Light-Promoted C–N Coupling of Aryl Halides with Nitroarenes

Article abstract of DOI:10.1002/anie.202012877

A photochemical C–N coupling of aryl halides with nitroarenes is demonstrated for the first time. Catalyzed by a Ni^II complex in the absence of any external photosensitizer, readily available nitroarenes undergo coupling with a variety of aryl halides, providing a step-economic extension to the widely used Buchwald–Hartwig C–N coupling reaction. The method tolerates coupling partners with steric-congestion and functional groups sensitive to bases and nucleophiles. Mechanistic studies suggest that the reaction proceeds via the addition of an aryl radical, generated from a Ni^I/Ni^III cycle, to a nitrosoarene intermediate.

Full text of DOI:10.1002/anie.202012877

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Light-Promoted C-N Coupling of Aryl Halides with Nitroarenes
Authors: Dong Xue, Gang Li, Liu Yang, Jian-Jun Liu, Wei Zhang, Rui
Cao, Chao Wang, Zunting Zhang, and Jianliang Xiao
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.202012877
Link to VoR: https://doi.org/10.1002/anie.202012877

10.1002/anie.202012877
Angewandte Chemie International Edition
COMMUNICATION
Light-Promoted C-N Coupling of Aryl Halides with Nitroarenes
Gang Li,[a] Liu Yang,[a] Jian-Jun Liu,[a] Wei Zhang,[a] Rui Cao,[a] Chao Wang,[a] Zunting Zhang,[a]
Jianliang Xiao, [b] and Dong Xue*[a]
Abstract: A photochemical C-N coupling of aryl halides with
nitroarenes is demonstrated for the first time. Catalyzed by a Ni(II)
complex in the absence of any external photosensitizer, readily
available nitroarenes undergo coupling with a variety of aryl halides,
providing a step-economic extension to the widely used Buchwald-
Hartwig C-N coupling reaction. The method tolerates coupling
partners with steric-congestion and functional groups sensitive to
bases and nucleophiles. Mechanistic studies suggest that the reaction
proceeds via the addition of an aryl radical, generated from a Ni (I)/Ni
(III) cycle, to a nitrosoarene intermediate.
The palladium-catalyzed Buchwald-Hartwig amination of aryl
halides[1] and copper-catalyzed Ullmann coupling[2] have emerged
as one of the most widely utilized reactions in modern organic
chemistry, with the former ranked amongst one of the 20 most
frequently used reactions in medicinal chemistry.[3] Since the first
report in the 1950s,[4] the nickel-catalyzed C-N coupling of aryl
Scheme 1. Methodologies for the formation of aryl C-N bonds.
halides with amines has been significantly improved (Scheme 1,
a).[5-6] In particular, the last a few years have witnessed the advent
acids are usually derived from the corresponding halides. Herein,
of
elegant
ligand-control,[7]
photochemical,[8]
and
we report a photochemical C-N coupling of aryl halides with
nitroarenes catalyzed by a Ni (II)-aryl complex using a mild
organic base, N,N-diisopropylethylamine (DIPEA) (Scheme 1, c).
Starting from readily available nitroarenes as the nitrogen source
and abundant aryl halides as the aryl source, this transformation
provides a step-economic strategy for furthering the widely used
Buchwald-Hartwig C-N coupling reaction.
electrochemical[9] strategies, greatly improving the efficacy and
scope of the Ni-catalyzed C-N cross coupling. Whilst these
seminal works provide innovative ideas for further developing the
Ni-catalyzed C-N coupling, all the thus-far reported amination
reactions employ amines, especially anilines,[10] as the nitrogen
source, which are usually obtained by reduction of nitroarenes.
The same is true with the regime of Pd and Cu catalysis. Could
the nitroarenes be used as the nitrogen source instead? The
ability to do so would widen the applicability of the C-N coupling,
circumventing the need for the step of reduction of nitroarenes to
amines while potentially improving the compatibility of functional
groups in the coupling.
Nitroarenes are commercially widely available and are easily
prepared building blocks in organic chemistry.[11] Since the early
report on nucleophilic C-N addition of aryl magnesium reagents to
nitroarenes by the Knochel group,[12] the following pioneering
studies from the Baran[13] and Hu[14] groups have successfully
demonstrated that nitroarenes are valuable precursor to anilines
in organic synthesis. [15] Of particular note is the recent seminal
work on organophosphorus[16] and molybdenum[17] catalyzed
coupling of nitroarenes with boronic acids, which provides a new,
effective process for the C-N bond formation (Scheme 1, b).
However, there has been no report on the more economic, direct
amination of aryl halides with nitroarenes. Note that aryl boronic
In our initial study, we discovered that a series of Ni complexes
could catalyze the cross-coupling of 4-nitroanisole (1) with 4-
bromobenzoate (2) under the irradiation of long-wave UV light
(390-395 nm, purple LEDs) in the absence of any external
photocatalyst. Notably, among all the surveyed Ni catalysts, the
air-stable Ni-aryl complex A[18] afforded the best product yield
(Table 1, entries 1-4). Light plays a crucial role in the reaction,
with only the long-wave UV light affording high product yields
(Table 1, entries 5–8). The choice of base also impacted the
success of this reaction. Among the examined bases, DIPEA
promoted the reaction significantly better than other organic
amines (Table S1). This is delighting, as a mild organic base
would enhance the compatibility of the reaction, as has been
advocated in recent years.[7, 19] The subsequent investigation of
solvent effect showed that toluene is the best solvent for this
coupling reaction (Table S2). Further studies on the effects of
additives and substrate concentration led to the optimized
conditions (Table S3). Under the irradiation of long-wave UV light,
with the Ni complex A as the catalyst, DIPEA as base and 4Å MS
as the additive, the desired product 3 was obtained with 75%
isolated yield at 70 oC for 12 h in toluene (4 mL) under argon. As
revealed by the control experiments, the reaction did not proceed
in the absence of nickel catalyst, light, or base (Table 1, entries 9-
11, Table S6).
[a]
Dr. G. Li, L. Yang, J.-J. Liu, Prof. Dr. W. Zhang, Prof. Dr. R. Cao, Prof.
Dr. C. Wang, Prof. Dr. Z. Zhang, Prof. Dr. D. Xue
Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of
Education and School of Chemistry and Chemical Engineering,
Shaanxi Normal University, Xi’an, 710062 (China),
E-mail: xuedong_welcome@snnu.edu.cn
[b]
Prof. Dr. J. Xiao
With the optimized reaction conditions in hands, the scope of
nitroarenes and aryl halides for nitro version of the Buchwald-
Hartwig C-N coupling reaction was investigated. First, the scope
Department of Chemistry
University of Liverpool, Liverpool, L69 7ZD, (UK)
1
This article is protected by copyright. All rights reserved.

10.1002/anie.202012877
Angewandte Chemie International Edition
COMMUNICATION
Table 1. Optimization of amination of aryl bromide with nitroarene.[a]
Entry
1
Variation from standard conditions
Yield (%)[b]
Standard conditions
75
74
54
16
16
0
2
Standard conditions, Ni(COD)2-dtbbpy as catalyst
Standard conditions, NiBr2(glyme)-dtbbpy as catalyst
Standard conditions, NiBr2-dtbbpy as catalyst
Standard conditions, UV (360-365 nm)
Standard conditions, blue LEDs (460-465 nm)
Standard conditions, white LEDs
3
4
5
6
7
0
8
Standard conditions, green LEDs (530-535 nm)
Standard conditions, no light, heating to 70 oC
Standard conditions, no Ni catalyst
0
9
0
10
11
0
Standard conditions, no base
0
[a] Standard conditions: 1 (0.2 mmol), 2 (0.4 mmol, 2.0 equiv), DIPEA (3.0
equiv), toluene (4.0 mL), 4Å MS (80 mg), 390-395 nm LEDs irradiation, 12 h,
Ar. [b] Isolated yield. DIPEA = N,N-diisopropylethylamine.
of nitroarenes was explored. As shown in Scheme 2, the electron-
donating (3-7) and electron-neutral (8-10) nitroarenes worked well
in coupling with 4-bromobenzoate, affording the desired products
with good to excellent yields. In addition, a nitroarene with a
pyrazolo substituent and polycyclic nitroarenes were also
compatible substrates (7, 12, 13). Notably, nitroarenes bearing
halogen could tolerate this reaction, giving the corresponding
halogen-substituted product (14, 15, 18), albeit at a higher
catalyst loading (15 mol%). Disubstituted nitroarenes also worked
successfully with this protocol (16-18), showcasing the wide
scope of nitroarenes in this C-N coupling reaction. In particular, it
is noted that nitroarenes with substitutes at the ortho position
successfully delivered the desired diarylamines with high yields
(19-25), revealing the good adaptability of the protocol to steric
hindrance of substrates. Furthermore, this Ni-catalyzed C-N
coupling reaction provides a convenient method for the synthesis
of chiral ligands useful in asymmetric catalysis (13) and a step-
economy route for the efficient synthesis of key intermediates of
carbazole alkaloids (19-25).[20] However, nitroarenes with
electron-withdrawing groups, such as -CO2Me and -CN, could not
provide the desired diarylamines.[21]
Next, a wide range of aryl halides were examined. As
summarized in Scheme 3, aryl bromides bearing electron-
withdrawing substituents, such as -CO2Me, -Ac, -CHO, -COPh, -
F, -Cl, -Br, -CF3, -OCF3 and -CN in the para or meta position were
employed, and they delivered the desired products with good to
excellent yields (26-34, 38-42). These important functional groups
provide the possibility for subsequent transformations. It is worth
noting that all the ester and cyano-containing electrophiles are
compatible in this protocol due to the use of a weak amine base.
This contrasts with the formation of transesterification products
and impurities in traditional coupling reactions where strong
bases are common place.[22] As in the case of nitroarenes, for the
ortho-substituted aryl bromides, the C-N coupling product was
Scheme 2. Scope of nitroarenes. Isolated yields are shown. [a] Ni complex A
(15 mol%).
obtained with moderate yield (43), again showcasing the good
adaptability to steric hindrance in substrates. The disubstituted
aryl bromides bearing either electron-donating or withdrawing
groups were well tolerated (44-49). In general, electron-deficient
aryl halides exhibit higher reaction efficiency in this reaction,
somewhat compensating the lack of reactivity of electron-deficient
nitroaromatics, while providing a new synthetic strategy for the
preparation of this type of diarylamines.
Notably, as shown in Scheme 3, cheaper but more challenging
aryl chlorides are also suitable for this reaction. Aryl chlorides
containing ester (3) ketone (26, 28, 54-57) or nitrile (34) units
afforded the desired products with good yields. Of particular note
is that Fenofibrate, a biologically relevant and more complex
substrate, is also tolerated in this transformation, yielding the
amination products with nitroarenes containing substitutes in the
para or ortho position (54-57).
To further investigate the potential application of this protocol
in synthetic chemistry, the synthesis of a key precursor to
koenoline derivative 58, a methyl ester of a known natural product,
was explored at gram scale. As shown in Scheme 4, the desired
diarylamine (24) was obtained with 48% isolated yield; by
extending the reaction time to 24 h. The following known
cyclization of the diarylamine intermediate led to the formation of
58. Using commercially available nitroarene as staring material,
this protocol avoids the challenging reduction of nitroarenes to
aromatic amine, providing a green and effective process for the
synthesis of 58.[20]
To gain understanding of the reaction mechanism, a series of
probing experiments were carried out. Firstly, when 2, 2, 6, 6-
2
This article is protected by copyright. All rights reserved.

10.1002/anie.202012877
Angewandte Chemie International Edition
COMMUNICATION
tetramethyl-1-piperidinyloxy (TEMPO) was added to the reaction
under the standard conditions, no desired diarylamine product 3
was obtained, suggesting that this C-N coupling may undergo a
radical pathway (Scheme 5, 1). We next searched for possible
intermediates. Inspired by Hu’s reports,[14] we studied the
reactions between five possibly existing intermediates in the
reduction of nitroarenes with two equivalents of Ni complex A.
Notably, only the nitroso compound could afford the desired
diarylamine 43 in 72% isolated yield along with the generation of
o-dimethylbiphenyl (Scheme 5, 2b). In addition, the following
reaction of Ni complex B with p-nitrosoanisole also delivered the
diarylamine 3 in 82% yield under the irradiation of light (Scheme
5, 3), which supports the nitroso compound to be a possible
intermediate in this light-promoted C-N coupling,[23] while
indicating that Ni(II) species are inactive without light irradiation.
Considering the recent, studies of the photochemistry of Ni(II)-
[18c]
aryl complex by Doyle,[18a-b] Scholes
and our group,[18e] the
results gave us a hint that aryl radicals and Ni(I) species,
generated in situ under the irradiation of light, could be key
intermediates or active catalyst species for this C-N coupling.
Therefore, we next studied the oxidative addition of Ni(I) complex
with aryl halide and the following reaction with a nitrosoanisole. In
the absence of substrates, the Ni (II) complex A was irradiated
under the purple light for 60 min, which was expected to generate
a Ni(I) complex. Then the irradiation was stopped, and the aryl
substrate was added to the mixture. The subsequent, expected
Scheme 3. Scope of aryl halides. Isolated yields are shown. [a] Ni complex A
(15 mol%).
Scheme 5. Preliminary mechanistic studies. [a] The yield of biphenyl was
determined by 1H NMR (parenthesises). [b] Isolated yield of biphenyl
(parenthesises).
Scheme 4. Gram-scale nitro C-N coupling.
3
This article is protected by copyright. All rights reserved.

10.1002/anie.202012877
Angewandte Chemie International Edition
COMMUNICATION
M. Kudisch, C.-H. Lim, P. Thordarson, G. M. Miyake, J. Am. Chem. Soc.
2019, 141, 19479-19486.
oxidative addition reaction was run for 60 min in the dark.
Following addition of nitrosoanisole to the reaction solution and
stirring for 12 h without irradiation, the corresponding diarylamine
was obtained with 51% yield (Scheme 5, 4). These results support
a sequence involving oxidative addition of aryl halides to a photo-
generated Ni(I). Next, the formation of aryl radicals was probed.
[9] C. Li, Y. Kawamata, H. Nakamura, J. C. Vantourout, Z. Liu, Q. Hou, D. Bao,
J. T. Starr, J. Chen, M. Yan, P. S. Baran, Angew. Chem. Int. Ed. 2017, 56,
13088-13093; Angew. Chem. 2017, 131, 6457-6461.
[10] For nickel-catalyzed coupling of aryl halides with anilines, see: a) K.
Matsubara, K. Ueno, Y. Koga, K. Hara, J. Org. Chem. 2007, 72, 5069-
5076; b) C. Chen, L.-M. Yang, J. Org. Chem. 2007, 72, 6324-6327; c) C.
M. Lavoie, P. M. MacQueen, N. L. Rotta-Loria, R. S.Sawatzky, A.
Borzenko, A. J. Chisholm, B. K. V. Hargreaves, R. McDonald, M. J.
Ferguson, M. Stradiotto, Nat. Commun. 2016, 7, 11073; d) C. M. Lavoie,
M. Stradiotto, ACS Catal. 2018, 8, 7228-7250; e) J. S. K. Clark, M. J.
Ferguson, R. McDonald, M. Stradiotto, Angew. Chem. Int. Ed. 2019,
58, 6391-6395; Angew. Chem. 2019, 131, 6457-6461.
A
spin-trapping experiment was carried out by replacing
nitrosoanisole with N-tert-butyl- α -phenylnitrone (PBN) as a
radical trap under the identical reaction and operational conditions
as above (Scheme 5, 5). The spin adduct of aryl radical was
indeed observed by electron paramagnetic resonance (EPR)
spectroscopy (Figure S5) and is characterized by the hyperfine
coupling constants, which is in agreement with the literature
data.[24] These observations suggest that the nitro C-N coupling
involves a Ni(I)/N(III) cycle, with light required to generate the Ni(I)
species and the Ni(III) being responsible for the formation of aryl
radicals.
[11] K. Nepali, H.-Y. Lee, J.-P. Liou, J. Med. Chem. 2019, 62, 2851-2893.
[12] I. Sapountzis, P. Knochel, J. Am. Chem. Soc. 2002, 124, 9390-9391.
[13] J. Gui, C.-M. Pan, Y. Jin, T. Qin, J. C. Lo, B. J. Lee, S. H. Spergel, M. E.
Mertzman, W. J. Pitts, T. E. La Cruz, M. A. Schmidt, N. Darvatkar, S. R.
Natarajan, P. S Baran, Science 2015, 348, 886-891.
[14] a) C. W. Cheung, X. Hu, Nat. Commun. 2016, 7, 12494; b) C. W. Cheung,
M. L. Ploeger, X. Hu, Nat. Commun. 2017, 8, 14878; c) C. W. Cheung, M.
L. Ploege, X. Hu, Chem. Sci. 2018, 9, 655-659; d) C. W. Cheung, J.-A. Ma,
X. Hu, J. Am. Chem. Soc. 2018, 140, 6789-6792; e) M. L. Ploeger, A. Darꢁ,
J. N. Harvey, X. Hu, ACS Catal. 2020, 10, 2845-2854.
In conclusion, we have developed a new protocol that allows
for the amination of aryl halides with nitroarenes. The amination
is catalyzed by a Ni(II)-aryl complex under purple light irradiation
with a trialkyl amine as the base, requiring no external
photosensitizers. Starting with commercially available nitroarenes
as the amines source, this reaction avoids the pre-reduction of
nitroarenes to anilines, providing a step-economic strategy for
further developing the Buchwald-Hartwig C-N coupling reaction.
[15] M. Rauser, C. Ascheberg, M. Niggemann, Angew. Chem. Int. Ed. 2017, 56,
11570-11574; Angew. Chem. 2017, 129, 11728-11732.
[16] a)T.V. Nykaza, J. C. Cooper, G. Li, N. Mahieu, A. Ramirez, M. R. Luzung,
A. T. Radosevich, J. Am. Chem. Soc. 2018, 140, 15200-15205; b) G. Li, T.
V. Nykaza, J. C. Cooper, A. Ramirez, M. R. Luzung, A. T. Radosevich, J.
Am. Chem. Soc. 2020, 142, 6786-6799.
[17] S. Suárez-Pantiga, R. Hernández-Ruiz, C. Virumbrales, M. R. Pedrosa, R.
Sanz, Angew. Chem. Int. Ed. 2019, 58, 2129-2133; Angew. Chem. 2019,
131, 2151-2155.
Acknowledgements
[18] a) B. J. Shields, A. G. Doyle, J. Am. Chem. Soc. 2016, 138, 12719-12722;
b) B. J. Shields, B. Kudisch, G. D. Scholes, A. G. Doyle, J. Am. Chem.
Soc. 2018, 140, 3035-3039; c) L. Tian, N. A. Till, B. Kudisch, D. W. C.
MacMillan, G. D. Scholes, J. Am. Chem. Soc. 2020, 142, 4555-4559; d)
S. I. Ting, S. Garakyaraghi, C. M. Taliaferro, B. J. Shields, G. D. Scholes,
F. N. Castellano, A. G. Doyle, J. Am. Chem. Soc. 2020, 142, 5800-5810;
e) L. Yang, H.-H. Lu, C.-H. Lai, G. Li, W. Zhang, R. Cao, F. Liu, C. Wang,
J. Xiao, D. Xue, Angew. Chem. Int. Ed. 2020, 59, 12714-12719; Angew.
Chem. 2020, 132, 12814-12819.
This research is supported by the National Natural Science
Foundation of China (No. 21702130 and 21871171), the China
Postdoctoral Science Foundation (No. 2018M633452) and the
111 project (B14041).
Keywords: amination • aryl halides • nitroarenes • nickel
catalysis • aryl radicals
[19] a) J. M. Dennis, N. A. White, R. Y. Liu, S. L. Buchwald, J. Am. Chem. Soc.
2018, 140, 4721-4725; b) P. S. Engl, A. P. Häring, F. Berger, G. Berger, A.
Pérez-Bitrián, T. Ritter, J. Am. Chem. Soc. 2019, 141, 13346-13351.
[20] G. Chakraborti, S. Paladhi, T. Mandal, J. Dash, J. Org. Chem. 2018, 83,
7347-7359.
[1] a) J. Bariwal, E. V. Van der Eycken, Chem. Soc. Rev. 2013, 42, 9283-9303;
b) P. Ruiz-Castillo, S. L. Buchwald, Chem. Rev. 2016, 116, 12564-12649;
c) P. A. Forero-Cortés, A. M. Haydl, Org. Process Res. Dev. 2019, 23, 1478-
1483.
[21] The failure may be attributed to the high reactivity of nitroarenes bearing
electron-withdrawing groups, which could be easily converted into the
corresponding nitroso compounds and further transformed into
azoxybenzenes or azobenzenes (Y.-F. Chen, J. Chen, L.-J. Lin, G. J.
Chuang, J. Org. Chem. 2017, 82, 11626-11630). These intermediates
would not undergo an addition reaction with the aryl radicals generated in
the reaction system, and therefore would not form the expected
diarylamines. In our study, the corresponding anilines were obtained with
low isolated yields. For details see: Table S7.
[2] a) C. Sambiagio, S. P. Marsden, A. J. Blacker, P. C. McGowan, Chem. Soc.
Rev. 2014, 43, 3525-3550; b) S. Bhunia, G. G. Pawar, S. V. Kumar, Y. Jiang,
D. Ma, Angew. Chem. Int. Ed. 2017, 56, 16136-16179; Angew. Chem. 2017,
129, 16352-16397.
[3] D. G. Brown, J. Bostrꢀm, J. Med. Chem. 2016, 59, 4443-4458.
[4] E. C. Hughes, F. Veatch, V. Elersich, Ind. Eng. Chem. 1950, 42, 787-790.
[5] a) J. P. Wolfe, S. L. Buchwald, J. Am. Chem. Soc. 1997, 119, 6054-6058; b)
G. Manolikakes, A. Gavryushin, P. Knochel, J. Org. Chem. 2008, 73, 1429-
1434; c) N. H. Park, G. Teverovskiy, S. L. Buchwald, Org. Lett. 2014, 16,
220-223; d) S. Ge, R. A. Green, J. F. Hartwig, J. Am. Chem. Soc. 2014, 136,
1617-1627; e) S. D. Ramgren, A. L. Silberstein, Y. Yang, N. K. Garg, Angew.
Chem.Int. Ed. 2011, 50, 2171-2173.
[22] a) Z. Chen, Y. Jiang, L. Zhang, Y. Guo, D. Ma, J. Am. Chem. Soc. 2019,
141, 3541-3549; b) J. B. Sperry, K. E. P. Wiglesworth, I. Edmonds, P. Fiore,
D. C. Boyles, D. B. Damon, R. L. Dorow, E. L. P. Chekler, J. Langille, J.
W. Coe, Org. Process Res. Dev. 2014, 18, 1752-1758.
[6] M. Marín, R. J. Rama, M. C. Nicasio, Chem. Rec. 2016, 16, 1819-1832.
[7] R. Y. Liu, J. M. Dennis, S. L. Buchwald, J. Am. Chem. Soc. 2020, 142,
4500-4507.
[23] The formation of the nitroso intermediate may be assisted by photo-
promoted nickel catalysis.
[24] M. Kamimori, H. Sakuragi, T. Suehiro, K. Tokumaru, M. Yoshida, Bull.
Chem. Soc. Jpn. 1977, 50, 1195-1200.
[8] a) E. B. Corcoran, M. T. Pirnot, S. Lin, S. D. Dreher, D. A. DiRocco, I. W.
Davies, S. L. Buchwald, D. W. C. MacMillan, Science 2016, 353, 279-283;
b) M. S. Oderinde, N. H. Jones, A. Juneau, M. Frenette, B. Aquila, S.
Tentarelli, D. W. Robbins, J. W. Johannes, Angew. Chem. Int. Ed. 2016, 55,
13219-13223; Angew. Chem. 2016, 128, 13413-13417; c) C.-H. Lim, M.
Kudisch, B. Liu, G. M. Miyake, J. Am. Chem. Soc. 2018, 140, 7667-7673; d)
4
This article is protected by copyright. All rights reserved.

10.1002/anie.202012877
Angewandte Chemie International Edition
COMMUNICATION
C-N coupling of aryl halides with nitroarenes is achieved by nickel catalysis under light irradiation and mild basic conditions, with no
need for any external photosensitizers, offering a nitro version for the Buchwald-Hartwig C-N coupling reaction.
5
This article is protected by copyright. All rights reserved.