Palladium-catalyzed decarboxylative cross-coupling reaction of cinnamic acid with aryl iodide

Article abstract of DOI:10.1039/b821870f

A highly effective decarboxylative cross-coupling reaction of cinnamic acid with aryl iodide catalyzed by the combination of palladium chloride and CyJohnPhos in the presence of Ag₂CO₃ as an additive is described. The desired carbon-

Full text of DOI:10.1039/b821870f

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www.rsc.org/obc | Organic & Biomolecular Chemistry
Palladium-catalyzed decarboxylative cross-coupling reaction of cinnamic acid
with aryl iodide†
Zhiyong Wang,a Qiuping Ding,a Xiaodan Hea and Jie Wu*a,b
Received 5th December 2008, Accepted 5th January 2009
First published as an Advance Article on the web 14th January 2009
DOI: 10.1039/b821870f
A highly effective decarboxylative cross-coupling reaction
of cinnamic acid with aryl iodide catalyzed by the com-
bination of palladium chloride and CyJohnPhos in the
presence of Ag2CO3 as an additive is described. The desired
carbon-carbon bond formation proceeds efficiently with
good functional-group tolerance.
acid 1a and 4-methoxyphenyl iodide 2a as model substrates. This
preliminary survey, carried out in the presence of a palladium
catalyst, allowed us to evaluate and optimize the most efficient
catalytic system (Table 1). Gratifyingly, in an initial experiment, we
observed the formation of the desired product 3a in 10% yield when
the reaction was catalyzed by PdCl2 (10 mol%) in the presence of
Ag2CO3 as an additive in DMA (Table 1, entry 1). No reaction
occurred without this additive (Table 1, entry 2). Different ligands
were then screened in the reaction. The yield could be increased
to 36% when (R)-BINAP was utilized as a ligand in the catalytic
system (Table 1, entry 3). A better result was generated when PPh3
was added as a replacement (50% yield, Table 1, entry 4). The
addition of 1,10-phenanthroline or bipyridine in the reaction gave
rise to product 3a in 20% or 38% yield, respectively (Table 1, entries
5 and 6). N-Heterocyclic carbene8 ligands were also effective,
leading to the final product in moderate yield (Table 1, entries
7 and 8). Similar results were observed when the reaction was
performed in the presence of P(C6F5)3, Ph3As, PCy3, or XPhos
(Table 1, entries 9, 13, 16, and 17). Only a trace amount of
product 3a was detected when other phosphine ligands such as P(2-
furanyl)3, P(o-Tol)3, P(1-Nap)3, and DPPF were screened (Table 1,
entries 10–12, 14). To our delight, we found that the yield could be
dramatically improved when ligand CyJohnPhos9 was utilized in
the reaction (77% yield, Table 1, entry 15). Further investigation
revealed that DMA was the best choice of solvent (Table 1,
entries 18 and 19). Inferior results were displayed when other
palladium catalysts were used in the reaction (Table 1, entries
20–24). The Ag2CO3 additive was also replaced by other salts and
no better results were generated (Table 1, entries 25–28). Decreas-
ing the reaction temperature or reducing the amount of catalyst
produced the product 3a in moderate yield (Table 1, entries 29
and 30).
With this promising result in hand, to demonstrate the general-
ity of this method, we investigated the scope of this decarboxylative
coupling reaction under the optimized reaction conditions [PdCl2
(10 mol%), CyJohnPhos (20 mol%), Ag2CO3 (3.0 equiv), DMA,
150 ◦C], and the results are shown in Table 2. From Table 2, it
was found that all reactions proceeded smoothly to afford the
desired product 3 in moderate to good yields. Additionally, the
reaction of cinnamic acid with aryl iodide was found to tolerate
a range of different groups with different electronic demands
on the aromatic rings involving electron-donating and electron-
withdrawing groups. For instance, cinnamic acid 1a reacted with
phenyl iodide 2b leading to (E)-1,2-diphenylethene 3b in 78% yield
(Table 2, entry 2). When 4-fluorophenyl iodide 2c was employed
in the reaction, the corresponding product 3c was generated in
73% yield (Table 2, entry 3). Reaction of cinnamic acid 1a with
3-methoxyphenyl iodide 2d gave rise to olefin 3d in 67% yield
Recently, the decarboxylative cross-coupling reaction has at-
tracted much attention since it opens a new avenue for carbon-
carbon formation. As highlighted by Baudoin,1 this method
has several advantages over the conventional transition metal-
catalyzed cross-coupling reactions and the direct arylation
through C–H activation, concerning the regioselectivity as well as
atom and step economy issues. Nilsson reported the first example
of transition-metal mediated decarboxylative biaryl coupling,2
and breakthrough was achieved by Myers,3 Goossen,4 and
others5,6 in the development of Pd-catalyzed decarboxylative cross-
coupling reactions. For instance, Myers reported a versatile de-
carboxylative Heck-type reaction between arenecarboxylic acids
and olefins under palladium catalysis.3 Goossen and co-workers
have described the efficient preparation of biaryls or ketones
via a Pd-catalyzed decarboxylative coupling of arenecarboxylic
acids and aryl halides.4 The group of Forgione and Bilodeau
reported Pd-catalyzed arylation of heteroaromatic carboxylic
acids.5d Becht and co-workers presented Pd-catalyzed couplings
of arenecarboxylic acids with aryl iodides or diaryliodonium
triflates.6a,d As part of a continuing effort in our laboratory
on C–C bond formation,7 we became interested in developing
a novel and efficient method via transition metal catalyzed
decarboxylative coupling of carboxylic acids with aryl halides.
Although decarboxylative coupling of arenecarboxylic acids has
been described recently,3–6 there is only one report4b of decar-
boxylative coupling of vinyl carboxylic acids (one substrate).
However, the reaction procedure was tedious and the reaction was
performed at 170 ◦C. Herein, we disclose our recent efforts on the
synthesis of 1,2-diaryl olefins via a decarboxylative cross-coupling
reaction of cinnamic acid with aryl iodides.
To verify our hypothesis of decarboxylative coupling of cin-
namic acid, a set of experiments was carried out using cinnamic
aDepartment of Chemistry, Fudan University, 220 Handan Road, Shanghai,
200433, China. E-mail: jie_wu@fudan.edu.cn; Fax: +86 21 6510 2412;
Tel: +86 21 5566 4619
bState Key Laboratory of Organometallic Chemistry, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road,
Shanghai, 200032, China
† Electronic supplementary information (ESI) available: General experi-
mental procedures, characterization data and NMR spectra of compounds
3a–q. See DOI: 10.1039/b821870f
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Table 1 Screening conditions for decarboxylative cross-coupling reaction of cinnamic acid 1a with 4-methoxyphenyl iodide 2a.a
Entry
[Pd]
ligand
additive
solvent
yield (%)b
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29c
30d
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
Pd(OCOCF3)2
Pd(OAc)2
PdCl2(PhCN)2
PdCl2(PPh3)2
PdCl2(dppf)2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
—
—
Ag2CO3
—
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMF
mesitylene
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
10
NR
36
50
20
38
41
49
34
trace
trace
trace
36
trace
77
36
49
60
trace
40
44
46
43
50
trace
trace
20
31
49
(R)-BINAP
PPh3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Ag2CO3
Cu(OAc)2
CuCl2
1,10-phenanthroline
bipyridine
IPr·HCl
IMes·HCl
P(C6F5)3
P(2-furanyl)3
P(o-Tol)3
P(1-Nap)3
Ph3As
DPPF
CyJohnPhos
PCy3
XPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
CyJohnPhos
AgOAc
Cs2CO3
Ag2CO3
Ag2CO3
PdCl2
55
a Reaction conditions: cinnamic acid 1a (0.3 mmol), 4-methoxyphenyl iodide 2a (0.36 mmol, 1.2 equiv), palladium catalyst (10 mol%), ligand (20 mol%),
additive (3.0 equiv), solvent (2.0 mL), 150 ◦C. b Isolated yield based on cinnamic acid 1a. c The reaction was carried out at 110 ◦C. d In the presence of
PdCl2 (5 mol%) and A (10 mol%).
(Table 2, entry 4), while reaction of acetyl- or trifluoromethyl-
substituted aryl iodide 2e or 2f afforded olefin 3e or 3f in 60%
or 50% yield, respectively (Table 2, entries 5 and 6). Methyl
2-iodobenzoate 2h was also a good substrate in the reaction
of cinnamic acid 1a, and the product 3h was isolated in 56%
yield (Table 2, entry 8). With respect to other cinnamic acids,
as expected both electron-rich and electron-poor acrylic acids are
suitable partners in this process, and the desired products were
isolated in good yields. Thus, 4-nitrocinnamic acid 1b reacted
with 4-methoxyphenyl iodide 2a, leading to the formation of
compound 3i in 86% yield (Table 2, entry 9). A similar result
was obtained when 3-nitrocinnamic acid 1c was utilized as a
replacement (80% yield, Table 2, entry 10). Chloro-, cyano-, or
fluoro-substituted cinnamic acid also worked well in the reaction
with 4-methoxyphenyl iodide 2a (Table 2, entries 11–14). Reaction
of (E)-3-(furan-2-yl)propenoic acid 1g with 4-methoxyphenyl
iodide 2a proceeded smoothly to give the desired product 3o in
55% yield (Table 2, entry 15). Good isolated yields were observed
for reactions of 4-methylcinnamic acid 1h with various aryl iodides
(Table 2, entries 16–19). Besides aryl iodides, we also tested the
reactions of aryl bromides. However, no reaction occurred under
the standard conditions shown in Table 2.
In conclusion, we have described a highly effective decar-
boxylative cross-coupling reaction of cinnamic acid with aryl
iodide catalyzed by the combination of palladium chloride and
CyJohnPhos in the presence of Ag2CO3 as additive. The desired
carbon-carbon bond formation proceeds efficiently with good
functional-group tolerance.
864 | Org. Biomol. Chem., 2009, 7, 863–865
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Table 2 Palladium-catalyzed decarboxylative cross-coupling reaction of
cinnamic acid 1 with aryl iodide 2.10
L. M. Levy, J. Am. Chem. Soc., 2007, 129, 4824; (c) L. J. Goossen and
B. Melzer, J. Org. Chem., 2007, 72, 7473; (d) L. J. Goossen, F. Rudolphi,
C. Oppel and N. Rodriguez, Angew. Chem., Int. Ed., 2008, 47, 3043.
For review, see: L. J. Goossen, N. Rodriguez and K. Goossen, Angew.
Chem., Int. Ed., 2008, 47, 3100.
5 (a) G. Lalic, A. D. Aloise and M. D. Shair, J. Am. Chem. Soc., 2003,
125, 2852; (b) S. Lou, J. A. Westbrook and S. E. Schaus, J. Am. Chem.
Soc., 2004, 126, 11440; (c) D. K. Rayabarapu and J. A. Tunge, J. Am.
Chem. Soc., 2005, 127, 13510; (d) P. Forgione, M.-C. Brochu, M. St-
Onge, K. H. Thesen, M. D. Bailey and F. Bilodeau, J. Am. Chem. Soc.,
2006, 128, 11350.
6 (a) J.-M. Becht, C. Catala, C. Le, Drian and A. Wagner, Org. Lett.,
2007, 9, 1781; (b) S. R. Waetzig and J. A. Tunge, J. Am. Chem. Soc.,
2007, 129, 14860; (c) A. A. Yeagley and J. J. Chruma, Org. Lett., 2007,
9, 2879; (d) J.-M. Becht and C. L. Drian, Org. Lett., 2008, 10, 3161;
(e) A. Voutchkova, A. Coplin, N. E. Leadbeaterb and R. H. Crabtree,
Chem. Commun., 2008, 6312.
7 (a) L. Zhang and J. Wu, J. Am. Chem. Soc., 2008, 130, 12250; (b) L.
Zhang, T. Meng and J. Wu, J. Org. Chem., 2007, 72, 9346; (c) L.
Zhang, T. Meng, R. Fan and J. Wu, J. Org. Chem., 2007, 72, 7279;
(d) Z. Wang, R. Fan and J. Wu, Adv. Synth. Catal., 2007, 349,
1943.
8 (a) For selected examples, see: F. Glorius, (Eds.), N-Heterocyclic
Carbenes in Transition Metal Catalysis, Springer, Berlin, 2007; (b) W. A.
Herrmann, Angew. Chem., Int. Ed., 2002, 41, 1290; (c) O. Navarro,
R. A. Kelly, III and S. P. Nolan, J. Am. Chem. Soc., 2003, 125, 16194;
(d) G. A. Grasa and S. P. Nolan, Org. Lett., 2001, 3, 119; (e) M. R.
Fructos, T. R. Belderrain, M. C. Nicasio, S. P. Nolan, H. Kaur, M. M.
Diaz-Requejo and P. J. Perez, J. Am. Chem. Soc., 2004, 126, 10846;
(f) C. Yang, H. M. Lee and S. P. Nolan, Org. Lett., 2001, 3, 1511; (g) R.
Singh, M. S. Viciu, N. Kramareva, O. Navarro and S. P. Nolan, Org.
Lett., 2005, 7, 1829; (h) G. A. Grasa, A. C. Hillier and S. P. Nolan,
Org. Lett., 2001, 3, 1077; (i) M. S. Viciu, R. F. Germaneau, O. Navarro-
Fernandez, E. D. Stevens and S. P. Nolan, Organometallics, 2002, 21,
5470.
9 For selected examples, see: (a) D. S. Surry and S. L. Buchwald, J. Am.
Chem. Soc., 2007, 129, 10354; (b) E. R. Strieter and S. L. Buchwald,
Angew. Chem., Int. Ed., 2006, 45, 925; (c) E. P. Gillis and M. D. Burke,
J. Am. Chem. Soc., 2007, 129, 6716; (d) E. McNeill, T. E. Barder and
S. L. Buchwald, Org. Lett., 2007, 9, 3785; (e) A. Joncour, A. Decor, S.
Thoret, A. Chiaroni and O. Baudoin, Angew. Chem., Int. Ed., 2006, 45,
4149; (f) M. L. Meketa and S. M. Weinreb, Org. Lett., 2006, 8, 1443;
(g) J. P. Wolfe, R. A. Singer, B. H. Yang and S. L. Buchwald, J. Am.
Chem. Soc., 1999, 121, 9550.
Entry
R
Ar
product
yield (%)a
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
C6H5 1a
4-MeOC6H4 2a
C6H5 2b
4-FC6H4 2c
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p
3g
3n
3q
77
78
73
67
60
50
62
56
86
80
65
55
60
71
55
65
82
71
60
C6H5 1a
C6H5 1a
C6H5 1a
3-MeOC6H4 2d
4-AcC6H4 2e
3-CF3C6H4 2f
4-MeC6H4 2g
2-MeO2CC6H4 2h
4-MeOC6H4 2a
4-MeOC6H4 2a
4-MeOC6H4 2a
4-MeOC6H4 2a
4-MeOC6H4 2a
4-MeC6H4 2g
4-MeOC6H4 2a
4-MeOC6H4 2a
C6H5 2b
C6H5 1a
C6H5 1a
C6H5 1a
C6H5 1a
4-NO2C6H4 1b
3-NO2C6H4 1c
4-ClC6H4 1d
4-CNC6H4 1e
4-FC6H4 1f
4-FC6H4 1f
2-Furanyl 1g
4-MeC6H4 1h
4-MeC6H4 1h
4-MeC6H4 1h
4-MeC6H4 1h
4-FC6H4 2c
2-MeO2CC6H4 2h
a Isolated yield based on cinnamic acid 1.
Acknowledgements
Financial support from National Natural Science Foundation of
China (20772018), Shanghai Pujiang Program, and Program for
New Century Excellent Talents in University (NCET-07-0208) is
gratefully acknowledged.
10 General procedure for palladium-catalyzed decarboxylative cross-
coupling reaction of cinnamic acid 1 with aryl iodide 2.: A mixture
of cinnamic acid 1 (0.30 mmol), aryl iodide 2 (0.36 mmol, 1.2 equiv),
Ag2CO3 (0.90 mmol, 247 mg, 3.0 equiv), CyJohnPhos (0.06 mmol,
21 mg, 0.2 equiv), and PdCl2 (0.03 mmol, 5.3 mg, 0.1 equiv) in DMA
(2.0 mL) was stirred at 150 ◦C under nitrogen for 12 h. After completion
of the reaction as indicated by TLC, the mixture was cooled and filtered
with Celite. After adding ethyl acetate (10 mL) to the filtrate, the organic
phase was washed with saturated NH4Cl, dried with MgSO4, and
concentrated under reduced vacuum. The residue was then purified
by flash chromatography on silica gel to afford product 3(for details,
please see Electronic Supplementary Information†).
Notes and references
1 O. Baudoin, Angew. Chem., Int. Ed., 2007, 46, 1373.
2 M. Nilsson, Acta Chem. Scand., 1966, 20, 423.
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2002, 124, 11250; (b) D. Tanaka and A. G. Myers, Org. Lett., 2004, 6,
433; (c) D. Tanaka, S. P. Romeril and A. G. Myers, J. Am. Chem. Soc.,
2005, 127, 10323.
4 (a) L. J. Goossen, G. Deng and L. M. Levy, Science, 2006, 313, 662;
(b) L. J. Goossen, N. Rodriguez, B. Melzer, C. Linder, G. Deng and
This journal is
The Royal Society of Chemistry 2009
Org. Biomol. Chem., 2009, 7, 863–865 | 865
©