Visible-Light-Assisted Cobalt-2-(hydroxyimino)-1-phenylpropan-1-one Complex Catalyzed Pd/Cu-Free Sonogashira–Hagihara Cross-Coupling Reaction

Article abstract of DOI:10.1002/cctc.201701253

An effective and inexpensive strategy for the Co(C₉H₉NO₂)₃ catalyzed Sonogashira–Hagihara cross-coupling reaction of aryl bromides containing electron-rich and electron-poor substituents with terminal alkynes wa

Full text of DOI:10.1002/cctc.201701253

Accepted Article
Title: Visible light-assisted cobalt-2-(hydroxyimino)-1-phenylpropan-1-
one complex catalyzed Pd/Cu-free Sonogashira-Hagihara cross-
coupling reaction
Authors: Jinyi Song, Xuan Zhou, He Song, Yang Liu, Hongyan Zhao,
Wenyi Chu, and Zhizhong Sun
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ChemCatChem
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Visible light-assisted cobalt-2-(hydroxyimino)-1-phenylpropan-1-
one complex catalyzed Pd/Cu-free Sonogashira-Hagihara cross-
coupling reaction
[a]
[a]
[a]
[a]
[a]
[a]
[a]
Jin-Yi Song, Xuan Zhou, He Song, Yang Liu, Hong-Yan Zhao, Zhi-Zhong Sun, and Wen-Yi Chu*
Abstract: An effective and inexpensive strategy for Co(C
9
H
9
NO
2
)
3
Furthermore, the straightforward approach avoids the
homocoupling reaction of aryl halides due to the high
temperature and other major side-effects in the cross-coupling
reaction.
complex catalyzed Sonogashira-Hagihara cross-coupling reaction of
aryl bromides containing electron-rich and electron-poor substituents
with terminal alkynes was demonstrated. The reaction proceeded
2 3
smoothly in the presence of ethylene glycol as additive, K CO as
Presently, transition metal complexes based on Au(III),[19-20]
Pt(II),[21] Pd(II)[22-23] and copper salts[24] have been utilized as
catalysts to initiate the cross-coupling reactions smoothly under
base in DMF under visible light illumination, and 23 alkynes products
were afforded in moderate to excellent yields, including four new
diaryl ethynes. Compared with the high-cost palladium catalyst,
cobalt as inexpensive catalyst with a preponderance of technologize
production, and the palladium/copper-free catalytic system not only the visible light. Nevertheless, these catalysts were expensive
provided an efficient process with mild reaction condition, but also
and required complicated synthesis process as well. So, the
enhanced the substrates of group tolerance.
researches focus on replacing them with developing an
inexpensive and easily available metal complex. Recent
orientation is concerned with employing Pd/Cu-free catalytic systems
Introduction
in Sonogashira-Hagihara cross-coupling reaction.[25-27] Cobalt-
Diaryl ethynes are important structual units in the fields of the
catalyzed couplings are of interest in organic synthesis, for cobalt is
synthesis of pharmaceuticals,[1-2] natural products,[3-4] organic
low-toxic, inexpensive, stable, and exhibits high catalytic activities.
luminescent materials[5-6] and biomolecules[7-8] etc. Palladium
There is an intensive focus on the cross coupling reactions that utilize
catalyzed Sonogashira-Hagihara cross-coupling reaction is proved to
be a more efficient approach to construct sp -sp compounds.[9-11] The
original catalytic system for Sonogashira coupling reactions include
the use of palladium catalyst and co-catalyst of copper(I) salt in the
protection of inert atmosphere.[12-13] However, the use of the
palladium systems is flawed in view of economic and environmental
factors owing to the high cost and toxicity of palladium. Furthermore,
using copper(I) salts may lead to the Glaser coupling of terminal
cobalt catalysts.[28-30] The reported Pd-Co catalysts with excellent
2
chemical stabilities would also go against the economic and
ecological principles. Therefore, it is necessary to seek an
appropriate cobalt catalyst to overcome these problems in
Sonogashira cross-coupling reaction. As reported by Oshima et al.[31]
,
2
NHC ligands/CoCl system could effectively catalyze cross-coupling
reaction in good yields.
alkynes.[14-15]
Therefore, improvements of catalysts or
methodologies for generating diaryl ethynes have gained significant
attention.
Currently, photocatalysis driven by visible light has emerged
as a mild and efficient catalytic way in the realm of organic
synthesis.[16-18] Compared with the conventional heating method,
the abundant visible light catalyzed reactions have obvious
advantages of clean, sustainability and environmentally benign.
9 9 2 3
Scheme 1. Synthesis of the Co(C H NO ) complex
Herein, in continuation of studies on the exploration of the N, O-
based ligand-mediated catalytic systems for cross-coupling
reactions, we report a simple and inexpensive strategy for visible
light-assisted Sonogashira-Hagihara coupling reactions using a new
cobalt complex as catalyst. The new Co(C
prepared by the reaction of Co(OAc) ·4H
hydroxyimino)-1-phenylpropan-1-one in EtOH at room
9
H
9
NO
2 3
) complex was
[a]
Department School of Chemistry and Materials Science
Key Laboratory of Chemical Engineering Process & Technology for
High efficiency Conversion
2
2
O with excessive 2-
(
Heilongjiang University, Harbin 150080, P. R. China.
Fax: +86-451-86609135.
temperature, and a reddish brown single crystal of the complex
was grown by diffusion of EtOH/n-hexane solvent system
E-mail: wenyichu@hlju.edu.cn
(Scheme 1). To date, Sonogashira coupling reactions only
employing cobalt complex as catalyst under visible light irradiation
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ChemCatChem
10.1002/cctc.201701253
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have not been previously reported. Under this catalytic system, the (DMF) at room temperature in the presence of ethylene glycol (EG)
Sonogashira-Hagihara coupling reactions of aryl bromides with as additive under visible light illumination, the reaction proceeded
alkynes could occur without using palladium and copper catalyst.
well and the yield of desired product could be achieved to 78%
Table 1, entry 4).
(
Table 1. Optimiazation of the Sonogashira-Hagihara cross-coupling reactionsa
Results and Discussion
between p-bromotoluene and phenylacetylene
The synthesized cobalt complex was characterized by X-ray
single crystal analysis. The ORTEP representation of the
Yieldb
(%)
Catal.
mol%)
Incident
light
Time
(h)
Entry
1
Base
Solvent Additive
(
9 9 2 3
molecular structure of Co(C H NO ) complex is presented in
Visible
Dark
45
CoCl
8.0)
2
K
2
CO
3
DMF
DMF
EG
EG
11.0
10.5
Figure 1, and the crystal data are listed in the Supporting
(
Trace
60
information. X-ray diffraction analysis demonstrated that the
Visible
Dark
Co(OAc)
8.0)
2
2
3
4
2 3
K CO
(
20
9 9 2 3
Co(C H NO ) complex was crystallized in monoclinic system
Visible
35
and space group P2(1)/c. The molecular structure of the
complex contains one Co atom and three 2-(hydroxyimino)-1-
phenylpropan-1-one (L) units, and the coordination sphere of
cobalt atom was completed by three oxime nitrogen (N1, N3 and
N2) atoms and three ketone oxygen (O1, O2 and O3) atoms.
The major objective in the paper is to validate that the new
cobalt complex as catalyst whether the Sonogashira cross-
coupling reaction could happen. To verify the catalytic activity of
cobalt complex catalyst in the Sonogashira-Hagihara cross
coupling reaction, the reaction of p-bromotoluene with
phenylacetylene was chosen as model system for exploration,
and the results were concluded in Table 1.
Co(NO
3 2
)
K
2
CO
3
DMF
DMF
EG
EG
10.5
10.5
(8.0)
Dark
Visible
Dark
Trace
78
Complex
8.0)
2 3
K CO
(
25
Complex
6.0)
Complex
4.0)
Complex
10.0)
Complex
8.0)
5
6
7
8
9
Visible
Visible
Visible
Visible
Visible
Visible
Visible
Visible
Visible
Visible
Visible
Visible
Visible
Visible
Visible
Visible
K
2
CO
CO
CO
3
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
EG
EG
EG
EG
EG
EG
EG
EG
EG
EG
EG
EG
EG
--
10.5
10.5
10.5
10.5
10.5
10.5
10.5
10.5
11.0
10.5
10.5
11.0
11.5
12.0
11.5
10.5
62
36
79
71
68
25
30
33
13
58
50
47
53
41
65
70
(
K
2
3
(
K
2
3
(
KOH
(
Complex
(8.0)
Complex
(8.0)
NaOH
1
0
1
3
Et N
Complex
1
Pyridine
EDA
(
8.0)
Complex
8.0)
Complex
8.0)
Complex
8.0)
Complex
8.0)
Complex
8.0)
Complex
8.0)
Complex
8.0)
Complex
8.0)
Complex
8.0)
12
(
13
14
15
16
17
18
19
20
K
2
CO
CO
CO
CO
CO
CO
CO
CO
3
2
H O
(
K
2
3
EtOH
(
K
2
3
2
CH CN
(
K
2
3
PhMe
DMF
DMF
DMF
DMF
(
K
2
3
(
K
2
3
(
K
2
3
3
CH OH
(
K
2
3
2 4
N H
(
[
a] Reaction conditions: p-bromotoluene (1.0 mmol, 1.0 equiv),
9 9 2 3
Figure 1. The molecular structure of Co(C H NO ) complex and H-atoms are
phenylacetylene (1.25 equiv), base (2.5 equiv), solvent (3 mL), additive (1.0
equiv), under air. Visible-light irradiation was proceeded from the side using a
omitted for clarity
The major objective in the paper is to validate that the novel
cobalt complex as catalyst whether the Sonogashira-Hagihara
cross-coupling reaction could happen. To verify the catalytic
activity of cobalt complex catalyst in the Sonogashira cross
coupling reaction, the reaction of p-bromotoluene with
phenylacetylene was chosen as model system for exploration,
5
00 W flament lamp (λ>400 nm). [b] Yield of isolated product.
9 9 2 3
The result illustrated that the Co(C H NO ) complex existed in
lower valent during the reaction process, and the stability of the
catalyst was good in the homogeneous reaction. Then, the other
condition parameters were also screened. Originally, in comparison
with equal cobalt catalysts, the reaction catalyzed by CoCl2,
and the results were concluded in Table 1. When Co(C
9
H
9
NO
2
)
3
Co(OAc)
2
or Co(NO
3
)
2
were clearly inferior to the remarkably
NO complex (Table 1, entries 1-4).
complex was selected as catalyst in the N,N-dimethylformamide
catalytic effect by Co(C
9
H
9
2 3
)
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ChemCatChem
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FULL PAPER
The visible light irradiation (λ>400 nm) significantly improved the bearing electron-donating substituents (-Me, -OMe) or electron-
catalytic activity compared to that under dark condition by withdrawing (-NO , -CN and -CHO) at the para-position could
employing the Co(C NO complex, and the highest yield
could exceed 78% (Table 1, entry 4). While the use of only pure
2
H
9 9
2
)
3
react smoothly with phenylacetylene to give the desire products
in moderate to excellent yields (Table 2, entries 2-6). A good
cobalt salts as catalysts exhibited poor activity, indicating that yield was also obtained in the coupling reaction of 1-
the addition of the ligand (L= 2-(hydroxyimino)-1-phenylpropan-
bromonaphthalene (81%, Table 2, entry 8).
1
-one) could promote the reaction. Then the influences of the
amounts of catalyst were selected. The results indiciated that
.0 mol% Co(C NO was conducive to the Sonogashira
Table 2. Visible light-enhanced Sonogashira-Hagihara cross-coupling
a
reactions of aryl bromides with terminal alkynes by using Co(C
9
H
9
NO
2
)
3
8
9
H
9
2 3
)
reaction process with a high yield. When reduced the catalyst
consumption to 4.0 mol%, only 36% yield of product was
detected (Table 1, entry 6). Increased the quantity of
b
Entry
R
1
R
2
Time (h)
8.0
No.
3a
3b
3c
3d
3e
3f
Yield (%)
82
1
2
3
4
5
6
7
8
9
H
C
C
C
C
C
C
C
C
C
6
6
6
6
6
6
6
6
6
H
H
H
H
H
H
H
H
H
5
5
5
5
5
5
5
5
5
9 9 2 3
Co(C H NO ) complex, the yield might be occured with small
4-Me
4-OMe
10.5
10.5
7.5
78
fluctuations (Table 1, entry 7). Bases have a momentous effect
on activation and transmetallation in the Sonogashira reaction.
When inorganic bases were added to the reaction system, the
yields were higher than 68% (Table 1, entries 4, 8-9). The
reaction was performed in the presence of organic bases, lower
than 35% yield was obtained (Table 1, entries 10-12). Inorganic
bases containing potassium were benefit for the reaction,
77
4-NO
2
85
4-CN
4-CHO
7.5
83
7.5
81
4-COCl
7.5
3g
3h
3i
75
1-Naphthalene
8.0
81
2-NO
H
2
16.5
11.0
12.5
13.0
9.0
68
10
4-EtC
6
H
4
4
4
4
4
4
4
4
4
3j
80
particularly K
2
CO
3
was more suitable for the reaction with a yield
11
12
4-Me
4-EtC H
3k
3l
75
6
of 78% (Table 1, entry 4). Solvents also play an increasingly
important part in the reaction, and the screening results revealed
that the product 1-methyl-4-(2-phenylethynyl)benzene could be
4-OMe
4-EtC
4-EtC
4-EtC
4-EtC
4-EtC
4-EtC
4-EtC
6
6
6
6
6
6
6
H
H
H
H
H
H
H
73
13
14
15
16
4-NO
2
3m
3n
3o
3p
3q
3r
82
4-CN
9.5
80
4-CHO
9.0
81
2
achieved in only 13% yield when used H O as solvent due to the
4-CH
1-Naphthalene
3, 4-(OBn)
2
CN
10.0
9.5
68
poor solubility of reactant (Table 1, entry 13). Also,
approximately 50% yield of desired product could be obtained
when the reaction was conducted in non-polar solvents(Table 1,
entries 15-16). However, when chosen DMF as solvent, the yield
could be up to 78% within 10.5 h (Table 1, entry 4). Surprisingly,
the promising result was observed that a little EG as additive
was added to the reaction would greatly promote the yield in
comparison with the reaction system in the presence of other
reductive additives (Table 1, entries 4, 18-20).
17
75
18
19
20
21
22
2
11.0
10.5
15.0
14.5
15.5
16.0
24.0
66
3, 5-(CF
H
3
)
2
4-Et-C
6
H
4
3s
3t
69
CH
CH
CH
CH
2
2
2
2
OH
OH
OH
OH
77
4-CN
3u
3v
3w
3x
80
4-CHO
4-Me
H
75
23
72
24
n-C
4
H
9
58
[
a] Reaction conditions: aryl bromides (1.0 mmol, 1.0 equiv), terminal alkynes
(
1.25 equiv), K CO (2.5 equiv), DMF (3 mL), EG (1.0 equiv), under air.
2
3
Visible-light irradiation was proceeded from the side using a 500 W flament
lamp (λ>400 nm). [b] Yield of isolated product.
The optimum Pd/Cu-free Sonogashira-Hagihara cross-
coupling reaction system was Co(C
9
9
H NO
2
)
3
as catalyst, K
2
CO
3
The effect of steric hindrance was also investigated. The
(
2.5 equiv), EG (1.0 equiv) as additive in the DMF (3 mL) in the
coupling
reaction
of
para-nitrobromobenzene
with
air under visible light illumination. Then the subsequent
reactions between different aryl bromides and terminal alkynes
were carried out to explore the group tolerance of substrates.
The results were shown in Table 2. The coupling reaction of
bromobenzen with phenylacetylene was efficiently completed in
phenylacetylene gave the corresponding diphenylacetylene in
85% yield (Table 2, entry 4). In contrast, ortho-
nitrobromobenzene with phenylacetylene gave a yield of 68%
due to the presence of the steric hindrance from ortho-position
(Table 2, entry 9). The cross-coupling reactions of both
phenylacetylene and 4-ethyl phenylacetylene were smoothly
proceeded (Table 2, entries 10-19), and the reactivity of aryl
9 9 2 3
the presence of Co(C H NO ) to obtain an excellent yield of
diphenylacetylene (82%, Table 2, entry 1). Aryl bromides
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ChemCatChem
10.1002/cctc.201701253
FULL PAPER
bromides adhering electron-withdrawing groups was also found
to be higher than those with electron-donating groups (Table 2,
entries 11-15). When chosen p-bromobenzyl cyanide and 1-
bromonaphthalene as substrates, the coupling reactions were
performed with medium yields in almost 10 h (Table 2, entries
9 9 2 3
in the Sonogashira reaction system. Co(C H NO ) complex as a
cobaloxime derivative is a useful radical precursor, and cobalt(Ⅲ)
intermediate (B) is obtained by the reaction of a preformed
cobalt(Ⅰ) complex (A) with an electrophile. Then, the light
emitted by flament lamp is sufficient to induce homolytic Co-R
bond cleavage and generate a cobalt(Ⅱ) complex (C) along with
the radical (D), which undergoes addition to phenylacetylene to
afford cobalt(Ⅲ) intermediate (E). The reductive elimination in
alkali condition in the presence of ethylene glycol produces the
target compound 1-methyl-4-(2-phenylethynyl)benzene and
regenerate the cobalt(Ⅰ) complex to resume the catalytic cycle.
16-17).
Remarkably, bromobenzene with multi-substituents involved
in the reaction, beyond 65% yield of products could be obtained
as well. Especially, 3,5-ditrifluoromethylbromobenzene coupled
with 4-ethyl phenylacetylene in 69% yield, which was better than
3,4-dibenzyloxybromobenzene as substrate (66%) (Table 2,
entries 18-19). When the less-reactive propargyl alcohol was
used as the substrate, the desired products were also obtained
in moderate yields (Table 2, entries 20-23). Particularly, p-
bromobenzonitrile (Table 2, entries 5, 14 and 21), p-
Conclusions
9 9 2 3
In summary, Co(C H NO ) complex as a new and efficient
nitrobromobenzene (Table 2, entries
4 and 13) and p-
catalyst for the visible light-assisted Pd/Cu-free Sonogashira-
Hagihara cross-coupling reactions in the presence of EG was
reported, where electron-rich and electron-poor functionalized
aryl bromides with terminal alkynes were catalyzed to afford the
corresponding products in moderate to high yields. The novel
bromobenzaldehyde (Table 2, entries 6, 15, 22) underwent the
reaction with terminal alkynes under the condition to afford
medium yields owning to electron-deficient aromatic ring. Aside
from propargyl alcohol, bromobenzene gave relative low yield
with aliphatic alkynes (58%, Table 2, entry 24). It is worth
emphasizing that four new diaryl ethynes products were
obtained under the efficient catalytic system (Table 2, entries
catalytic system could provide
a simple and inexpensive
condition for Sonogashira reaction proceeded and the
substrates had a good group tolerance. Therein, four new diaryl
ethynes products were isolated under the efficient catalytic
system.
16-19).
Experimental Section
All starting materials were purchased and used without further
purification. 1H NMR and 13C NMR spectra were recorded on a Bruker
3
DRX 400 MHz and 100 MHz spectrometer in CDCl or DMSO. Chemical
shifts were reported in ppm with tetramethylsilane (TMS) as internal
standard, and coupling constants (J) are reported in Hertz (Hz). High
resolution mass spectra were recorded on Agilent 1100 (VL) mass
spectrometer. Melting points were measured on a digital melting point
apparatus without correction. The experimental process was monitored
by thin layer chromatography (TLC), and column chromatography was
carried out on silica gel (200 ~ 300 mesh).
General procedure for Sonogashira-Hagihara Cross-Coupling
Scheme 2. Possible mechanism for visible light-assisted cobalt complex
catalyzed Sonogashira-Hagihara reaction
In 10 mL reaction flask was charged with aryl bromides (1.0 mmol, 1.0
Based on the previous literature reports,[32-38] a possible
equiv), alkyne (1.25 equiv), K
2 3 9 9 2 3
CO (2.5 equiv), Co(C H NO ) (8.0 mol %),
mechanism for the visible light-assisted Sonogashira-Hagihara
DMF (3 mL) and EG (1.0 equiv). The reaction mixture was stirred under
coupling reaction is hypothesized in Scheme 2. Firstly, cobalt(Ⅰ) visible light illumination and the reaction progress was monitored by TLC.
At the end of the reaction, the reaction mixture was poured into water
complex (A) is formed by the reduction of cobalt(Ⅱ/Ⅲ) complex
and the aqueous layer was extracted with ethyl acetate 4 times (4 × 5
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ChemCatChem
10.1002/cctc.201701253
FULL PAPER
mL), then the combined organic layer was dried over anhydrous sodium
sulfate. After filtration and removal of the solvent, the residue was
purified by column chromatography to obtain the pure products. The
characterizations of the synthesized alkynes products were all closed to
the authentic samples.
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6
) δ =
[15] K. S. Sindhu and G. Anilkumar, RSC adv. 2014, 4, 27867-27887.
[16] F. Wang, C. Li, H. Chen, R. Jiang, L.-D. Sun, Q. Li, J. Wang, J. C. Yu and
C. H. Yan, J. Am. Chem. Soc. 2013, 135, 5588-5601.
43.2, 136.6, 133.9, 133.3, 132.4, 131.7, 129.3, 129.0, 128.7, 128.6,
28.2, 127.4, 126.8, 126.4, 126.3, 126.1, 125.8, 28.2, 15.6. Anal. Calcd
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Zhu, Green Chem. 2014, 16, 4272-4285.
for (C20
H
16): C, 93.71; H, 6.29. Found: C, 93.78; H, 6.22. HRMS (EI)
+
calcd for C20
H
16 (M ): 256.1252; found: 256.1250.
[18] C. J. Wu, J. J. Zhong, Q. Y. Meng, T. Lei, X. W. Gao, C. H. Tung and L. Z.
Wu, Org. Lett. 2015, 17, 884-887.
{
[(4-((4-ethylphenyl)ethynyl)-1,2-phenylene)bis(oxy)
[
19] S. Kim, J. R. Martin and F. D. Toste, Chem. Sci. 2016, 7, 85-88.
20] A. T. Aca, M. N. Hopkinson, B. Sahoo and F. Glorius, Chem. Sci. 2016, 7,
89-93.
bis(methylene)}dibenzene (3r)
[
Yellow liquid; 1H NMR (400 MHz, CDCl
3
) δ = 7.51 – 7.28 (m, 15H), 7.13
[
21] J. J. Zhong, Q. Y. Meng, G. X. Wang, Q. Liu, B. Chen, K. Feng, C. H.
Tung and L. Z. Wu, Chem. Eur. J. 2013, 19, 6443-6450.
22] K. Mori, M. Kawashima and H. Yamashita, Chem. Commun. 2014, 50,
(
d, J = 1.9 Hz, 1H), 6.93 (t, J = 9.0 Hz, 1H), 5.29 – 5.07 (m, 4H), 2.97 (s,
1
1
1
9
H), 2.90 (s, 1H), 0.99 – 0.83 (m, 3H). 13C NMR (100 MHz, CDCl
) δ =
3
[
49.4, 148.7, 136.9, 131.5, 128.5, 128.5, 128.3, 128.0, 127.9, 127.3,
27.3, 127.2, 126.3, 125.6, 125.1, 117.8, 116.2, 115.3, 114.7, 113.3,
14501-14503.
[23] M. Osawa, H. Nagai and M. Akita, Dalton Trans. 2007, 8, 827-829.
[
[
[
[
24] S. E. Creutz, K. J. Lotito, G. C. Fu and J. C. Peters, Science 2012, 338,
3.9, 89.2, 71.1, 29.7, 14.1. Anal. Calcd for (C30
H
26
O
2
): C, 86.09; H, 6.26.
647-650.
+
Found: C, 86.11; H, 6.25. HRMS (EI) calcd for C30
found: 418.1935.
H
26
O
2
(M ): 418.1933;
25] A. R. Hajipour, E. Boostani and F. Mohammadsaleh, RSC Adv. 2015, 5,
94369-94374.
26] A. R. Hajipour, F. Rezaei and Z. Khorsandi, Green Chem. 2017, 19, 1353-
1
-[(4-ethylphenyl)ethynyl]-3,5-bis(trifluoromethyl)benzene (3s)
1361.
Yellow liquid; 1H NMR (400 MHz, CDCl
3
) δ = 8.38 (s, 1H), 8.25 (s, 1H),
27] X. X. Qi, L. B. Jiang and X. F. Wu, Tetrahedron Lett. 2016, 57, 1706-1710.
7
.70 (d, J = 6.6 Hz, 1H), 7.53 (d, J = 7.4 Hz, 1H), 7.18 (d, J = 7.7 Hz, 1H),
.09 (s, 1H), 6.81 (s, 1H), 6.57 (s, 1H), 2.42 (q, J = 7.6 Hz, 2H), 1.04 (q, J
7.5 Hz, 3H). 13C NMR (100 MHz, CDCl
) δ = 142.7, 133.0, 132.6, 131.7,
[28] M. Dabiri and M. P. Vajargahy, Appl. Organometal. Chem. 2017, 31,
e3549.
7
[
29] S. Pramanik, V. Bhalla and M. Kumar, Chem Commun. 2014, 50, 13533-
3536.
30] Y. S. Feng, X. Y. Lin, J. Hao and H. J. Xu, Tetrahedron 2014, 70, 5249-
=
3
1
1
30.9, 130.6, 130.1, 130.0, 129.5, 129.3, 128.8, 127.3, 127.2, 126.3,
25.8, 125.5, 123.7, 123.4, 121.0, 120.7, 119.8, 94.7, 86.1, 27.4, 14.4.
[
1
5253.
[
31] H. Someya, H. Ohmiya, H. Yorimitsu and K. Oshima, Org. Lett. 2007, 9,
Anal. Calcd for (C18
H
12
F
6
): C, 63.16; H, 3.53; F, 33.31. Found: C, 63.18;
1565-1567.
+
H, 3.55; F, 33.27. HRMS (EI) calcd for C18
42.0841.
H
12
F
6
(M ): 342.0843; found:
[32] T. Hatakeyama, S. Hashimoto, K. Ishizuka and M. Nakamura, J. Am.
3
Chem. Soc. 2009, 131, 11949-11963.
[
33] M. Karak, L. C. A. Barbosa and G. C. Hargaden, RSC adv. 2014, 4,
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[
[
[
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We are thanks to the financial support of Fund of Natural
Science Foundation with grant (No. B201207 and B201208)
of Heilongjiang Province of China.
3
592.
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[
[
9 9 2 3
Keywords: Co(C H NO ) complex • Sonogashira-Hagihara
3
cross-coupling reaction • visible light illumination • new diaryl
ethynes • inexpensive catalyst
38] M. E. Weiss, L. M. Kreis, A. Lauber and E. M. Carreira, Angrew. Chem. Int.
Ed. 2011, 50, 11125-11128.
This article is protected by copyright. All rights reserved.

ChemCatChem
10.1002/cctc.201701253
FULL PAPER
FULL PAPER
Jin-yi Song, Xuan Zhou, He Song,Yang
Liu, Hong-yan Zhao, Zhi-zhong Sun and
Wen-yi Chu*
Page No. – Page No.
Visible
light-assisted
cobalt-2-
9 9 2 3
Co(C H NO ) complex catalyzed Sonogashira-Hagihara cross-coupling reaction of
aryl bromides with terminal alkynes was demonstrated. Novel diaryl ethynes were
afforded in moderate yields under the mild system. Compared with the high-cost
palladium catalyst, cobalt as inexpensive catalyst with a preponderance of
technologize production, and the Pd/Cu-free catalytic system provided an efficient
process and enhanced the substrates of group tolerance.
(hydroxyimino)-1-phenylpropan-1-one
complex
catalyzed
Pd/Cu-free
cross-
Sonogashira-Hagihara
coupling reaction
This article is protected by copyright. All rights reserved.