Heterogeneous Suzuki and Stille coupling reactions using highly efficient palladium(0) immobilized MCM-41 catalyst

Article abstract of DOI:10.1016/j.tetlet.2009.05.098

An efficient palladium(0) immobilized MCM-41 catalytic system for C-C cross-coupling reaction has been developed. Ligand-free Pd(0)-MCM-41 catalyst can be successfully used in coupling reaction between various aryl halides including deactivated chlorobenzene with aryl borane and organotin to give biaryls in excellent yields with high turnover frequency (TOF) (the maximal TOFs are up to 6990 for the reaction of bromobenzene with phenylboronic acid). The catalyst can be recycled and reused without any loss of catalytic activity.

Full text of DOI:10.1016/j.tetlet.2009.05.098

Tetrahedron Letters 50 (2009) 4820–4823
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Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Heterogeneous Suzuki and Stille coupling reactions using highly efficient
palladium(0) immobilized MCM-41 catalyst
Sreyashi Jana, Satyajit Haldar, Subratanath Koner *
Department of Chemistry, Jadavpur University, Kolkata 700 032, India
a r t i c l e i n f o
a b s t r a c t
Article history:
An efficient palladium(0) immobilized MCM-41 catalytic system for C–C cross-coupling reaction has been
developed. Ligand-free Pd(0)-MCM-41 catalyst can be successfully used in coupling reaction between
various aryl halides including deactivated chlorobenzene with aryl borane and organotin to give biaryls
in excellent yields with high turnover frequency (TOF) (the maximal TOFs are up to 6990 for the reaction
of bromobenzene with phenylboronic acid). The catalyst can be recycled and reused without any loss of
catalytic activity.
Received 25 February 2009
Revised 15 May 2009
Accepted 27 May 2009
Available online 30 May 2009
Keywords:
Suzuki reaction
Ó 2009 Elsevier Ltd. All rights reserved.
Stille coupling reactions
Heterogeneous catalysis
Catalyst recycling
Compounds containing biaryl linkage are an important class of
organic compounds and have found widespread applications in
many areas of organic synthesis, natural product synthesis such
via covalent bond shows impressive catalytic properties.16 In the
course of our continuing investigation in different organic reac-
tions using ordered mesoporous silica materials as heterogeneous
catalyst we have found that the hybrid organic–inorganic material
demonstrates excellent catalytic efficacy. Herein, we describe an
entirely heterogeneous ligand-free palladium-catalyzed carbon–
carbon cross-coupling reaction system that is very effective with
the less expensive bromobenzenes, and requires very small
amounts of the solid palladium catalyst which is entirely recover-
able and reusable.
1
2
,3
4
5
as tellimagrandins, gossypol, polymer science, and in material
6
science as precursors to rigid liquid crystals. Several methods are
available in the literature for the preparation of biaryls.
Amongst them Suzuki and Stille cross-coupling reactions are found
to be most effective. The relative thermal stability, insensitivity
to air or moisture, and low toxicity1 of boronic acid constitute a
highly valuable practical advantage for both academic and indus-
trial applications. Besides, the tin reagents that are used in the
Stille coupling reactions can be easily synthesized and purified.
For the Suzuki reactions soluble palladium complexes such as
Pd(PPh and Pd(PPh Cl are usually used as catalysts along with
1
,7–10
1
,8
The catalyst, Pd(0)-MCM-41 was prepared via simultaneous
1
1
2+
incorporation of [Pd(NH
3
)
4
]
ions into the mesoporous material
during the synthesis of MCM-41 and subsequently upon treat-
2
+
3
)
4
3
)
2
2
ments with hydrazine hydrate, Pd ions present in mesoporous
silica matrix were reduced to Pd(0) almost instantaneously.
Pd(0)-MCM-41 has been characterized thoroughly and reported
the bases such as soluble amines. Although homogeneous palla-
dium catalysts have proven to be efficient, it is difficult to recover
them from products and it is still very uneconomic to use them for
large-scale preparation. From the standpoint of environmentally
1
7
in our recent publication. The Pd content of the catalyst was
quantified by PerkinElmer A-Analyst 200 atomic absorption spec-
12
À5
benign organic synthesis, development of ligand-free immobi-
lized palladium catalysts is challenging and important.13
The mesoporous silica-based materials designated as M41S
trometer and found to be 0.008 (wt %) (7.52 Â 10 mol %).
To illustrate the catalytic activity, Pd(0)-MCM-41 was first used
as a heterogeneous catalyst for the synthesis of biphenyls via Suzu-
ki cross-coupling reactions. In a typical experiment for Suzuki cou-
14
have attracted a lot of attention in catalysis study since its inven-
tion by the scientists of Mobil Corporation.15 MCM-41 is one of the
members of this family having uniform hexagonal arrays of one-
dimensional channels of mesopores with pore diameter in the
range of 20–100 Å. Heterogenization of homogeneous catalysts
by anchoring metal complex on the modified surface of MCM-41
18
pling reaction, substituted and non-substituted aryl halides,
2 3
phenylboronic acid, K CO , and solvent were placed in the flask,
followed by the addition of the catalyst. The reactions are conve-
niently carried out in air at atmospheric pressure and at a temper-
ature of 80 °C. In all our experiments dry and distilled solvents
were used, while the distilled water was used for mixed solvent
system. The organic products were isolated by extraction and then
*
Corresponding author. Tel.: +91 33 2414 6666x2778; fax: +91 33 2414 6223.
1
E-mail address: snkoner@chemistry.jdvu.ac.in (S. Koner).
analyzed by the H NMR spectroscopy. As for bases, potassium
0
040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.05.098

S. Jana et al. / Tetrahedron Letters 50 (2009) 4820–4823
4821
Table 1
Pd(0)-MCM-41 catalyzed Suzuki cross-coupling reaction of aryl halides and phenylboronic acida
B(OH)2
X
Pd(0)-MCM-41
+
R
20% H
2
O/EtOH,
R
o
K CO , 80 C
2
3
R = H, NO , OCH , COCH
2
3
3
X = I, Br, Cl
Entry
1
Aryl halide
Product
Time (h)
Conversionb (wt %)
100
Yieldc (wt %)
93
TOFd (hÀ1
)
Ph
Ph
Ph
I
20
12
24
12
20
24
3911
2
3
4
5
Br
Cl
Br
Br
Br
100
24
97
97
65
90
24
97
97
64
6990
803
Ph
Ph
6585
4139
2172
NO2
O N
2
OMe
MeO
Ph
6
COCH3
H COC
3
a
Reaction conditions: 3 mmol of aryl halide, 3.6 mmol of phenylboronic acid, 3 mmol of K
Conversion of reactant is determined by gas chromatography.
Isolation yields were calculated from the mass of the product after separation by column chromatography. All the isolated products showed more than 99% of GC purity.
TOF (turnover frequency) = moles converted/(mol of active site  time).
2 3 2
CO , and 0.05 g of Pd(0)-MCM-41 in 20% H O/EtOH at 80 °C.
b
c
d
carbonate appeared to be a better choice. The use of sodium ace-
tate or trialkylamine as base in coupling reaction between iodo-
benzene and phenylboronic acid resulted in low yield (10% for
undergoes exchange with coordinated iodide in the oxidative addi-
tion product prior to the transmetalation step in the catalytic cycle
2
3,24
of Stille reaction.
The chloro complex of palladium thus formed
NaOAc and ꢀ2% for Et
3
N). Among non-substituted aryl halides,
facilitates the transmetalation via the formation of stable
Bu SnCl. The reaction does not occur in ethanol and acetonitrile
3
media. Both bromobenzene and iodobenzene showed impressive
conversion with comparable yields (Table 2, entries 1 and 2) in
Stille reactions among the non-substituted aryl halides while chlo-
robenzene exhibited only about 30% conversion.
2
5
iodobenzene and bromobenzene (Table 1, entries 1 and 2) showed
comparable yields which are higher than that of chlorobenzene.
However, iodobenzene requires longer time for 100% conversion.
Iodobenzene generally shows greater reactivity than bromoben-
zene in the cross-coupling reactions. Nevertheless, there are some
exceptions where reverse catalytic activity is observed in palla-
In searchof an efficientheterogeneouscatalystfor cross-coupling
19,20
dium nanoparticle-based catalysts.
been proposed that the I or I
In a recent study it has
2 3
reactions several systems such as Pd/C, Pd onto KF/Al O and other
À
26
2
generated from iodobenzene can
systems have been used. Recently, Cai et al. have used MCM-41-
supported sulfur palladium(0) complex and MCM-41-supported
20
act as inhibitor during the catalytic process. Pd(0)-MCM-41 cat-
alyst is capable of activating chlorobenzene (Table 1, entry 3)
which normally remains unreactive in C–C coupling reactions,
however, the yield is much lower in comparison to the recent re-
port on Suzuki reaction using Pd nanoparticle catalyst in ionic li-
2
6c
27
bidentate phosphine palladium(0) complex in Suzuki and Stille
coupling reactions, respectively. However, the catalytic turnover
number (TON) for a single run is very low (less than 200) with their
catalyst. This is themajordrawback of a heterogeneouscatalyticsys-
tem in comparison to their homogeneous counterpart. Palladium–
phosphine complex impregnated onto MCM-41 matrix is found to
be active toward Suzuki cross-coupling reaction of 4-iodoanisole
2
1
quid media.
ÀOCH , and ÀCOCH
afford 99% selectivity of the products in Suzuki reactions.
The para-substituted substrates (R
1
= ÀNO
2
,
3
3
) not only exhibit enhanced activity but also
2
8
Catalytic efficacy of Pd(0)-MCM-41 has been tested also with
Stille reaction. Substituted and non-substituted aryl halides are
coupled with organotin, namely, tributylphenyltin in DMF in the
presence of LiCl in air at 100 °C. The desired products are ob-
tained in good yields and TOFs of the reactions are remarkably
high. Notably the reaction does not proceed without the use of LiCl.
The exact role of LiCl as an additive in Stille reaction is not well
understood. However, it has been proposed that the chloride ion
with phenylboronic acid. In this case also low TONs and leaching
29
of Pd complex are the major problems. Coelho et al. reported
ligand-free Pd/CaCO for the Stille reaction and proposed a reaction
3
22
mechanism revealing that the leaching occurred to give rise to a very
active ‘mononuclear Pd(0) species’ that react faster with aryl halide
resulting in a homogeneous catalytic cycle.
The most definitive test available to date to ascertain the true
heterogeneity of the Pd-based catalyst in C–C coupling reactions

4
822
S. Jana et al. / Tetrahedron Letters 50 (2009) 4820–4823
Table 2
a
Pd(0)-MCM-41 catalyzed Stille cross-coupling reaction of aryl halides and tributylphenyltin
SnBu3
X
Pd(0)-MCM-41
+
o
DMF, LiCl, 80 C
R
R
R = H, NO , OCH , COCH
2
3
3
X = I, Br, Cl
Entry
1
Aryl halide
Product
Time (h)
20
Conversionb (wt %)
80
Yieldc (wt %)
72
TOFd (hÀ1
)
Ph
Ph
Ph
I
522
2
3
4
5
Br
Cl
Br
Br
Br
18
24
24
24
24
76
70
32
99
42
98
715
315
549
255
557
32
Ph
100
43
NO2
O N
2
Ph
OMe
MeO
Ph
6
COCH3
100
H COC
3
a
Reaction conditions: 1 mmol of aryl halide, 1 mmol of tributylphenyltin, 2.89 mmol of LiCl, and 0.05 g of Pd(0)-MCM-41 in 4 mL of DMF at 100 °C.
Conversion of reactant is determined by gas chromatography.
Isolation yields were calculated from the mass of the product formed from aryl halide after separation by column chromatography.
TOF (turnover frequency) = moles converted/(mole of active site  time).
b
c
d
Table 3
3
1
Performance of the Pd(0)-MCM-41 catalyst in solid-phase poisoning test
Aryl halide
Phenylboronic acid/tributylphenyltin
Coupling reaction
Temp (°C)
SH-SiO
No
2
added
Conversionc (Yield) (wt %)
100 (93)
I
B(OH)2
80
Yes
No
100 (95)
97 (96)
95 (94)
80 (72)
78 (69)
100 (99)
Suzukia
Br
I
OMe
B(OH)2
SnBu3
SnBu3
80
Yes
No
100
100
Yes
No
Stilleb
Br
NO2
Yes
100 (>99)
a
Reactions were carried out in air using 3 mmol of aryl halide, 3.6 mmol of phenylboronic acid, 3 mmol of K
2
CO
3
, 0.12 mmol of SH-SiO
2
, and 0.05 g of Pd(0)-MCM-41 in 20%
H
2
O/EtOH at 80 °C.
b
2
Reactions were carried out in air using 1 mmol of aryl halide, 1 mmol of tributylphenyltin, 2.89 mmol of LiCl, 0.12 mmol of SH-SiO , and 0.05 g of Pd(0)-MCM-41 in 4 mL
of DMF at 100 °C.
c
Conversion of reactant is determined by gas chromatography.

S. Jana et al. / Tetrahedron Letters 50 (2009) 4820–4823
4823
Table 4
References and notes
Recycling of Pd(0)-MCM-41 catalysts in the Suzuki and Stille cross-coupling reactions
with iodobenzene
1. Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457–2483.
Entry Run Coupling reaction Conversionc (wt %) Yield (wt %)
TOFc (hÀ1
2. Okuda, T.; Yoshida, T.; Hatano, T. In Phenolic Compounds in Food and Their Effects
on Health XI; Huang, M., Ho, C., Lee, C., Eds.; American Chemical Society:
Washington, D.C., 1992; p 160. Chapter 13.
3. Wilkins, C. K.; Bohn, B. A. Phytochemistry 1976, 15, 211–214.
4. Huang, L.; Si, Y.-K.; Snatzka, G.; Zheng, D. K.; Zhou, J. Collect. Czech. Chem.
Commun. 1988, 53, 2664–2666.
)
1
2
3
4
1st
100
100
95
93
95
90
93
3911
3911
3715
3832
2nd Suzukia
3rd
4th
98
5.
Elsenbauer, R. L.; Schacklett, L. W. In Handbook of Conducting Polymers;
5
6
7
8
1st
80
78
75
72
72
70
72
68
522
509
490
470
Skotheim, T. A., Ed.; Marcel-Dekker: New York, 1986; Vol. 1, Chapter 7.
6. Solladle, G.; Gottarelli, G. Tetrahedron 1987, 43, 1425–1437.
7. Bringmann, G.; Walter, R.; Weirich, R. Angew. Chem., Int. Ed. Engl. 1990, 29, 977–
2nd Stilleb
3rd
4th
991.
8. Stille, J. K. Angew. Chem., Int. Ed. Engl. 1986, 25, 508–524.
a
Reactions were carried out in air using 3 mmol of iodobenzene, 3.6 mmol of
9. Negishi, E.; King, A. O.; Okukado, N. J. Org. Chem. 1977, 42, 1821–1823.
10. Bumagin, N. A.; Luzikova, E. V. J. Organomet. Chem. 1997, 532, 271–273.
11. Farina, V.; Krishnamurthy, V.; Scott, W. J. The Stille Reaction; John Wiley & Sons
Inc., 1998.
2 3 2
phenylboronic acid, 3 mmol of K CO , and 0.05 g of Pd(0)-MCM-41 in 20% H O/
EtOH at 80 °C.
b
Reactions were carried out in air using 1 mmol of iodobenzene, 1 mmol of
tributylphenyltin, 2.89 mmol of LiCl, and 0.05 g of Pd(0)-MCM-41 in 4 mL of DMF at
12. Astruc, D. Inorg. Chem. 2007, 46, 1884–1894.
1
3. Loch, J. A.; Crabtree, R. H. Pure Appl. Chem. 2001, 73, 119–128.
14. For review: Heitbaum, M.; Glorius, F.; Escher, I. Angew. Chem., Int. Ed. 2006, 45,
732–4762.
1
00 °C.
c
TOF (turnover frequency) = moles converted/(mole of active site  time).
4
1
5. (a) Beck, J. S.; Chu, C. T. -W.; Johnson, I. D.; Kresge, C. T.; Leonowicz, M. E.; Roth,
W. J.; Vartuli, J. C. U.S. Patent, 5,108,725, 1992.; (b) Beck, J. S.; Vartuli, J. C.; Roth,
W. J.; Leonowizc, M. E.; Kresge, C. T.; Schmitt, K. D.; Chu, C. T.-W.; Olson, D. H.;
Shepard, E. W.; McCullen, S. B.; Higgins, J. B.; Schlenker, J. L. J. Am. Chem. Soc.
is the solid-phase poisoning test suggested by Richardson and
3
0
Jones. Since, recovery and reuse of catalyst are important issues
in the C–C cross-coupling reactions, we have performed solid-
phase poisoning tests using commercially available (purchased
from Sigma–Aldrich) 3-mercaptopropyl-functionalized silica (SH-
1992, 114, 10834–10843.
1
6. Jana, S.; Dutta, B.; Bera, R.; Koner, S. Langmuir 2007, 23, 2492–2496.
17. Jana, S.; Dutta, B.; Bera, R.; Koner, S. Inorg. Chem. 2008, 47, 5512–5520.
1
8. General procedure for Suzuki cross-coupling reaction: The coupling reaction was
carried out in a glass batch reactor. At first, aryl halide (3 mmol) and
phenylboronic acid (0.73 g, 3.3 mmol) were dissolved in 4 mL ethanol. This
2
SiO ) as an effective palladium scavenger which selectively coordi-
nates and deactivates the leached out palladium. Poisoning test
3
1
was performed for both Suzuki and Stille coupling reactions.
Comparison of percentage of conversion in C–C coupling reactions
Table 3) clearly shows that the catalytic efficacy of Pd(0)-MCM-41
is not affected when SH-SiO is added to the reaction mixture. This
2 3
reactant mixture was then added to the solution of K CO (1.658 g, 3 mmol) in
1
mL of water under stirring condition. To this 0.05 g of Pd(0)-MCM-41 (Pd
À5
content 7.52 Â 10 mol %) catalyst was added and the reaction mixture was
refluxed at a temperature of 80 °C in an oil bath. To study the progress of the
reaction the products were collected at different time intervals and identified
and quantified by a Varian CP-3800 Gas Chromatograph using a CP-Sil 8 CB
capillary column. For isolation of products at the end of the catalytic reaction,
the catalyst was first separated out by filtration and then the filtrate was
extracted with hexane (3 Â 15 mL). The organic layers thus collected were
(
2
indicates that probably no leaching of Pd species is occurring in the
Pd(0)-MCM-41 catalyzed C–C coupling reactions.
For the recycling study, both Suzuki and Stille coupling reac-
tions were performed with iodobenzene maintaining the same
combined and washed with water to remove excess K
2
CO
3
, with brine and
1
8,22
dried over Na SO
2
4
, filtered and concentrated in vacuo. The residue was purified
reaction conditions.
After first cycle of reaction the catalyst
by flash column chromatography on silica gel using n-hexane/ethyl acetate
mixture (9:1 v/v) to give the corresponding biphenyl. The product was
analyzed by GC/MS, 1H NMR, C NMR reported in the Supplementary data.
9. Shimizu, K.; Kan-no, T.; Kodama, T.; Hagiwara, H.; Kitayama, Y. Tetrahedron
Lett. 2002, 43, 5653–5655.
was recovered by centrifugation and then washed thoroughly with
DMF followed by copious amount of water to remove the base
present in the used catalyst and finally by dichloromethane. The
recovered catalyst was dried under vacuum at 110 °C overnight.
The performance of the recycled catalyst in C–C coupling reactions
up to four successive runs is summarized in Table 4. The catalytic
efficacy of the recovered Pd(0)-MCM-41 remains almost the same
for both coupling reactions in every run.
In conclusion, Pd(0) immobilized mesoporous ligand-free heter-
ogeneous catalyst, Pd(0)-MCM-41, shows high activity toward Su-
zuki and Stille carbon–carbon coupling reactions. The catalyst has
shown a notable activity toward a wide variety of substrates with a
high turnover frequency. Additionally, the possibility of easy re-
cycle makes the catalyst cheap and highly desirable to address
the environmental concerns.
13
1
2
0. Primo, A.; Liebel, M.; Quignard, F. Chem. Mater. 2009, 21, 621–627.
21. Cal, V.; Nacci, A.; Monopoli, A.; Montingelli, F. J. Org. Chem. 2005, 70, 6040–
044.
2. In a glass batch reactor, aryl halide (1 mmol), LiCl (0.12 g, 2.89 mmol), and
mL of DMF were added successively. To this 0.05 g of Pd(0)-MCM-41 catalyst
6
2
5
was added and the mixture was heated to a temperature of 100 °C in an oil
bath. Finally, tributylphenyltin (0.204 g, 1 mmol) was added and the reaction
mixture was stirred vigorously. Progress of the reaction was monitored by GC
at regular intervals and when the reaction was completed, the solid catalyst
was filtered. The filtrate was treated similarly as given in Ref.18
.
2
3. Stang, P. J.; Kowalski, M. H.; Schiavelli, M. D.; Longford, D. J. Am. Chem. Soc.
989, 111, 3347–3356.
4. Hoshino, M.; Degenkolb, P.; Curran, D. P. J. Org. Chem. 1997, 62, 8341–8349.
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2
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2
6. (a) Kohler, K.; Heidenreich, R. G.; Krauter, J. G. E.; Pietsch, J. Chem. Eur. J. 2002, 8,
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Acknowledgments
2
2
7. Zhao, H.; Wang, Y.; Sha, J.; Sheng, S.; Cai, M. Tetrahedron 2008, 64, 7517–7523.
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Financial support from the Department of Science and Technol-
ogy (DST), Government of India, by a grant (SR/S1/IC-23/2003) (to
SK) is gratefully acknowledged. Financial assistance from Ministry
of Environment and Forest, Govt. of India is also acknowledged. S.J.
2
9. Coelho, A. V.; de Souza, A. L. F.; de Lima, P. G.; Wardell, J. L.; Antunes, O. A. C.
Tetrahedron Lett. 2007, 48, 7671–7674.
0. Richardson, J. M.; Jones, C. W. J. Catal. 2007, 251, 80–93.
3
3
1. Solid-phase poisoning test: For Suzuki reaction, SH-SiO
2
(0.10 g, 0.12 mmol) and
(
SRF) and S.H. thank CSIR for the research fellowship.
À5
0
.05 g of Pd(0)-MCM-41 catalyst (Pd content 7.52 Â 10 mol %) were taken in
the solution containing aryl halides (3 mmol), phenylboronic acid (0.4 g,
.3 mmol), and K CO (0.14 g, 1 mmol) in 5 mL of 20% H O/EtOH. The mixture
3
2
3
2
Supplementary data
was stirred continuously maintaining the temperature of the oil bath at 80 °C.
The progress of the reaction was monitored by the method described above.
Poisoning test was also performed for Stille reaction using aryl halide
(1 mmol), tributylphenyltin (0.204 g, 1 mmol), and LiCl (0.12 g, 2.89 mmol) in
All products are known compounds. The detailed experimental
1
procedures, and H NMR spectrum of the isolated products. Sup-
5
0
2
mL of DMF at a temperature of 100 °C in the presence of SH-SiO (0.10 g,
.12 mmol) and 0.05 g of Pd(0)-MCM-41 catalyst.
plementary data associated with this article can be found, in the
online version, at doi:10.1016/j.tetlet.2009.05.098.