Heck and oxidative boron Heck reactions employing Pd(II) supported amphiphilized polyethyleneimine-functionalized MCM-41 (MCM-41@aPEI-Pd) as an efficient and recyclable nanocatalyst

Article abstract of DOI:10.1002/aoc.4123

A novel nanocatalyst was developed based on covalent surface functionalization of MCM-41 with polyethyleneimine (PEI) using [3-(2,3-Epoxypropoxy)propyl] trimethoxysilane (EPO) as a cross-linker. Amine functional groups on the surface of MCM-41 were then conjugated with iodododecane to render an amphiphilic property to the catalyst. Palladium (II) was finally immobilized onto the MCM-41@PEI-dodecane and the resulted MCM-41@aPEI-Pd nanocatalyst was characterized by FT-IR, TEM, ICP-AES and XPS. Our designed nanocatalyst with a distinguished core-shell structure and Pd²⁺ ions as catalytic centers was explored as an efficient and recyclable catalyst for Heck and oxidative boron Heck coupling reactions. In Heck coupling reaction, the catalytic activity of MCM-41@aPEI-Pd in the presence of triethylamine as base led to very high yields and selectivity. Meanwhile, the MCM-41@aPEI-Pd as the first semi-heterogeneous palladium catalyst was examined in the C-4 regioselective arylation of coumarin via the direct C-H activation and the moderate to excellent yields were obtained toward different functional groups. Leaching test indicated the high stability of palladium on the surface of MCM-41@aPEI-Pd as it could be recycled for several runs without significant loss of its catalytic activity.

Full text of DOI:10.1002/aoc.4123

Received: 17 June 2017
DOI: 10.1002/aoc.4123
Revised: 30 August 2017
Accepted: 2 September 2017
F U L L P A P E R
Heck and oxidative boron Heck reactions employing Pd(II)
supported amphiphilized polyethyleneimine‐functionalized
MCM‐41 (MCM‐41@aPEI‐Pd) as an efficient and recyclable
nanocatalyst
Seyed Farshad Motevalizadeh † | Masoumeh Alipour2† | Fatemeh Ashori |
1
3
4
5
6,7
Alireza Samzadeh‐Kermani | Hosein Hamadi | Mohammad Reza Ganjali
|
8
8
2,9
8
Hamideh Aghahosseini | Ali Ramazani
| Mehdi Khoobi | Elham Gholibegloo
1
Particulate Fluids Processing Centre,
A
novel nanocatalyst was developed based on covalent surface
School of Chemistry, The University of
Melbourne, Melbourne, VIC 3010,
Australia
functionalization of MCM‐41 with polyethyleneimine (PEI) using [3‐(2,3‐
Epoxypropoxy)propyl] trimethoxysilane (EPO) as a cross‐linker. Amine func-
tional groups on the surface of MCM‐41 were then conjugated with
iodododecane to render an amphiphilic property to the catalyst. Palladium
2
Nanobiomaterials Group,
Pharmaceutical Sciences Research Center,
Tehran University of Medical Sciences,
Tehran 1417614411, Iran
(II) was finally immobilized onto the MCM‐41@PEI‐dodecane and the resulted
3
Department of Applied Chemistry,
MCM‐41@aPEI‐Pd nanocatalyst was characterized by FT‐IR, TEM, ICP‐AES
and XPS. Our designed nanocatalyst with a distinguished core‐shell structure
Faculty of Pharmaceutical Chemistry,
Pharmaceutical Sciences Branch, Islamic
Azad University, Tehran, Iran
2+
and Pd ions as catalytic centers was explored as an efficient and recyclable
catalyst for Heck and oxidative boron Heck coupling reactions. In Heck cou-
pling reaction, the catalytic activity of MCM‐41@aPEI‐Pd in the presence of
triethylamine as base led to very high yields and selectivity. Meanwhile, the
MCM‐41@aPEI‐Pd as the first semi‐heterogeneous palladium catalyst was
examined in the C‐4 regioselective arylation of coumarin via the direct C‐H
activation and the moderate to excellent yields were obtained toward different
functional groups. Leaching test indicated the high stability of palladium on the
surface of MCM‐41@aPEI‐Pd as it could be recycled for several runs without
significant loss of its catalytic activity.
4
Department of Chemistry, Faculty of
Sciences, University of Zabol, Zabol, Iran
5
Department of Chemistry, College of
Science, Shahid Chamran University,
Ahvaz, Iran
6
Center of Excellence in Electrochemistry,
Faculty of Chemistry, University of
Tehran, Tehran, Iran
7
Biosensor Research Center,
Endocrinology & Metabolism Molecular‐
Cellular Sciences Institute, Tehran
University of Medical Sciences, Tehran,
Iran
KEYWORDS
8
Department of Chemistry, University of
Heck coupling reaction, mesoporous structure, oxidative boron Heck coupling reaction, palladium,
polyethyleneimine
Zanjan, P.O. Box 45195‐313, Zanjan, Iran
9
Department of Pharmaceutical
Biomaterials and Medical Biomaterials
Research Center, Faculty of Pharmacy,
Tehran University of Medical Sciences,
Tehran, Iran
This work is dedicated in memory of Prof. Abbas Shafiee (1937–2016).
†
These authors have the same contribution to this paper.
Appl Organometal Chem. 2017;e4123.
wileyonlinelibrary.com/journal/aoc
Copyright © 2017 John Wiley & Sons, Ltd.
1 of 9
https://doi.org/10.1002/aoc.4123

2
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MOTEVALIZADEH ET AL.
Correspondence
Ali Ramazani, Department of Chemistry,
University of Zanjan, P O Box 45195‐313,
Zanjan, Iran.
Email: aliramazani@gmail.com
Mehdi Khoobi, Department of
Pharmaceutical Biomaterials and Medical
Biomaterials Research Center, Faculty of
Pharmacy, Tehran University of Medical
Sciences, Tehran, Iran.
Email: m‐khoobi@tums.ac.ir
1
| INTRODUCTION
supported mesoporous catalysts for various organic reac-
tions are attractive approaches to find a new heteroge-
[
15]
Carbon–carbon bond coupling catalysed by transition
metal is one of the most fundamental and important meth-
odologies for the preparation of complex organic mole-
cules like pharmaceuticals and natural products. Among
different commonly used coupling reactions, Mizoroki‐
Heck coupling reaction (MHCR) has been attracted as
one of the fascinating reactions for the formation of
C(sp )– C(sp ) from the catalytic aspects. This reaction
has risen in popularity due to the high tolerance toward
various commercial available starting materials, stability
of the applied reagents during the reaction, and suitable
neous synthetic method.
Different methods were
taken into account to stabilize nanometals on the support
using various types of functional molecules such as poly-
[
16–18]
[19]
[20]
mers,
surfactants, and different types of ligands
as capping agents. Both dendrimers and hyperbranched
polymers covalently or noncovalently functionalized with
catalytically active transition metal complexes are one of
2
2
[21–
promising scaffolds with respect to catalyst recovery.
23]
In many aspects, dendrimers can be replaced by
hyperbranched polymers due to their similar proper-
[
24]
ties,
such as low viscosity, high functionalities and
[
1–3]
regioselectivity of the products.
On the other hand,
spheroid‐like shape. The silica‐supported palladium nano-
particles‐mediated organic transformations have been
developed remarkably. Palladium nanoparticles were
encapsulated in various forms of silica supports that were
represented improved properties in carbon–carbon bond‐
conventional MHCR bank on providing pre‐activated cou-
pling reagents causing a synthetic sequence to introduce
the functionality, especially for the preparation of impor-
tant biological molecules. Oxidative Heck reaction has
opened a new way to overcome this obstacle and eliminate
introducing protecting groups and reactive functionalities
[
25–29]
forming reactions gradually.
By now, catalytic activ-
ity of covalently or noncovalently functionalized
hyperbranched macromolecules like hyperbranched
polyethylenimine (HPEI) has received limited atten-
[4–6]
prior to C–C bond formation.
These types of reactions
generally proceed in the presence of a homogeneous palla-
dium catalyst, which makes its separation and recovery
tedious, if not impossible, and might result in unacceptable
palladium contamination of the products. However, the
[
30–34]
tion.
Therefore, it is worthwhile to develop a general,
simple, and scalable approach to fabricate a reusable and
stable nanocatalyst. In this work, we report a convenient
methodology to stabilize palladium as a catalyst on a poly-
amine functionalized MCM‐41 that leads to a reusable
high‐active semi‐heterogeneous nanocatalyst for Heck
coupling and oxidative Heck reactions (Scheme 1). To the
best of our knowledge, there is no report about application
of semi‐heterogeneous palladium catalyst for direct
arylation of coumarins.
‘naked’ Pd species have been postulated to be the true
[7–9]
active catalytic species in many cases.
this regard is the de Vries et al. work, which they employed
ligand‐free Pd(OAc) (0.01–0.1 mol %) as a catalyst in the
Heck reaction of aryl bromides. At higher concentra-
tions palladium black forms and the reaction stops. One
of the strategies to overcome these drawbacks is their
encapsulation or immobilization on porous solid matrices.
Different types of supports were used to immobilize palla-
dium and prepare environmental‐friendly, efficient and
An example in
2
[7]
2 | EXPERIMENTAL
[10–13]
simpler heterogeneous catalysts.
The immobilization
of the metal on porous supports with high‐surface area
Hyperbranched PEI (Mw = 60000) and EPO (98% purity)
were purchased from Aldrich. The following materials
were purchased from Merck: cetyl trimethylammonium
bromide (CTAB), tetraethyl orthosilicate (TEOS), aqueous
ammonia (28 wt. % solution), absolute ethanol (EtOH),
brings better stability and dispersity as well as recyclability
[14]
of the catalyst.
Mesoporous materials have shown con-
siderable activity as heterogeneous catalysts. The develop-
ment of mesoporous catalysts and transition metal

MOTEVALIZADEH ET AL.
3 of 9
Heck Reaction
B(OH)
SCHEME 1 MCM‐41@aPEI‐Pd
catalyzed heck and oxidative heck
coupling reactions
O
O
Oxidative Heck Reaction
MCM-41@aPEI-Pd(II)
methanol (MeOH) and palladium chloride. Other
reagents and solvents were obtained from Aldrich or
Fluka and used without further purification.
Fourier transform infrared (FT‐IR) spectra were
recorded as KBr pellets using a Bruker Equinox 55 (detec-
tor: DTGS) spectrophotometer. The morphology of the
catalyst was studied by high resolution transmission elec-
tron microscopy (HRTEM) on a Philips CM30T (150–
2.2 | Preparation of MCM‐41@PEI
MCM‐41@PEI was synthesized according to the proce-
[
36]
dure reported previously.
To a stirred solution of
150 ml dry toluene containing 3.0 mmol of PEI, 1.0 mmol
of 3‐(2, 3‐Epoxypropoxy) propyltrimethoxysilane was
added. The resulting mixture was allowed to react at
8
4
0 °C for 24 h. To this solution, 2.5 g of calcined MCM‐
[
37]
1
and 25 ml of EtOH were added and the solution
3
00 kV). Thermogravimetric analysis (TGA) was carried
−
1
was stirred at 80 °C for 24 h. The MCM‐41@PEI was iso-
lated by filtration and washed with MeOH and EtOH.
Then, it was refluxed with EtOH during 1 h, filtered again
and dried at 40 °C for two days. Low‐angle X‐ray diffrac-
tion, nitrogen sorption isotherms, specific surface area
out on a TGA Q50 with a heating rate of 10 °C min from
5 °C to 800 °C under a nitrogen atmosphere. The surface
2
chemistry and chemical state of the supports were
analysed by X‐ray photoelectron spectroscopy (XPS; VG
Escalab 250 iXL ESCA instrument, VG Scientific) using
monochromatic Al‐Kα radiation of energy 1486.6 eV. A
hemispherical analyser (Specs EA 10 Plus) under vacuum
(
as BET), pore volume, and pore diameter were measured
for MCM‐41 before and after grafting PEI (Figure S1 c‐e,
Table S1).
−
9
(
10 Torr) was used for energy analysis.
2
.3 | Modifying of MCM‐41@PEI with 1‐
2
.1 | Preparation of mesoporous silica
iodododecane
The molar compositions of the reaction medium were
To a stirred solution of 200 ml dry Ethanol containing 4 g
MCM‐41@PEI, 13.5 mmol 1‐iodododecane was added.
The resulting mixture was allowed to reflux for 24 h.
The MCM‐41@PEI‐dododecane was separated by evapo-
ration of solvent and washed with MeOH and EtOH.
The above procedure was repeated 3 times to obtain max-
imum modifying with 1‐iodododecane.
applied at 1.0 for TEOS, 0.3 for CTAB, 11 for NH , 144
3
for H O and 28 for EtOH, where the mesoporous phase
2
[35]
with high ordering degree was achieved.
MCM‐41 preparation procedure is described as follows:
3.0 g of CTAB was dissolved in 167.0 g of deionized
water; then, 163.7 g of the aqueous ammonia and
31.5 g of the absolute ethanol was added to the surfactant
A typical
1
1
solution. The solution was stirred for 15 min, and after-
wards 24.8 g of TEOS was added. After 2 h of vigorous stir-
ring with the mechanical stirrer at 1500 rpm and
filtration, the white precipitate was successfully washed
with plenty of deionized water and dried at 60 °C for
2
4
.4 | Palladium loading onto the MCM‐
1@PEI‐dododecane
2
4 h. Before using MCM‐41, a part of MCM‐41 sample
MCM‐41@PEI‐dododecane (300 mg) was charged into a
round bottomed flask containing an acetonitrile solution
(25 ml) of palladium chloride (0.6 mmol) and stirred
under a nitrogen atmosphere for 48 h. The resultant res-
idue was filtered off and washed with acetonitrile
followed by acetone. The residue was dried in air for
was calcined under oxygen atmosphere by applying a
heating ramp of 1 °C /min up to 600 °C and then kept
at this temperature for 6 h. The high‐resolution TEM
image of MCM‐41 was provided which indicated its fine
morphological structure with hexagonal array of uniform
channels (Figure S1 a, b).
[
38]
24 h.

4
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MOTEVALIZADEH ET AL.
2
.5 | Heck coupling and oxidative Heck
prepared via a two steps reaction. First, PEI was attached
to the EPO through the reaction of amine groups of PEI
with epoxy groups of EPO. Then, PEI was grafted to the
surface of MCM‐41 through the reaction of
trimethoxysilane part with hydroxyl groups of MCM‐41.
reactions
In a typical experiment, iodobenzene (1.1 mmol) and sty-
rene (1.0 mmol) were added to N,N‐dimethylformamide
(DMF, 1 ml). MCM‐41@aPEI‐Pd as catalyst (1 mol %
1‐Iodododecane was then used to render an amphiphilic
based on initial idobenzene) and triethylamine (1.5 mmol)
were added to this system under stirring at 90 °C. After
completion of the reaction, the catalyst was recovered by
centrifugation and washed thoroughly with a mixed sol-
vent of ethanol and water. The product was analysed by
gas chromatography (GC).
character to the target catalyst providing a proper area
for hydrophobic substrates. Palladium was finally loaded
onto the catalyst via chelating by amine groups on the
catalyst.
In oxidative Heck reactions, coumarin was reacted
with phenyl boronic acid. The feasibility of the reaction
was investigated under the following conditions: couma-
rin (1 mmol), phenylboronic acid (1.2 mmol), Pd catalyst
3.1 | FTIR spectroscopy
FT‐IR spectra of MCM‐41, MCM@PEI and MCM‐
4
1@aPEI‐Pd are shown in Figure 1. The band at
(
4 mol %), ligand (20 mol %), O (balloon pressure) in
−1
−1
−1
2
1060 cm , 801 cm and 463 cm are attributed to
the solvent (0.4 M) were heated in a sealed tube at
00 °C for 24 h. After completion of the reaction, the cat-
asymetric stretching vibration, symmetric stretching
1
vibration and bending vibration of Si‐O‐Si bonds in
alyst was recovered by centrifugation and washed thor-
oughly with ethyl acetate and water. The structural
properties of the recycled MCM‐41@aPEI‐Pd was moni-
tored by BET and wide angle XRD analysis (Figure S2,
S3 and Table S2).
[38–40]
MCM‐41, respectively.
The strong bands of OH
related to the stretching and bending vibration indicate
that a large number of OH groups are present on the sur-
face of MCM‐41 (3485 and 1639 cm , respectively). A
comparison between the FT‐IR spectra of MCM‐41 and
−1
MCM@PEI reveals additional bands around 1465 and
−
1
2
900 cm which could be due to the stretching vibration
3
| RESULTS AND DISCUSSION
of the C–N and C–H bonds of polymer on the surface of
[
41]
MCM‐41 (Figure 1a and 1b).
The modification with
The process for the preparation of MCM‐41@aPEI‐Pd is
schematically described in Scheme 2. MCM‐41@PEI was
1‐iodododecane has increased the intensity of the peaks
at about 2855 and 2927 cm which is assignable for the
−
1
PdCl
Iodododecane
H N
NH
MCM-41@aPEI-Pd(II)
N
N
N
n
H
NH
PEI
MCM-41@PEI
NH
O
O
O
Si
O
O
H2N
NH
EPO
O
Si
O
OHH
N
N
N
N
H
O
Calcined MCM-41
O
n
NH
EPO/ PEI
SCHEME 2 Schematic representation
of the formation of MCM‐41@aPEI‐Pd
H N

MOTEVALIZADEH ET AL.
5 of 9
FIGURE 3 TGA curves of the MCM@PEI and MCM@PEI‐
dodecane nanocomposites
FIGURE 1 FT‐IR spectra of (a) MCM‐41, (b) MCM@PEI and (c)
MCM@PEI‐dodecane
stretching mode of CH(−CH ) and CH(−CH ‐) groups of
the 1‐iodododecane species.
determined to be approximately 17%. In comparison with
MCM‐41@PEI, the TGA curve of MCM‐41@PEI‐
dodecane shows bigger decomposition at the temperature
range from 200 to 800 °C than MCM‐41@PEI, indicating
the successful modifying procedure with dodecyl moiety.
The weight loss of dodecyl part grafted MCM‐41@PEI is
observed to be around 22%. According to these results, it
was concluded that identical amounts of PEI and
dododecane are grafted onto the mesoporous silica materials.
3
2
3
.2 | Transmission electron microscopy
(TEM)
Figure 2 shows the TEM image of MCM‐41@aPEI‐Pd pre-
senting a core‐shell structure with average size of about
3
00 nm. The thickness of the polymer layer was almost
2
0–30 nm.
3
.4 | Quality and quantity of the
palladium immobilized onto the MCM‐
1@aPEI‐Pd
3
.3 | Thermal analysis
4
Further experiments were carried out to prove the suc-
cessful linking procedure and to estimate the percentage
of functionalization in each step. Figure 3 showed the
TGA measurement of the support after grafting with PEI
and dodecyl moiety. As expected, there was no weight loss
for MCM‐41 till 600 °C. It is observed that the MCM‐41
lose around 5% of its total weight because of the removal
of adsorbed water below 150 °C. After the grafting reac-
tion, the amount of the loaded PEI on MCM‐41 was
ICP‐OES technique was used to identify the presence of
palladium and quantify the amount of the metal onto
the nanocatalyst. It was found that 10.56% of palladium
was loaded onto the MCM‐41@PEI‐dodecane. For further
confirmation, XPS was also used to investigate the ele-
mental composition of the MCM‐41@aPEI‐Pd
nanocatalyst (Figure 4). The XPS result showed
FIGURE 4 X‐ray photoelectron spectroscopy pattern of the
MCM‐41@aPEI‐Pd nanocatalyst
FIGURE 2 TEM image of the MCM‐41@aPEI‐Pd nanocatalyst

6
of 9
MOTEVALIZADEH ET AL.
significant amounts of organic moiety on the surface of
MCM‐41@aPEI‐Pd as indicated by the C 1s1/2, N 1s1/2
and O 1s appeared at 285, 405, and 537 eV, respectively.
To investigate the scope of the reaction, the ability of
the nanocatalyst for Heck coupling reaction was further
studied by using other styrene derivatives (Table 2). As
illustrated in Table 3, it could be concluded that the cata-
lyst could successfully catalyse both styrene and acrylate
derivatives. The percentage of conversion and selectivity
were in the range of 65–100%. Excellent yield was
achieved for the reaction between iodobenzene and butyl
acrylate, and the product was obtained in highest
selectivity.
,
1/2
[42,43]
Two sharp peaks were indicated at 340 and 348 eV
for Pd 3d5/2 and Pd 3d3/2, respectively, confirming the
[
44]
presence of Pd at +2 state.
Based on the observed
+
2
XPS peaks, it can be concluded that, Pd ions were
entrapped into the polymer layer through amine groups.
3.5 | Application of the catalyst in Heck
coupling reaction
The MCM‐41@aPEI‐Pd nanocatalyst was first evaluated
for the C–C bond formation via Heck coupling reaction.
For initial assessment, the Suzuki coupling reaction of
iodobenzene and styrene was chosen as a model reaction
to optimize the reaction conditions (Table 1). Variation of
temperature in the range 75–100 °C revealed that the opti-
mum temperature for the reaction is 90 °C (Table 1,
entries 1–3). In addition, further experiments showed that
3
.6 | Reusability of the catalyst
Leaching test was also applied to obtain the amount of the
metal desorption from the solid catalyst. In order to deter-
mine metal species desorbed from the solid catalyst,
TABLE 2 Using different styrene derivatives in the Heck cou-
pling reaction
1
0 mg of the catalyst was sufficient to guarantee a good
Conversion Selectivity %
a
conversion (Table 1, entry 4). It was found that the
highest yield could be achieved in the presence of DMF;
while, the highset selectivity was obtained in DMSO
Entry ArX Substrate
%
(trans)
1
2
3
4
5
6
PhI Styrene
96
91
PhI 4‐methylstyrene
PhI Acrylonitrile
PhI Methyl acrylate
PhI Butyl acrylate
88
82
95
86
(Table 1, entries 5 and 2). The reaction did not proceed
successfully in the presence of inorganic bases like
sodium acetate (data not shown) or nonpolar solvents like
xylene and protic solvent like water and EtOH. But,
clearly polar solvents showed proper efficiency for the
reaction (Table 1, entries 4–6). With these results in hand,
triethylamine and DMSO were chosen as best base and
solvent, respectively.
90
87
100
65
100
90
PhI Ethyl methyl
acrylate
a
Condition: ArI (1 mmol), trietylemine (1.5 mmol), styrene derivatives
(1.1 mmol); temperature: 90 °C; time: 9 h; Catalyst: MCM‐41@aPEI‐Pd.
TABLE 1 Optimization of the reaction conditions for Heck coupling reaction
a
Entry
Catalyst (g)
0.05
Solvent
DMSO
DMSO
DMSO
DMSO
DMF
Base
Temperature
Conversion %
Selectivity %(3)
1
2
3
4
5
6
7
8
Triethylamine
Triethylamine
Triethylamine
Triethylamine
Triethylamine
Triethylamine
Triethylamine
Triethylamine
75
90
78
89
83
75
96
92
73
2
94
98
96
90
91
89
92
51
0.05
0.05
120
90
0.01
0.05
90
b
0.05
DMA
90
0.05
CH
3
CN
90
0.05
p‐xylene
90
a
Condition: iodobenzene (1 mmol), trietylemine (1.5 mmol), styrene (1.1 mmol), catalyst: MCM‐41@aPEI‐Pd. Time: 9 h. Conversion and selectivity were deter-
mined by GC analysis.
b
DMA: dimethylacetamide.

MOTEVALIZADEH ET AL.
7 of 9
TABLE 3 Quantity of the leached palladium which obtained
from ICP analysis and reusability of the catalyst in coupling reaction
for at least five next runs without detectable loss in the
yield of the product and selectivity.
Entry
Pd (ppm)
Yield (%)
Run 1
<0.2
95
3.7 | Application of the catalyst in
Run 2
Run 3
Run 4
Run 5
<0.1
94
92
92
91
86
oxidative Heck coupling reaction
<0.1
Synthesis of 4‐arylcoumarins via direct‐arylation of
inactivated coumarins has also attracted a great attention
due to their diverse biological activities. Direct
functionalization of desired scaffold through regioselec-
tive C–H bond activation provides an efficient cost‐effec-
tive and atom‐economical entry to these compounds as
it eliminates the need for introducing protecting groups
<0.015
<0.010
%
trans‐product after fifth run
a
Condition: PhI (1 mmol), trietylemine (1.5 mmol), styrene (1.1 mmol), tem-
perature 90 °C, time 9 h. Catalyst: MCM‐41@aPEI‐Pd.
[5]
MCM‐41@aPEI‐Pd was stirred in aqueous media for
and reactive functionalities prior to C–C formation.
1
day. After separation of the catalyst, the solution was
Therefore, development of general, atom‐economical
and regioselective arylation methods merits further con-
siderations. Catalytic activity of MCM‐41@aPEI‐Pd nano-
composite was also investigated in oxidative Heck
reaction of coumarins 5 with phenylboronic acid 6. To
begin, coumarin was chosen as the test substrate in the
oxidative Heck reaction with phenylboronic acid. We
checked optimal conditions by screening various palla-
dium sources. Fortunately, the reaction was efficiently
catalysed in the presence of only 4 mol% of MCM‐
41@aPEI‐Pd as optimized amount of the catalyst to
achieve 4‐phenylcoumarin 7 with only 5% of homo‐cou-
pling product 8 (Table 4, entry 1). But, the presence of
phenantroline as ligand was necessary to perform the
reaction, as in ligand free conditions, biphenyl 8 was
concentrated and tested for verification of the leached
metal ion by ICP analysis and the isolated catalyst was
also used for the next five runs under the above‐men-
tioned condition. ICP analysis was revealed that the
amount of the leached palladium from the catalyst is less
than 0.2 ppm for the first run and less than 0.010 ppm
even after the fifth run (Table 3). These results can imply
that palladium was strongly chelated by MCM‐41@PEI‐
dodecane. To confirm the reusability of MCM‐41@aPEI‐
Pd, we next run five‐cycle reusability test of MCM‐
4
1@aPEI‐Pd in the reaction between PhI and styrene. At
the end of each run, the nanocatalyst was recovered,
washed, and then dried before being used for the next
run. The results confirmed the potential of the catalyst
a
TABLE 4 Screening of reaction conditions for the intermolecular oxidative heck‐reaction of coumarin and phenylboronic acid
a
Entry
Cat.
Lig.
Solv.
Yield
3
4
1
2
3
4
5
6
7
MCM‐41@aPEI‐Pd
MCM‐41@aPEI‐Pd
MCM‐41@aPEI‐Pd
MCM‐41@aPEI‐Pd
MCM‐41@aPEI‐Pd
MCM‐41@aPEI‐Pd
MCM‐41@aPEI‐Pd
Phenantroline
Free ligand
DMF
87%
‐
<5%
40%
<5%
<5%
<5%
10%
10%
10%
37%
DMF
Phenantroline
Phenantroline
Phenantroline
Phenantroline
Phenantroline
Phenantroline
Phenantroline
Toluene
1,4‐Dioxane
20%
10%
5%
3
CH CN
EtOH
DMF/H
DMF
40%
50%
53%
‐
2
O(80/20)
b
8
Pd(OAc)
2
b
9
MCM/Pd
DMF
a
2
Condition: coumarin (1 eq.), phenylboronic acid (1.2 eq.), Pd catalyst (4 mol%), ligand (20 mol%), O (balloon pressure) in the corresponding solvent (0.4 M)
were heated in a sealed tube at 100 °C for 24 h.
b
10 mol% of Pd catalyst was used in the reaction.

8
of 9
MOTEVALIZADEH ET AL.
a
TABLE 5 Scope of the regioselective arylation of coumarins
reusability and selectivity for the preparation of the
desired products are some of advantages of this semi‐het-
erogeneous nanocatalyst. Based on the above mentioned
results, it could be concluded that this green and cost‐
effective catalyst, with convenient experimental proce-
dure, could be a valuable alternative for Heck and oxida-
tive Heck coupling reaction.
a
Entry
R
R’
Yield
87%
82%
68%
82%
78%
‐
ACKNOWLEDGEMENTS
1
2
3
4
5
6
7
8
H
H
6‐Me
6‐NO
H
H
This work was supported financially by the grants from
Tehran University of Medical Sciences and Iran Science
Elite Federation (ISEF), Tehran, Iran.
2
H
4‐Me
4‐Et
4‐NO
4‐Me
4‐Me
H
ORCID
H
2
6‐Me
73%
67%
Ali Ramazani http://orcid.org/0000-0003-3072-7924
7‐OMe
a
Conditions: coumarin 1(1 equiv.), arylboronic acid 2(1.1 mmol), MCM‐
1@aPEI‐Pd (4 mol%), 1,10‐phenanthroline (20 mol%), O (balloon pressure)
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How to cite this article: Motevalizadeh SF,
Alipour M, Ashori F, et al. Heck and oxidative
boron Heck reactions employing Pd(II) supported
amphiphilized polyethyleneimine‐functionalized
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