Electrochemical Arylation of Electron-Deficient Arenes through Reductive Activation

Article abstract of DOI:10.1002/anie.201909600

An electrochemical method has been developed to achieve arylation of electron-deficient arenes through reductive activation. Various electron-deficient arenes and aryldiazonium tetrafluoroborates are amenable to this transformation within the conditions of an undivided cell, providing the desired products in up to 92 % yield. Instead of preparing diazonium reagents, these reactions can begin from anilines, and they can be carried out in one pot. Electron paramagnetic resonance studies indicate that cathodic reduction of quinoxaline occurs using the transformation. Moreover, cyclic voltammetry indicates that both quinoxaline and aryl diazonium salt have relatively low reduction potentials, which suggests they can be activated through reduction during the reaction.

Full text of DOI:10.1002/anie.201909600

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Accepted Article
Title: Electrochemical Arylation of Electron-Deficient Arenes through
Reductive Activation
Authors: Pan Wang, Zhenlin Yang, Ziwei Wang, Chenyang Xu, Lei
Huang, Shengchun Wang, Heng Zhang, and Aiwen Lei
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201909600
Angew. Chem. 10.1002/ange.201909600
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10.1002/anie.201909600
Angewandte Chemie International Edition
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Electrochemical Arylation of Electron-Deficient Arenes through
Reductive Activation
Pan Wang,[a] Zhenlin Yang,[a] Ziwei Wang,[a] Chenyang Xu,[a] Lei Huang,[a] Shengchun Wang,[a] Heng
Zhang,*[a] and Aiwen Lei*[a]
Abstract: An electrochemical protocol has been developed to
achieve arylation of electron-deficient arenes through reductive
activation. Various electro-deficient arenes and aryl diazonium
tetrafluoroborate have been examined in this transformation under the
conditions of undivided cell, providing the desired products up to 92%
yield. Instead of preparing diazonium reagents, these reactions could
also be carried from anilines in a one-pot fashion. EPR studies
supported that the cathodic reduction of quinoxaline occurred in this
transformation. At the same time, cyclic voltammetry indicated that
both quinoxaline and aryl diazonium salt had relatively low reduction
potential, which suggested that they could be activated through
reduction in the reaction.
alternative strategy to achieve C-H functionalization of arenes is
to activate C-H bonds synergistically with electricity and transition
metals (Scheme 1b).[8] In these transformations, directing groups
are usually indispensable to achieve C-H activation. Alkylation,
acylation and amination of electron-deficient arenes through
radical addition process have been achieved.[9] Due to the high
oxidation potential, electron-deficient arenes are hard to be
oxidized at the anode. We speculate the possibility that electron-
deficient arenes could be reduced at the cathode to generate the
corresponding radical anion, which is undoubtedly a challenging
but environmentally friendly way to achieve direct C-H
functionalization of electron-deficient arenes. Herein, we would
like to communicate our progress on the electrochemical arylation
of electro-deficient arenes by cathodic reduction (Scheme 1c).
Electron-deficient arenes are one kind of the most important
components found in the structures of various functional
molecules (Scheme S1).[1] For example, these kind of structures
have shown pharmacologically potent in antibiotics and inhibitors.
Over the past years, many efforts have been paid to develop C-H
functionalization of electron-deficient arenes. C-H bond activation
through transition metal catalysis is a general method to achieve
functionalization of electron-deficient arenes.[2] Besides that,
radical addition is an alternative way to construct new chemical
bonds.[3] For example, the Minisci acylation and alkylation have
been recognized as efficient pathways to realize direct C-H
functionalization of electron-deficient N-heteroarenes.[4] Despite
the significance, transition-metal catalyst and external redox
reagents are necessary for most of the reported methods, which
would bring about environmentally deleterious wastes. Therefore,
Scheme 1. Electrochemical functionalization of arenes.
Initially, in the presence of strong acid, we tried to electrolyze
various electron-deficient N-heteroarenes in undivided cells. The
homocoupling product of quinoxaline was detected when no other
radical partner was added, which meant that the activation of
quinoxaline occurred in the electrolysis. On the other hand, aryl
diazonium salts are easily available arylation reagents which have
been used for organic electrochemistry.[10] We commenced our
study by using quinoxaline (1a) and 4-methylbenzenediazonium
tetrafluoroborate (2a) as model coupling substrates to optimize
the reaction conditions. Utilizing CH3CN and trifluoroacetic acid
(TFA) as the co-solvent, the arylation of quinoxaline could be
obtained with 85% yield under 10 mA constant current in 3 h
(Table 1, entry 1). The acid played a key role in this transformation.
Only 18% desired product could be obtained when the reaction
was carried out in the absence of TFA (Table 1, entry 2). Instead
of TFA, other acids were examined in this transformation. Both
TsOH and HCl were less efficient than TFA, while acetic acid
could not promote the reaction at all (Table 1, entry 3-5). The
reaction could be carried out in the absence of supporting
electrolyte as well in slightly decreased yield (Table 1, entry 6).
The reaction was less efficient when CH3CN was substituted with
MeOH or H2O (Table 1, entry 7-8). Although the same yield was
achieved in DMSO as in CH3CN, quite a lot of homocoupling
product of quinoxaline was detected (Table 1, entry 9). Other
it is desirable to develop
functionalization of electron-deficient arenes.
a new strategy to achieve
Utilizing traceless electrons as redox reagents, organic
electrochemistry is an efficient and highly selective tool for
constructing new chemical bonds.[5] Recently, many efforts have
been paid to develop electrochemical C-H functionalization of
arenes.[6] Anodic oxidation of arenes could furnish the
corresponding radical cations, which is a widely used strategy to
build C-C and C-X bonds (Scheme 1a).[5f, 6c, 7] But for this method,
various electron-rich arenes including naphthalenes, anisoles,
anilines, indoles, phenols, thiophenes and so on are always
employed as substrates due to their lower oxidation potential. An
[a]
P. Wang, Z. Yang, Z. Wang, C. Xu, L. Huang, S. Wang, H. Zhang,*
A. Lei*
Institute for Advanced Studies (IAS), College of Chemistry and
Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P.
R. China
Homepage: http://aiwenlei.whu.edu.cn/lawsys/
E-mail: hengzhang@whu.edu.cn; aiwenlei@whu.edu.cn
Prof. A. Lei
National Research Center for Carbohydrate Synthesis, Jiangxi
Normal University, Nanchang 330022, P. R. China
Supporting information for this article is given via a link at the end of
the document
This article is protected by copyright. All rights reserved.

10.1002/anie.201909600
Angewandte Chemie International Edition
COMMUNICATION
cheap cathodic materials were also evaluated. Using nickel as
cathode, a good yield was delivered in the electrochemical
transformation while both iron plate and carbon rod showed worse
reactivity compared with platinum plate cathode (Table, 10-12).
Replacing carbon rod with platinum plate as anode, a moderate
yield was furnished (Table 1, 13). No desired product could be
detected without electricity (Table 1, entry 14)
hindrance effect (3ba). Moreover, 5-methylquinoxaline and 6-
bromoquinoxaline were used to test the reactivity, the
corresponding desired products were delivered in a mixture of
isomers (3ca-3da). A decreased yield was furnished when
relatively electron-rich 6,7-dimethylquinoxaline was used (3ea). In
view of the good solubility in DMSO, a series of quinoxalinones
showed good reaction efficiency when they were applied in this
electrochemical arylation of electron-deficient arenes (3fa-3ha).
In addition, pyrazine derivatives were employed as substrates,
providing the corresponding desired products in moderate yields
Table 1. Optimizing conditions.a
(3ia-3ka). Moreover,
naphthyridine, pyridazine and quinoline derivatives could be
tolerated in this transformation (3la-3oa). 4-
Isoquinolinecarbonitrile furnished the desired arylation products
in 87% yield (3pa). It was noticeable that electron-deficient
benzene ring could also be tolerated under 15 mA constant
current for 3 h but with the concomitantly formed reduction side
product (3qa).
Other
N-heteroarenes such as
Entry
1
Variation from standard conditions
none
Yield (%)
82
2
3b
without TFA
18
TsOH instead of TFA
HCl instead TFA
65
4
35
5
AcOH instead of TFA
without nBu4NBF4
10
6
78
Table 2. Substrate Scope of Diazonium Salts.a
7
MeOH instead of CH3CN
H2O instead of MeCN
DMSO instead of CH3CN
carbon rod as cathode
Ni plate as cathode
Fe plate as cathode
Pt plate as anode
41
8
30
9
82
10
11
12
13
14
55
79
67
68
no electric current
n.d.
aStandard conditions: graphite rod anode (ф 6 mm), Pt plate cathode (15
mm×15 mm×0.3 mm), constant current = 10 mA, 1a (1.5 mmol), 2a (0.5 mmol),
nBu4NBF4 (0.5 mmol), CH3CN/TFA (5.0/0.5 mL), rt, 4.5 h, undivided cell (3.6 F).
b 5 equiv. TsOH was used.
With the optimized conditions in hand, many efforts have been
paid to explore the applicability of this transformation (Table 2).
Aryl diazonium tetrafluoroborate bearing substituents at the meta
or ortho position showed good reactivity in this transformation
(3aa-3ac). Electron-donating group such as methoxyl, tertiary
butyl and phenyl could also be tolerated in this electrochemical
reaction, providing the corresponding products in 56% to 86 yields
(3ad-3af). Halide substituents including F, Cl and I could all afford
the desired products in moderate yields (3ag-3aj). In addition,
phenyl diazonium tetrafluoroborate bearing electron-poor
substituents such as ester group and trifluoromethyl group at para
position were also suitable for this transformation in decreased
yields
(3ak-3al).
When
4-(N,N-diethylsulfamoyl)-2-
methoxybenzenediazonium tetrafluoroborate and 2-methoxy-4-
(phenylcarbamoyl)benzenediazonium tetrafluoroborate were
applied in this electrochemical transformation, good yields were
obtained in 48% to 77% (3am-3an). Ethynyl group could also be
tolerated and moderate yield was delivered (3ao). Moreover,
other aryl diazonium tetrafluoroborates were applied as
substrates to examine the reactivity. Naphthalene-2-diazonium
aStandard conditions: graphite rod anode (ф 6 mm), Pt plate cathode (15
mm×15 mm×0.3 mm), constant current = 10 mA, 1a (1.5 mmol), 2 (0.5 mmol),
nBu4NBF4 (0.5 mmol), CH3CN/TFA (5.0/0.5 mL), rt, 4.5 h, undivided cell (3.6 F),
isolated yield. b5 equiv. 1a was used.
tetrafluoroborate
and
9-ethyl-9H-carbazole-3-diazonium
Compared with the aryl diazonium tetrafluoroborate, anilines
were more stable and commercially available for organic
synthesis. Employing anilines as starting materials directly, it is
highly fulfilling to carry out in situ electrochemical arylation
reaction (Table 4). Anilines bearing electron-neutral group on
para or meta positon were well tolerated in this transformation
(3aa, 3ab, 3as, 3at). Generally, anilines with an electron-donating
group gave relatively high yields than electron-deficient aniline
(3ae, 3ak). To our delight, quinoxaline derivatives were also
tetrafluoroborate furnished the desired arylation products in 52%
and 75% yields, respectively (3ap-3aq). When 2-
(methoxycarbonyl)thiophene-3-diazonium tetrafluoroborate was
employed as substrate, a lower yield could be obtained (3ar).
At the same time, various electron-deficient arenes were
explored to examine the reactivity (Table 3). When quinoxaline
bearing substituents at C2 position was applied in this
transformation, moderate yield was obtained due to steric
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10.1002/anie.201909600
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COMMUNICATION
suitable for this one-pot method, providing the corresponding
Considering the price of platinum electrode, nickel plate was
employed as cathode. In the electrochemical flow cell, the
reaction with quinoxaline smoothly furnished the desired product
in 66% yield (Scheme 2a). At the same time, the reaction could
also be carried out in the absence of supporting electrolyte with a
slightly decreased yield (Scheme 2b). These results highlighted
the great potential of this electrochemical cross-coupling protocol
in practical synthesis.
products in 45% and 65% yields, respectively (3ba, 3fa).
Table 3. Substrate Scope of Electron Deficient Arenes.a
Next, we also did several control experiments to explore the
reaction mechanism. Simple quinoxalinone could resonate with 2-
hydroxyquinoxaline, which could be easily reduced to furnish the
corresponding radical anion. Employing the simple quinoxalinone
as substrate, a good yield was obtained (Scheme S2, c). Although
N-protected quinoxalinones were easy to undergo radical
addition,[9a, 11] no desired products were detected when they were
applied in this transformation. Moreover, the homocoupling
product of quinoxaline was detected in 67% yield in the absence
of diazonium salt, which proposed that quinoxaline could be
activated in the electrochemical condition (Scheme S2, d).
Scheme 2. Gram scale synthesis.
a
Standard conditions: graphite rod anode (ф 6 mm), Pt plate cathode (15
mm×15 mm×0.3 mm), constant current = 10 mA, 1a (1.5 mmol), 2 (0.5 mmol),
nBu4NBF4 (0.5 mmol), CH3CN/TFA (5.0/0.5 mL), rt, 4.5 h, undivided cell (3.6 F),
c
isolated yield. b DMSO instead of CH3CN was used as solvent. Product was
isolated as a mixture, since the starting materials was a mixture of isomers. d
5
equiv. 1 was added. e TsOH (2.5 mmol) instead of TFA was added. f15 mA, 60
oC, 3 h.
Table 4. Substrate Scope of Arylamine.a
Figure 1. EPR measurements of a solution in CH3CN/TFA of nBu4NBF4, under
constant current conditions for 30 min; a). 1a; b). 1a and 2a.
Furthermore, EPR experiments have been done to probe the
electrically generated radical species. Firstly, when the reaction
was carried out in the absence of diazonium salt for 30 min, an
EPR signal was detected (Figure 1a), which was identified as
quinoxaline radical anion (g=2.0040, 2 AN=6 G, 6 AH=6 G).[12] To
further identify the radical species of quinoxaline, we also did the
experiments in the divided cell. When quinoxaline was added to
the cathodic chamber, a similar EPR signal was obtained (Figure
S3, c, g=2.0040, 2 AN=6 G, 6 AH=6 G). On the contrary, no signal
could be detected when quinoxaline was added to the anodic
chamber (Figure S3, d). These results indicated that quinoxaline
could be reduced at cathode to generate the corresponding
radical anion. However, when 1a and 2a were added at the same
time, a different EPR signal was observed. The parameters
observed for the spin adduct are g=2.0039, 2 AN=6.3 G and 10
AH=3.16 G (Figure 1b). We proposed that this signal could be
ascribed to the aryl radical, which was generated through
t
a Standard conditions: aryl amine (0.5 mmol), BuONO (0.5 mmol), HBF4 (48
wt% in H2O, 0.1 mL), CH3CN (5 mL), 0 ºC -rt, 0.5 h; then 1a (2.5 mmol),
nBu4NBF4 (0.5 mmol), TFA (0.5 mL), graphite rod anode (ф 6 mm), Pt plate
cathode (15 mm×15 mm×0.3 mm), constant current = 10 mA, rt, 4.5 h, undivided
cell (3.6 F), isolated yield.
To further demonstrate the utility of this electrochemical
method, we carried out the scale-up reaction in 7 mmol scale.
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10.1002/anie.201909600
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oxidation of 2-(p-tolyl)-1,2-dihydroquinoxaline. The same AH also
meant the existence of aryl radical resonance contributors.
Previous work has reported that aryl diazonium salt was easy to
deliver aryl radical through cathodic reduction.[10a]
Based on the above experiment results, a plausible
mechanism between 1a and 2a was depicted in Scheme 3. Firstly,
quinoxaline or protonated quinoxaline was reduced to generate
the corresponding radical species. At the same time, 4-
methylbenzenediazonium tetrafluoroborate could also be reduced
at cathode to furnish the 4-methylphenyl radical. This radical
could react with quinoxaline radical or radical anion through
In addition, the cyclic voltammetry of 1a and 2a were also
carried out (see ESI, Fig. S2). An obvious reduction peak of 1a
was observed at -1.06 V (vs Ag/AgCl, the same below). A new
reduction peak came out at -0.34 V in the presence of TFA.
According to the computational results, the reduction potential of
protonated quinoxaline was calculated to be -0.38 V (see ESI).
Based on the above results, we speculated that the new reduction
peak at -0.34 V might be originated from the reduction of
protonated quinoxaline. Reduction peak of 2a was obtained at -
0.62 V[13] and no obvious change occurred after the addition of
TFA. DFT calculations suggested that both the radical addition
(between quinoxaline and 4-methylphenyl radical) and radical-
radical cross coupling (between quinoxaline radical anion and 4-
methylphenyl radical) were feasible pathways (see ESI, Fig. S5).
radical-radical
coupling
to
deliver
2-(p-tolyl)-1,2-
dihydroquinoxaline which could be oxidized at anode to generate
the resonant aryl radical. The generated radical subsequently
underwent the second single-electron-transfer (SET) oxidation
and deprotonation to deliver the desired product.
Next, the reaction was also carried out in constant voltage
mode to demonstrate the reactivity of substrates. When the
cathode potential was set at -0.1 V (vs. Ag/AgCl, the same below),
no desired product was yielded (Table 2, entry 1). At the same
time, we detected the formation of p-acetotoluidide (5a) which
was generated by cross-coupling between aryl diazonium salt and
acetonitrile.[14] Then the cathode potential was controlled to -0.3
V, both 3aa and 5a were detected (Table 2, entry 2). The yield of
desired product increased while p-acetotoluidide (5a) was
basically suppressed when the cathodic voltage was set from -0.6
V to -1.0 V (Table 2, entry 3-4). In addition, the homo-coupling of
quinoxaline (4aa) was obtained, which meant that the reduction
of quinoxaline occurred (Table 2, entry 3). These results indicated
that the desired product couldn’t be formed even though aryl
diazonium salt had been reduced (e.g. the formation of p-
acetotoluidide) at relatively positive reduction potential. With the
decrease of reductive voltage, 3aa could be detected, which
meant that the quinoxaline had been involved in the cross
coupling reaction through reductive activation. These series
experiments proposed that the reduction of both 1a and 2a was
indispensable for this reaction. In addition, preliminary kinetic
studies were also carried out to evaluate the effect of the
concentration of quinoxaline on reaction rate. The results
indicated that the initial reaction rates increased with the
increasing concentration of quinoxaline (see ESI, Fig. S4), which
suggested that the reduction of quinoxaline was likely to be the
rate-limiting step during electrolysis.
Scheme 3. Proposed mechanism.
In summary, an electrochemical arylation of electron-deficient
arenes through reductive activation have been developed.
Various aryl diazonium tetrafluoroborate and electron-deficient
arenes were compatible in this transformation. In addition, it is
efficient to perform the one pot electrochemical arylation reaction
with the in situ formed aryl diazonium salts when employing
anilines as starting material. Gram-scale experiments also
highlighted the synthetic practicability of this electrochemical
strategy. Mechanistically, EPR experiments, control experiments,
cyclic voltammetry experiments and DFT calculations indicated
reduction of quinoxaline was the key step to achieve this
transformation. More efforts will be paid to develop this
electrochemical method in our laboratory.
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (21520102003) and the Hubei Province
Natural Science Foundation of China (2017CFA010). The
Program of Introducing Talents of Discipline to Universities of
China (111 Program) is also appreciated. The numerical
calculations in this paper have been done on the supercomputing
system in the Supercomputing Center of Wuhan University. We
are grateful to the guidance and advice from Dr. Yi-Hung Chen in
this work.
Table 2. Constant voltage reaction.a
Entry
Voltage (V)
-0.1
Yield of 3aa (%)
Yield of 5a (%)
1
2
n.d.
28
27
42
-0.3
3
4b
-0.6
37
trace
n.d.
Keywords: Electrochemistry • arylation • cathodic reduction •
radical anion • cross coupling
-1.0
53
aStandard conditions: graphite rod anode (ф 6 mm), Pt plate cathode (15
mm×15 mm×0.3 mm), Ag/AgCl reference electrode, 1a (1.5 mmol), 2a (0.5
mmol), nBu4NBF4 (0.5 mmol), CH3CN/TFA (5.0/0.5 mL), rt, 16 h, undivided cell.
b1 h.
[1]
a) J. D. Bower, F. F. Stephens, D. G. Wibberley, J. Am. Chem. Soc. 1950,
3341-3344; b) P. Corona, A. Carta, M. Loriga, G. Vitale, G. Paglietti, Eur.
J. Med. Chem. 2009, 44, 1579-1591; c) A. Ivanov, S. Boldt, Z. u. Nisa, S.
This article is protected by copyright. All rights reserved.

10.1002/anie.201909600
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COMMUNICATION
J. Ali Shah, P. Ehlers, A. Villinger, G. Schneider, J. Wölfling, Q. Rahman,
J. Iqbal, P. Langer, RSC Adv. 2016, 6, 11118-11127; d) F. McCapra, A.
Burford, J. Chem. Soc., Chem. Commun. 1976, 607-608.
[2]
a) X. Cong, H. Tang, C. Wu, X. Zeng, Organometallics 2013, 32, 6565-
6575; b) W. J. Geldenhuys, S. R. Kuzenko, M. A. Simmons, J. Med.
Chem. 2010, 53, 8080-8088; c) F. Khan, M. Dlugosch, X. Liu, M. G.
Banwell, Acc. Chem. Res. 2018, 51, 1784-1795; d) X. Qin, H. Liu, D. Qin,
Q. Wu, J. You, D. Zhao, Q. Guo, X. Huang, J. Lan, Chem. Sci. 2013, 4,
1964-1969; e) D.-H. Wang, T.-S. Mei, J.-Q. Yu, J. Am. Chem. Soc. 2008,
130, 17676-17677; f) Y. Wei, W. Su, J. Am. Chem. Soc. 2010, 132,
16377-16379; g) D. Whitaker, J. Burés, I. Larrosa, J. Am. Chem. Soc.
2016, 138, 8384-8387; h) S. Zhang, L. Shi, Y. Ding, J. Am. Chem. Soc.
2011, 133, 20218-20229.
[3]
[4]
a) A. Hu, J.-J. Guo, H. Pan, Z. Zuo, Science 2018, 361, 668-672; b) P.
Liu, W. Liu, C.-J. Li, J. Am. Chem. Soc. 2017, 139, 14315-14321; c) D.
Xue, Z.-H. Jia, C.-J. Zhao, Y.-Y. Zhang, C. Wang, J. Xiao, Chem. Eur. J.
2014, 20, 2960-2965; d) J. Zhang, J. Chen, X. Zhang, X. Lei, J. Org.
Chem. 2014, 79, 10682-10688.
a) J. Dong, X. Lyu, Z. Wang, X. Wang, H. Song, Y. Liu, Q. Wang, Chem.
Sci. 2019, 10, 976-982; b) J. D. Galloway, D. N. Mai, R. D. Baxter, Org.
Lett. 2017, 19, 5772-5775; c) G.-X. Li, C. A. Morales-Rivera, Y. Wang, F.
Gao, G. He, P. Liu, G. Chen, Chem. Sci. 2016, 7, 6407-6412; d) S.
Mandal, T. Bera, G. Dubey, J. Saha, J. K. Laha, ACS Catal. 2018, 8,
5085-5144; e) L. Zhang, Z.-Q. Liu, Org. Lett. 2017, 19, 6594-6597.
a) E. J. Horn, B. R. Rosen, P. S. Baran, ACS Cent. Sci. 2016, 2, 302-
308; b) A. Jutand, Chem. Rev. 2008, 108, 2300-2347; c) K. D. Moeller,
Chem. Rev. 2018, 118, 4817-4833; d) J. E. Nutting, M. Rafiee, S. S. Stahl,
Chem. Rev. 2018, 118, 4834-4885; e) S. Tang, Y. Liu, A. Lei, Chem 2018,
4, 27-45; f) J. I. Yoshida, A. Shimizu, R. Hayashi, Chem. Rev. 2018, 118,
4702-4730.
[5]
[6]
[7]
a) Y. Jiang, K. Xu, C. Zeng, Chem. Rev. 2018, 118, 4485-4540; b) N.
Sauermann, T. H. Meyer, Y. Qiu, L. Ackermann, ACS Catal.2018, 8,
7086-7103; c) A. Wiebe, T. Gieshoff, S. Mohle, E. Rodrigo, M. Zirbes, S.
R. Waldvogel, Angew. Chem. Int. Ed. 2018, 57, 5594-5619; d) Y. Zhao,
W. Xia, Chem. Soc. Rev. 2018, 47, 2591-2608.
a) K. Liu, S. Tang, T. Wu, S. Wang, M. Zou, H. Cong, A. Lei, Nature
Commun. 2019, 10, 639; b) P. Wang, S. Tang, P. Huang, A. Lei, Angew.
Chem. Int. Ed. 2017, 56, 3009-3013; c) C. C. Zeng, D. W. Ping, L. M. Hu,
X. Q. Song, R. G. Zhong, Org. Biomol. Chem. 2010, 8, 2465-2472; d) R.
Hayashi, A. Shimizu, J.-i. Yoshida, J. Am. Chem. Soc. 2016, 138, 8400-
8403; e) A. Wiebe, D. Schollmeyer, K. M. Dyballa, R. Franke, S. R.
Waldvogel, Angew. Chem. Int. Ed. 2016, 55, 11801-11805.
[8]
[9]
a) J. Chen, S. Lv, S. Tian, ChemSusChem 2019, 12, 115-132; b) C. Ma,
P. Fang, T.-S. Mei, ACS Catal. 2018, 8, 7179-7189; c) N. Sauermann, T.
H. Meyer, Y. Qiu, L. Ackermann, ACS Catal. 2018, 7086-7103; d) S.
Tang, D. Wang, Y. Liu, L. Zeng, A. Lei, Nat Commun 2018, 9, 798.
a) K.-J. Li, K. Xu, Y.-G. Liu, C.-C. Zeng, B.-G. Sun, Adv. Synth. Catal.
2019, 361, 1033-1041; b) Q.-Q. Wang, K. Xu, Y.-Y. Jiang, Y.-G. Liu, B.-
G. Sun, C.-C. Zeng, Org. Lett. 2017, 19, 5517-5520; c) H. Yan, Z.-W.
Hou, H.-C. Xu, Angew. Chem. Int. Ed., 2019, 58, 4592 –4595.
[10] a) Q. Liu, B. Sun, Z. Liu, Y. Kao, B.-W. Dong, S.-D. Jiang, F. Li, G. Liu,
Y. Yang, F. Mo, Chem. Sci. 2018, 9, 8731-8737; b) F.-X. Felpin, S.
Sengupta, Chem. Soc. Rev. 2019, 48, 1150-1193.
[11] a) L. Wang, Y. Zhang, F. Li, X. Hao, H.-Y. Zhang, J. Zhao, Adv. Synth.
Catal. 2018, 360, 3969-3977; b) W. Wei, L. Wang, P. Bao, Y. Shao, H.
Yue, D. Yang, X. Yang, X. Zhao, H. Wang, Org. Lett. 2018, 20, 7125-
7130.
[12] a) B. J. Botter, D. C. Doetschman, J. Schmidt, J. H. van der Waals, Mol.
Phys. 1975, 30, 609-620; b) K. Lušpai, A. Staško, V. Lukeš, D.
Dvoranová, Z. Barbieriková, M. Bella, V. Milata, P. Rapta, V. J. J. o. S.
S. E. Brezová, J. Solid State Electrochem. 2015, 19, 113-122; c) J. S.
Vincent, J. Chem. Phys. 1970, 52, 3714-3717.
[13] P. Xiong, H. Long, J. Song, Y. Wang, J.-F. Li, H.-C. Xu, J. Am. Chem.
Soc. 2018, 140, 16387-16391.
[14] a) F. Mo, G. Dong, Y. Zhang, J. Wang, Org. Biomol. Chem. 2013, 11,
1582-1593; b) B. Xiong, G. Wang, T. Xiong, L. Wan, C. Zhou, Y. Liu, P.
Zhang, C. Yang, K. Tang, Tetrahedron Lett. 2018, 59, 3139-3142.
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10.1002/anie.201909600
Angewandte Chemie International Edition
COMMUNICATION
COMMUNICATION
P. Wang, Z. Yang, Z. Wang, C. Xu, L.
Huang, S. Wang, H. Zhang,* A. Lei*
Page No. – Page No.
Electrochemical Arylation of
Electron-Deficient Arenes through
Reductive Activation
An electrochemical protocol has been developed to achieve arylation of electron-deficient arenes through reductive activation. Various
electro-deficient arenes and aryl diazonium tetrafluoroborate have been examined in this transformation under the conditions of
undivided cell, providing the desired products with up to 92% yields. Mechanistically, EPR, control experiments, cyclic voltammetry
experiments and DFT calculations indicated reduction of quinoxaline was the key step to achieve this transformation.
This article is protected by copyright. All rights reserved.