Suzuki-Miyaura coupling reactions of aryl chlorides catalyzed by a new nickel(II) σ-aryl complex

Article abstract of DOI:10.1002/aoc.3000

A new nickel(II) σ-aryl complex, trans-chloro(9-phenanthrenyl) bis(triphenylphosphine)nickel(II), was used as a precatalyst for the Suzuki-Miyaura coupling reactions of aryl chlorides. The catalytic conditions were optimized by investigating the cross-coupling of p-chloroanisole with phenylboronic acid. The results show that this complex is efficient for both electron-rich and electron-deficient aryl chlorides, though it gives better yields for activated arylboronic acids than deactivated ones. All isolated cross-coupled biaryl products have been characterized by ¹H and ¹³C NMR, and their spectral data are consistent with those reported. Side products from the coupling of arylboronic acid with the precatalyst complex have also been isolated and characterized, which is helpful for understanding the coupling mechanism. Copyright

Full text of DOI:10.1002/aoc.3000

Full Paper
Received: 3 February 2013
Revised: 3 April 2013
Accepted: 4 April 2013
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/aoc.3000
Suzuki–Miyaura coupling reactions of aryl
chlorides catalyzed by a new nickel(II)
s-aryl complex
Xiangyang Lei*, Karla A. Obregon and Jhansi Alla
A new nickel(II) s-aryl complex, trans-chloro(9-phenanthrenyl)bis(triphenylphosphine)nickel(II), was used as a precatalyst for
the Suzuki–Miyaura coupling reactions of aryl chlorides. The catalytic conditions were optimized by investigating the cross-
coupling of p-chloroanisole with phenylboronic acid. The results show that this complex is efficient for both electron-rich
and electron-deficient aryl chlorides, though it gives better yields for activated arylboronic acids than deactivated ones. All
isolated cross-coupled biaryl products have been characterized by 1H and 13C NMR, and their spectral data are consistent with
those reported. Side products from the coupling of arylboronic acid with the precatalyst complex have also been isolated and
characterized, which is helpful for understanding the coupling mechanism. Copyright © 2013 John Wiley & Sons, Ltd.
Keywords: Ni(II) s-aryl complex; Suzuki–Miyaura reaction; aryl chlorides; arylboronic acids; biaryls
conveniently reduced to the active Ni(0) species at elevated tem-
Introduction
perature via the homo-coupling of arylboronic acids under basic
conditions.[16] Afterwards, a few examples of Ni-based catalysts
The biaryl scaffold has attracted considerable attention as a
privileged structural unit because it widely exists in numerous bi-
ologically active natural products,[1–3] pharmaceutical and agri-
cultural chemicals,[4,5] electro-optical materials,[6] and organic
struts in metal–organic frameworks.[7] Aryl–aryl bond formation
is one of the most important tools to construct biaryl com-
pounds, and many transition metal-catalyzed coupling reactions
for constructing C-C bonds have been named.[1,2,8] Among these
reactions, the Pd-catalyzed Suzuki–Miyaura reaction has become
the powerful and practical synthetic strategy because of its broad
functional group tolerance, mild reaction conditions, and the
stability and low toxicity of the boronic acids.[5] The Pd catalysts
have been extensively investigated and popularly applied for the
cross-coupling of arylboronic acids with aryl bromides, iodides and
triflates that are easily activated by active Pd(0) species.[1] However,
the more economical and accessible but less reactive aryl chlorides
(except when they are activated by electron-withdrawing groups)
have rarely been used as electrophiles for the Pd-catalyzed Suzuki
coupling because the oxidative insertion of Pd(0) species into the
Ar-Cl bond is usually difficult.[9,10]
Compared to Pd-based catalysts, Ni-based catalysts particularly
exhibit good activity toward aryl chlorides because the reactivity
of the Ni(0) complexes toward aryl chlorides is much greater than
that of the Pd(0) complexes.[11] In addition, Ni catalysts are inex-
pensive and common phosphine and nitrogen-based ligands can
be used for the coupling reactions.[12–14] Since Miyaura and co-
workers reported the first Ni-catalyzed cross-coupling of aryl
chlorides with arylboronic acids,[15] many successful Ni-
catalyzed coupling reactions of aryl chlorides have been
reported.[9,16–18] Ni(0) complexes, which are generally regarded
as catalytically active species, are air- and moisture-sensitive, so
the air- and thermal-stable Ni(II) complexes are often used as
precatalysts activated to generate the active Ni(0) species in situ.
In 1997, Indolese reported that Ni(II) complexes can be
such as NiCl2(dppf), NiCl2(PPh3)2, NiCl2(dppe), Ni(COD)2, NiCl2
(PCy3)2, NiCl2(dppp) and NHC–Ni(II) complexes have revealed
their great potential in the Suzuki–Miyaura coupling reactions
of aryl halides (particularly chlorides), aryl tosylates and
mesylates, and other phenol derivatives.[3,19–25] Among these Ni
catalysts, Ni(COD)2 and NiCl2(PCy3)2 are the most popularly used
catalysts for Suzuki coupling reactions. However, Ni(COD)2 and
the phosphine ligand PCy3 are expensive and air-sensitive. Re-
cently, Hu reported a Ni(II) s-aryl complex as a general catalyst
for the Suzuki–Miyaura cross-coupling of aryl sulfonates with
arylboronic acids.[26] Meanwhile, Yang reported a readily avail-
able and air-stable Ni(II) s-aryl complex as an efficient precatalyst
for the Suzuki–Miyaura reactions of aryl halides and sulfo-
nates.[14,27] The same precatalyst has been used by Percec and
co-workers to study the Suzuki–Miyaura cross-coupling of aryl
and heteroaryl neopentylglycolboronates with aryl and
heteroaryl mesylates and sulfamates.[28] As part of our research
interest in the catalytic activities of transition metal complexes,
we prepared
a new Ni(II) s-aryl complex, trans-chloro
(9-phenanthrenyl)bis(triphenylphosphine)nickel(II) (1) (Fig. 1).[29]
In comparison with its known analogs with naphtharene and
benzene rings, the phenanthrene ring of this complex is more
highly conjugated and more electron-rich. Herein we report the
*
Correspondence to: Xiangyang Lei, Department of Chemistry and Biochemistry,
PO Box 10022, Lamar University, Beaumont, TX 77710, USA. E-mail: xlei@lamar.
edu
Department of Chemistry and Biochemistry, Lamar University, Beaumont, TX,
77710, USA
Appl. Organometal. Chem. 2013, 27, 419–424
Copyright © 2013 John Wiley & Sons, Ltd.

X. Lei et al.
Cl
Ni
entries 2 and 10). p-Bromoanisole is less reactive than p-
chloroanisole under the same catalytic conditions (entries 2 and
11). No significant yield improvement was observed when the
catalyst load was doubled (entries 2 and 12, 4 and 13, respec-
tively). However, the yield decreased from 92% to 76% and
15%, respectively, when the catalyst load was reduced from 5.0
to 2.5 and 1.3 mol%, respectively (entries 2, 14 and 15). These re-
sults indicated that the Ni(II) catalyst load should not be less than
5 mol% to maintain the catalyst’s efficiency. According to the
reported Ni-catalyzed Suzuki reactions, the addition of further
phosphine ligand is essential to stabilize the in situ generated
Ni(0) catalyst and the intermediate aryl nickel species during
the entire catalytic cycle.[30] Since the cheap and readily available
PPh3 showed efficiency during the initial screening, there was
no further screening for phosphine ligands. It is worth
pointing out that in addition to the cross-coupling product,
4-methoxybiphenyl, in all cases about 2–3% of biphenyl, which
was formed by homo-coupling of phenylboronic acid, was
observed. No homo-coupling of p-chloroanisole was observed
under any reaction conditions.
After the reaction conditions were optimized, the cross-coupling
reactions of a variety of aryl chlorides with phenylboronic acid were
investigated to examine the electronic and steric effects of aryl
chlorides on the efficiency of the catalytic reactions. As seen in
Table 2, steric effects were observed as the ortho-substituted aryl
chlorides gave lower yields than their para-substituted analogs
(entries 1 and 2, 3 and 4, 6 and 7, respectively). Aryl chlorides
bearing electron-donating groups such as methyl, methoxy
and hydroxymethyl groups can efficiently couple with
phenylboronic acid to provide the corresponding biaryl prod-
ucts in good to excellent yields (59–95%, entries 1–5). These re-
sults confirm that in contrast to Pd-catalyzed cross-coupling of
aryl chlorides with arylboronic acids where aryl chlorides with
electron-donating groups are generally not reactive,[15,31] Ni
Ph3P
PPh3
1
Figure 1. Ni(II) s-aryl complex used as a precatalyst in this study.
catalytic activities of this Ni(II) s-aryl complex in the Suzuki–Miyaura
coupling reactions of aryl chlorides with arylboronic acids.
Results and Discussion
In order to optimize the catalytic reaction conditions, the cou-
pling of chlorobenzene with phenylboronic acid was initially cho-
sen as a model reaction. However, it was found that the gas
chromatography (GC) yields of biphenyl were always a little
higher than the conversions of chlorobenzene, which indicated
that the homo-coupling of phenylboronic acid might have oc-
curred under the reaction conditions. In order to obtain reliable
yields of cross-coupling reactions and determine the amount of
homo-coupling products, the reaction of p-chloroanisole and
phenylboronic acid was studied for screening the reaction condi-
tions. As shown in Table 1, a short reaction time of 3 h gave only
19% yield, whereas a yield of 92% was achieved when the reac-
tion lasted for 18 h (entries 1 and 2). Base K2CO3 is more efficient
than Na2CO3, K3PO4 or Cs2CO3 when toluene was used as solvent
(entries 2, 3, 4 and 5). The greater efficiency of K2CO3 compared
with K3PO4 was further confirmed in 1,4-dioxane (entries 6 and
8) and THF (entries 7 and 9), respectively. Among toluene, 1,4-
dioxane and THF, toluene is the best choice for solvent (entries
2, 6 and 7). With toluene as the solvent, decreasing reaction tem-
perature from 110 to 65 ꢀC resulted in lower yield (92% vs. 57%,
Table 1. Screening reaction conditions for Ni-catalyzed cross-coupling of p-chloroanisole with phenylboronic acida
Entry
Precat. 1 (mol%)
Base
Solvent
Temp (ꢀC)
Time (h)
Yield (%)b
1
5
5
K2CO3
K2CO3
Na2CO3
K3PO4
Cs2CO3
K2CO3
K2CO3
K3PO4
K3PO4
K2CO3
K2CO3
K2CO3
K3PO4
K2CO3
K2CO3
Toluene
Toluene
Toluene
Toluene
Toluene
1,4-Dioxane
THF
110
110
110
110
110
110
65
3
18
18
18
18
18
18
18
18
18
18
18
18
18
18
19
92
43
85
62
88
81
67
77
57
73
94
85
76
15
2
3
5
4
5
5
5
6
5
7
5
8
5
1,4-Dioxane
THF
110
65
9
5
10
11c
12
13
14
15
5
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
65
5
110
110
110
110
110
10
10
2.5
1.3
aReaction conditions: p-chloroanisole (1.0 mmol), phenylboronic acid (1.2 mmol), precatalyst 1 (0.05 mmol), PPh3 (0.10 mmol), base (3.0 mmol),
solvent (3 ml).
b
GC yields (average of two runs).
c
p-Chloroanisole was replaced by p-bromoanisole.
wileyonlinelibrary.com/journal/aoc
Copyright © 2013 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2013, 27, 419–424

Ni-catalyzed Suzuki–Miyaura reactions of aryl chlorides
Table 2. The Suzuki cross-coupling of aryl chlorides with phenylboronic acida
Entry
ArCl
Product
o-Me–Ph–Ph
Yield (%)b
Reference
[33]
[33]
[34]
[33]
[35]
[33]
[36]
[36]
[33]
[37]
[38]
[39]
[40]
[40]
[14]
[14]
[41]
[41]
[33]
1
o-Me–Ph–Cl
p-Me–Ph–Cl
71
95
78
86
59
50
91
83
79
84
81
87
0
2
p-Me–Ph–Ph
3
2,5-Dimethoxy-Ph–Cl
p-MeO-Ph-Cl
2,5-Dimethoxy–Ph–Ph
p-MeO–Ph–Ph
4
5
p-HOCH2–Ph–Cl
o-MeO2C–Ph–Cl
p-MeO2C–Ph–Cl
p-OHC–Ph–Cl
p-HOCH2–Ph–Ph
o-MeO2C–Ph–Ph
p-MeO2C–Ph–Ph
p-OHC–Ph–Ph
6
7
8
9
p-NC–Ph–Cl
p-NC–Ph–Ph
10
11
12
13
14
15
16
17
18
19
p-PhOC–Ph–Cl
p-F–Ph–Cl
p-PhOC–Ph–Ph
p-F–Ph–Ph
3,5-Difluoro–Ph–Cl
p-O2N–Ph–Cl
3,5-Difluoro–Ph–Ph
p-O2N–Ph–Ph
o-O2N–Ph–Cl
o-O2N–Ph–Ph
0
p-Ph–Ph–Cl
p-Ph–Ph–Ph
84
88c
91c
72c
78
p-Cl–Ph–Cl
p-Ph–Ph–Ph
1,3,5-Trichlorobenzene
1,2,4,5-Tetrachlorobenzene
1-Cl–naphthalene
1,3,5-Triphenylbenzene
1,2,4,5-Tetraphenylbenzene
1-Ph–naphthalene
aReaction conditions: aryl chloride (1.0 mmol), phenylboronic acid (1.2 mmol), precatalyst 1 (0.05 mmol), PPh3 (0.10 mmol), K2CO3 (3.0 mmol),
toluene (3 ml).
bIsolated yield.
cPrecatalyst 1 usage: 0.05 mol per mole of chloride.
catalysts work efficiently for electron-rich aryl chlorides. The
relatively low yield of the coupling of p-chlorobenzyl alcohol
with phenylboronic acid was probably due to the effect of
the active hydroxyl group. Aryl chlorides containing electron-
withdrawing groups also yielded the corresponding biaryl
products in good to excellent yields (50–91%, entries 6–12)
except for the nitro-substituted aryl chlorides (entries 13
and 14), which did not yield any detectable cross-coupling prod-
uct at all. This is because the catalyst may lose its activity by the
formation of a stable (nitroso)nickel(II) species.[9,32] The coupling
of 4-chlorobiphenyl, 1,4-dichlorobenzene, 1,3,5-trichlorobenzene
and 1,2,4,5-tetrachlorobenzene with phenylboronic acid gave the
corresponding polyphenyls in good to excellent yields (72–91%,
entries 15–18), which suggests that this catalytic protocol was
efficient in the formation of polyaryls. In addition, the coupling of
1-chloronaphthelene with phenylboronic acid also achieved good
yield (entry 19).
Next, the cross-coupling reactions of p-chloroanisole with vari-
ous arylboronic acids were conducted to determine the generality
of this catalytic method towards arylboronic acids, and the results
are summarized in Table 3. As shown in the table, phenylboronic
acids bearing electron-donating groups and naphthylboronic
acids were successfully coupled with p-chloroanisole to give the
cross-coupling products in good to excellent yields (72–98%)
(entries 1–6). However, phenylboronic acids containing electron-
withdrawing groups and pyridylboronic acids gave low yields or
no product (entries 7–14). This could be for the following reasons:
(i) electron-deficient boronic acids are generally less reactive than
electron-rich ones because of the rate-determining transmetalation
step of the catalytic cycle[42,43]; (ii) the poor solubility of some
arylboronic acids in toluene; (iii) the strong coordination ability of
functional groups (such as pyridyl, CN and CO2Me) to the active
Ni(0) species; and (iv) the protodeboronation of arylboronic acids
bearing electron-withdrawing groups. Generally, arylbornic acids
are stable to water and base, but the presence of electron-
withdrawing groups enhances the rate of protodeboronation of
arylboronic acids, which often reduces the yields of their coupling
reactions.[10] Meanwhile, steric effects were also observed in Table 3
as the yields followed the sequence p-tolylboronic acid> m-
tolylboronic acid > o-tolylboronic acid (entries 1–3). Moreover,
2-naphthylboronic acid gave
a
higher yield than 1-
naphthylboronic acid (entries 5 and 6).
The unsymmetrical biaryls bearing both electron-withdrawing
and methoxy groups, which were obtained in low yields or not
obtained at all in Table 3 (entries 7–12), were successfully synthe-
sized by the coupling reactions of p-methoxyphenylboronic acid
with aryl chlorides bearing electron-withdrawing groups in good
to excellent yields (68–96%, Table 4). This provides a general way
to synthesize unsymmetrical biaryls that contain both electron-
donating and -withdrawing groups by the Ni-catalyzed Suzuki–
Miyaura reaction. The coupling partner should be the arylboronic
acids with electron-donating groups and the aryl chlorides with
electron-withdrawing groups.
This Ni-catalyzed cross-coupling reaction is believed to follow a
mechanism similar to the Pd-catalyzed cross-coupling.[14,19,33] The
proposed mechanism is shown in Fig. 2. The catalytic cycle involves
three sequential steps: oxidative addition, transmetalation and re-
ductive elimination. First, precatalyst 1 is reduced by arylboronic
acid in the presence of base through sequential transmetalation
and reductive elimination, prior to the main catalytical cycle, to
Appl. Organometal. Chem. 2013, 27, 419–424
Copyright © 2013 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

X. Lei et al.
Table 3. The Suzuki cross-coupling of p-chloroanisole with arylboronic acidsa
Entry
Ar–B(OH)2
Product
Yield (%)b
Reference
[37]
[44]
[37]
[37]
[45]
[45]
[46]
[45]
[28]
[28]
[28]
[24]
[45]
[45]
1
o-Me–PhB(OH)2
p-MeO–Ph–Ph–o-Me
72
85
2
m-Me–PhB(OH)2
p-MeO–Ph–Ph–m-Me
p-MeO–Ph–Ph–p-Me
3
p-Me–PhB(OH)2
90
4
p-MeO–PhB(OH)2
1-B(OH)2–naphthalene
2-B(OH)2–naphthalene
3,5-Difluoro–PhB(OH)2
p-F–PhB(OH)2
p-MeO–Ph–Ph–p-OMe
1-(p-MeO–Ph)–naphthalene
2-(p-MeO–Ph)–naphthalene
p-MeO–Ph–Ph–3,5-difluoro
p-MeO–Ph–Ph–p-F
87
5
92
6
98
7
8
8
54
9
p-MeO2C–PhB(OH)2
m-MeO2C–PhB(OH)2
p-NC–PhB(OH)2
p-MeO–Ph–Ph–p-CO2Me
p-MeO–Ph–Ph–m-CO2Me
p-MeO–Ph–Ph–p-CN
Tracec
Tracec
Tracec
Tracec
Tracec
Tracec
10
11
12
13
14
p-OHC–PhB(OH)2
4-B(OH)2–Pyridine
3-B(OH)2–Pyridine
p-MeO–Ph–Ph–p-CHO
4-(p-MeO–Ph)–pyridine
3-(p-MeO–Ph)–pyridine
aReaction conditions: p-chloroanisole (1.0 mmol), arylboronic acid (1.2 mmol), precatalyst 1 (0.05 mmol), PPh3 (0.10 mmol), K2CO3 (3.0 mmol),
toluene (3 ml).
bIsolated yield.
cGC results.
Table 4. The Suzuki cross-coupling of p-methoxyphenylboronic acid with aryl chlorides bearing electron-withdrawing groupsa
Entry
ArCl
Product
Yield (%)b
Reference
[46]
[45]
[28]
[28]
[28]
[24]
1
2
3
4
5
6
3,5-Difluoro–Ph–Cl
p-F–Ph–Cl
3,5-Difluoro–Ph–Ph–p-OMe
p-F–Ph–Ph–p-OMe
86
91
96
92
68
85
p-MeO2C–Ph–Cl
o-MeO2C–Ph–Cl
p-NC–Ph–Cl
p-MeO2C–Ph–Ph–p-OMe
o-MeO2C–Ph–Ph–p-OMe
p-NC–Ph–Ph–p-OMe
p-OHC–Ph–Cl
p-OHC–Ph–Ph–p-OMe
aReaction conditions: aryl chloride (1.0 mmol), p-methoxyphenylboronic acid (1.2 mmol), precatalyst 1 (0.05 mmol), PPh3 (0.10 mmol), K2CO3
(3.0 mmol), toluene (3 ml).
bIsolated yield.
afford the active Ni(0) species stabilized by additional ligand
PPh3. The formation and identification of side product 9-
phenylphenanthrene (7a, Fig. 3) in all reactions of phenylboronic
acid with various aryl chlorides and other side products (7b–g,
Fig. 3) when substituted-arylboronic acids were used as nucleo-
philes confirmed this precatalyst activation process. This activation
process is also consistent with that reported by Percec.[28] Except
for compound 7 g, these side products are known and their spec-
tral data are consistent with those in the literature.[47,48] Next, the
active catalytic Ni(0) species undergoes oxidative addition by aryl
chloride to yield Ni(II) s-aryl complex 2, which contains the weakly
coordinated chloride ion and might undergo ligand exchange with
base-provided anion to form potentially more reactive oxo-nickel
intermediate 3.[19] The transmetalation of the aryl group of the ac-
tivated arylboronic acid 4 to intermediate 3 gives Ni(II) diaryl com-
plex 5. Reductive elimination of complex 5 facilitates the catalytic
cycle by regenerating the active Ni(0) species while the cross-
coupled product 6 is produced. Similar to the Ni-catalyzed
Suzuki–Miyaura cross-coupling of aryl esters,[42] aryl carbamates
and aryl sulfamates,[43] transmetalation is believed to be the rate-
determining step of the catalytic cycle. This argument appears to
be supported by the experimental results that electron-rich boronic
acids are more reactive than electron-deficient ones under the
same reaction conditions (Table 3).
Conclusions
We have demonstrated that the easy-to-handle, air-stable Ni(II)
s-aryl complex 1 is an efficient precatalyst for the Suzuki–
Miyaura cross-coupling of aryl chlorides with arylboronic acids
in the absence of a reducing agent. This precatalyst works
wileyonlinelibrary.com/journal/aoc
Copyright © 2013 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2013, 27, 419–424

Ni-catalyzed Suzuki–Miyaura reactions of aryl chlorides
Precatalyst activation
(0.10 mmol) were added to a 25 ml three-neck round-bottom
flask equipped with a magnetic stirring bar, septum inlet and re-
flux condenser. The flask was evacuated and refilled with nitro-
gen flow, and this process was repeated three times. Aryl
chloride (if it is a liquid) (1.0 mmol) and degassed solvent (3 ml)
were added at this time via a syringe. The reaction mixture was
heated to the described temperature for the required time. After
the reaction cooled to room temperature, water (10 ml) was
added to the reaction mixture. The resulting mixture was
extracted with ethyl acetate (10 ml). The organic layer was dried
over anhydrous Na2SO4. The solvents were evaporated under re-
duced pressure and the residue was analyzed by GC or purified
by flash chromatography on silica gel with ethyl acetate–hexane
(0–20% of ethyl acetate in hexane) as the eluent. All isolated
products and side products were characterized by 1H and 13C
NMR spectra. The spectral data of known compounds are consis-
L
Ar1 Ni Cl
Reductive elimination
L
1
Ar'B(OH)2 + b-
Isolated side product
Ar-Cl
Ar-Ar'
6
Ar1-Ar'
Ni(0)L2
Oxidative
addition
L
L
Ar Ni L
Ar Ni Cl
Ar'
5
L
2
L
b-
Ar Ni b
-
b2B(OH)2
L
3
Cl-
b-
-
1
tent with those reported.[14,24,28,33–41,44–48] The H and 13C NMR
Ar'B(OH)2
Ar' B(OH)2
4
b
data of unknown side product 7 g are given below. Yields are
summarized in Tables 1–4.
Transmetalation
Figure 2. Catalytic cycle for the Ni-catalyzed cross-coupling of aryl chlo-
9-(40-Formylphenyl)phenanthrene (7 g)
rides with arylboronic acids (Ar1 = 9-phenanthrenyl, L = PPh3).
1
White solid. H NMR (400 MHz, CDCl3): d 10.14 (s, 1H, CHO), 8.80
(d, J = 8.3 Hz, 1H, H-5), 8.74 (d, J = 8.3 Hz, 1H, H-4), 8.04 (d,
J = 7.8 Hz, 2H, H-30, H-50), 7.91 (d, J = 7.7 Hz, 1H, H-8), 7.84 (d,
J = 8.3 Hz, 1H, H-1), 7.73 (d, J = 7.8 Hz, 2H, H-20, H-60), 7.70–7.68
(m, 3H, H-6, H-7, H-10), 7.64 (dd, J = 7.5, 7.4 Hz, 1H, H-3), 7.56
(dd, J = 7.8, 7.4 Hz, 1H, H-2). 13C NMR (101 MHz, CDCl3): d 192.00
(CΗΟ), 147.35 (C-10), 137.45 (C-40), 135.48 (C-9), 131.27 (C-11),
130.80 (C-8, C-10), 130.71 (C-13), 130.43 (C-14), 130.24 (C-12),
129.80 (C-30, C-50), 128.84 (C-1), 127.82 (C-2), 127.12 (C-7), 127.09
(C-6), 126.79 (C-20, C-60), 126.45 (C-3), 123.11 (C-5), 122.62 (C-4).
R
5'
4'
7a, R = H
6'
3'
7
7b, R = 2'-Me
7c, R = 4'-Me
7d, R = 4'-OMe
7e, R = 3',5'-F
7f, R = 4'-F
1' 2'
9
10
11
14
1
8
2
13
12
7g, R = 4'-CHO
3
4
5
6
Figure 3. Isolated side products.
Acknowledgments
efficiently for both electron-rich and electron-deficient aryl chlo-
rides. However, the presence of electron-withdrawing groups in
arylboronic acids resulted in poor yields under the optimized
conditions. The isolation and characterization of side products
confirmed the precatalyst activation process prior to the main
catalytic cycle.
We thank the Welch Foundation (V-004) and Lamar Research
Enhancement Grant for financial support.
References
[1] J.-P. Corbet, G. Mignani, Chem. Rev. 2006, 106, 2651.
[2] I. Cepanec, Synthesis of Biaryls, Elsevier, San Diego, CA, 2004.
[3] K. Muto, J. Yamaguchi, K. Itami, J. Am. Chem. Soc. 2012, 134, 169.
[4] L. J. Gooßen, G. Deng, L. M. Levy, Science 2006, 313, 662.
[5] C. C. C. J. Seechurn, M. O. Kitching, T. J. Colacot, V. Snieckus, Angew.
Chem. Int. Ed. 2012, 51, 5062.
[6] Z. Zhao, S. Chen, C. Y. K. Chan, J. W. Y. Lam, C. K. W. Jim, P. Lu, Z. Chang,
H. S. Kwok, H. Qiu, B. Z. Tang, Chem. Asian J. 2012, 7, 484.
[7] O. M. Yaghi, M. O’Keeffe, N. W. Ockwig, H. K. Chae, M. Eddaoudi, J. Kim,
Nature 2003, 423, 705.
[8] J. H. M. Sévignon, C. Gozzi, E. Schulz, M. Lemaire, Chem. Rev. 2002,
102, 1359.
[9] S. Saito, S. Oh-tani, N. Miyaura, J. Org. Chem. 1997, 62, 8024.
[10] M. Ueda, A. Saitoh, S. Oh-tani, N. Miyaura, Tetrahedron 1998, 54,
13079.
[11] V. V. Grushin, H. Alper, Chem. Rev. 1994, 94, 1047.
[12] N. E. Leadbeater, S. M. Resouly, Tetrahedron 1999, 55, 11889.
[13] W.-H. Sun, Z. Li, H. Hu, B. Wu, H. Yang, N. Zhu, X. Leng, H. Wang, New J.
Chem. 2002, 26, 1474.
[14] C. Chen, L.-M. Yang, Tetrahedron Lett. 2007, 48, 2427.
[15] S. Saito, M. Sakai, N. Miyaura, Tetrahedron Lett. 1996, 37, 2993.
[16] A. F. Indolese, Tetrahedron Lett. 1997, 38, 3513.
[17] K. Inada, N. Miyaura, Tetrahedron 2000, 56, 8657.
[18] V. Percec, G. M. Golding, J. Smidrkal, O. Weichold, J. Org. Chem. 2004,
69, 3447.
Experimental
Materials and Methods
Precatalyst 1 was prepared according to a literature method.[29]
Bases (Na2CO3, K2CO3, Cs2CO3 and K3PO4) were ground into pow-
der and dried under vacuum at 125 ꢀC for 4 h prior to use. THF
was distilled over Na–benzophenone. All other reagents and sol-
vents were purchased from commercial suppliers and used as re-
ceived. NMR spectra were recorded on a Bruker Avance 400 MHz
spectrometer using CDCl3 as the solvent and tetramethylsilane as
an internal standard. An Agilent 6890 N Network gas chromato-
graph, equipped with a capillary column (HP-5) and a thermal
conductivity detector, was used to assay the reaction yields for
the optimization of reaction conditions. All glassware was dried
in an oven at 120 ꢀC for 8 h and cooled under N2 atmosphere in
a desiccator before use.
General Procedure for the Suzuki Coupling Reactions
[19] B. M. Rosen, K. W. Quasdorf, D. A. Wilson, N. Zhang, A.-M. Resmerita,
N. K. Garg, V. Percec, Chem. Rev. 2011, 111, 1346.
Aryl chloride (if it is a solid) (1.0 mmol), arylboronic acid
(1.2 mmol), base (3.0 mmol), precatalyst 1 (0.05 mmol) and PPh3
[20] P. Leowanawat, N. Zhang, V. Percec, J. Org. Chem. 2012, 77, 1018.
Appl. Organometal. Chem. 2013, 27, 419–424
Copyright © 2013 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

X. Lei et al.
[21] N. Zhang, D. J. Hoffman, N. Gutsche, J. Gupta, V. Percec, J. Org. Chem.
2012, 77, 5956.
[22] T. Zell, M. Feierabend, B. Halfter, U. Radius, J. Organometallic, Chem.
2011, 696, 1380.
[23] H. Gao, Y. Li, Y.-G. Zhou, F.-S. Han, Y.-J. Lin, Adv. Synth. Catal. 2011,
353, 309.
[24] Y.-L. Zhao, Y. Li, S.-M. Li, Y.-G. Zhou, F.-Y. Sun, L.-X. Gao, F.-S. Han, Adv.
Synth. Catal. 2011, 353, 1543.
[35] Y. Ashikari, T. Nokami, Org. Lett. 2012, 14, 938.
[36] X. Chen, H. Ke, Y. Chen, C. Guan, G. Zou, J. Org. Chem. 2012, 77, 7572.
[37] X.-H. Fan, L.-M. Yang, Eur. J. Org. Chem. 2011, 1467.
[38] K. Tanimoro, M. Ueno, K. Takeda, M. Kirihata, S. Tanimori, J. Org.
Chem. 2012, 77, 7844.
[39] A. S. Demir, H. Findik, N. Saygili, N. T. Subasi, Tetrahedron 2010, 66,
1308.
[40] R. Ghosh, N. N. Adarsh, A. Sarkar, J. Org. Chem. 2010, 75, 5320.
[41] T. Tu, Z. Sun, W. Fang, M. Xu, Y. Zhou, Org. Lett. 2012, 14, 4250.
[42] Z. Li, S.-L. Zhang, Y. Fu, Q.-X. Guo, L. Liu, J. Am. Chem. Soc. 2009, 131,
8815.
[25] G.-J. Chen, F.-S. Han, Eur. J. Org. Chem. 2012, 3575.
[26] C.-H. Xing, J.-R. Lee, Z.-Y. Tang, J. R. Zheng, Q.-S. Hu, Adv. Synth. Catal.
2011, 353, 2051.
[27] X.-H. Fan, L.-M. Yang, Eur. J. Org. Chem. 2010, 2457.
[28] P. Leowanawat, N. Zhang, M. Safi, D. J. Hoffman, M. C. Fryberger,
A. George, V. Percec, J. Org. Chem. 2012, 77, 2885.
[29] X. Lei, K. A. Obregon, Acta Cryst. 2011, E67, m1272.
[30] V. Percec, J.-Y. Bae, M. Zhao, D. H. Hill, J. Org. Chem. 1995, 60, 176.
[31] W. Shen, Tetrahedron Lett. 1997, 38, 5575.
[32] R. S. Berman, J. K. Kochi, Inorg. Chem. 1980, 19, 248.
[33] D. Zim, V. R. Lando, J. Dupont, A. L. Monteiro, Org. Lett. 2001, 3, 3049.
[34] S. Vuoti, J. Autio, M. Haukka, J. Pursiainen, Inorg. Chim. Acta 2009,
362, 4685.
[43] K. W. Quasdorf, A. Antoft-Finch, P. Liu, A. L. Silberstein, A. Komaromi,
T. Blackburn, S. D. Ramgren, K. N. Houk, V. Snieckus, N. K. Garg, J. Am.
Chem. Soc. 2011, 133, 6352.
[44] Z.-Y. Wang, G.-Q. Chen, L.-X. Shao, J. Org. Chem. 2012, 77, 6608.
[45] Y.-L. Zhao, Y. Li, Y. Li, L.-X. Gao, F.-S. Han, Chem. Eur. J. 2010, 16, 4991.
[46] X. Wang, L. He, Y. He, J. Zhang, C.-Y. Su, Inorg. Chim. Acta 2009, 362,
3513.
[47] D. García-Cuadrado, P. d. Mendoza, A. A. C. Braga, F. Maseras, A. M.
Echavarren, J. Am. Chem. Soc. 2007, 129, 6880.
[48] K. Funaki, H. Kawai, T. Sato, S. Oi, Chem. Lett. 2011, 40, 1050.
wileyonlinelibrary.com/journal/aoc
Copyright © 2013 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2013, 27, 419–424