P. Das et al. / Tetrahedron Letters 51 (2010) 1479–1482
1481
Table 3
Suzuki–Miyaura reactiona of various substrates
1L1 (2 mol%)
+
Y
B(OH)2
DMF, K2CO3, rt
R
R
R'
R'
Entry
Y
R
R/
Timeb (h)
Yieldc (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Br
Br
Br
Br
Br
Br
Cl
Cl
Cl
Cl
Cl
Cl
Br
Br
Cl
Cl
H
H
H
H
H
H
H
H
H
H
H
H
H
24
16
16
18
18
30
36
30
30
30
30
36
16
18
36
36
82
90
97
92
91
72
45
64
43
46
76
32
82
76
56
58
4-CHO
4-NO2
4-COOH
4-COOMe
4-OMe
H
4-CHO
4-COOH
4-COOMe
4-NO2
4-OMe
4-NO2
4-NO2
4-NO2
4-NO2
4-OMe
3-NO2
4-OMe
3-NO2
a
b
c
Reaction conditions: Ar-Y (0.5 mmol), Ar-B(OH)2 (0.55 mmol), [PdCl2(PPh3O)2] (2 mol %) K2CO3 (1.5 mmol), DMF (3 ml).
Reactions were monitored by TLC.
Isolated yield.
(d) Guo, M.; Jian, F.; He, R. Tetrahedron Lett. 2005, 46, 9017; (e) Teo, S.; Weng, Z.;
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E.; Daryanavard, M.; Xiao, J.; Baillie, C. J. Mol. Catal. A: Chem. 2006, 259, 35; (g)
Shi, J.-C.; Yang, P.-Y.; Tong, Q.; Wu, Y.; Peng, Y. J. Mol. Catal. A: Chem. 2006, 259,
7; (h) Braun, L.; Liptau, P.; Kehr, G.; Ugolotti, J.; Frohlich, R.; Erker, G. J. Chem.
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1998, 39, 7529.
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formed triphenylphosphine oxide complex 1L1 as a catalyst (Table
3). It is seen from Table 3 that in general, the aryl bromides with elec-
tron-withdrawing substituents such as NO2, CHO, and CO2Me (en-
tries 2–5) underwent the coupling reactions in nearly quantitative
yields (90–97%) whereas the corresponding aryl chlorides (entries
8–11) gave the desired products in good to moderate yield (upto
76%). The nonactivated aryl bromides such as 4-bromobenzene
and 4-bromoanisole also gave the coupling products in reasonably
good yields (Table 3, entries 1 and 6). However, the nonactivated aryl
chlorides such as 4-chlorobenzene and 4-chloroanisole gave only
45% and 32% yields, respectively (Table 3, entries 7 and 12). Besides
phenylboronic acid, other boronic acids such as 4-tolylboronic acid
and 3-nitrophenylboronic acid were successfully used to yield the
desired products in high yields (Table 3, entries 13–16).
In conclusion, we have developed a simple catalytic system
based on PdCl2 and triphenylphosphine chalcogenides (PPh3X;
X = O, S, Se) for Suzuki–Miyaura reaction of aryl halides with aryl
boronic acid at room temperature. The aryl bromides and the less
reactive aryl chlorides underwent the coupling reaction in good-
to-excellent yields. Under the same experimental conditions, tri-
phenylphosphine chalcogenides as ligands are more active com-
pared to the free triphenylphosphine.
13. Bohm, V. P. W.; Gstottmayr, C. W. K.; Weskamp, T.; Hermann, W. H. J.
Organomet. Chem. 2000, 595, 186.
Acknowledgment
14. Synthesis of [PdCl2(PPh3O)2]: A solution of ligand PPh3O (0.34 mmol) in 10 ml of
acetonitrile was added drop by drop to a solution of PdCl2 (0.17 mmol) in 10 ml
of acetonitrile. The reaction was refluxed for 3 h, during which a yellow
precipitate was formed. After filtration, the residue was washed with
acetonitrile and then dried under vacuum to get the complex 1L1 as bright
yellow powder (yield: 96%); mp: 179 °C; Anal. Calcd for C36H30Cl2P2O2Pd: C,
58.93; H, 4.09%. Found: C, 59.41; H, 4.13%. IR (KBr/cmÀ1): 1165 (v(PO). NMR
(300 MHz, in CDCl3), 1H: 7.70–7.27 (m, C6H5); 31P{1H}: 36.81(s). The complexes
1L2 and 1L3 were also synthesized by a similar procedure and the identities of
the complexes were confirmed by melting point determination and infra red
spectra.15a
We gratefully acknowledge the University Grants Commission
(UGC), New Delhi for a Research Grant (No: 36-73/2008 SR).
References and notes
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B.; Elshof, J. E.; Rothenberg, G. Chem. Eur. J. 2007, 13, 6908; (f) Maegawa, T.;
Kitamura, Y.; Sako, S.; Udzu, T.; Sakurai, A.; Tanaka, A.; Kobayashi, Y.; Endo, K.;
Bora, U.; Kurita, T.; Kozaki, A.; Monguchi, Y.; Sajiki, H. Chem. Eur. J. 2007, 13,
5937; (g) Guo, M.; Zhu, Z.; Huang, H.; Zhang, Q. Catal. Commun. 2009, 10, 865.
2. (a) Zapf, A.; Ehrentraut, A.; Beller, M. Angew. Chem., Int. Ed. 2000, 39, 4153; (b)
Nobre, S. M.; Monteiro, A. L. Tetrahedron Lett. 2004, 45, 8225; (c) Nobre, S. M.;
Wolke, S. I.; Rosa, R. G.; Monteiro, A. L. Tetrahedron Lett. 2004, 45, 6527.
3. (a) Bei, X.; Turner, H. W.; Weinberg, W. H.; Guram, A. S. J. Org. Chem. 1999, 64,
6797; (b) Kwong, F. Y.; Lam, W. H.; Yeung, C. H.; Chan, K. S.; Chan, A. S. C. Chem.
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Ham, A. G. J.; Haan, A. B. J. Appl. Catal. A: Gen. 2006, 312, 144.
16. General procedure for the Suzuki–Miyaura reaction: An oven-dried round-
bottomed flask was charged with
a mixture of aryl halide (0.5 mmol),
arylboronic acid (0.55 mmol), K2CO3 (1.5 mmol) PdCl2 (2 mol %), and ligand
(4 mol %), and the mixture was stirred in DMF (3 ml) at room temperature for
required time. After completion, the reaction mixture was diluted with water
(20 ml) and extracted with ether (20 ml  3). The combined extract was