2,2′-Diamino-6,6′-dimethylbiphenyl as an efficient ligand in the palladium- catalyzed SuzukiMiyaura and MizorokiHeck reactions

Article abstract of DOI:10.1016/j.tet.2010.04.099

2,2′-Diamino-6,6′-dimethylbiphenyl was found to be an efficient ligand in the palladium-catalyzed SuzukiMiyaura coupling reactions of awl iodides, bromides, and chlorides and Mizoroki1-Ieck reactions of awl iodides and bromides. Under appropriate conditions, all reactions gave the desired products in moderate to excellent yields. The ligand is inexpensive, air-stable and easy to available.

Full text of DOI:10.1016/j.tet.2010.04.099

Tetrahedron 66 (2010) 5185e5189
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2,20-Diamino-6,60-dimethylbiphenyl as an efficient ligand in the palladium-
catalyzed SuzukieMiyaura and MizorokieHeck reactions
,
Jian-Mei Lu a, Hui Ma a, Sha-Sha Li b, Dan Ma a, Li-Xiong Shao a
*
a College of Chemistry and Materials Engineering, Wenzhou University, Chashan University Town, Wenzhou, Zhejiang Province 325035, People’s Republic of China
b Oujiang College, Wenzhou University, Chashan University Town, Wenzhou, Zhejiang Province 325035, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
2,20-Diamino-6,60-dimethylbiphenyl was found to be an efficient ligand in the palladium-catalyzed Su-
zukieMiyaura coupling reactions of aryl iodides, bromides, and chlorides and MizorokieHeck reactions
of aryl iodides and bromides. Under appropriate conditions, all reactions gave the desired products in
moderate to excellent yields. The ligand is inexpensive, air-stable and easy to available.
Ó 2010 Elsevier Ltd. All rights reserved.
Article history:
Received 28 February 2010
Received in revised form 20 April 2010
Accepted 23 April 2010
Available online 29 April 2010
Keywords:
2,20-Diamino-6,60-dimethylbiphenyl
Palladium
SuzukieMiyaura reaction
MizorokieHeck reaction
Synthetic methods
1. Introduction
iodides, bromides, and chlorides and MizorokieHeck reactions of
aryl iodides and bromides. Herein, we wish to report these results
Palladium-catalyzed cross-coupling reactions are versatile and
efficient methods for carbonecarbon bond formations.1 Among
them, the SuzukieMiyaura and MizorokieHeck coupling reactions
play important roles in modern synthetic chemistry.2,3 Improve-
ment of these reactions is greatly relied on the reactivity of the
palladium catalyst by using increasing efficient supporting ligands.
To date, many efforts are made to the search for more efficient li-
gands. During the past decades, the most common ligands used for
these two coupling reactions are phosphine-based ones.4 Since
most of the phosphine-based ligands are air and/or moisture-sen-
sitive, in recent years, phosphine-free ligand as N-heterocyclic
carbenes (NHCs) have also been employed.5 In addition, alkyl-
substituted diamines, such as ethylenediamines and cyclohexane-
1,2-diamines, acting as versatile ligands, have been widely used in
the transition-metal catalyzed carbonecarbon bonds and carbon
eheteroatom bonds formations during the last years.6,7 As part of
our ongoing research toward effective ligands for transition-metal
catalyzed cross-coupling reactions for carbonecarbon bond for-
mations, it was found that easily available 2,20-diamino-6,60-
dimethylbiphenyl (L1),8 is a useful ligand for the palladium-cata-
lyzed SuzukieMiyaura coupling reactions of aryl halides including
in detail.
2. Results and discussion
In initial investigations, we examined the SuzukieMiyaura
coupling reaction of the model substrate 4-methoxyphenyl iodide
(1a) with 4-methylphenylboronic acid (2a), using 2,20-diamino-
6,60-dimethylbiphenyl (L1) (10 mol %) (Scheme 1) as the ligand and
Pd(OAc)2 (5 mol %) as the catalyst in THF at room temperature for
48 h (Table 1). As can be seen from Table 1, of the bases screened,
Cs2CO3 showed the best result and the corresponding coupling
product 3a was obtained in 90% yield (Table 1, entry 5). For the
other solvents as toluene, CH2Cl2, dioxane, DCE, and CH3CN, all
showed inferior results compared to that of THF (Table 1, entries
8e12). When L1 was replaced by other analogues as L2,9 L3,10 L4,11
L5,12 and L6,12 inferior results were found (Table 1, entries 13e17).
Finally, it was found that if the reaction temperature was elevated
to 40 ꢀC, the corresponding reactions can be finished within 12 h
with 96% yield using L1 as the ligand (Table 1, entry 18).
Thus, the optimal reaction conditions are using Pd(OAc)2 (5 mol
%) as the catalyst, L1 (10 mol %) as the ligand, Cs2CO3 (2.0 equiv) as
the base and THF (2.0 mL) as the solvent at the temperature of
40 ꢀC.
With the optimal reaction conditions in hand, we firstly ex-
plored the scope and limitations of the reaction with a set of aryl
* Corresponding author. Tel./fax: þ86 577 86689300; e-mail address: Shaolix@
wzu.edu.cn (L.-X. Shao).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.04.099

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J.-M. Lu et al. / Tetrahedron 66 (2010) 5185e5189
aryl bromides and arylboronic acids have little effect on the re-
action. For instance, the reaction of 3-methoxyphenyl bromide 1f
with 4-chlorophenylboronic acid 2d only gave the coupling product
3g in 72% yield (Table 2, entry 11). It is worthy of noting that at this
temperature (70 ꢀC), Cl atom on the phenyl ring kept untouched
(Table 2, entries 8 and 11).
Table 2
Pd(OAc)2-catalyzed SuzukieMiyaura coupling reaction of 1 with 2
Entrya
1 (R1/X)
2 (R2)
Yieldb (%)
Scheme 1. Ligands screened.
1
2
3
1a (4-MeO/I)
1b (4-Cl/I)
1c (H/I)
2b (H)
2c (4-MeO)
2c
3b (86)
3c (92)
3b (92)
iodides and arylboronic acids. We were pleased to find out that all
reactions afforded the desired coupling products 3 in high yields
within 12 h and substituents, either electron-donating group as
methoxy group or electron-withdrawing group as Cl atom on the
phenyl ring of 1 have almost no significant effect on these reactions
(Table 2, entries 1e3). 2-Thiophenyl iodide 1d also led to the cor-
responding coupling product 3d in high yield (Table 2, entry 4).
Nevertheless, to our disappointment, when arylbromide as 4-
methoxyphenyl bromide 1e was used as the substrate, almost no
desired product was obtained under the optimal reaction condi-
tions (Table 2, entry 5). Gratifyingly, when the reaction temperature
was elevated to 70 ꢀC, consistent with the above studies, the re-
actions of aryl bromides 1 with arylboronic acids 2 also took place
smoothly to give the corresponding products 3 in moderate to high
yields (Table 2, entries 6e13). Substituents on the phenyl rings of
4
2c
3d (95)
5c
6
7
8
9
10
11
12
13
1e (4-MeO/Br)
1e
1e
1e
2b
2b
2a (4-Me)
2d (4-Cl)
Trace
3b (95)
3a (91)
3c (75)
3e (94)
3f (94)
3g (72)
3h (90)
3b (94)
1e
2e (3,5-Me, Me)
1f (3-MeO/Br)
1f
1g (4-F/Br)
1h (H/Br)
2b
2d
2c
2c
a
Otherwise specified, all reactions were carried out using
1
(0.5 mmol), 2
(0.6 mmol), Pd(OAc)2 (5 mol %), L1 (10 mol %), and Cs2CO3 (1.0 mmol) in THF
(2.0 mL) at 40 ꢀC for 12 h (for iodides) or 70 ꢀC for 24 h (for bromides).
b
Isolated yields.
c
The reaction was carried out at 40 ꢀC.
Table 1
Optimization for the reaction conditions of 1a with 2a
It is known to all that despite the lower reactivity of aryl chlo-
rides comparable to the common partners as organic bromides,
iodides, and triflates, chlorides are arguably the most useful single
class of substrates, because of their lower cost and the wider di-
versity of available compounds.13 Encouraged by the success on the
palladium-catalyzed SuzukieMiyaura coupling reactions of aryl
iodides and bromides with arylboronic acids using 2,20-diamino-
6,60-dimethylbiphenyl (L1) as the ligand, we then turned our in-
terests to the reactions of aryl chlorides. Optimization procedure
was carried out using 4-methoxyphenyl chloride 1i (0.5 mmol) and
phenylboronic acid 2b (0.75 mmol) as the substrates, Pd(OAc)2
(5 mol %) as the catalyst, L1 (10 mol %) as the ligand, Cs2CO3
(2.0 equiv) as the base and DMF as the solvent. The results are
shown in Table 3. After several trials and errors, to our delight, it
was found that the best result can be obtained using 1.0 mL DMF as
the solvent at 110 ꢀC and the corresponding coupling product 3b
was obtained in 75% yield (Table 3, entry 2). In other solvents as
toluene and DMSO, only very lower yield or no product was
obtained for the same reaction (Table 3, entries 5 and 6).
Under the reaction conditions using Pd(OAc)2 (5 mol %) as the
catalyst, L1 (10 mol %) as the ligand, Cs2CO3 (2.0 equiv) as the base
and DMF (1.0 mL) as the solvent at 110 ꢀC, a variety of aryl chlorides
and arylboronic acids were examined (Table 4). All the substituted
aryl chlorides tested afforded the corresponding products 3 in
moderate to good yields. Substituents on the phenyl ring of chlo-
rides slightly affected the reaction and electron-withdrawing group
on the phenyl ring of aryl chloride gave better result (Table 4, en-
tries 1 vs 3).
Entrya
Ligand
Base
Solvent
Yield (%)b
1
2
3
4
5
6
7
8
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L2
L3
L4
L5
L6
L1
NaOH
KOH
THF
THF
THF
THF
THF
THF
THF
Toluene
CH2Cl2
Dioxane
DCE
CH3CN
THF
THF
THF
THF
THF
10
82
9
CH3COOK
KHCO3
Cs2CO3
Na2CO3
K2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
3
90
15
24
48
36
73
24
76
10
14
63
79
74
96
9
10
11
12
13
14
15
16
17
18c
THF
a
Otherwise specified, all reactions were carried out using 1a (0.5 mmol), 2a
(0.6 mmol), Pd(OAc)2 (5 mol %), ligand (10 mol %), and base (2.0 equiv) in solvent
(2.0 mL) at rt for 48 h.
b
Isolated yields.
The reaction was carried out at 40 ꢀC for 12 h.
c

J.-M. Lu et al. / Tetrahedron 66 (2010) 5185e5189
5187
Table 3
A series of aryl halides and alkenes were then subjected to the
reaction under the optimal conditions described above (Table 5).
The results indicated that the combination of Pd(OAc)2 and L1 is
also efficient for the MizorokieHeck coupling reaction of aryl io-
dides. Both alkenes, such as methyl acrylate 4a and styrene 4b
could be efficiently converted to the corresponding coupling
products 5 in good to high yields (Table 5, entries 1e6). Besides aryl
iodides, aryl bromides could also give products 5 in moderate to
good yields under the similar reaction conditions (Table 5, entries
7e9). Nonetheless, the combination of Pd(OAc)2 and L1 showed no
activity for the MizorokieHeck coupling reaction of aryl chlorides.
Optimization for the SuzukieMiyaura reaction of 4-methoxyphenyl chloride 1i
Entrya
Solvent (mL)
Yieldb (%)
Table 5
1
2
3
4
5
6
DMF (2.0)
DMF (1.0)
DMF (0.5)
DMF (0.25)
Toluene (1.0)
DMSO (1.0)
54
75
21
13
5
MizorokieHeck reaction of aryl halides 1 with alkenes 4
d
a
All reactions were carried out using 1 (0.5 mmol), 2 (0.75 mmol), Pd(OAc)2
(5 mol %), L1 (10 mol %), and Cs2CO3 (1.0 mmol) at 110 ꢀC for 48 h.
b
Isolated yields.
Entrya
1 (R1/X)
4 (R2)
Temp/Time
Yieldb (%)
1
2
3
1a (4-MeO/I)
1b (4-Cl/I)
1c (H/I)
4a (CO2Me)
4a
4b (Ph)
90 ꢀC/36 h
90 ꢀC/24 h
110 ꢀC/24 h
5b, 99
5c, 82
5d, 71
Table 4
SuzukieMiyaura reaction of chlorides 1
4
4a
90 ꢀC/36 h
5e, 80
5
6
1a
1b
4b
4b
4a
4a
4a
110 ꢀC/24 h
110 ꢀC/32 h
140 ꢀC/24 h
140 ꢀC/24 h
110 ꢀC/24 h
5f, 64
5g, 67
5a, 57
5h, 68
5c, 61
7c
8c
9c
1h (H/Br)
1o (4-Me/Br)
1p (4-Cl/Br)
a
Otherwise specified, all reactions were carried out using
1
(2.5 mmol), 4
(3.0 mmol), Pd(OAc)2 (1 mol %), L1 (1 mol %), and K2CO3 (5.0 mmol) in DMF (5.0 mL).
b
Entrya
1 (R1)
2 (R2)
Yieldb (%)
Isolated yields.
Pd(OAc)2 (5 mol %) and L1 (5 mol %) were used.
c
1
2
3
4
5
1j (4-COCH3)
1k (H)
1l (3-MeO)
1m (2-Me)
1n (4-Me)
2b (H)
2c (4-MeO)
2b
2c
2c
3i (66)
3b (75)
3f (54)
3j (59)
3a (62)
3. Conclusion
a
In conclusion, we have developed a new combination of Pd
(OAc)2-2,20-diamino-6,60-dimethylbiphenyl, which is proved to be
efficient for SuzukieMiyaura reactions of various aryl iodides,
bromides, and chlorides with arylboronic acids and MizorokieHeck
olefination of aryl iodides and bromides with various substituted
alkenes under the appropriate reaction conditions. It also demon-
strates great tolerance to a wide range of groups on all substrates
of aryl halides, arylboronic acids and alkenes. The ligand is
inexpensive, air-stable and easy to available.
All reactions were carried out using 1 (0.5 mmol), 2 (0.75 mmol), Pd(OAc)2
(5 mol %), L1 (10 mol %), and Cs2CO3 (1.0 mmol) in DMF (1.0 mL) at 110 ꢀC for 48 h.
b
Isolated yields.
Further, we investigated the MizorokieHeck coupling reaction
using 2,20-diamino-6,60-dimethylbiphenyl (L1) as the ligand and Pd
(OAc)2 as the catalyst. For our initial investigation, we chose iodo-
benzene 1c (2.5 mmol) and methyl acrylate 4a (3.0 mmol) as the
model substrates. After several trials and errors, we were pleased to
find out that in the presence of Pd(OAc)2 (1 mol %), L1 (1 mol %),
K2CO3 (2 equiv) at 90 ꢀC, the corresponding coupling product 5a
can be obtained in 94% yield (Scheme 2) (please see in the
Supplementary data for the details).
4. Experimental section
4.1. General methods
1H and 13C NMR spectra were recorded on a Bruker Avance-
300 MHz spectrometer for solution in CDCl3 with tetramethylsilane
(TMS) as an internal standard; J-values are in hertz. THF, toluene,
and dioxane were distilled from sodium (Na) under nitrogen (N2)
atmosphere. DMF, CH3CN, CH2Cl2, and 1,2-dichloroethane (DCE)
were distilled from CaH2 under nitrogen (N2) atmosphere. Com-
mercially obtained reagents were used without further purification.
Flash column chromatography was carried out using Huanghai
300e400 mesh silica gel at increased pressure.
Scheme 2. Optimal conditions for the coupling of 1c.

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J.-M. Lu et al. / Tetrahedron 66 (2010) 5185e5189
4.2. Experimental procedures
4.2.2.7. Compound 3g18. A colorless oil. 1H NMR (CDCl3,
300 MHz, TMS) 3.83 (s, 3H, OCH3), 6.87e6.91 (m, 1H, Ar),
7.05e7.13 (m, 2H, Ar), 7.30e7.39 (m, 3H, Ar), 7.47e7.51 (m, 2H, Ar).
13C NMR (CDCl3, 75 MHz, TMS)
55.2, 112.7, 112.8, 119.4, 128.4,
d
4.2.1. General procedure for the palladium-catalyzed Suzu-
kieMiyaura cross-coupling reaction of arylboronic acids with aryl
iodides and bromides. (If Aryl halide is liquid). Under N2 atmosphere,
arylboronic acid 2 (0.6 mmol), Pd(OAc)2 (5 mol %), ligand L1
(10 mol %), Cs2CO3 (2.0 equiv), and THF (2.0 mL) were added into
a Schlenk reaction tube, then aryl halide (0.5 mmol) was added. The
mixture was stirred at 40 ꢀC for 12 h (for iodide) or 70 ꢀC for 24 h
(for bromide). Then the solvent was removed under reduced
pressure and the residue was purified by a flash column chroma-
tography (SiO2).
d
128.8, 129.9, 133.4, 139.4, 141.4, 159.9.
4.2.2.8. Compound 3h15. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
7.07e7.13 (m, 2H, Ar), 7.45e7.51 (m, 4H, Ar). 13C NMR (CDCl3,
75 MHz, TMS)
d 3.85 (s, 3H, OCH3), 6.96e6.98 (m, 2H, Ar),
d
55.2, 114.2, 115.5 (d, JCeF¼21.4 Hz), 128.0, 128.1 (d,
JCeF¼7.7 Hz), 132.7, 136.9 (d, JCeF¼3.2 Hz), 159.0, 162.0 (d,
JCeF¼244.3 Hz).
(If Aryl halide is solid). Under N2 atmosphere, aryl halide 1
(0.5 mmol), arylboronic acid 2 (0.6 mmol), Pd(OAc)2 (5 mol %), li-
gand L1 (10 mol %), Cs2CO3 (2.0 equiv), and THF (2.0 mL) were
added into a Schlenk reaction tube. The mixture was stirred at 40 ꢀC
for 12 h (for iodide) or 70 ꢀC for 24 h (for bromide). Then the sol-
vent was removed under reduced pressure and the residue was
purified by a flash column chromatography (SiO2).
4.2.2.9. Compound 3i19. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
d 2.62 (s, 3H, CH3), 7.36e7.49 (m, 3H, Ar),
7.60e7.68 (m, 4H, Ar), 8.02 (d, J¼8.1 Hz, 2H, Ar). 13C NMR (CDCl3,
75 MHz, TMS)
145.7, 197.6.
d 26.6, 127.1, 127.2, 128.2, 128.8, 128.9, 135.8, 139.8,
4.2.2.10. Compound 3j20. A colorless oil. 1H NMR (CDCl3,
4.2.2. General procedure for the palladium-catalyzed Suzu-
kieMiyaura cross-coupling reaction of arylboronic acids with aryl
chlorides. Under N2 atmosphere, arylboronic acid 2 (0.6 mmol), Pd
(OAc)2 (5 mol %), ligand L1 (10 mol %), Cs2CO3 (2.0 equiv), and DMF
(1.0 mL) were added into a Schlenk reaction tube, then aryl chloride
1 (0.5 mmol) was added. The mixture was stirred at 110 ꢀC for 48 h.
Then the solvent was diluted with EtOAc, washed with saturated
brine, dried over anhydrous Na2SO4 and purified by a flash column
chromatography (SiO2).
300 MHz, TMS) d 2.27 (s, 3H, CH3), 3.83 (s, 3H, OCH3), 6.94 (d,
J¼9.0 Hz, 2H, Ar), 7.20e7.25 (m, 6H, Ar). 13C NMR (CDCl3, 75 MHz,
TMS) d 20.5, 55.2, 113.5, 125.7, 126.9, 129.9, 130.2, 130.3, 134.4, 135.4,
141.5, 158.5.
4.2.3. General procedure for the palladium-catalyzed HeckeMizoroki
cross-coupling reaction of aryl halides with alkenes. Under N2 at-
mosphere, Pd(OAc)2 (1 mol %), L1 (1 mol %), and K2CO3 (2.0 equiv)
and DMF (5.0 mL) were added into a Schlenk reaction tube suc-
cessively, then aryl halides (2.5 mmol) and alkenes (3.0 mmol)
were added. The mixture was stirred at the temperature and times
listed in Scheme 2 and Table 5. Then the reaction solution was di-
luted with EtOAc, washed with saturated brine, dried over anhy-
drous Na2SO4 and purified by a flash column chromatography
(SiO2).
4.2.2.1. Compound 3a14. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
d 2.36 (s, 3H, CH3), 3.80 (s, 3H, OCH3), 6.94 (d,
J¼8.7 Hz, 2H, Ar), 7.20 (d, J¼7.5 Hz, 2H, Ar), 7.43 (d, J¼7.5 Hz,
2H, Ar), 7.49 (d, J¼8.7 Hz, 2H, Ar). 13C NMR (CDCl3, 75 MHz,
TMS)
d 21.0, 55.2, 114.1, 126.5, 127.9, 129.4, 133.6, 136.3, 137.9,
158.9.
4.2.3.1. Compound 5a21. A white solid. 1H NMR (CDCl3,
4.2.2.2. Compound 3b14. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
3.79 (s, 3H, OCH3), 6.94 (d, J¼8.4 Hz, 2H, Ar), 7.27
300 MHz, TMS)
d
3.80 (s, 3H, OMe), 6.44 (d, J¼16.2 Hz, 1H),
d
7.37e7.39 (m, 3H, Ar), 7.50e7.54 (m, 2H, Ar), 7.70 (d, J¼16.2 Hz,
(t, J¼6.9 Hz, 1H, Ar), 7.39 (t, J¼7.5 Hz, 2H, Ar), 7.49e7.54 (m, 4H, Ar).
1H).
13C NMR (CDCl3, 75 MHz, TMS)
128.7, 133.6, 140.7, 159.1.
d 55.2, 114.1, 126.6, 126.7, 128.1,
4.2.3.2. Compound 5b22. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
d 3.79 (s, 3H, OMe), 3.83 (s, 3H, OMe), 6.31 (d,
4.2.2.3. Compound 3c14. A white solid. 1H NMR (CDCl3,
J¼15.9 Hz, 1H), 6.90 (d, J¼8.7 Hz, 2H, Ar), 7.47 (d, J¼8.7 Hz, 2H, Ar),
300 MHz, TMS)
d
3.84 (s, 3H, OCH3), 6.97 (d, J¼9.0 Hz, 2H, Ar), 7.37
7.65 (d, J¼15.9 Hz, 1H).
(d, J¼9.0 Hz, 2H, Ar), 7.45e7.50 (m, 4H, Ar). 13C NMR (CDCl3,
75 MHz, TMS)
159.3.
d
55.3, 114.2, 127.9, 128.0, 128.8, 132.4, 132.6, 139.2,
4.2.3.3. Compound 5c22. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
J¼8.7 Hz, 2H, Ar), 7.46 (d, J¼8.7 Hz, 2H, Ar), 7.64 (d, J¼15.9 Hz, 1H).
d
3.81 (s, 3H, OMe), 6.41 (d, J¼15.9 Hz, 1H), 7.36 (d,
4.2.2.4. Compound 3d15. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
3.78 (s, 3H, OCH3), 6.88 (d, J¼8.7 Hz, 2H, Ar),
d
4.2.3.4. Compound 5d22. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
4H, Ar).
7.00e7.03 (m, 1H, Ar), 7.16e7.18 (m, 2H, Ar), 7.51 (d, J¼9.0 Hz, 2H,
d 7.07 (s, 2H), 7.19e7.34 (m, 6H, Ar), 7.46e7.49 (m,
Ar). 13C NMR (CDCl3, 75 MHz, TMS)
127.3, 127.8, 144.3, 159.1.
d 55.2, 114.2, 122.0, 123.7, 127.41,
4.2.3.5. Compound 5e23. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
4.2.2.5. Compound 3e16. A white solid. 1H NMR (CDCl3,
d
3.78 (s, 3H, OMe), 6.23 (d, J¼15.6 Hz,1H), 7.03 (dd,
300 MHz, TMS)
d
2.37 (s, 3H, CH3), 3.84 (s, 3H, OCH3), 6.94e6.97 (m,
J¼3.9, 5.1 Hz, 1H), 7.24 (d, J¼3.9 Hz, 1H), 7.36 (d, J¼5.1 Hz, 1H), 7.78
(d, J¼15.6 Hz, 1H).
3H, Ar), 7.17 (s, 2H, Ar), 7.51 (d, J¼9.0 Hz, 2H, Ar). 13C NMR (CDCl3,
75 MHz, TMS)
140.8, 158.9.
d 21.4, 55.2, 114.0, 124.6, 128.1, 128.3, 133.9, 138.1,
4.2.3.6. Compound 5f24. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
d
3.80 (s, 3H, OMe), 6.89 (d, J¼7.8 Hz, 2H, Ar), 6.96
4.2.2.6. Compound 3f17. A colorless oil. 1H NMR (CDCl3,
300 MHz, TMS) 3.83 (s, 3H, OCH3), 6.86e6.90 (m, 1H, Ar),
7.11e7.19 (m, 2H, Ar), 7.30e7.36 (m, 2H, Ar), 7.39e7.44 (m, 2H, Ar),
7.56e7.59 (m, 2H, Ar). 13C NMR (CDCl3, 75 MHz, TMS)
55.2, 112.6,
112.8, 119.6, 127.1, 127.4, 128.7, 129.7, 141.0, 142.7, 159.9.
(d, J¼16.8 Hz, 1H), 7.06 (d, J¼16.8 Hz, 1H), 7.20e7.36 (m, 3H, Ar),
d
7.44 (d, J¼8.1 Hz, 2H, Ar), 7.48 (d, J¼7.8 Hz, 2H, Ar).
d
4.2.3.7. Compound 5g24. A white solid. 1H NMR (CDCl3,
300 MHz, TMS)
d 7.05 (s, 1H), 7.06 (s, 1H), 7.24e7.52 (m, 9H, Ar).

J.-M. Lu et al. / Tetrahedron 66 (2010) 5185e5189
5189
4.2.3.8. Compound 5h25. A white solid. 1H NMR (CDCl3,
300 MHz, TMS) 2.35 (s, 3H, Me), 3.78 (s, 3H, OMe), 6.39 (d,
W.; Ittel, S. D. Homogeneous Catalysis, 2nd ed.; John Wiley: New York, NY, 1992,
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d
J¼16.8 Hz, 1H), 7.17 (d, J¼8.1 Hz, 2H, Ar), 7.40 (d, J¼8.1 Hz, 2H, Ar),
7.66 (d, J¼16.8 Hz, 1H).
Acknowledgements
Financial support from the National Natural Science Foundation
of China (No. 20702013) and the start-up fund of Wenzhou Uni-
versity is greatly acknowledged. J.-M.L. thanks the Department of
Education of Zhejiang Province for financial support (No.
Y200907072). D.M. thanks Science and Technology Department of
Zhejiang Province for financial support (No. 2008R40G2250090).
Supplementary data
Supplementary data associated with this article can be found in
online version at doi:10.1016/j.tet.2010.04.099. These data include
MOL files and InChIkeys of the most important compounds de-
scribed in the article.
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