Amine-based ionic liquids (R3N+PPh2) as a reusable reaction medium and Pd(II) ligand in Heck reactions of aryl halides with styrene and n-butyl acrylate

Article abstract of DOI:10.1016/j.molcata.2014.01.005

Amine-based ionic liquids (R₃N⁺PPh₂) are reported as an effective reusable medium, suitable Pd(II) ligand and also reducing agent for the Heck coupling reaction of aryl iodides and bromides with styrene and n-butyl acrylate. The ionic liquid, still containing its corresponding Pd(0) complex, was easily recovered and reused in several runs without losing its efficiency.

Full text of DOI:10.1016/j.molcata.2014.01.005

Journal of Molecular Catalysis A: Chemical 385 (2014) 13–17
Contents lists available at ScienceDirect
Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
Amine-based ionic liquids (R3N+PPh2) as a reusable reaction medium
and Pd(II) ligand in Heck reactions of aryl halides with styrene and
n-butyl acrylate
Najmeh Nowrouzia,∗, Dariush Tarokha, Somayeh Motevallib
a Department of Chemistry, Faculty of Sciences, Persian Gulf University, Bushehr 75169, Iran
b Department of Chemistry, Shiraz University, Shiraz 71454, Iran
a r t i c l e i n f o
a b s t r a c t
Amine-based ionic liquids (R3N+PPh2) are reported as an effective reusable medium, suitable Pd(II) ligand
and also reducing agent for the Heck coupling reaction of aryl iodides and bromides with styrene and
n-butyl acrylate. The ionic liquid, still containing its corresponding Pd(0) complex, was easily recovered
and reused in several runs without losing its efficiency.
Article history:
Received 18 November 2013
Received in revised form
30 December 2013
Accepted 2 January 2014
Available online 10 January 2014
© 2014 Elsevier B.V. All rights reserved.
Keywords:
Ionic liquids
Palladium
Mizoroki–Heck reaction
Aryl halides
1. Introduction
have been reported in ILs [7,8c,13]. The Heck reaction as a versatile
method provides an efficient route for the synthesis of substi-
Transition-metal catalyzed carbon–carbon bond forming reac-
tions have become one of the most important tools in synthetic
chemistry [1]. Among different transition metals [2], Pd based cat-
alysts have been used extensively in these reactions during the
last decades. In this regard, the chemists have been interested in
improving and development of different aspects of Pd catalysts
involving types of new ligands [3] or the use of heterogeneous Pd
catalyst which Pd is fixed to a solid support such as activated car-
bon [4], complex matrices immobilized on silica and functionalized
silica [5], polymers [6] alongside techniques such as microwave
irradiation [7] or reaction media including ionic liquids [8], PEG [9]
and also reaction under solvent-free conditions [5a,10] have also
been considered as potential tools for this purpose. The importance
of green reactions in organic synthesis has encouraged scientists to
use from ionic liquids (ILs) as environmentally friendly reaction
media, catalysts, reagents, and also in separation processes [11].
ILs usually possesses unique properties, such as nonvolatility, non-
flammability, and remarkable chemical and thermal stability [12]. A
variety of reactions [7b,8b–c], including transition-metal catalyzed
carbon–carbon coupling reactions such as Mizoroki–Heck reaction
tuted olefins through cross-coupling of aryl halides and olefins in
organic synthesis. In 1984, in a pioneering work Jeffery reported
the palladium-catalyzed vinylation of organic iodides under solid
liquids phase transfer conditions using tetrabutylammonium chlo-
ride. This salt as an additive has been proved to have a crucial effect
on the rate and yield of reaction through much probably the role
of tetrabutylammonium chloride as the stabilizing agent for the
colloidal palladium, which hinders its agglomeration to metallic
palladium [13b]. However, the first application of ILs in palladium-
catalyzed Heck reaction was reported by Kauffmann et al. in the
presence of Pd(OAc)2 or PdCl2 as appropriate catalyst precursors
for this reaction without additive ligands in [C16H33PBu3]Br. The
use of [bmim]PF6 and other ILs, such as hexylpyridinium salts
(C6PyCl, C6PyPF6, C6PyBF4), has also been described for phosphine-
free Heck reaction. The addition of Ph3P as ligand promoted the
reactions which required longer reaction times and higher tem-
perature to go to completion [14]. Generally, due to the importance
of phosphines and phosphinites as phosphorous-based ligands in
organometallic chemistry, their metal complexes have been used
in many catalytic reactions [5a,6,15]. Common ILs have a tendency
to leach dissolved catalysts into the co-solvent used to extract the
product(s). To avoid metal catalysts leaching out of the IL system,
significant efforts have been made to enhance the solubility of the
catalysts in ILs and one of approaches is to insert functional groups
∗
Corresponding author. Tel.: +98 771 4222341; fax: +98 771 4541494.
E-mail address: nowrouzi@pgu.ac.ir (N. Nowrouzi).
1381-1169/$ – see front matter © 2014 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molcata.2014.01.005

14
N. Nowrouzi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 13–17
able to coordinate with metal centers into the ILs [13b]. In this
regard, the task-specific ionic liquids are developing in the Heck
reaction. An imidazolium-based phosphinite, a room temperature
task-specific IL, was reported by Iranpoor et al. as Pd ligand and
solvent for the efficient carbon–carbon coupling reactions of aryl
halides [8c,16].
N
P
N
P
Cl
Cl
2. Experimental
(IL1)
(IL2)
Transmission electron microscopy (TEM) analyses were per-
formed on a Philips model CM 10 instrument. Scanning electron
micrograph was obtained by SEM, XL-30 FEG SEM, Philips, at 20 kV.
IR spectra were run on a Shimadzu FTIR-8300 spectrometer. The
1H and 13C NMR spectra were recorded on a Brucker Avance
DPX-250 MHz spectrometer using tetramethylsilane as internal
standard.
Scheme 1. Structures of N-(diphenylphosphino)trietylammonium chloride (IL1)
and N-(diphenylphosphino)tributylammonium chloride (IL2).
afford the highly pure products. The products were identified by
their spectral data and comparison with authentic samples.
2.4. General procedure for the Mizoroki–Heck reaction in the
presence of PdCl2/IL2
2.1. Typical procedure for the preparation of
N-(diphenylphosphino)triethylammonium chloride (IL1):
Aryl halides (1.0 mmol) were added to a flask containing
IL2 (0.5 mmol, 0.20 g), PdCl2 (3 mol%, 0.0053 g), NaOH (2.0 mmol,
0.08 g) and olefin (2.0 mmol) and the mixture was stirred at 120 ◦C.
After completion of the reaction, which was detected by TLC analy-
ses, the mixture was cooled to room temperature and the coupled
products were extracted with diethyl ether (3 × 3 mL). The sol-
vent was then evaporated to leave the crude products, which
were purified by column chromatography over silica gel using n-
hexane/ethyl acetate (4:1) as the eluent to give pure products. The
products were identified by their spectral data and comparison
with authentic samples.
Under argon atmosphere, to a two-necked flask containing
triethylamine (15.0 mmol, 2.0 mL), chlorodiphenylphosphine
(10.0 mmol, 1.8 mL) was added drop wise with vigor-
ous stirring. Stirring was continued for 5 min at 50 ◦C to
obtain the product as
a white solid. The produced N-
(diphenylphosphino)triethylammonium chloride (IL1) was
washed with diethyl ether (3 × 5 mL) to remove the remaining
substrates, then filtered, dried under vacuum, and was stored in
a capped bottle without any change for months (3.0 g, 93%). m.p.:
120–122 ◦C; IR (KBr): 3055 ( CH), 2974 (C–H), 2937 (C–H), 1590
(C C), 1475 (C C), 1178 (C–N), 1128 (P-Ph), 961 (P-N) cm−1; ıH
(250 MHz, CDCl3) 7.30–6.87 (10H, m, Ph), 2.64 (6H, m, CH2), 0.88
(9H, t, J 7.3 Hz, Me); ıC (62.9 MHz, CDCl3) 131.78, 131.74, 131.15,
130.99, 130.64, 130.46, 128.38, 128.16, 45.88, 8.63.
3. Results and discussion
3.1. Synthesis and characterization
In this work we report
a
very easy method for
the synthesis of new amine-based ionic liquids of N-
2.2. Typical procedure for the preparation of
N-(diphenylphosphino)tributylammonium chloride (IL2):
(diphenylphosphino)trietylammonium
chloride
(IL1)
and
N-(diphenylphosphino)tributylammonium
chloride
(IL2)
(Scheme 1). Triethylamine and tributylamine were function-
alized by treatment with ClPPh2 under argon atmosphere at 50 ◦C
and room temperature, respectively. Then, their successful appli-
cation has been studied both as reaction media and as a potential
complexing agent through the phosphine group, in conjunction
with Pd(II) salts for Heck reaction of aryl iodides and bromides
with styrene and n-butyl acrylate.
In order to have more information about the reducing property
of these ILs, We probed the ultraviolet (UV) spectrum of Pd(II) in
aqueous solution of IL1. The white color of the IL changed almost
immediately to gray upon the addition of PdCl2 at room tem-
perature; this demonstrated the efficiency of the generation of
zero-valent palladium by this IL. The UV spectrum of palladium
chloride solution is shown in curve A of Fig. 1. The peak at around
450 nm shows the presence of Pd(II). Curve B belongs to the aque-
ous solution of IL1 including PdCl2. The disappearance of the peak
around 450 nm confirms that Pd(II) has been reduced to the Pd(0)
species in the presence of IL1.
Under argon atmosphere, to a flask containing tributylamine
(15.0 mmol, 3.6 mL) was added ClPPh2 (10.0 mmol, 1.8 mL) drop
wise at room temperature. The mixture was stirred with a mechan-
ical stirrer. After 30 min, the reaction mixture was cooled in ice bath
for 1 h and then washed with diethyl ether (3 × 5 mL), filtered and
dried under vacuum. IL2 was obtained as a room temperature ionic
liquid in 85% yield (3.4 g), which was stored in a capped bottle with-
out any change for months. IR (KBr): 3054 ( CH), 2973 (C–H), 2936
(C–H), 1590 (C C), 1474 (C C), 1178 (C–N), 1127 (P-Ph), 959 (P-
N) cm−1; ıH (250 MHz, CDCl3) 7.62–7.20 (10H, m, Ph), 2.96 (6H,
m, NCH2), 1.28 (12H, m, CH2CH2), 0.86 (9H, m, Me); ıC (62.9 MHz,
CDCl3) 131.86, 131.82, 131.26, 128.41, 128.20, 52.23, 25.13, 20.11,
13.58.
2.3. General procedure for the Mizoroki–Heck reaction in the
presence of PdCl2/IL1
PdCl2 (3 mol%, 0.0053 g), IL1 (0.5 mmol, 0.16 g), NaOH (2.0 mmol,
0.08 g), olefin (2.0 mmol), and aryl halide (1.0 mmol) were placed
in a 25 mL flask equipped with a magnetic stirring bar and heated
at 120 ◦C. The completion of the reaction was monitored by TLC
analysis. After completion of the reaction, the reaction mixture was
cooled to room temperature and the products were extracted with
diethyl ether (3 × 3 mL). The solvent was then evaporated to leave
the crude products, which were purified by column chromatogra-
phy over silica gel using n-hexane/ethyl acetate (4:1) as eluent to
The simplest of the spectrophotometric techniques that have
been used for the study of the composition of complexes is the mole
ratio method which the amount of one reactant, usually the moles
of metal, is held constant, which the amount of the other reactant
is varied. In order to find out the nature of the catalyst, initially
the solution of PdCl2 (0.002 M), base (0.13 M), and IL1 (0.03 M) in
DMSO were prepared, separately. Then, the solution of Pd(II) and
base were mixed and the absorbance of the solution was measured
by UV spectra. It was in the wavelength of 281 nm in related to

N. Nowrouzi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 13–17
15
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
The information about the surface of catalyst was obtained by
the scanning electron microscopy (SEM) image as presented in
Fig. 3.
Transmission electron microscopy (TEM) image of the catalyst
shows that Pd nanoparticles are formed and dispersed on the IL1
with a size ∼20 nm (Fig. 4).
A
B
3.2. Catalytic activity of the catalyst in C–C coupling reactions
300 350 400 450 500 550 600 650 700
Wavelength (nm)
We initially studied the efficiency of N-(diphenylphosphino)
triethylammonium chloride both as solvent and as ligand for the
coupling of bromobenzene with styrene as a model reaction in
the presence of catalytic amounts of PdCl2 and different bases
at 120 ◦C (Table 1). Among applied organic and inorganic bases,
sodium hydroxide (NaOH) showed the most suitable one for this
reaction (Table 1, entry 5). In the absence of base, the starting mate-
rial remained unchanged under the same reaction condition after
24 h (Table 1, entry 1).
The use of this ionic liquid also allows to be avoided the use
of organic solvents such as DMF or DMSO, and toluene widely
employed in Heck reactions. Under our optimized reaction con-
ditions (1.0 mmol of aryl halide, 2.0 mmol of NaOH, 2.0 mmol of
styrene, 0.03 mmol (3 mol%) PdCl2, 0.5 mmol of ILs), the desired
products were obtained in good to excellent yields for a wide
array of aryl iodides and bromides both in IL1 and in IL2 at 120 ◦C.
The results are shown in Table 2. The cross-coupling reaction pro-
ceeded smoothly for iodobenzene and p-iodotoluene as benzene
bearing electron-donating group at the para position with styrene
and n-butyl acrylate (Table 2, entries 1, 3, 9, 11). The ortho-methyl
Fig. 1. UV spectra of the palladium catalyst. (A) PdCl2, (B) IL1 + PdCl2.
the complexation of Pd(II) and DMSO (Fig. 2). In the next step, a
series of solutions were prepared which contain equal formal con-
centrations of metal ion (Pd2+) but different formal concentrations
of the ligand. The ratio of these concentrations varied from 0.5 to 5.
The absorbance of each solution was then measured. A plot of the
absorbance against the ratio of the number of moles of ligand to the
number of moles of the metal ion showed the stochiometric ratio
of ligand to metal (Fig. 2). As shown in this figure, the absorbance
reduced by adding ligand to the solution of metal ion gradually due
to the replacement of ligand with DMSO in complex and finally it
remained constant. The use of the mole ratio method [17] for the
complex formation between this IL and PdCl2 is in good agreement
with the ML2 structure.
Fig. 2. Mole ratio plot for complex formation between PdCl2 and IL1.
Table 1
Effect of different bases on Heck reaction of bromobenzene and styrene.a
Br
PdCl2, IL1
+
Base
120 oC
.
Entry
Base
Time (h)
Yield of trans stylbene (%)b
1
2
3
4
5
6
7
–
24
24
24
25 min
8 min
24
–
–
–
90
93
60
50
Na2CO3
CaCO3
DBU
NaOH
Et3N
Bu3N
24
a
Reaction conditions: 0.03 mmol of PdCl2, 0.5 mmol of IL1, 1.0 mmol of bromobenzene, 2.0 mmol of styrene and 2.0 mmol of base at 120 ◦C.
Isolated yield.
b

16
N. Nowrouzi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 13–17
Table 2
Heck reaction of n-butyl acrylate and styrene with aryl halides.a
X
Y
PdCl2, IL
Y
+
NaOH
120 oC
R
R
.
Entry
1
ArX
Y
Yield (%)b
Time (h)
I
I
-Ph
90 (90)
70 (73)
5 min (35 min)c
CH 3
2
3
-Ph
-Ph
1 (2)c
I
85 (81)
1.5 (2.5)c
Fig. 3. Scanning electron micrograph (SEM) image of Pd-supported IL1.
H3C
O2N
I
4
5
6
-Ph
-Ph
-Ph
60 (56)
95 (90)
90 (81)
24 (24)c
iodobenzene which has some steric effect also produced the desired
coupled products in good to excellent yields (Table 2, entries 2,
10). The catalytic system was equally efficient for aryl bromides:
complete conversion had been achieved in the reactions of bro-
mobenzene and 4-bromotoluene with styrene and n-butylacrylate
in excellent yields (Table 2, entries 5, 6, 13, 14). Also, the Heck
reaction of sterically hindered 1-bromonaphthalene afforded mod-
erate and good yields of the corresponding coupled products with
styrene and n-butylacrylate, respectively (Table 2, entries 8, 16).
In general, the reaction of the substrates bearing –NO2 group pro-
ceeded slowly in the same reaction conditions (Table 2, entries 4,
7, 12, 15). Probably the elongation of the reaction time for these
aryl halides refers to its less solubility in ILs. Unfortunately, this
catalytic system is not efficient for chloro arenes.
Br
8 min (45 min)c
45 min (1)c
Br
Br
H3C
O2N
7
-Ph
60 (61)
15 (24)c
Br
The reusability of catalyst is the major area of interest due
to environmental concerns, costs of the catalyst and its toxicity.
Regarding the property of these ILs as complexing agent with the
Pd(II) species, the recovery and reusability of IL1 and its Pd(0) com-
plex was investigated in the Heck reaction of bromobenzene with
styrene for four cycles without any pre-treatment. The results are
tabulated in Table 3.
8
9
-Ph
60 (53)
95 (91)
95 (95)
24 (24)c
3 (4)c
I
I
-CO2Bu-n
-CO2Bu-n
CH 3
10
4 (6)c
I
I
11
-CO2Bu-n
90 (89)
3 (4)c
H3C
O2N
12
13
14
-CO2Bu-n
-CO2Bu-n
-CO2Bu-n
65 (61)
80 (82)
85 (80)
24 (24)c
6 (8)c
Br
Br
Br
2 (3)c
H3C
O2N
15
-CO2Bu-n
60 (60)
24 (24)c
Fig. 4. Transmission electron microscopy (TEM) of Pd-supported IL1.

N. Nowrouzi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 13–17
17
Table 2 (Continued)
References
Entry
ArX
Y
Yield (%)b
80 (87)
Time (h)
20 (24)c
[1] (a) S. Brase, A. de Meijere, in: F. Diederich, P.J. Stang (Eds.), Metal-Catalyzed
Cross-coupling Reactions, Wiley-VCH, Weinheim, 1998;
(b) J.T. Link, L.E. Overman, in: F. Diederich, P.J. Stang (Eds.), Metal-Catalyzed
Cross-coupling Reactions, Wiley-VCH, Weinheim, 1998;
(c) G.T. Crisp, Chem. Soc. Rev. 27 (1998) 427–436;
Br
16
-CO2Bu-n
(d) I.P. Beletskaya, A.V. Cheprakov, Chem. Rev. 100 (2000) 3009–3066;
(e) V. Nair, S. Vellalath, B.P. Babu, Chem. Soc. Rev. 37 (2008) 2691–2698.
[2] (a) P.M. Maitlis, A. Haynes, in: G.P. Chiusoli, P.M. Maitlis (Eds.), Metal-Catalysis
in Industrial Organic Processes, RSC Publishing, Cambridge, UK, 2006, pp.
146–162;
a
Reaction conditions: 0.03 mmol of PdCl2, 0.5 mmol of IL, 1.0 mmol of aryl halide,
2.0 mmol of styrene or n-butyl acrylate and 2.0 mmol of NaOH at 120 ◦C.
b
Isolated yield.
(b) F. Calderazzo, M. Catellani, G.P. Chiusoli, in: G.P. Chiusoli, P.M. Maitlis (Eds.),
Metal-catalysis in Industrial Organic Processes, RSC Publishing, Cambridge, UK,
2006, pp. 163–175;
c
Data in the brackets show isolated yields and reaction time in IL2.
(c) S.L. Zultanski, G.C. Fu, J. Am. Chem. Soc. 135 (2013) 624–627.
[3] (a) H. Firouzabadi, N. Iranpoor, M. Gholinejad, Tetrahedron 65 (2009)
7079–7084;
Table 3
Coupling of bromobenzene with styrene in the presence of recycled ionic liquid (IL1)
and its Pd complex.a
(b) E. Jung, K. Park, J. Kim, H.T. Jung, I.K. Oh, S. Lee, Inorg. Chem. Commun. 13
(2010) 1329–1331;
(c) N. Iranpoor, H. Firouzabadi, A. Tarassoli, M. Fereidoonnezhad, Tetrahedron
66 (2010) 2415–2421.
Cycle
Time (min)
Yield (%)b
Pd-leaching %c
1
2
3
4
8
40
95
95
90
80
75
1.22
1.12
1.31
1.43
[4] H. Hagiwara, Y. Shimizu, T. Hoshi, T. Suzuki, M. Ando, K. Ohkubo, C. Yokoyama,
Tetrahedron Lett. 42 (2001) 4349–4351.
[5] (a) N. Iranpoor, H. Firouzabadi, S. Motevalli, M. Talebi, J. Organomet. Chem.
708–709 (2012) 118–124;
(b) N. Iranpoor, H. Firouzabadi, A. Safavi, S. Motevallia, M.M. Doroodmand, Appl.
Organometal. Chem. 26 (2012) 417–424.
[6] B. Tamami, S. Ghasemi, J. Mol. Catal. A: Chem. 322 (2010) 98–105.
[7] (a) K.S.A. Vallin, P. Emilsson, M. Larhed, A. Hallberg, J. Org. Chem. 67 (2002)
6243–6246;
135
a
Reaction conditions: 1.0 mmol of bromobenzene, 0.03 mmol of PdCl2, 0.5 mmol
of IL1, 2.0 mmol of styrene or n-butyl acrylate and 2.0 mmol of NaOH at 120 ◦C.
b
Isolated yield.
The analysis was performed by ICP.
c
(b) X. Xie, J. Lu, B. Chen, J. Han, X. She, X. Pan, Tetrahedron Lett. 45 (2004)
809–811.
To probe the palladium-leaching in the system, the filtrate of
the reaction between bromobenzene with styrene after completion
of the reaction was analyzed by ICP in four repeating cycles. Low
palladium contamination was observed during this experiment. It
showed that the catalyst was highly reusable. The Pd catalyst exhib-
ited only a slight loss in its activity and required a bit longer time
to achieve full conversion during four cycles shown in Table 3.
[8] (a) L. Xu, W. Chen, J. Ross, J. Xiao, Org. Lett. 3 (2001) 295–297;
(b) N. Iranpoor, H. Firouzabadi, Y. Ahmadi, Eur. J. Org. Chem. 2 (2012) 305–311;
(c) N. Iranpoor, H. Firouzabadi, R. Azadi, Eur. J. Org. Chem. 13 (2007) 2197–2201;
(d) G.K. Datta, K.S.A. Vallin, M. Larhed, Mol. Div. 7 (2003) 107–114.
[9] (a) Y. Uozumi, T. Watanabe, J. Org. Chem. 64 (1999) 6921–6923;
(b) L. Wang, Y. Zhang, Ch. Xie, Y. Wang, Synlett 12 (2005) 1861–1864.
[10] H. Firouzabadi, N. Iranpoor, A. Ghaderi, M. Ghavami, S.J. Hoseini, Bull. Chem.
Soc. Jpn. 84 (2011) 100–109.
[11] (a) J.R. Harjani, S.J. Nara, M.M. Salunkhe, Tetrahedron Lett. 43 (2002) 1127;
(b) V.V. Namboodiri, R.S. Varma, Chem. Commun. 4 (2002) 342;
(c) W. Sun, C.G. Xia, H.W. Wang, Tetrahedron Lett. 44 (2003) 2409;
(d) K. Qiao, C. Yakoyama, Chem. Lett. 33 (2004) 472;
(e) Z.G. Le, Z.C. Chen, Y. Hu, Q.G. Zheng, Synthesis 17 (2004) 2809;
(f) M.J. Earle, S.P. Katdare, K.R. Seddon, Org. Lett. 6 (2004) 707.
[12] (a) P. Wasserscheid, W. Keim, Angew. Chem. 112 (2000) 3926–3945, Angew.
Chem. Int. Ed (2000) 39 3772–3789;
4. Conclusion
In conclusion, we have developed a very easy and cheap method
for phosphorylation of trialkylamines and their application in the
Heck cross-coupling reaction of aryl halides. The obtained trialky-
lammonium phosphines can be complexed to PdCl2 in order to
reduce Pd(II) to Pd(0) and generate in situ Pd(0) nanoparticles.
The insolubility of Pd(0) supported trialkylammonium phosphine
provides a very simple workup procedure and the catalyst can be
simply recovered by filtration. The stability, and also recyclability
of the catalyst can be regarded as other advantages of this system.
(b) J. Dupont, R.F. Souza, P.A.Z. Suarez, Chem. Rev. 102 (2002) 3667–3692;
(c) J.S. Wilkes, Green Chem. 4 (2002) 73–80.
[13] (a) W.A. Herrmann, V.P.W. Böhm, J. Organomet. Chem. 572 (1999) 141–145;
(b) F. Bellina, C. Chiappe, Molecules 15 (2010) 2211–2245;
(c) K. Selvakumar, A. Zapf, M. Beller, Org. Lett. 4 (2002) 3031–3033.
[14] D. Kaufmann, M. Nouroozian, H. Henze, Synlett 11 (1996) 1091–1092.
[15] (a) A. Mansour, M. Portnoy, J. Mol. Catal. A: Chem. 250 (2006) 40–43;
(b) G. Singh, S. Bali, A.K. Singh, Polyhedron 26 (2007) 897–903;
(c) D.E. Bergbreiter, A.M. Kippenberger, G. Tao, Chem. Commun. 18 (2002)
2158–2159;
Acknowledgment
(d) M. Guino, K.K. Hii, Tetrahedron Lett. 46 (2005) 6911–6913;
(e) R. Chanthateyanonth, H. Alper, J. Mol. Catal. A: Chem. 201 (2003) 23–31;
(f) H. Kosslick, I. Mönnich, E. Paetzold, H. Fuhrmann, R. Fricke, D. Müller, G.
Oehme, Micropor. Mesopor. Mater. 44–45 (2001) 537–545;
(g) E. Paetzold, G. Oehme, H. Fuhrmann, M. Richter, R. Eckelt, M.M. Pohl, H.
Kosslick, Micropor. Mesopor. Mater. 44–45 (2001) 517–522.
[16] (a) N. Iranpoor, H. Firouzabadi, R. Azadi, J. Organomet. Chem. 695 (2010)
887–890;
We thank the Persian Gulf University Research Council for gen-
erous partial financial support of this study.
Appendix A. Supplementary data
(b) N. Iranpoor, H. Firouzabadi, R. Azadi, J. Organomet. Chem. 693 (2008)
2469–2472.
[17] B. Gaugain, J. Barbet, N. Capelle, B.P. Roques, J.B. Le Pecq, Biochemistry 17 (1978)
5078–5088.
Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/j.molcata.
2014.01.005.