Nickel-catalyzed cross-coupling reaction of alkynyl bromides with Grignard reagents

Article abstract of DOI:10.1016/j.cclet.2014.04.019

We describe a convenient method for the synthesis of 1,2-disubstituted acetylenes via a cross-coupling reaction of (bromoethynyl)benzene with Grignard reagents. The reaction of (bromoethynyl)benzene (1 mmol) with Grignard reagent (1.3 mmol) mediated by NiCl₂ (4 mol%) and (p-CH₃Ph)₃P (8 mol%) in THF could produce 1,2-disubstituted acetylenes in good yields at room temperature.

Full text of DOI:10.1016/j.cclet.2014.04.019

G Model
CCLET 2963 1–5
Chinese Chemical Letters xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
1
2
Original article
3
4
Nickel-catalyzed cross-coupling reaction of alkynyl bromides with
Grignard reagents
5
6
Q1 Qing Han Li *, Yong Ding, Xue Jun Yang
College of Chemistry and Environmental Protection Engineering, Southwest University for Nationalities, Chengdu 610041, China
A R T I C L E I N F O
A B S T R A C T
Article history:
We describe a convenient method for the synthesis of 1,2-disubstituted acetylenes via a cross-coupling
Received 31 January 2014
Received in revised form 3 April 2014
Accepted 4 April 2014
Available online xxx
reaction of (bromoethynyl)benzene with Grignard reagents. The reaction of (bromoethynyl)benzene
(1 mmol) with Grignard reagent (1.3 mmol) mediated by NiCl
2 3 3
(4 mol%) and (p-CH Ph) P (8 mol%) in
THF could produce 1,2-disubstituted acetylenes in good yields at room temperature.
ß 2014 Qing Han Li. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Keywords:
1
,2-Disubstituted acetylene
Nickel
Bromoethynyl)benzene
(
Grignard reagent
Cross-coupling
7
8
1. Introduction
Although the synthesis of 1,2-disubstituted alkynes by copper- 30
catalyzed cross-coupling of Grignard reagents with alkynyl 31
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
Nickel-catalyzed cross-coupling reactions represent a versatile
tool for the C–X (X = C, N, O, etc.) bond formation with aryl halides
and analogs [1–6]. The palladium mediated Sonogashira coupling
reaction [7] is one of the most widely used reactions in organic
synthesis [8–12] for the preparation of potential bioactive
compounds [13,14], new materials [15–17], and natural products
[18–20], but the same transformation catalyzed by nickel has not
been explored much. In the past decade, researchers have directed
their efforts toward the development of more efficient or single
metal catalyst systems with milder reaction conditions and other
desirable attributes [19–25]. While these efforts have provided
alternative methods for the synthesis of alkynes, the development
of rapid and more efficient procedures for the preparation of
alkynes by Sonogashira coupling still remains a challenge. Aryl
halides, especially aryl iodides and bromides, and alkynes are the
preferred coupling partners in these reactions. Particularly,
(bromoethynyl)benzene (1a), which is easily synthesized from
1-ethynylbenzene, has been studied in cross-coupling reactions
[26–29].
bromide has been described [33], the synthesis based on direct 32
coupling of alkynyl halide with Grignard reagents using nickel 33
catalysts has been rarely studied. Herein, we report a new method 34
for the synthesis of 1,2-disubstituted alkynes via Nickel-catalyzed 35
cross-couplings between (bromoethynyl)benzene (1a) and 36
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Grignard reagents in the presence of NiCl
CH Ph) P (8 mol%) at room temperature.
2
(4 mol%) and (p- 37
3
3
38
2. Experimental
39
1
13
H NMR and CNMR spectra were recorded on a Varian 40
00 MHz spectrometer. The chemical shifts are reported relative to 41
4
4
Me Si. Analytical thin-layer chromatography (TLC) was performed 42
on silica gel 60 F254 plates. Flash column chromatography was 43
carried out on silica gel (200–400 mesh). All reactions were carried 44
out under a nitrogen atmosphere. The starting material (bro- 45
moethynyl)benzene was prepared according to literature proce- 46
dures [34]. Chemical reagents and solvents were purchased from 47
Aldrich or Alfa Aesar, and were used without further purification 48
Grignard reagents are reactive nucleophilic reagents and can
easily be prepared from the corresponding halides [30–32].
with the exception of the following reagents: THF, Et
and toluene were distilled from sodium under nitrogen, and 50
dichloromethane was distilled from CaH . Mass spectra were 51
carried out on a Finnigan MAT-4510 spectrometer. 52
2
O, hexane 49
2
*
Corresponding author.
General procedure for cross-coupling of (bromoethynyl)ben- 53
zene with Grignard reagent: under an atmosphere of nitrogen, 54
E-mail address: lqhchem@163.com (Q.H. Li).
http://dx.doi.org/10.1016/j.cclet.2014.04.019
001-8417/ß 2014 Qing Han Li. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
1
Please cite this article in press as: Q.H. Li, et al., Nickel-catalyzed cross-coupling reaction of alkynyl bromides with Grignard reagents,
Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.04.019

G Model
CCLET 2963 1–5
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Q.H. Li et al. / Chinese Chemical Letters xxx (2014) xxx–xxx
Table 1
a
Effect of the nickel source and ligand on the cross-coupling reaction.
Nickel Salt (2 mol%)
MgBr
Ligand (4 mol%)
Br
+
r.t., 2 mL THF, 3 h
1a
2a
3
aa
b
Entry
Nickel salt (2 mol%)
–
Ligand (4 mol%)
Yield of 3aa (%)
1
2
3
4
5
6
7
8
9
–
0
72
78
68
75
77
73
66
78
67
82
77
77
78
74
66
NiCl
NiCl
2
2
–
PPh
PPh
PPh
PPh
PPh
PPh
3
3
3
3
3
3
NiBr
Ni(acac)
Ni(ClO
Ni(OAc)
Ni(NO
2
2
4 2
)
2
3 2
)
NiCl
NiCl
NiCl
NiCl
NiCl
NiCl
NiCl
NiCl
2
2
2
2
2
2
2
2
CH
3 2
Ph P
10
11
12
13
14
15
16
PCy
3
(p-CH
(o-CH
(C
3
Ph)
Ph)
3
P
P
3
3
6
F
5
)
3
P
(2-Furanly)
dppm
3
P
dppe
a
1
.0 mmol 1a, 1.3 mmol 2a, 2 mL THF, 3 h.
b
1
The yield of 3aa was determined by H NMR of the crude reaction mixture.
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
NiCl
2
(6.6 mg, 0.04 mmol), (p-CH
3
Ph)
3
P (0.08 mmol), and THF
1-Phenyl-2-(p-methoxyphenyl)acetylene (3af) [35]. White
95
96
97
98
1
(2 mL) were mixed in a Schlenk flask. Shortly afterwards, the
reaction mixture was cooled to 0 8C and a solution of ArylMgBr or
AlkylMgBr (1.3 mmol) was added with a syringe pump, and
subsequently the (bromoethynyl)benzene was added. After the
addition, the reaction mixture was allowed to stir for an additional
3–4 h at room temperature. After the completion of the reaction,
the reaction mixture was diluted with 1 mol/L aqueous HCl
solution (10 mL) and extracted with Et
combined organic layers were dried over anhydrous Na
filtered and evaporated in vacuo. The residue was subjected to flash
column chromatography on silica gel (hexane gradient) to afford
the corresponding products.
Diphenylacetylene (3aa) [35]. White solid, mp 60–61 8C (lit.
[35] 59–60 8C). H NMR (400 MHz, CDCl
7.36–7.33 (m, 6H); C NMR (100 MHz, CDCl
128.2, 123.4, 89.3; EI-MS (m/z): 178 (M ).
1-Phenyl-2-(o-tolyl)acetylene (3ab) [35]. Colorless oil. H NMR
(400 MHz, CDCl
7.14 (m, 3H), 2.52 (s, 3H); C NMR (100 MHz, CDCl
131.8, 131.5, 129.4, 128.3, 128.1, 125.6, 123.5, 123.0, 93.3, 88.3,
solid, mp 55–56 8C (lit. [35] 55 8C). H NMR (400 MHz, CDCl
3
):
d
7.53 –7.45 (m, 4H), 7.37–7.26 (m, 3H), 6.88 (d, 2H, J = 9.0 Hz), 3.82
1
3
(s, 3H); C NMR (100 MHz, CDCl
3
):
d
159.6, 133.0, 131.4, 128.3,
+
127.9, 123.6, 115.4, 114.0, 89.3, 88.0, 55.3; EI-MS (m/z): 208 (M ).
99
1-(3,5-Dimethylphenyl)-2-phenylacetylene (3ag) [35]. White
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
1
solid, mp 44–45 8C (lit. [35] 45 8C). H NMR (400 MHz, CDCl
3
):
d
7.55–7.43 (m, 2H), 7.36–7.27 (m, 3H), 7.30 (s, 2H), 7.15 (s, 1H), 2.28
1
3
2
O
(15 mL Â 3). The
SO
3
(s, 6H). C NMR (100 MHz, CDCl ): d 138.1, 132.3, 131.7, 129.3,
+
2
4
,
128.8, 128.4, 128.3, 128.3, 89.7, 89.1, 21.4; EI-MS (m/z): 206 (M ).
1-Phenyl-2-(p-chloro)acetylene (3ah) [35]. White solid, mp 82–
1
83 8C (lit. [35] 84 8C). H NMR (400 MHz, CDCl
3
):
d
7.54–7.51 (m,
13
2H), 7.47–7.45 (d 2H, J = 8.4 Hz,), 7.37–7.31 (m, 5H); C NMR
(100 MHz, CDCl ): 134.2, 132.8, 131.6, 128.6, 128.4, 128.0, 122.9,
121.7, 90.3, 88.2; EI-MS (m/z): 212 (M ).
3
d
1
+
3
):
d
7.56–7.52 (m, 4H),
13
3
):
d
131.2, 128.3,
1-Phenyl-2-(p-floro)acetylene (3ai) [35]. Pale yellow solid, mp
+
1
109–110 8C (lit. [35] 110 8C). H NMR (400 MHz, CDCl
3
):
d
7.60–
1
13
7.45 (m, 4H), 7.40–7.32 (m, 3H), 7.08–7.00 (m, 2H); C NMR
(100 MHz, CDCl ): 164.3, 161.0, 133.6 (d, J = 8.60 Hz), 131.7,
3
):
d
7.56–7.48 (m, 3H), 7.38–7.31 (m, 3H), 7.24–
3
d
13
3
):
d
140.2,
128.5 (d, J = 2.87 Hz), 123.2, 119.5, 115.7 (d, J = 21.5 Hz), 89.1, 88.4;
+
EI-MS (m/z): 196 (M ).
+
20.7; EI-MS (m/z): 192 (M ).
1
1-Phenyl-2-(m-tolyl)acetylene (3ac) [23]. Colorless oil.
NMR (400 MHz, CDCl ):
7.24 (t, 1H, J = 7.6 Hz), 7.06 (d, 1 H, J = 7.6 Hz), 2.35 (s, 3 H).
NMR (100 MHz, CDCl ): 138.1, 132.3, 131.7, 129.3, 128.8,
128.4, 128.3, 128.3, 121.7, 121.5, 89.7, 89.1, 21.4; EI-MS (m /z):
192 (M ).
1-Phenyl-2-(p-tolyl)acetylene (3ad) [23]. White solid, mp 70–
71 8C (lit. [23] 71–72 8C). H NMR (400 MHz, CDCl
(m, 2H), 7.43 (d, 2H, J = 8.1 Hz), 7.37–7.30 (m, 3H), 7.14 (d, 2H,
H
3
d 7.60–7.48 (m, 2H), 7.45–7.30 (m, 5H),
1
3
Table 2
C
Effect of the solvent and the molar ratio of NiCl
2
/(p-CH
3
Ph)
3
P on the cross-coupling
3
d
reaction.
a
+
Entry
NiCl
2
(mmol%)
(p-CH
3
Ph)
3
Solvent
DME
Yield of
b
P (mmol%)
3aa (%)
1
1
2
3
4
5
6
7
8
9
2
2
2
2
2
2
2
4
6
4
4
4
78
61
73
40
75
77
75
82
78
79
3
):
d
7.54–7.49
2
Et O
4
Hexane
Toluene
13
3
J = 8.1 Hz), 2.36 (s, 3H); C NMR (100 MHz, CDCl ): d 138.4, 131.5,
131.4, 129.1, 128.3, 128.0, 123.4, 120.1, 89.5, 88.7, 21.5; EI-MS (m/
z): 192 (M ).
4
4
2 2
CH Cl
+
2
THF
THF
THF
THF
THF
1
6
1-Phenyl-2-(m-methoxyphenyl)acetylene (3ae) [36]. H NMR
(400 MHz, CDCl
7.29 (m, 3H), 7.15 (d, 1H, J = 8.0 Hz), 7.08 (s, 1H), 6.90–6.92 (m, 1H),
3.84 (s, 1H); C NMR (100 MHz, CDCl
128.33, 128.28, 124.24, 124.16, 123.2, 116.3, 114.9, 89.3, 89.2,
55.3; EI-MS (m/z): 208 (M ).
8
3
): d 7.54–7.57 (m, 2H), 7.35–7.37 (m, 1H), 7.25–
12
8
c
10
13
3
):
d
159.3, 131.6, 129.4,
a
1
.0 mmol 1a, 1.3 mmol 2a, 2 mL THF, 3 h.
b
c
1
The yield of 3aa was determined by H NMR of the crude reaction mixture.
1.0 mmol 1a, 1.5 mmol 2a.
+
Please cite this article in press as: Q.H. Li, et al., Nickel-catalyzed cross-coupling reaction of alkynyl bromides with Grignard reagents,
Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.04.019

G Model
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Q.H. Li et al. / Chinese Chemical Letters xxx (2014) xxx–xxx
3
Table 3
a
NiCl
2
/p-CH
3 3
Ph P-catalyzed cross-coupling reaction of (bromoethynyl)benzene (1a) with Grignard reagent.
NiCl (4 mol%)
2
(
p-CH Ph) P (8 mol%)
3
3
Br
+
R
MgBr
R
r.t., 2 mL THF
1
a
2
3
b
Entry
1
Grignard reagent 2
Time (h)
3
Product 3
Yield (%)
MgBr
3ag
75
2
a
2
4
73
3
aa
2h
Cl
BrMg
3
4
3
3
71
72
2
3
b
3ah
2i
Cl
F
MgBr
ab
F
BrMg
5
6
MgBr
4
4
70
71
2
3
c
3ai
2j
ac
CF
3
BrMg
BrMg
7
8
4
3
70
73
2
3
d
3aj
2k
CF
3
BrMg
ad
SiMe
3
9
3
3
67
68
H CO
3
MgBr
3ak
2l
2
3
e
SiMe3
1
0
1
OCH
3
MgBr
ae
1
OCH3
4
81
2
f
3al
BrMg
BrMg
1
1
2
3
4
4
62
53
3
2
af
g
2
m
MgBr
4
OCH3
3am
a
1
.0 mmol 1a, 1.3 mmol 2a, 2 mL THF.
b
Isolated yield.
Please cite this article in press as: Q.H. Li, et al., Nickel-catalyzed cross-coupling reaction of alkynyl bromides with Grignard reagents,
Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.04.019

G Model
CCLET 2963 1–5
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Q.H. Li et al. / Chinese Chemical Letters xxx (2014) xxx–xxx
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
1-Phenyl-2-(p-trifloromethyl)acetylene (3aj) [37]. White solid,
1
mp 125–126 8C. H NMR (400 MHz, CDCl
3
):
7.55–7.59 (m, 2H), 7.36–7.39 (m, 3H); C NMR (100 MHz, CDCl
131.9, 131.8, 129.9 (J = 32.4 Hz), 128.9, 128.5, 127.1 (J = 1.4 Hz),
d
7.61–7.64 (m, 4H),
13
3
):
d
125.2 (J = 3.9 Hz), 123.9 (J = 270.1 Hz), 122.6, 91.8, 87.9; EI-MS (m/
+
z): 246 (M ).
1-Phenyl-2-(p-trimethylsilane)acetylene (3ak) [24]. White
1
solid, mp 119–121 8C. H NMR (400 MHz, CDCl
3
):
d
7.57–7.53
1
3
(m, 6H), 7.38–7.35 (m, 3H), 7.14 (d, 2H, J = 8.1 Hz), 2.36 (s, 3H);
NMR (100 MHz, CDCl ): 141.0, 133.2, 131.6, 130.6, 129.2, 128.4,
C
3
d
+
128.3, 123.5, 89.5, 88.7, 2.5; EI-MS (m/z): 250 (M ).
1
1-(1-Naphthyl)-2-phenylacetylene (3al) [24]. Colorless oil.
H
3
NMR (400 MHz, CDCl ): d 8.45 (d, 1H, J = 7.5 Hz), 7.85 (t, 2H,
J = 8.1 Hz), 7.77 (dd, 1H, J = 7.2 Hz, 1.2 Hz), 7.67–7.63 (m, 2H), 7.60
(dt, 1H, J = 6.9 Hz, 1.5 Hz), 7.53 (dt, 1H, J = 6.9 Hz, 1.5 Hz), 7.45 (dd,
13
1H, J = 8.4 Hz, 7.2 Hz), 7.43–7.35 (m, 3H); C NMR (100 MHz,
CDCl ): 133.3, 133.2, 131.7, 130.4, 128.8, 128.4, 128.3, 128.2,
3
d
126.8, 126.4, 126.2, 125.3, 123.4, 120.9, 94.3, 87.5; EI-MS (m/z):
+
228 (M ).
1
1-Phenyl-1-octyne (3am) [35]. Colorless oil. H NMR (400 MHz,
CDCl
3
): d 7.41–7.35 (m, 2H), 7.31–7.24 (m, 3H), 2.40 (t, 2H,
Fig. 1. Proposed reaction mechanism.
J = 7.04 Hz), 1.66–1.52 (m, 2H), 1.50–1.38 (m, 2H), 1.38–1.26 (m,
13
3
4H), 0.91 (t, 3H, J = 6.53 Hz). C NMR (100 MHz, CDCl ): d 131.6,
128.3, 127.5, 124.2, 90.6, 80.6, 31.5, 28.8, 28.7, 22.7, 19.5, 14.2; EI-
With the optimized conditions in hand, the scope of this
reaction was studied using various Grignard reagents. The alkynyl
halide 1a reacted smoothly with a series of aryl Grignard reagents
2 (a–m) at room temperature to give the corresponding products 3
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
+
MS (m/z): 186 (M ).
1
41
3. Results and discussion
(
aa–am) in moderate to good yields (Table 3, entries 1–13). As
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
Our initial studies used (bromoethynyl)benzene (1a) and
phenyl magnesium bromide (2a) as model substrates. Treatment
of 1a with the Grignard reagent (2a) in THF at ambient
temperature in the absence of metal and ligand did not give the
listed in Table 3, even with sterically hindered Grignard reagents
(Table 3, entries 2, 7, 12), the coupling reaction underwent
smoothly to give the products in moderate yields. The reaction was
not significantly affected by the substituents on the aromatic ring
of the Grignard reagent. Both electron-rich (Table 3, entries 2–7)
and electron-deficient substituents (Table 3, entries 8–10) were
tolerated. Notably, alkoxy, methyl, chloro, fluoro, trifluoromethyl,
and trimethylsilanyl groups posed no challenges under the
described reaction conditions. The reaction also worked well with
the alkyl Grignard reagents and gave moderate yields (Table 3,
entry 13).
2
1,2-diphenylethyne (3aa) (Table 1, entry 1). When NiCl was used
as the catalyst, the reaction of 1a with the Grignard reagent (2a)
produced the substituted alkyne (3aa) with a 72% conversion
(Table 1, entry 2). To our delight, when 2 mol% PPh
3
was used as the
ligand, the NiCl -catalyzed coupling of the substrates produced the
2
product 3aa in 78% conversion (Table 1, entry 3). To further
understand the nature of this catalysis, we tested the reaction of 1a
with 2a under various conditions and the results are listed in
Based on established nickel chemistry, we propose a mecha-
nism to account for the formation of products 3 (Fig. 1). The first
step is the oxidative addition of (bromoethynyl)benzene (1a) to
Tables 1 and 2. Thus, different nickel precursors such as NiBr
Ni(acac) , Ni(ClO , Ni(OAc) and Ni(NO were found effective to
catalyze the coupling (Table 1, entries 4–8). The catalyst of NiCl
PPh complex showed the highest capability of conversion (78%)
among metals/PPh combinations (Table 1, entry 3). The effect of
ligand in the generation of 3aa using NiCl as the catalyst was
investigated as shown in Table 1 (entries 9–16). The highest
conversion was obtained when (p-CH Ph) P was used (Table 1,
entry 11). Other ligands such as PPh , PCy , (C P, CH Ph P, (o-
CH Ph) P, (2-furanyl) P, dppm and dppe were less effective than
(p-CH Ph) P (Table 1, entries 3, 9–16).
2
,
2
4
)
2
2
3 2
)
2
/
2
Ni(0) phosphine complex (5) (which in turn from NiCl and
3
Grignard reagents) to form the organonickel(II) bromide interme-
diate (6). Transmetalation of aryl magnesium bromide with 6 gives
aryl-(alkenyl)nickel(II) intermediate (7) and MgBrX. Finally,
complex 7 undergoes reductive elimination to afford the desired
product 3 and regenerate the active Ni(0) species (5) for the next
catalytic cycle.
3
2
3
3
3
3
6
F
5
)
3
3
2
3
3
3
3
3
A brief examination of the influence of solvent on the yield of
the product 3aa revealed that THF was the solvent of choice. In
4. Conclusion
206
toluene, hexane, CH
efficient (Table 2, entries 1–5). The molar ratio of metal and ligand
was examined. It was found that a NiCl /(p-CH Ph) P ratio of 1.0/
2
Cl
2
, DME or Et
2
O, the conversion was less
We have developed an improved procedure for the nickel-
catalyzed cross-couplings of (bromoethynyl)benzene with
Grignard reagents and demonstrated that this methodology is a
simple and efficient method for the preparation of 1,2-disubsti-
207
208
209
210
211
212
213
214
215
216
217
218
219
2
3
3
2.0 gave the product 3aa in an optimal conversion of 82% (Table 2,
entry 8). Further studies indicated that the catalyst loading
dramatically influenced the conversion of the product 3aa. It was
2
tuted acetylenes. In the presence of NiCl (4 mol%)/8 mol% (p-
CH Ph) P, (bromoethynyl)benzene reacts smoothly with 1.3 equiv.
3
3
found that the most favorable catalyst loading is 4 mol% NiCl
8 mol% (p-CH Ph) P (Table 2, entry 8). However, when the amount
2
/
of aryl or alkyl Grignard reagents in THF at room temperature to
generate the corresponding cross-coupled products in moderate to
good yields. This coupling reaction is compatible with a wide range
of functional groups. Notably, no other co-catalysts are necessary
in the present procedure. Further applications of these 1,2-
disubstituted acetylenes in organic synthesis are being investigat-
ed.
3
3
of the 2a was increased, the conversion of the product 3aa was
decreased (Table 2, entry 10). Extensive screening showed that the
optimized coupling conditions were 4 mol% NiCl
CH Ph) P, 1.0 mmol 1a, 1.3 mmol 2a in THF at room temperature
(Table 2, entry 8).
2
/8 mol% (p-
3
3
Please cite this article in press as: Q.H. Li, et al., Nickel-catalyzed cross-coupling reaction of alkynyl bromides with Grignard reagents,
Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.04.019

G Model
CCLET 2963 1–5
Q.H. Li et al. / Chinese Chemical Letters xxx (2014) xxx–xxx
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[
2
(PPh
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This work was financially supported by the Fundamental
Research Funds for the Central Universities, Southwest University
for Nationalities (No. 12NZYTH03), and the Natural Science
Foundation of Southwest University for Nationalities (No.
381010), and the Project of Postgraduate Degree Construction,
Southwest University for Nationalities (No. 2013XWD-S0703), and
the State Administration of Foreign Experts Affairs project (No.
2012-10).
[
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Please cite this article in press as: Q.H. Li, et al., Nickel-catalyzed cross-coupling reaction of alkynyl bromides with Grignard reagents,
Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.04.019