N-Heterocyclic carbene-Pd(II) complex derived from proline for the Mizoroki-Heck reaction in water

Article abstract of DOI:10.1016/j.tet.2011.10.033

N-Heterocyclic carbene-Pd(II) complex 1 derived from proline was found to be an efficient catalyst in the Mizoroki-Heck reaction of aryl bromides and iodides performed in water. The reactions can tolerate various functional groups in the substrates and all gave the corresponding coupling products in good to high yields.

Full text of DOI:10.1016/j.tet.2011.10.033

Tetrahedron 67 (2011) 9479e9483
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journal homepage: www.elsevier.com/locate/tet
N-Heterocyclic carbeneePd(II) complex derived from proline for the
MizorokieHeck reaction in water
a
a
a
b
a,
*
Yi-Qiang Tang , Chun-Yan Chu , Lei Zhu , Bin Qian , Li-Xiong Shao
a
College of Chemistry and Materials Engineering, Wenzhou University, Chashan University Town, Wenzhou, Zhejiang Province 325035, People’s Republic of China
Oujiang College, Wenzhou University, Chashan University Town, Wenzhou, Zhejiang Province 325035, People’s Republic of China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
N-Heterocyclic carbeneePd(II) complex 1 derived from proline was found to be an efficient catalyst in the
MizorokieHeck reaction of aryl bromides and iodides performed in water. The reactions can tolerate
various functional groups in the substrates and all gave the corresponding coupling products in good to
high yields.
Received 11 September 2011
Received in revised form 28 September 2011
Accepted 11 October 2011
Available online 19 October 2011
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
N-Heterocyclic carbene
Palladium complex
MizorokieHeck reaction
Water
Synthetic method
1. Introduction
complexes derived from proline and found them to be efficient
catalysts in carbonecarbon bond formations performed in water.
6
Palladium-catalyzed MizorokieHeck coupling reaction, sharing
For instance, NHCePd(II) complexes derived from N-benzyl pro-
line were proved to be good catalysts in the room temperature
SuzukieMiyaura coupling reaction of aryl iodides and bromides
carried out in pure water. These results prompted us to further
investigate the applications of these complexes in other carbone
carbon bond formation reactions. In continuing research, we found
that NHCePd(II) complex 1 (Fig. 1) derived from N-benzyl proline
was also a favourable catalyst for the MizorokieHeck reaction of
aryl iodides and bromides performed in pure water. Herein, we
wish to report these results in detail.
the 2010 Nobel Prize, is a powerful and versatile method for ary-
1
lation and vinylation of olefins. During the past decades, most
6
c
efficient MizorokieHeck reactions reported were carried out in
organic solvents with phosphine-based compounds as the ancillary
ligand. In order to overcome the toxicity of organic solvents and the
toxicity, air and/or moisture-sensitivity of phosphine-based li-
gands, many efforts have been made to find out alternative ligands
and clean solvents.2 Compared to toxic and volatile organic sol-
vents, water, as a non-toxic, non-flammable and the most envi-
ronmentally friendly solvent, had attracted much attention in
organic synthesis.3 On the other hand, in contrast to phosphine-
,3
based ligands, N-heterocyclic carbenes (NHCs), as excellent
s-do-
N Me
N
nors and weaker -acceptors, can produce stable NHCemetal
p
complexes with strong NHCemetal bonds, which usually exhibits
N
higher stability in the solid state and even in solution than
Pd
4
phosphine-based ligands. Although NHCemetal complexes have
Ph
Br
Br
1
attracted much attention in the carbonecarbon and carbone
heteroatom bond formation reactions performed in routine
organic solvents, their applications in pure water were rarely
reported.5 Recently, we have developed some NHCemetal
Fig. 1. NHCePd(II) complex 1 derived from proline.
2
. Results and discussion
Initial examinations were carried out using bromobenzene 2a
1.0 mmol) and acrylic acid 3a (1.5 equiv) as the substrates,
NHCePd(II) complex 1 (1.0 mol %) as the catalyst, H O (2.0 mL) as
(
*
Corresponding author. Tel./fax: þ86 577 86689300; e-mail addresses: Shaolix@
wzu.edu.cn, shaolix@163.com (L.-X. Shao).
2
0
040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.10.033

9480
Y.-Q. Tang et al. / Tetrahedron 67 (2011) 9479e9483
ꢀ
the solvent at 100 C to find out the best base (Table 1, entries 1e9).
Table 3
NHCePd(II) complex 1 catalyzed reactions of aryl bromides and iodides 2 with
acrylic acid 3a
As can be seen from Table 1, the best result was obtained with
KO Bu as the base and the corresponding coupling product 4a can
be achieved in 91% yield (entry 3). The yield can be further in-
creased to 96% at elevated temperature (120 C) (entry 10).
t
O
X
ꢀ
NHC-Pd(II) complex 1
OH
(1.0 mol%)
OH
+
t
KO Bu, H O, 24 h
Table 1
O
2
R1
4
Optimization for the NHCePd(II) complex 1 catalyzed reaction of bromobenzene 2a
with acrylic acid 3a
1
3a
R 2
O
Entrya
1
Yieldb (%)
Br
2 (R /X)
NHC-Pd(II) complex 1
1
2
3
4
5
6
7
8
9
2b (4-MeO/Br)
2c (4-Me/Br)
2d (3-MeO/Br)
2e (4-Cl/Br)
2f (4-F/Br)
2g (4-NO
2h (H/I)
4b, 83
4c, 99
4d, 96
4e, 77
4f, 80
4g, 54
4a, 92
4b, 95
4f, 95
OH
(1.0 mol%)
OH
+
base, H O, 24 h
2
O
3a
4a
2
a
2
/Br)
Entrya
Base
Yieldb (%)
t
1
2
3
4
5
6
7
8
9
1
NaO Bu
47
42
91
55
17
10
13
<5
12
96
2i (4-MeO/I)
2j (4-F/I)
KOH
t
KO Bu
NaOH
10
2k
4h, 49
Br
Br
K
2
CO
3
S
Na
CO
2 3
KHCO
3
2
KF$2H O
K
3
PO
4
$3H
2
O
11
4i, 50
0c
t
2l
KO Bu
S
a
Otherwize specified, all reactions were carried out using 2a (1.0 mmol), 3a
a
t
ꢀ
All reactions were carried out using 2 (1.0 mmol), 3a (1.5 mmol), KO Bu
(3.0 equiv), 1 (1.0 mol %) in H O (2.0 mL) at 120
(
1.5 mmol), base (3.0 equiv), 1 (1.0 mol %) in H
Isolated yields.
The temperature is 120 C.
2
O (2.0 mL) at 100 C for 24 h.
b
ꢀ
C (for bromide) or 100
ꢀ
C (for
2
c
ꢀ
iodide) for 24 h.
b
Isolated yields.
t
It is conceivable that the base KO Bu will rapidly hydrolyze to
donating groups, such as 4-MeO (2b), 4-Me (2c) and 3-MeO (2d)
gave better yields (entries 1e3). On the contrary, aryl bromides
with electron-poor groups, such as 4-Cl (2e) and 4-F (2f) gave in-
ferior results (entries 4 and 5). Only moderate yield of product 4g
was obtained when strongly electron-withdrawing group-
substituted 4-nitrophenyl bromide 2g was used as the substrate
t
KOH and BuOH under the identical reaction conditions. Further
t
studies showed that BuOH was essential for the reactions with
KOH as the base, which clearly illustrated the differences between
t
the results using KOH and BuOK as the base, respectively (Table 2).
So the optimal reaction conditions were then established as
t
using NHCePd(II) complex 1 (1.0 mol %) as the catalyst, KO Bu
(entry 6). Heteroaryl bromides, such as 2-bromothiophene 2k and
(
3.0 equiv) as the base, H
perature of 100 or 120 C.
2
O (2.0 mL) as the solvent at the tem-
3-bromothiophene 2l were also proved to be suitable reaction
ꢀ
partners to give the corresponding products 4h and 4i in reason-
able yields, respectively (entries 10 and 11). In addition, aryl io-
dides showed better reactivity in these MizorokieHeck reactions to
give products 4 in excellent yields, with no differences between the
substituents on the aryl rings (entries 7e9).
Table 2
NHCePd(II) complex 1 catalyzed reaction of bromobenzene 2a with acrylic acid 3a
t
using KOH as the base in the presence of different amount of BuOH
O
Br
The reactions of bromobenzene 2a with some acrylate esters,
such as acrylate methyl ester 3b, ethyl ester 3c and n-butyl ester 3d
were also investigated under the similar conditions. The reactions
NHC-Pd(II) complex 1
OH (1.0 mol%), KOH
OH
+
t
o
BuOH, H O, 100 C,
2
ꢀ
O
4a
can be performed at 100 C to give product 4a, the coupling-
2
a
3a
24 h
hydrolyzed product, in good to excellent yields in all cases
(
2
Table 4). Maybe the high solubility of product 4a in H O accelerates
Entrya
tBuOH (equiv)
Yieldb (%)
the hydrolysis of the coupling products, the esters, resulting cin-
namic acid 4a as the sole product.
1
2
3
4
0
42
88
96
98
1.0
2.0
5.0
Table 4
NHCePd(II) complex 1 catalyzed reactions of bromobenzene 2 with acrylate esters 3
a
All reactions were carried out using 2a (1.0 mmol), 3a (1.5 mmol), KOH
O
(
3.0 equiv), 1 (1.0 mol %) in H
2
O (2.0 mL) in the presence of the listed amount of
Br
NHC-Pd(II) complex 1
t
ꢀ
BuOH at 100 C for 24 h.
t
b
OR' (1.0 mol%), KO Bu
OH
Isolated yields.
+
o
H O, 100 C, 24 h
2
O
3
4a
2
a
To survey the generality of this NHCePd(II) complex 1 catalyzed
MizorokieHeck reaction performed in water, we next investigated
the reactions of a variety of aryl bromides and iodides 2 with
acrylic acid 3a under the identical conditions (Table 3). As can be
seen from Table 3, all reactions took place smoothly to give the
coupling products 4 in good to excellent yields in most cases.
Substituents on the aryl bromides have some effect on the re-
actions. For instance, it seems that aryl bromides with electron-
Entrya
0
Yieldb (%)
3 (R )
1
2
3
3b (Me)
3c (Et)
89
94
97
n
3d ( Bu)
a
t
All reactions were carried out using 2a (1.0 mmol), 3 (1.5 mmol), KO Bu
ꢀ
(3.0 equiv), 1 (1.0 mol %) in H O (2.0 mL) at 100
2
C for 24 h.
b
Isolated yields.

Y.-Q. Tang et al. / Tetrahedron 67 (2011) 9479e9483
9481
Furthermore, the reactions between aryl bromides 2 and a kind
4.2. Experimental procedures
of styrenes were also carried out under the identical conditions. As
can be seen from Table 5, all reactions can give the corresponding
coupling products 6 in moderate to high yields, despite the
electron-rich or poor, or sterically hindered substituents on the aryl
rings of both of aryl bromides and styrenes. The reaction between
4.2.1. General procedure for the NHCePd(II) complex 1-catalyzed
MizorokieHeck reaction. (If olefin is acrylic acid) Under N atmo-
sphere, acrylic acid 3a (1.5 mmol), KO Bu (3.0 equiv) and H
2
t
2
O
(2.0 mL) were added into a seal tube and the mixture was stirred at
room temperature for 10 min. Then NHCePd(II) complex 1
(1.0 mol %) and aryl halides 2 (1.0 mmol) were added. The mixture
3
6
-bromopyridine 2o and styrene 5a also works well to give product
j in 84% yield (entry 10).
ꢀ
ꢀ
was stirred vigorously at 120 C (for bromides) or 100 C (for io-
dides) for 24 h. After cooling to room temperature, HCl (4 M) was
dropped into the reaction mixture to reach a pH of 1, extracted with
Table 5
NHCePd(II) complex 1 catalyzed reactions of aryl bromides 2 with styrenes 5
2 4
EtOAc, washed with brine, dried over anhydrous Na SO . The sol-
Br
R1
NHC-Pd(II) complex 1
vent was removed under reduced pressure and the residue was
purified by a flash column chromatography (SiO ) to give the pure
2
product.
t
R'
(
1.0 mol%), KO Bu
+
R1
o
H O, 120 C, 24 h
2
(
If olefin is acrylate esters) Under N
2
atmosphere, NHCePd(II)
R'
6
2
5
t
complex 1 (1.0 mol %), KO Bu (3.0 equiv) and H O (2.0 mL) were
2
added into a seal tube, then acrylate esters 3 (1.5 mmol) and aryl
bromides 2 (1.0 mmol) were added. The mixture was stirred vig-
orously at 100 C for 24 h. After cooling to room temperature, HCl
Entrya
2 (R1)
2a (H)
2b (4-MeO)
2c (4-Me)
2d (3-MeO)
2e (4-Cl)
3 (R )
0
Yieldb (%)
1
2
3
4
5
6
7
8
9
5a (H)
5a
6a, 90
6b, 80
6c, 69
6d, 88
6e, 80
6f, 86
6g, 85
6h, 90
6i, 81
ꢀ
(
4 M) was dropped into the reaction mixture to reach a pH of 1,
extracted with EtOAc, washed with brine, dried over anhydrous
Na SO . The solvent was removed under reduced pressure and the
5a
5a
5a
5a
5a
5a
5a
2
4
2f (4-F)
2
residue was purified by a flash column chromatography (SiO ) to
give the pure product.
2g (4-NO2)
2m (2-Me)
2n (4-Ac)
(If olefin is styrenes) Under N
2
atmosphere, NHCePd(II) complex
(1.0 mol %), KO Bu (3.0 equiv) and H O (2.0 mL) were added into
a seal tube, then styrenes (1.5 mmol) and aryl bromides 2
t
1
2
Br
10
2o
5a
6j, 84
(
1
1.0 mmol) were added. The mixture was stirred vigorously at
20 C for 24 h. After cooling to room temperature, the solvent was
N
ꢀ
1
1
1
1
1
2
3
4
2b
2g
2b
2g
5b (4-Me)
5b
5c (4-Cl)
5c
6k, 92
6l, 75
6m, 80
6n, 85
extracted with EtOAc, washed with brine, dried over anhydrous
Na SO . Then the solvent was removed under reduced pressure and
the residue was purified by a flash column chromatography (SiO )
2
2
4
to give the pure product.
a
t
All reactions were carried out using 2 (1.0 mmol), 5 (1.5 mmol), KO Bu
ꢀ
(
3.0 equiv), 1 (1.0 mol %) in H
2
O (2.0 mL) at 120 C for 24 h.
7
1
b
4.2.1.1. Compound 4a . A white solid. H NMR (CDCl
3
, 500 MHz,
Isolated yields.
TMS)
d
6.47 (d, J¼16.0 Hz, 1H), 7.41e7.43 (m, 3H, Ar), 7.55e7.57 (m,
13
2H, Ar), 7.80 (d, J¼16.0 Hz, 1H); C NMR (CDCl
3
, 125 MHz) d 117.2,
In further investigations, we found that NHCePd(II) complex 1
128.4, 129.0, 130.7, 134.1, 147.1, 171.8.
showed no catalytic activity towards aryl chlorides under the
identical reaction conditions. In addition, we found that when
enone, such as 1-phenyl-propenone was used as the substrate, the
reaction became disordered and no desired product can be
obtained.
7
1
4.2.1.2. Compound 4b . A white solid. H NMR (CDCl
d
3
, 500 MHz,
TMS) 3.85 (s, 3H, OMe), 6.32 (d, J¼16.0 Hz, 1H), 6.92 (d, J¼9.0 Hz,
2H, Ar), 7.51 (d, J¼9.0 Hz, 2H, Ar), 7.74 (d, J¼16.0 Hz, 1H); C NMR
(CDCl , 125 MHz) 55.4, 114.4, 114.6, 126.8, 130.1, 146.7, 161.8, 172.1.
13
3
d
7
1
4
.2.1.3. Compound 4c . A white solid. H NMR (CDCl
TMS)
2.39 (s, 3H, Me), 6.41 (d, J¼16.0 Hz,1H), 7.21 (d, J¼8.0 Hz, 2H,
Ar), 7.45 (d, J¼8.0 Hz, 2H, Ar), 7.77 (d, J¼16.0 Hz, 1H); C NMR
CDCl , 125 MHz) 21.5, 116.1, 128.4, 129.7, 131.3, 141.3, 147.1, 172.1.
3
, 500 MHz,
3
. Conclusion
d
13
In summary, NHCePd(II) complex 1 derived from proline
(
3
d
showed good to excellent catalytic activities upon MizorokieHeck
reaction performed in water, with aryl bromides and iodides as the
electrophilic partners. We, for the first time, systematically in-
vestigated the NHCePd complex catalyzed MizorokieHeck re-
actions performed in pure water. The complex is air- and moisture
stable and can be stored under air for several months.
8
1
4
.2.1.4. Compound 4d . A white solid. H NMR (CDCl
TMS)
3.84 (s, 3H, OMe), 6.44 (d, J¼16.0 Hz, 1H), 6.97 (dd, J¼8.0,
.5 Hz, 1H, Ar), 7.07 (s, 1H), 7.15 (d, J¼8.0 Hz, 1H, Ar), 7.51 (dd,
3
, 500 MHz,
d
2
13
J
1
¼J
25 MHz)
72.1.
2
¼8.0 Hz, 1H, Ar), 7.76 (d, J¼16.0 Hz, 1H); C NMR (CDCl
3
,
1
d
55.3, 113.1, 116.7, 117.5, 121.1, 130.0, 135.4, 147.0, 159.9,
1
4
4
. Experimental section
8
4
.2.1.5. Compound 4e . A white solid. 1H NMR (DMSO-d
6
6
,
,
.1. General methods
500 MHz)
d
6.55 (d, J¼16.0 Hz,1H), 7.46 (d, J¼8.0 Hz, 2H, Ar), 7.58 (d,
13
J¼16.0 Hz, 1H, Ar), 7.74 (d, J¼8.0 Hz, 2H); C NMR (DMSO-d
1H and 13C NMR spectra were recorded on Bruker Avance-300 or
125 MHz)
d
120.0, 128.9, 129.9, 133.2, 134.8, 142.6, 167.3.
5
00 MHz spectrometer for solution in CDCl
3
with tetramethylsilane
; J-values are in hertz.
4.2.1.6. Compound 4f . A white solid. 1H NMR (DMSO-d
7
,
(
TMS) as an internal standard or in DMSO-d
6
6
Commercially obtained reagents were used without further puri-
fication. Flash column chromatography was carried out using
Huanghai 300e400 mesh silica gel at increased pressure.
500 MHz)
7.59 (d, J¼16.0 Hz, 1H), 7.76 (dd, J
NMR (DMSO-d , 125 MHz)
115.9 (d, JCeF¼22.5 Hz), 119.0 (d,
d
6.49 (d, J¼16.0 Hz, 1H), 7.24 (dd, J
1
¼J
2
¼8.5 Hz, 2H, Ar),
13
1
¼5.5 Hz, J
2
¼8.5 Hz, 2H, Ar).
C
6
d

9482
Y.-Q. Tang et al. / Tetrahedron 67 (2011) 9479e9483
J
1
CeF¼2.5 Hz), 130.5 (d, JCeF¼8.75 Hz), 130.9 (d, JCeF¼3.75 Hz), 142.7,
3
(CDCl , 125 MHz) d 19.9, 125.4, 126.2, 126.55, 126.57, 127.5, 127.6,
128.7, 130.0, 130.4, 135.8, 136.4, 137.7.
63.1 (d, JCeF¼246.25 Hz), 167.4.
7
4.2.1.18. Compound 6i . A white solid. 1H NMR (CDCl
11
4
.2.1.7. Compound 4g . A yellow solid. 1H NMR (DMSO-d
00 MHz)
J¼8.5 Hz, 2H, Ar), 8.23 (d, J¼8.5 Hz, 2H, Ar); C NMR (DMSO-d
25 MHz) 123.5, 123.9, 129.3, 140.7, 141.4, 148.0, 166.9.
6
6
,
,
3
,
5
d
6.74 (d, J¼16.0 Hz, 1H), 7.69 (d, J¼16.0 Hz, 1H), 7.97 (d,
500 MHz, TMS)
d
2.61 (s, 3H, Me), 7.14 (d, J¼16.0 Hz, 1H), 7.23 (d,
13
J¼16.0 Hz, 1H), 7.30 (t, J¼7.5 Hz, 1H, Ar), 7.38 (t, J¼7.5 Hz, 2H, Ar),
1
d
7.54 (d, J¼7.5 Hz, 2H, Ar), 7.59 (d, J¼8.0 Hz, 2H, Ar), 7.96 (d, J¼8.0 Hz,
13
2
3
H, Ar). C NMR (CDCl , 125 MHz) d 26.6, 126.5, 126.8, 127.5, 128.3,
9
1
4
.2.1.8. Compound 4h . A white solid. H NMR (300 MHz, CDCl
3
,
128.8, 128.9, 131.5, 136.0, 136.7, 142.0, 197.5.
TMS)
d
6.25 (d, J¼15.6 Hz, 1H), 7.08 (dd, J¼5.1, 3.6 Hz, 1H, Ar), 7.31
(
1
d, J¼3.6 Hz, 1H, Ar), 7.43 (d, J¼5.1 Hz, 1H, Ar), 7.89 (d, J¼15.6 Hz,
4.2.1.19. Compound 6j13. A white solid. 1H NMR (300 MHz,
1
3
H). C NMR (125 MHz, CDCl
3
)
d
116.8, 125.2, 127.2, 129.0, 137.3,
CDCl
3
, TMS)
d
7.07 (d, J¼16.5 Hz, 1H), 7.18 (d, J¼16.5 Hz, 1H),
140.4, 172.0.
7.27e7.33 (m, 2H, Ar), 7.38 (t, J¼7.2 Hz, 2H, Ar), 7.53 (d, J¼7.2 Hz, 2H,
Ar), 7.83 (d, J¼7.8 Hz, 1H, Ar), 8.49 (dd, J¼4.8, 1.5 Hz, 1H, Ar), 8.73 (d,
.2.1.9. Compound 4i10. A white solid. H NMR (300 MHz, CDCl
1
,
J¼2.1 Hz, 1H, Ar). C NMR (125 MHz, CDCl
13
4
3
3
) d 123.5, 124.9, 126.7,
TMS)
d
6.27 (d, J¼15.6 Hz, 1H), 7.32e7.38 (m, 2H, Ar), 7.56 (d,
128.2, 128.8, 130.8, 132.6, 133.0, 136.7, 148.5.
13
J¼1.5 Hz, 1H, Ar), 7.77 (d, J¼15.6 Hz, 1H). C NMR (125 MHz, CDCl
3
)
d
115.9, 128.2, 129.3, 131.6, 139.2, 139.3, 171.7.
4.2.1.20. Compound 6k14. A white solid. 1H NMR (300 MHz,
CDCl , TMS) 2.35 (s, 3H, Me), 3.83 (s, 3H, OMe), 6.89 (d, J¼8.7 Hz,
3
d
.2.1.10. Compound 6a . A white solid. 1H NMR (CDCl
00 MHz, TMS)
7.11 (s, 2H), 7.25 (t, J¼7.5 Hz, 2H, Ar), 7.36 (dd,
¼J ¼7.5 Hz, 4H, Ar), 7.52 (d, J¼7.5 Hz, 4H, Ar). C NMR (125 MHz,
CDCl 126.5, 127.6, 128.66, 128.70, 137.3.
11
2H), 6.98 (d, J¼8.4 Hz, 2H, Ar), 7.15 (d, J¼7.8 Hz, 2H, Ar), 7.39 (d,
4
3
,
13
5
d
J¼8.1 Hz, 2H), 7.44 (d, J¼8.7 Hz, 2H). C NMR (125 MHz, CDCl
21.2, 55.3, 114.1, 126.2, 126.6, 127.3, 127.6, 129.3, 130.4, 134.9, 137.0,
159.2.
3
)
13
J
1
2
d
3
) d
1
1
4.2.1.21. Compound 6l15. A yellow solid. 1H NMR (300 MHz,
CDCl , TMS)
2.38 (s, 3H, Me), 7.09 (d, J¼16.5 Hz, 1H), 7.19e7.28 (m,
3H, ArþC]CH), 7.45 (d, J¼7.8 Hz, 2H, Ar), 7.61 (d, J¼9.0 Hz, 2H, Ar),
4
.2.1.11. Compound 6b . A white solid. 1H NMR (CDCl
00 MHz, TMS)
3.83 (s, 3H, OMe), 6.90 (d, J¼8.5 Hz, 2H, Ar), 6.98
d, J¼16.0 Hz, 1H), 7.07 (d, J¼16.0 Hz, 1H), 7.23 (t, J¼7.5 Hz, 1H, Ar),
3
,
5
(
7
d
3
d
13
13
.34 (t, J¼7.5 Hz, 2H, Ar), 7.45e7.50 (m, 4H, Ar). C NMR (CDCl
25 MHz) 55.3, 114.1, 126.2, 126.6, 127.2, 127.7, 128.2, 128.6, 130.2,
37.7, 159.3.
3
,
8.21 (d, J¼9.0 Hz, 2H, Ar). C NMR (125 MHz, CDCl
3
) d 21.3, 124.1,
1
d
125.3, 126.7, 127.0, 129.6, 133.3, 133.5, 139.0, 144.1, 146.6.
1
4
.2.1.22. Compound 6m16. A white solid. 1H NMR (300 MHz,
CDCl , TMS)
6.88e6.93 (m, 3H, ArþC]CH), 7.03 (d, J¼16.2 Hz,1H),
7.30 (d, J¼8.4 Hz, 2H, Ar), 7.41 (d, J¼9.0 Hz, 2H, Ar), 7.44 (d, J¼9.0 Hz,
11
4
.2.1.12. Compound 6c . A white solid. 1H NMR (CDCl
3
,
3
d
5
00 MHz, TMS)
d
2.36 (s, 3H, Me), 7.05 (d, J¼16.0 Hz, 1H), 7.14 (d,
13
J¼16.0 Hz, 1H), 7.17 (d, J¼8.0 Hz, 2H, Ar), 7.24 (t, J¼7.5 Hz, 1H, Ar),
2H, Ar). C NMR (125 MHz, CDCl
3
) d 55.3, 114.2, 125.3, 127.4, 127.8,
7
2
.33 (t, J¼8.0 Hz, 2H, Ar), 7.41 (d, J¼8.0 Hz, 2H, Ar), 7.50 (d, J¼7.5 Hz,
128.8, 128.9, 129.8, 132.7, 136.2, 159.5.
13
H, Ar). C NMR (CDCl
3
, 125 MHz) d 21.2, 126.37,126.41,127.4,127.7,
4.2.1.23. Compound 6n . A yellow solid. 1H NMR (300 MHz,
CDCl , TMS)
7.11 (d, J¼16.5 Hz, 1H), 7.17 (d, J¼16.5 Hz, 1H), 7.37 (d,
J¼8.4 Hz, 2H, Ar), 7.48 (d, J¼8.4 Hz, 2H, Ar), 7.63 (d, J¼9.0 Hz, 2H,
17
1
28.61, 128.62, 129.4, 134.5, 137.48, 137.50.
3
d
11
4
.2.1.13. Compound 6d . A yellow liquid. 1H NMR (CDCl
3
,
1
3
5
00 MHz, TMS)
d
3.85 (s, 3H, OMe), 6.82 (d, J¼7.5 Hz, 1H), 7.05e7.12
Ar), 8.23 (d, J¼9.0 Hz, 2H, Ar). C NMR (125 MHz, CDCl
3
) d 124.2,
(
m, 4H), 7.25e7.29 (m, 2H), 7.36 (t, J¼7.5 Hz, 2H, Ar), 7.51 (d,
126.89, 126.93, 128.2, 129.1, 131.9, 134.6, 134.7, 143.5, 147.0.
13
J¼7.5 Hz, 2H, Ar). C NMR (CDCl
3
, 125 MHz)
d 55.3, 111.8, 113.3,
1
19.3, 126.5, 127.7, 128.6, 128.7, 129.6, 137.3, 138.8, 159.9.
Acknowledgements
.2.1.14. Compound 6e . A white solid. 1H NMR (CDCl
11
,
4
3
Y.-Q.T. thanks Science and Technology Department of Zhejiang
5
00 MHz, TMS)
d
7.05 (d, J¼16.5 Hz, 1H), 7.09 (d, J¼16.5 Hz, 1H),
Province for financial support (No. 2010R424050).
7.26e7.38 (m, 5H, Ar), 7.44 (d, J¼8.5 Hz, 2H, Ar), 7.51 (d, J¼7.0 Hz,
13
2
H, Ar). C NMR (CDCl
3
, 125 MHz)
d
126.5, 127.4, 127.6, 127.9, 128.7,
Supplementary data
128.8, 129.3, 133.2, 135.9, 137.0.
Supplementary data associated with this article can be found in
the online version, at doi:10.1016/j.tet.2011.10.033. These data in-
clude MOL files and InChiKeys of the most important compounds
described in this article.
.2.1.15. Compound 6f . A white solid. 1H NMR (CDCl
00 MHz, TMS)
¼J ¼7.5 Hz, 2H, Ar), 7.46e7.50 (m, 4H, Ar). C NMR (CDCl
25 MHz)
d, JCeF¼8.0 Hz), 128.5 (d, JCeF¼2.3 Hz), 128.7, 133.5 (d, JCeF¼3.3 Hz),
11
,
4
3
5
(
1
(
d
7.00e7.09 (m, 4H), 7.26 (t, J¼7.5 Hz, 1H, Ar), 7.36
13
dd, J
1
2
3
,
d
115.6 (d, JCeF¼21.7 Hz), 115.6, 126.4, 127.5, 127.7, 128.0
References and notes
1
37.2, 162.33 (d, JCeF¼247.6 Hz).
1. (a) Mizoroki, T.; Mori, K.; Ozaki, A. Bull. Chem. Soc. Jpn. 1971, 44, pp 581e581; (b)
.2.1.16. Compound 6g12. A yellow solid. 1H NMR (CDCl
00 MHz, TMS)
7.15 (d, J¼16.0 Hz, 1H), 7.28 (d, J¼16.0 Hz, 1H),
Heck, R. F.; Nolley, J. P., Jr. J. Org. Chem. 1972, 37, 2320e2322; (c) Heck, R. F.
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4
3
,
5
d
7
2
d
.34e7.42 (m, 3H, Ar), 7.56 (d, J¼8.0 Hz, 2H, Ar), 7.64 (d, J¼8.5 Hz,
1
3
H, Ar), 8.22 (d, J¼8.5 Hz, 2H, Ar). C NMR (CDCl
3
, 125 MHz)
124.2, 126.3, 126.9, 127.0, 128.8, 128.9, 133.3, 136.2, 143.9, 146.8.
11
1
4
.2.1.17. Compound 6h . A pale-yellow liquid. H NMR (CDCl
3
,
5
(
00 MHz, TMS)
d
2.43 (s, 3H, Me), 7.00 (d, J¼16.5 Hz, 1H), 7.05e7.38
2
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13
m, 7H), 7.52 (d, J¼7.5 Hz, 2H, Ar), 7.59 (d, J¼7.5 Hz, 1H, Ar). C NMR

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