Palladium-DABCO complex supported on γ-Fe2O3 magnetic nanoparticles: A new catalyst for CC bond formation via Mizoroki-Heck cross-coupling reaction

Article abstract of DOI:10.1016/j.apcata.2014.04.028

In this paper, palladium-DABCO complex supported on γ-Fe ₂O₃ magnetic nanoparticles (Pd-DABCO-γ-Fe ₂O₃) was synthesized and characterized by HRTEM, SEM, XRD, XPS, ICP, FT-IR, TGA, VSM and elemental analysis. The synthesized catalyst was successfully applied as a new magnetically recyclable heterogeneous catalyst in Mizoroki-Heck cross-coupling reaction of aryl halides with alkyl acrylates and styrene under solvent-free conditions.

Full text of DOI:10.1016/j.apcata.2014.04.028

Accepted Manuscript
Title: Palladium-DABCO complex supported on ␥-Fe2O3
magnetic nanoparticles: A new catalyst for C–C bond
formation via Mizoroki-Heck cross-coupling reaction
Author: Sara Sobhani Zahra Pakdin-Parizi
PII:
S0926-860X(14)00269-5
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.apcata.2014.04.028
APCATA 14801
To appear in:
Applied Catalysis A: General
Received date:
Revised date:
Accepted date:
14-12-2013
14-4-2014
15-4-2014
Please cite this article as: S. Sobhani, Palladium-DABCO complex supported on
rmgamma-Fe2O3 magnetic nanoparticles: A new catalyst for C-C bond formation
via Mizoroki-Heck cross-coupling reaction, Applied Catalysis A, General (2014),
http://dx.doi.org/10.1016/j.apcata.2014.04.028
This is a PDF file of an unedited manuscript that has been accepted for publication.
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*Graphical Abstract (for review)
R3
R2
X
Pd -DABCO--Fe2O3
R2
+
R3
R1
R1
R2 = Ph, CO2R4
R1 = H, OMe, Me, Cl, CN, NO2
X = I, Br, Cl
(R4 = Me, Et, n-Bu)
R3 = H, Me
Page 1 of 33

*Highlights (for review)
Research Highlights:
 Palladium-DABCO complex supported on γ-Fe2O3 (Pd-DABCO-γ-Fe2O3) was synthesized.
 Pd-DABCO-γ-Fe2O3 is a new phosphine-free palladium catalyst.
 Pd-DABCO-γ-Fe2O3 was successfully applied in Mizoroki-Heck cross-coupling reaction.
 Pd-DABCO-γ-Fe2O3 was isolated from the reaction mixture by magnetic decantation.
Page 2 of 33

Palladium-DABCO complex supported on γ-Fe2O3 magnetic nanoparticles: A new catalyst
for C-C bond formation via Mizoroki-Heck cross-coupling reaction
Sara Sobhani,* Zahra Pakdin-Parizi
Department of Chemistry, College of Sciences, University of Birjand, Birjand, Iran
*Corresponding author. Tel. +98 (561) 2502065; Fax: +98 (561) 2502065
E-mail address: ssobhani@birjand.ac.ir, sobhanisara@yahoo.com
Abstract
In this paper, palladium-DABCO complex supported on γ-Fe2O3 magnetic nanoparticles
(Pd-DABCO-γ-Fe2O3) was synthesized and characterized by HRTEM, SEM, XRD, XPS, ICP,
FT-IR, TGA, VSM and elemental analysis. The synthesized catalyst was successfully applied as
a new magnetically recyclable heterogeneous catalyst in Mizoroki-Heck cross-coupling reaction
of aryl halides with alkyl acrylates and styrene under solvent-free conditions.
Keywords: Palladium, Magnetic nanoparticle, Heterogeneous catalyst, Mizoroki-Heck, DABCO
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1. Introduction
Palladium is one of the most crucial metals in catalysis and it is commonly used to
catalyze a large variety of carbon–carbon (Csp2-Csp2) bond forming reactions [1-4]. Among
these reactions, palladium-catalyzed arylation of olefins, the Mizoroki-Heck cross-coupling
reaction, is an extremely useful and general technique for the synthesis of biologically active
functionalized olefins [5-8]. These cross-coupling reactions are commonly catalyzed by
homogeneous palladium complexes containing phosphine ligands. However, the soluble
palladium phosphine complexes suffer from problems associated with the separation, recovery,
and instability at high temperatures. Moreover, most of phosphine ligands are expensive, toxic,
not easily available, sensitive to air and moisture [9-11]. Consequently, the development of new
heterogeneous phosphine-free palladium catalysts is an ongoing challenge in this field of study
[12-16].
1,4-Diazabicyclo[2.2.2]octane (DABCO) is a medium-hindrance tertiary amine with
cage-like structure, which used as an inexpensive, eco-friendly, highly reactive and non-toxic
ligand or catalyst for various organic transformations [17-20]. DABCO was also appeared as a
substitute to phosphine ligands for the palladium-catalyzed Suzuki-Miyaura and Mizoroki-Heck
cross-coupling reactions. Due to the importance of using heterogeneous catalysts, recently,
palladium-DABCO complex supported on polymer, silica or SBA-15 was synthesized and used
as solid catalysts for cross-coupling reactions [21-24]. Despite the high catalytic activity of these
heterogeneous palladium catalysts, their separation techniques were energy and time consuming
and caused loss of the catalyst. Immobilization of palladium-DABCO complex on magnetic
nanoparticles (MNPs) offers a solution to this problem due to the ease of catalyst separation by
applying an appropriate magnetic field. Magnetic separation of MNPs, which is an alternative to
2
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filtration or centrifugation, prevents loss of the catalyst, facilitates its recycling and saves time
and energy. To benefit the valuable applications of MNPs and unique properties of DABCO as a
ligand, and in continues of our recent works on the development of new heterogeneous catalysts
[25-32], herein, we report the synthesis of palladium-DABCO complex supported on γ-Fe2O3
magnetic nanoparticles (Pd-DABCO-γ-Fe2O3). We have also used the synthesized Pd-DABCO-
γ-Fe2O3 as a new magnetically recyclable heterogeneous catalyst for Mizoroki-Heck cross-
coupling reactions under solvent-free conditions.
2. Experimental
Chemicals were purchased from Merck Chemical Company. NMR spectra were
recorded in ppm in CDCl3 on a Bruker Avance DPX-400 instrument using TMS as internal
standard. The purity of the products and the progress of the reactions were accomplished by
TLC on silica-gel polygram SILG/UV254 plates. HRTEM analysis were performed using
HRTEM microscope (Philips CM30). The morphology of the products was determined by using
Hitachi Japan, model s4160 Scanning Electron Microscopy (SEM) at accelerating voltage of 15
KV. FT-IR spectra were recorded on a JASCO FT-IR 460 plus spectrophotometer. Thermo
gravimetric analysis (TGA) was performed using a Shimadzu thermo gravimetric analyzer (TG-
50). Elemental analysis was carried out on a Costech 4010 CHNS elemental analyzer. Power X-
ray diffraction (XRD) was performed on a Bruker D8-advance X-ray diffractometer or on a
X’Pert Pro MPD diffractometer with Cu Kα (λ = 0.154 nm) radiation. Surface analysis
spectroscopy of the catalyst were performed in an ESCA/AES system. This system was
equipped with a concentric hemispherical (CHA) electron energy analyzer (Specs model EA10
plus) suitable for X-ray photoelectron spectroscopy (XPS). Room temperature magnetization
3
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isotherms were obtained using a vibrating sample magnetometer (VSM, LakeShore 7400). The
content of Pd in the catalyst was detemined by OPTIMA 7300DV ICP analyzer.
2.1. Synthesis of γ-Fe2O3 MNPs
γ-Fe2O3 MNPs were synthesized by a reported chemical co-precipitation technique of
ferric and ferrous ions in alkali solution with minor modifications [33,34]. FeCl2.4H2O (1.99 g)
and FeCl3.6H2O (3.25 g) were dissolved in deionized water (30 mL) under Ar atmosphere at
room temperature. A NH4OH solution (0.6 M, 200 mL) was then added drop wise (drop rate = 1
mL.min-1) to the stirring mixture at room temperature to reach the reaction pH to 11. The
resulting black dispersion was continuously stirred for 1 h at room temperature, and heated to
reflux for 1 h to yield a brown dispersion. The magnetic nanoparticles were subsequently
separated by a magnetic bar and washed with deionized water until it was neutralized. The as-
ο
synthesized sample was heated at 2 C.min-1 up to 250 οC and then kept in the furnace for 3 h to
give a reddish-brown powder.
2.2. Synthesis of chloro-functionalized γ-Fe2O3
The prepared γ-Fe2O3 (3.6 g) was sonicated in dry toluene (50 mL) for 30 min. 3-
chloropropyltrimethoxysilane (4 mL) and triethylamine (as a catalyst, 0.4 mL) was added to the
dispersed γ-Fe2O3 in toluene, slowly heated to 105 °C and stirred at this temperature for 48 h.
The resulting chloro-functionalized γ-Fe2O3 was separated by an external magnet and washed
with toluene, ethanol-water mixture, deionized water and ethanol in turn, and dried under
vaccum.
2.3. Synthesis of γ-Fe2O3 supported with DABCO (DABCO-γ-Fe2O3)
4
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DABCO (2 g) was added to a magnetically stirred mixture of chloro-functionalized γ-
Fe2O3 (3.6 g) in dry acetone (100 mL). After refluxing for 36 h, the mixture was cooled to room
temprature. The resulting DABCO-γ-Fe2O3 was separated by an external magnet, washed with
acetone and dried in oven under vaccum.
2.4. Synthesis of palladium-DABCO complex supported on γ-Fe2O3 (Pd-DABCO-γ-Fe2O3)
DABCO-γ-Fe2O3 (3.3 g) was added to a solution of palladium acetate (0.11 g) in dry
acetone (30 mL). The reaction mixture was stirred at room temperature for 24 h. After stirring,
the solid was separated by an external magnet, and washed with acetone, ethanol and ether. It
was then dried in an oven at 90 °C overnight to furnish Pd-DABCO-γ-Fe2O3.
2.5. General procedure for heterogeneous Mizoroki-Heck cross-coupling reaction
A mixture of aryl halid (1 mmol), olefin (1.1 mmol), Et3N (2 mmol) and catalyst (0.06 g,
1 mol%) was stirred at 100 °C for an appropriate time (Table 2). The reaction mixture was
diluted with EtOAc. The catalyst was separated by an external magnet, washed with EtOAc,
dried and re-used for a consecutive run under the same reaction conditions. Evaporation of the
solvent of the filtrate under reduced pressure gave the crude products. The pure products were
isolated by chromatography on silica gel eluted with n-hexane:EtOAc (50:1).
(E)-Methyl cinnamate
1H NMR (400 MHz, CDCl3)  3.74 (s, 3H), 6.38 (d, 1H, 3J = 16.4 Hz), 7.31-7.33 (m, 3H),
7.45-7.47 (m, 2H), 7.63 (d, 1H, 3J = 16.4 Hz) ppm.
(E)-n-Butyl cinnamate
5
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3
1H NMR (400 MHz, CDCl3),  0.88 (t, 3H, J = 7.6 Hz), 1.33-1.40 (m, 2H), 1.59-1.65 (m, 2H),
4.13 (t, 2H, 3J = 6.8 Hz), 6.36 (d, 1H, 3J = 16.0 Hz), 7.29-7.30 (m, 3H), 7.43-7.45 (m, 2H), 7.60
(d, 1H, 3J = 16.4 Hz) ppm.
(E)-n-Butyl 3-(4-chlorophenyl) acrylate
3
1H NMR (400 MHz, CDCl3),  0.90 (t, 3H, J = 7.2 Hz), 1.34-1.39 (m, 2H), 1.57-1.64 (m, 2H),
4.14 (t, 2H, 3J = 6.8 Hz), 6.64 (d, 1H, 3J = 16.0 Hz), 7.45 (d, 2H, 3J = 8.0 Hz), 7.63 (d, 1H, 3J =
16.0 Hz), 7.74 (d, 2H, 3J = 8.0 Hz) ppm.
3. Results and discussion
3.1. Catalyst synthesis and characterization
At first, γ-Fe2O3 NPs were synthesized by a chemical co-precipitation technique of ferric
and ferrous ions in alkali solution [33,34]. The magnetic nanoparticles were then allowed to react
with an appropriate concentration of 3-chloropropyl trimethoxysilane to give chloro-
functionalized γ-Fe2O3. The obtained chloro-functionalized γ-Fe2O3 was reacted with DABCO to
produce γ-Fe2O3 supported with DABCO (DABCO-γ-Fe2O3). To this end, the reaction of
DABCO-γ-Fe2O3 with Pd(OAc)2 in dry acetone led to the formation of palladium-DABCO
complex supported on γ-Fe2O3 MNPs (Pd-DABCO-γ-Fe2O3) (Scheme 1).
Scheme 1
The size and structure of Pd-DABCO-γ-Fe2O3 were evaluated using scanning electron
microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The SEM
image and HRTEM (Figure 1) showed uniformity and spherical-like morphology of
nanoparticles with an average diameter from ∼50 to 60 and 17±5 nm, respectively.
6
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Figure 1
FT-IR spectra of γ-Fe2O3, DABCO-γ-Fe2O3 and Pd-DABCO-γ-Fe2O3 were shown in
Figure 2. The band at around 627–648 cm−1 was assigned to the stretching vibrations of Fe-O
bond in these compounds [35]. The peaks positioned at 2910, 2930 and 1475 cm-1 in the FT-IR
spectrum of DABCO-γ-Fe2O3 and Pd-DABCO-γ-Fe2O3 were related to the stretching and
bending of the CH2 bonds, respectively [18]. Si–O stretching bond was observed at about 1000–
1110 cm−1 [18]. The anchoring of DABCO on γ-Fe2O3 was evidenced by the presence of C–N+
stretching at 1615 cm−1 in the spectra of DABCO-γ-Fe2O3 and Pd-DABCO-γ-Fe2O3 [18]. In the
spectrum of Pd-DABCO-γ-Fe2O3, new peaks appeared at 1360 and 1600 cm-1 for COO (in
acetate) [36], and at 1400 and 1640 cm−1 for COO (in bridged acetate) and confirmed the
presence of Pd in the catalyst [37].
Figure 2
The reflection planes of (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1) and (4 4 0) at around 2θ =
30.4ο, 35.8ο, 43.6ο, 53.7ο, 57.6°, 63.2ο were readily recognized from the XRD pattern of γ-Fe2O3
and Pd-DABCO-γ-Fe2O3 (Figure 3). The observed diffraction peaks agree with the cubic
structure of maghemite (JCPDS file No 04-0755). The same set of characteristic peaks was
observed in the XRD pattern of Pd-DABCO-γ-Fe2O3, which indicates the stability of the
crystalline phase of nanoparticles during the subsequent surface modification. The average
crystallite size of Pd-DABCO-γ-Fe2O3 (16 nm) was estimated using the Debye-Scherrer formula.
It is important to note that XRD results gave little meaningful data for palladium immobilization
on γ-Fe2O3 due to the low palladium loading on the support [38].
Figure 3
7
Page 9 of 33

In the X-ray photoelectron spectrum (XPS) of Pd-DABCO-γ-Fe2O3, binding energies at
338.5 and 343.0 eV corresponding to Pd 3d5/2 and Pd 3d3/2, respectively, confirmed the presence
of Pd (II) in the catalyst (Figure 4). XPS analysis of Pd-DABCO-γ-Fe2O3 after the Mizoroki-
Heck cross-coupling reaction showed almost identical patterns of Pd (II) in Pd-DABCO-γ-Fe2O3
(Figure 5). No peaks corresponding to Pd (0) in the metallic state was detected.
Figure 4
Figure 5
The Pd content of Pd-DABCO-γ-Fe2O3 was determined by inductively coupled plasma
(ICP). The ICP analysis showed that 0.16 mmol of Pd was anchored on 1.0 g of Pd-DABCO-γ-
Fe2O3.
The thermogravimetric analysis (TGA) of Pd-DABCO-γ-Fe2O3 was used to determine
the thermal stability and content of organic functional groups on the surface of MNPs (Figure 6).
ο
The small amount of weight loss around 100 C was attributed to the desorption of adsorbed
ο
water. Another mass loss appeared at around 220 C and the organic parts decomposed
ο
completely at 380 C. According to the TGA profile, the amount of organic components
supported on γ-Fe2O3 is estimated to be 0.14 mmol.g-1. These results are in good agreement with
the elemental analysis data (N = 0.40% and C = 2.42%).
Figure 6
The magnetization curves of Pd-DABCO-γ-Fe2O3 and γ-Fe2O3 were measured at room
temperature using a vibrating sample magnetometer (VSM). No reduced remanence and
coercivity were detected, indicating both unmodified and Pd-DABCO-γ-Fe2O3 are
superparamagnetic (Figure 7). The value of saturation magnetic moments of γ-Fe2O3 and Pd-
DABCO-γ-Fe2O3 are 68.5 and 60.3 emu/g, respectively.
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Figure 7
3.2. Evaluation of catalytic activity of Pd-DABCO-γ-Fe2O3 in the Mizoroki-Heck cross-coupling
reaction
Initially, the Mizoroki-Heck cross-coupling reaction of iodobenzene with n-butyl
acrylate in the presence of Pd-DABCO-γ-Fe2O3 (1 mol%) was chosen as a model for
optimizing reaction parameters such as the base and solvent at 100 °C (Scheme 2, Table 1).
Among the examined bases, triethylamine (Et3N) showed the best results for this reaction in
terms of reaction time and yield (Entries 1-4). The importance of the base was shown by
performing the reaction in the absence of the base. The results showed that under these
conditions, a trace amount of the desired cross-coupling product was obtained after 24 h (Entry
5). The model reaction was also examined in several solvents including DMF, H2O, EtOH,
CH3CN, CHCl3 and toluene (Entries 6-11) and the best yield was obtained in DMF as solvent
(Entry 6). To avoid the use of toxic and expensive organic solvents, the reaction was studied
under solvent-free conditions. It was observed that the coupling reaction gave excellent yield of
the product in 0.5 h (Entry 1). The yield of the product in a similar reaction at 80 °C was
decreased to 80% (Entry 12). Coupling reactions did not take place in the absence of the
catalyst or in the presence of γ-Fe2O3 and DABCO-γ-Fe2O3 even after 24 h (Entries 13-15).
The catalytic activity of Pd-DABCO-γ-Fe2O3 was also higher than that of Pd-supported γ-
Fe2O3 (Pd/γ-Fe2O3) as a catalyst (Entry 16).
Scheme 2
Table 1
The reaction of aryl halides with olefins in the presence of Pd-DABCO-γ-Fe2O3 under the
best reaction conditions was then investigated (Table 2).
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Table 2
The catalyst was effective for coupling reactions of olefins and iodobenzene to give the
corresponding products in excellent yields (Table 2, Entries 1-4). Iodobenzene functionalized
with electron-withdrawing or electron-donating substituents reacted with olefins rapidly and
generated the corresponding products in high yields (Entries 5 and 6). This catalytic system was
also successfully applied for the coupling reaction of substituted aryl bromides with n-butyl
acrylate (Entries 7-10). Various aryl chlorides underwent the coupling reactions with n-butyl
acrylate and gave the desired products in relatively good yields. However, the reaction proceeded
in longer reaction time compared with aryl bromides and iodides (Entries 11-15).
3
It is worth to note that JH-H value of 16 Hz for vinyllic hydrogens of (E)-methyl
cinnamate, (E)-n-butyl cinnamate and (E)-n-butyl 3-(4-chlorophenyl) acrylate was obtained
1
using H NMR spectra and showed an excellent selectivity for the formation of trans isomer of
the products. The Mizoroki-Heck cross-coupling reactions of aryl halides with styrene were also
examined. The corresponding products were obtained in 61-87% yields in 1–8 h (Entries 16-21).
The magnetic property of Pd-DABCO-γ-Fe2O3 facilitates efficient recovery of the
catalyst from the reaction mixture during work-up procedure. After performing the cross-
coupling reaction of iodobenzene with n-butyl acrylate under the present conditions, EtOAc was
added to the reaction mixture. The catalyst was separated by an external magnet from the
ο
reaction mixture (Figure 8b), washed with EtOAc, dried 30 min at 100 C and reused for a
consecutive run under the same reaction conditions. The average isolated yield of the product for
five consecutive runs was 90%, which clearly demonstrates the practical reusability of this
catalyst (Figure 9).
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Figure 8
Figure 9
4. Conclusions
In summary, palladium-DABCO complex supported on γ-Fe2O3 magnetic nanoparticles
as a new phosphine-free palladium catalyst was synthesized and applied as a magnetically
recyclable heterogeneous catalyst for Mizoroki-Heck cross-coupling reaction of aryl halides with
olefins under solvent-free conditions. The catalyst was easily isolated from the reaction mixture
by an external magnet and reused at least five times without significant degradation in its
activity.
Acknowledgements
We are thankful to University of Birjand Research Council for their support on this work.
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15
Page 17 of 33

Figure captions
Figure 1. SEM images (a, b) and HRTEM images (c, d, e) of Pd-DABCO-γ-Fe2O3
Figure 2. FT-IR spectra of γ-Fe2O3, DABCO-γ-Fe2O3 and Pd-DABCO-γ-Fe2O3
Figure 3. XRD patterns of a) γ-Fe2O3 and b) Pd-DABCO-γ-Fe2O3
Figure 4. X-ray photoelectron spectroscopy (XPS) of fresh Pd-DABCO-γ-Fe2O3
Figure 5. X-ray photoelectron spectroscopy (XPS) of used Pd-DABCO-γ-Fe2O3
Figure 6. TGA diagram of Pd-DABCO-γ-Fe2O3
Figure 7. Magnetization curves of γ-Fe2O3 and Pd-DABCO-γ-Fe2O3
Figure 8. a) Reaction mixture, b) Separation of Pd-DABCO-γ-Fe2O3 from the reaction mixture
by an external magnet
Figure 9. Reusability of Pd-DABCO-γ-Fe2O3 as a magnetically recyclable heterogeneous
catalyst for the Mizoroki–Heck cross-coupling reaction of iodobenzene with n-buthyl acrylate at
100 °C in 0.5 h
16
Page 18 of 33

O
O
OH
Cl
Si
O
OH
OH
O
Cl
Cl
Cl
Si
Si
Si
O
O
OH
OH
OH


-
(MeO)3Si(CH2)3Cl
F
-
DABCO
F
e
e
2
O
2
dry acetone, reflux, 36 h
dry toluene, Et3N, reflux, 48 h
O
O
O
O
3
3
OH
OH
OH
O
O
O
OAc
O
O
O
O
O
O
N
N
N
N
Si
Si
Pd
Cl
Cl
O
O
O
Pd
OAc
OAc
O
O
O
O
O
O
O
N
N
N
N
N
N
N
Si
Si
Si
Si

Cl
Cl
Cl
Cl

-
-
F
Pd (OAc)2
dry acetone, rt, 24 h
F
e
e
2
2
O
O
O
O
O
O
O
O
3
3
N
Pd
O
O
O
Pd
OAc
O
O
O
O
O
O
O
N
N
N
N
Si
Si
Cl
Cl
Scheme 1. Synthesis of Pd-DABCO-γ-Fe2O3
17
Page 19 of 33

(a)
(b)
(c)
(d)
(e)
Figure 1. SEM images (a,b) and HRTEM images (c,d,e) of Pd-DABCO-γ-Fe2O3
18
Page 20 of 33

Figure 2. FT-IR spectra of γ-Fe2O3, DABCO-γ-Fe2O3 and Pd-DABCO-γ-Fe2O3
19
Page 21 of 33

Figure 3. XRD patterns of a) γ-Fe2O3 and b) Pd-DABCO-γ-Fe2O3
20
Page 22 of 33

Figure 4. X-ray photoelectron spectroscopy (XPS) of fresh Pd-DABCO-γ-Fe2O3
21
Page 23 of 33

Figure 5. X-ray photoelectron spectroscopy (XPS) of used Pd-DABCO-γ-Fe2O3
22
Page 24 of 33

Figure 6. TGA diagram of Pd-DABCO-γ-Fe2O3
23
Page 25 of 33

Figure 7. Magnetization curves of γ-Fe2O3 and Pd-DABCO-γ-Fe2O3
24
Page 26 of 33

O
I
OBun
OBun
Catalyst
Base
+
O
Scheme 2. Mizoroki-Heck cross-coupling reaction of iodobenzene with n-butyl acrylate
25
Page 27 of 33

Table 1 Mizoroki–Heck cross-coupling reaction of iodobenzene with n-butyl acrylate under
different conditions.
Entry
1
Iodobenzene: n-Butyl acrylate
Base
Et3N
K2CO3
KOH
NaOAC
-
Solvent
Time (h) Yield (%)a
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
1:1.1
-
0.5
2
92
70
2
-
3
-
2
81
4
-
2
74
5
-
24
0.5
3
Trace
96
6
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
DMF
7
H2O
49
8
EtOH
3
41
9
CH3CN
3
53
10
11
12b
13c
14d
15e
16f
CHCl3
3
34
toluene
3
26
-
-
-
-
-
0.5
24
24
24
1
80
Trace
Trace
Trace
64
a Isolated yield. Reaction conditions: Et3N (2 equivalents), Pd-DABCO-γ-Fe2O3 (1 mol%, except for entries 12-14),
temperature = 100 oC.
bTemperature: 80 °C.
c No catalyst.
d Catalyst: γ-Fe2O3 (0.04 g).
e Catalyst: DABCO- γ-Fe2O3 (1 mol%).
f Catalyst: Pd/γ-Fe2O3 (1 mol%).
26
Page 28 of 33

Table 2 Mizoroki-Heck cross-coupling reaction of olefins with aryl halides in the presence of
Pd-DABCO-γ-Fe2O3 as a catalyst at 100 °C.
Entry
Arylhalide
Olefin
Product
Time (h) Yield (%)a
O
I
OBun
OBun
1
0.5
92
O
O
O
I
OMe
OMe
OEt
2
3
4
0.5
0.5
0.5
90
84
88
OMe
OMe
OEt
O
I
I
O
O
O
O
O
I
O Bun
OBun
5
4
82
MeO
MeO
O
I
OBun
OBun
OBun
6
7
8
4
7
8
86
83b
65b
Cl
Cl
O
O
Br
OBun
O
O
O
Br
OBun
OBun
Me
Me
27
Page 29 of 33