argon atmosphere,
and the resulting solution was mechanically stirred for
20–30 min. After that, the Fe3O4 magnetic nanoparticles
were collected by applying external magnetic field and
washed with the double distilled water and ethanol
(3 × 20). In the next step, 1.0 g of the synthesized Fe3O4
NPs was dispersed in ethanol (50 ml) by using of ultra-
sonic waves for 20 min. Then, 0.5 ml tetraethyl ortho sil-
icate was added gradually to the dispersed Fe3O4 NPs. In
the following, the pH of the solution was adjusted to 10
using ammonia solution. Finally, the temperature of the
mixture increases to 40 °C and stirring was continued
for other 24 h. At the end, the silica‐coated MNPs
(Fe3O4@SiO2) were separated using an external magnetic
field and washed with ethanol (3 × 10 ml) and dried
under vacuum at 50 °C.
A round‐bottom flask equipped with a magnetic stirring
bar, successively charged with aryl halides (1 mmol), phe-
nols (1 mmol), potassium carbonate (1.5 mmol), catalyst
(5 mg, 0.036 mol%), H2O (2 ml) and refluxed for the
required period of time in Table 3. In each case, after the
completion of reaction as monitored by TLC (EtOAc/n‐
Hexane, 1:9) catalyst separation by magnet and product
extracted with ethyl acetate (2*5 ml). If require additional
purification the crude residue was purified by recrystalliza-
tion from ethanol and water or using plate chromatogra-
phy. 1HNMR and 13CNMR date are available in
supporting information (see Figures S1‐S39).
4.6 | Spectroscopic characterization of the
products 4e and 4f
1
1‐methyl‐4‐phenoxybenzene (4e); H NMR (500 MHz,
CDCl3, ppm): δ 7.33 (t, 2H, J = 8.6 Hz), 7.15 (d, 2H,

12 of 13
MOGHADDAM AND ESLAMI
Chem. Int. Ed. 2016, 55, 6211. h) F. Gao, J. D. Webb, J. F.
Hartwig, Angew. Chem. 2016, 128, 1496.
J = 6.5 Hz), 7.07 (t, 1H, J = 5.8), 6.99 (d, 2H, J = 7.7 Hz),
6.99 (d, 2H, J = 7.1 Hz), 2.34 (s, 3H); 13C NMR (125 MHz,
CDCl3, ppm) δ = 158.05, 155.11, 133.07, 129.78, 130.12,
123.04, 120.11, 118.35, 21.02; Elemental Analysis: C,
84.81; H, 6.60; O, 8.72.
[12] S. Yang, C. Wu, M. Ruan, Y. Yang, Y. Zhao, J. Niu, W. Yang, J.
Xu, Tetrahedron Lett. 2012, 53, 4288.
[13] a) F. M. Moghaddam, S. E. Ayati, RSC Adv. 2015, 5, 3894. b) F.
M. Moghaddam, S. E. Ayati, S. H. Hosseini, A. Pourjavadi, RSC
Adv. 2015, 5, 34502. c) F. M. Moghaddam, S. E. Ayati, H. R.
Firouzi, F. Ghorbani, Appl. Organomet. Chem. 2016, 30, 488.
d) F. M. Moghaddam, S. E. Ayati, H. R. Firouzi, S. H. Hosseini,
A. Pourjavadi, Appl. Organomet. Chem. 2017. e) F. M.
Moghaddam, V. Saberi, S. Kalhor, S. E. Ayati, RSC Adv. 2016,
6, 80234.
1‐methoxy‐4‐phenoxybenzene (4f); 1H NMR
(500 MHz, CDCl3, ppm): δ 7.n30 (t, 2H, J = 6.0), 7.1 (t,
1H, J = 5.76), 6.99 (d, 2H, J = 6.9), 6.95 (d, 2H,
J = 6.4 Hz), 6.89 (t, 2H, J = 6.89), 3.8 (s, 3H); 13C NMR
(125 MHz, CDCl3, ppm) δ = 158.64, 156.10, 150.32,
130.09, 122.14, 121.08, 116.99, 114.68, 56.04; Elemental
Analysis: C, 78.01; H, 6.11; O, 16.03.
[14] a) B. Karimi, F. Mansouri, H. M. Mirzaei, ChemCatChem 2015,
7, 1736. b) M. B. Gawande, P. S. Branco, R. S. Varma, Chem.
Soc. Rev. 2013, 42, 3371. c) H.‐J. Xu, X. Wan, Y. Geng, X.‐L.
Xu, Curr. Org. Chem. 2013, 17, 1034.
ACKNOWLEDGMENTS
We gratefully acknowledge the funding support received
for this project from the Sharif University of Technology
(SUT), Islamic Republic of Iran.
[15] a) F. M. Moghaddam, G. Tavakoli, A. Moafi, V. Saberi, H. R.
Rezvani, ChemCatChem 2014, 6, 3474.
[16] N. Xia, M. Taillefer, Chem. A Eur. J. 2008, 14, 6037.
[17] R. L. Antipin, D. A. Beshnova, R. A. Petrov, A. S. Shiryaeva, I.
P. Andreeva, V. G. Grigorenko, M. Y. Rubtsova, A. G. Majouga,
V. S. Lamzin, A. M. Egorov, Bioorg. Med. Chem. Lett. 2017, 27,
1588.
ORCID
Firouz Matloubi Moghaddam
http://orcid.org/0000-0002-
8418-9888
[18] Y. Zhang, G. Ni, C. Li, S. Xu, Z. Zhang, X. Xie, Tetrahedron
2015, 71, 4927.
[19] L. Liu, J. Tang, J. Qiang, J. Li, M. He, J. Chem. Res. 2016, 40,
REFERENCES
261.
[1] S. V. Ley, A. W. Thomas, Angew. Chem. Int. Ed. 2003, 42, 5400.
[2] G. Evano, N. Blanchard, M. Toumi, Chem. Rev. 2008, 108, 3054.
[20] M. A. Khalilzadeh, A. Hosseini, A. Pilevar, Eur. J. Org. Chem.
2011, 2011, 1587.
[21] R. G. R. Bacon, O. J. Stewart, J. Chem. Soc. (Resumed) 1965,
[3] R. H. F. Manske, The alkaloids: Ahemistry and Physiology, Vol.
7, Academic Press, Cambridge 1960.
4953.
[22] A. Ghatak, S. Khan, R. Roy, S. Bhar, Tetrahedron Lett. 2014, 55,
[4] J. W. Janetka, D. H. Rich, J. Am. Chem. Soc. 1997, 119, 6488.
7082.
[5] M. S. Choi, S. H. Lee, H. S. Cho, Y. Kim, Y. P. Yun, H. Y. Jung,
J. K. Jung, B. C. Lee, H. B. Pyo, J. T. Hong, Eur. J. Pharmacol.
2007, 556, 181.
[23] A. Mishra, H. Batchu, K. Srivastava, P. Singh, P. K. Shukla, S.
Batra, Bioorg. Med. Chem. Lett. 2014, 24, 1719.
[24] N. Otto, T. Opatz, Beilstein J. Org. Chem. 2012, 8, 1105.
[6] M. Iyoda, M. Sakaitani, H. Otsuka, M. Oda, Tetrahedron Lett.
1985, 26, 4777.
[25] J. Chen, X. Wang, X. Zheng, J. Ding, M. Liu, H. Wu, Tetrahe-
dron 2012, 68, 8905.
[7] S. Tamai, M. Kaneda, S. Nakamura, J. Antibiot. 1982, 35, 1130.
[26] G. W. Yeager, D. N. Schissel, Synthesis 1995, 1995, 28.
[8] S. Zenitani, S. Tashiro, K. Shindo, K. Nagai, K. Suzuki, M.
[27] D. Wang, Z. Xu, X. Yu, Y. Li, H. Wan, J. Chem. Res. 2016, 40,
Imoto, J. Antibiot. 2003, 56, 617.
691.
[9] F. Ullmann, J. Bielecki, Eur. J. Inorg. Chem. 1901, 34, 2174.
[28] H. Xu, Y. Chen, Synth. Commun. 2007, 37, 2411.
[10] a) D. A. Evans, J. A. Ellman, J. Am. Chem. Soc. 1989, 111, 1063.
b) D. L. Boger, M. A. Patane, J. Zhou, J. Am. Chem. Soc. 1994,
116, 8544. c) D. L. Boger, D. Yohannes, J. Org. Chem. 1990, 55,
6000.
[29] C. Qian, L. Qin, Q. Zong, L. Wu, D. Fang, Bull. Kor. Chem. Soc.
2013, 34, 3915.
[30] N. R. Bandna, A. K. Guha, D. Shil, P. D. Sharma, Tetrahedron
Lett. 2012, 53, 5318.
[11] a) J. P. Wan, C. Wang, Y. Liu, Appl. Organomet. Chem. 2012,
26, 445. b) N. Iranpoor, H. Firouzabadi, A. Rostami, Appl.
Organomet. Chem. 2013, 27, 501. c) S. Harkal, K. Kumar, D.
Michalik, A. Zapf, R. Jackstell, F. Rataboul, T. Riermeier, A.
Monsees, M. Beller, Tetrahedron Lett. 2005, 46, 3237. d) D.
Kikelj, Synthesis 2006, 2006, 2271; e) A. B. Naidu, O. R.
Raghunath, D. J. C. Prasad, G. Sekar, Tetrahedron Lett. 2008,
49, 1057. f) B. H. Lipshutz, J. B. Unger, B. R. Taft, Org. Lett.
2007, 9, 1089. g) M. Fan, W. Zhou, Y. Jiang, D. Ma, Angew.
[31] H. Keipour, A. Hosseini, A. Afsari, R. Oladee, M. A.
Khalilzadeh, T. Ollevier, Can. J. Chem. 2015, 94, 95.
[32] X. Zhang, G.‐P. Lu, C. Cai, Green Chem. 2016, 18, 5580.
[33] T. Satoh, J.‐i. Inoh, Y. Kawamura, Y. Kawamura, M. Miura, M.
Nomura, Bull. Chem. Soc. Jpn. 1998, 71, 2239.
[34] H. Suzumura, Bull. Chem. Soc. Jpn. 1962, 35, 622.
[35] M. Murai, K. Origuchi, K. Takai, Org. Lett. 2014, 16, 3828.

MOGHADDAM AND ESLAMI
13 of 13
[36] S. M. Baghbanian, H. Yadollahy, M. Tajbakhsh, M. Farhang, P.
SUPPORTING INFORMATION
Biparva, RSC Adv. 2014, 4, 62532.
Additional supporting information may be found online
in the Supporting Information section at the end of the
article.
[37] L. Salvi, N. R. Davis, S. Z. Ali, S. L. Buchwald, Org. Lett. 2011,
14, 170.
[38] M. A. Khalilzadeh, H. Keipour, A. Hosseini, D. Zareyee, New J.
Chem. 2014, 38, 42.
[39] M. A. Zolfigol, V. Khakyzadeh, A. R. Moosavi‐Zare, A.
Rostami, A. Zare, N. Iranpoor, M. H. Beyzavi, R. Luque, Green
Chem. 2013, 15, 2132.
How to cite this article: Moghaddam FM,
Eslami M. Immobilized palladium nanoparticles on
MNPs@A‐N‐AEB as an efficient catalyst for C‐O
bond formation in water as a green Solvent. Appl
Organometal Chem. 2018;32:e4463. https://doi.org/
10.1002/aoc.4463
[40] S. Sadeghi, M. Jafarzadeh, A. R. Abbasi, K. Daasbjerg, New J.
Chem. 2017, 41, 12014.
[41] S. Yang, C. Wu, H. Zhou, Y. Yang, Y. Zhao, C. Wang, W. Yang,
J. Xu, Adv. Synth. Catal. 2013, 355, 53.
[42] F. M. Moghaddam, G. Tavakoli, A. Aliabadi, RSC Adv. 2015, 5,
59142.
[43] P. Puthiaraj, W.‐S. Ahn, Cat. Sci. Technol. 2016, 6, 1701.