NBS-assisted palladium-catalyzed bromination/cross-coupling reaction of 2-alkynyl arylazides with KSCN: an efficient method to synthesize 3-thiocyanindoles

Article abstract of DOI:10.1039/d0nj05894g

A novel and efficient method for the synthesis of 3-thiocyanindoles from 2-alkynyl arylazides with KSCN is described. NBS (N-bromosuccinimide) plays an important role in this cascade bromination/cross-coupling reaction. This reaction provides the 3-thiocy

Full text of DOI:10.1039/d0nj05894g

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NBS-assisted palladium-catalyzed bromination/
cross-coupling reaction of 2-alkynyl arylazides
with KSCN: an efficient method to synthesize
Cite this: New J. Chem., 2021,
45, 3828
3-thiocyanindoles†
Guiwen Hu, Ping Li, Zhiqiang Zhou, Fan Yang, Shijie Xu, Hui Fan, Xuechun Zhao
and Xiaoxiang Zhang
*
Received 3rd December 2020,
Accepted 20th January 2021
A novel and efficient method for the synthesis of 3-thiocyanindoles from 2-alkynyl arylazides with KSCN
is described. NBS (N-bromosuccinimide) plays an important role in this cascade bromination/cross-
coupling reaction. This reaction provides the 3-thiocyanindole products in good to excellent yields
under mild reaction conditions.
DOI: 10.1039/d0nj05894g
rsc.li/njc
In the past few years, 2-alkynyl arylazides were employed as easily
accessible starting materials for the preparation of nitro-
Introduction
Organic thiocyanates are one of the most important sulfur- gen-containing heterocycles via a-imino metal carbene inter-
1
2–16
17
containing compounds that can be found in many biologically active mediates or a radical process.
In our previous work, we also
1,2
compounds. They are also employed as valuable synthetic pre- reported the synthesis of various N-heterocycles by trapping a-imino
cursors for further transformation to sulfides, thioesters or palladium or gold carbenes generated in situ from 2-alkynyl
sulphur-containing heterocycles. Therefore, a range of synthetic arylazides. In continuation of our metal carbene work, we recently
3
4
5
methods have been established for the construction of organic tried to trap the a-imino palladium carbenes with KSCN and found
18
thiocyanates. Among the reported strategies, the thiocyanation that no desired 3-thiocyanindoles were formed. To our surprise,
7
of aryl or hetero-aryl compounds with thiocyanate salts (MSCN, 3-thiocyanindoles were obtained after the addition of NBS
+
+
+
M = Na , K , and NH
method for the preparation of organic thiocyanates (Scheme 1a–c).
In these thiocyanation reactions, oxidation with stoichiometric with KSCN and NBS has not been reported yet. Therefore, based on
4
) was considered as an efficient synthetic (N-bromosuccinimide) to the same reaction (Scheme 1e). Further-
6,7
more, this tandem thiocyanation reaction from 2-alkynyl arylazides
8
8a
8b
8c
oxidants such as CAN,
oxone,
Mn(OAc)
3
,
N-halosucci- our previous work on 2-alkynyl arylazides, we report herein a NBS-
8
d
8e
8f
nimides, hypervalent iodine reagents and K
2
S
2
O
8
,
photo- assisted palladium-catalyzed bromination/cross-coupling reaction of
9
10
catalysis and electrolysis were the major thiocyanation methods. 2-alkynyl arylazides with KSCN.
In addition, the metal-catalyzed cross-coupling reaction of prefunc-
tionalized aryl or hetero-aryl derivatives with thiocyanate salts was
also an important strategy for the construction of organic thiocya-
11
nates (Scheme 1d). Although the thiocyanation reactions have
been well explored, they still have some limitations such as harsh
reaction conditions, narrow substrate scope, low product yields or
preactivation. In contrast to the vast thiocyanation of arenes, aryl
halides, aryl diazonium salts or aryl boronic acids, general methods
of thiocyanation with novel starting materials have not been well
studied. Given these limitations, it is necessary to develop a highly
efficient and general thiocyanation method with novel starting
materials.
Co-Innovation Center for Efficient Processing and Utilization of Forest Products,
College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037,
China. E-mail: zhangxiaoxiang@njfu.edu.cn
†
Electronic supplementary information (ESI) available. See DOI: 10.1039/
d0nj05894g
Scheme 1 Synthetic methods to obtain organic thiocyanates.
3828 | New J. Chem., 2021, 45, 3828À3832
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Results and discussion
(Table 2). Under the standard reaction conditions, 2-alkynyl
arylazides 1 containing electron-withdrawing or electron-
To begin our investigation, we chose 1-azido-2-(phenylethynyl)-
benzene 1a, KSCN 2 and NBS as model substrates to explore the
optimal reaction conditions (Table 1). This revealed that treat-
ing a solution containing 1a (1 equiv.), KSCN (2 equiv.) and NBS
1
donating groups on the aromatic ring (R = Me, halide and
CF ) were efficiently converted to the corresponding products
3
3b–3j in yields of 78–98%.
Besides, various substituted aryl groups on the terminal
2
(1.5 equiv.) with Pd(OAc) (5 mol%) in a mixture solvent of
alkyne carbon of 1 were also examined and gave the desired
products 3k–3o in 73–88% yields. In addition, changing the
ethanol and water (1 : 1) at 90 1C for 36 h gave the 2-phenyl-3-
thiocyanato-1H-indole 3a in 74% yield, which was confirmed by
2
substituted aromatic group R to the alkyl group provided the
1
H NMR (entry 1). Then, the control experiments revealed that
corresponding products 3p–3r in excellent yields, which
might be due to the steric effects of substrates 1. Substrates
Pd(OAc)
entries 2 and 3). When the reaction temperature was decreased
to 60 1C, a low yield of 47% was obtained (entry 4). Later, other
solvents were examined such as EtOH, H O, DMF, 1,4-dioxane,
2
and NBS were essential for this transformation
(
2
with R = thiophene group afforded the corresponding product
1
2
3
s in 86% yield. When the two substituents R and R of
2
2-alkynyl arylazides 1 were both changed with halogen and
MeCN and mixed solvents of ethanol/water. Interestingly, the
desired product 3a was obtained either in low yields of 46–65%
or not detected with a single solvent (entries 5–9). A mixed solvent
of ethanol/water (2 : 1) was considered as the best solvent system
and afforded the product 3a in 94% yield (entries 10 and 11). In
addition, there was no significant change of the product yield by
increasing or reducing the amount of NBS or KSCN (entries
alkyl groups, the desired products 3t–3w were obtained in
ab
Table 2 Substrate scope of the 2-alkynyl arylazides
12–15). We also tested other palladium catalysts and found that
the reaction catalyzed by PdCl gave the best result, which
2
afforded the desired product in 97% yield (entries 16–18).
A similar yield of the corresponding product 3a was also obtained
when KSCN was replaced by NH SCN (entry 19).
4
With the optimized reaction conditions in hand, we subse-
quently investigated the scope of various 2-arkynyl arylazides 1
a
Table 1 Optimization of the reaction conditions
b
Entry
Catalyst
Solvent
Time/h
Yield /%
1
2
3
4
5
6
7
8
9
Pd(OAc)
Pd(OAc)
—
2
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH
H O
2
DMF
2
2
2
2
O (1 : 1)
O (1 : 1)
O (1 : 1)
O (1 : 1)
36
36
36
36
36
8
36
24
24
36
36
36
24
36
36
2
74
c
2
Trace
d
nr
e
Pd(OAc)
Pd(OAc)
Pd(OAc)
Pd(OAc)
Pd(OAc)
Pd(OAc)
Pd(OAc)
Pd(OAc)
Pd(OAc)
Pd(OAc)
Pd(OAc)
Pd(OAc)
2
2
2
2
2
2
2
2
2
2
2
2
47
65
57
Nr
59
46
94
87f
93
1,4-Dioxane
MeCN
10
11
12
13
14
15
16
17
18
19
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
2
2
2
2
2
2
2
2
2
2
O (2 : 1)
O (4 : 1)
O (2 : 1)
O (2 : 1)
O (2 : 1)
O (2 : 1)
O (2 : 1)
O (2 : 1)
O (2 : 1)
O (2 : 1)
g
91
h
82i
90
97
94
91j
93
PdCl
Pd(NO
Pd(PPh
PdCl
2
3
)
3
2
ÁH
2
Cl
O
2
24
24
2
)
2
2
a
Reaction conditions: 1a (0.1 mmol), catalyst (5 mol%), KSCN
b
(
0.2 mmol), NBS (1.5 equiv.), solvent (1 mL), at 90 1C. Isolated yield.
c
d
e
f
a
Without NBS. Without Pd(OAc)
2
. i 60 1C. 1.1 equiv. NBS.
2
Reaction conditions: 1a (0.1 mmol), PdCl (5 mol%), 2 (2.0 equiv.),
b
g
h
j
3
.0 equiv. NBS. 1.1 equiv. KSCN. 4.0 equiv. KSCN. NH
4
SCN
NBS (1.5 equiv.), EtOH (0.67 mL), and H
yield.
2
O (0.33 mL) at 90 1C. Isolated
instead of KSCN.
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(
Scheme 2e). Additionally, the yield of product 3a was
slightly decreased when the free radical scavenger TEMPO
was added to the reaction (Scheme 2f). These results have
shown that a free radical pathway of the reaction might be
ruled out.
Based on the above results and previous reports, we proposed
a plausible reaction mechanism as shown in Scheme 3. First,
Pd-catalyzed activation of 1-azido-2-(phenylethynyl)benzene 1a
was carried out to give Pd-active complex A. After intramolecular
amination of azide to alkyne, the vinyl-Pd complex B was formed.
Next, a-imino palladium carbene C was generated after the
expulsion of N , which was then trapped by HBr generated
2
1
9
in situ from NBS and H O to give the brominated Pd complex
2
D. After demetalation and protonation of D, the intermediate
3-bromo-2-phenyl-1H-indole E was generated. An oxidative
addition of E led to the formation of F, which was followed by
a ligand exchange with KSCN to give complex G. Finally, a
reductive elimination of G resulted in the formation of desired
product 2-phenyl-3-thiocyanato-1H-indole 3a and regeneration of
the palladium(II) catalyst.
To examine the efficiency and practicality of this method, a
large-scale experiment was carried out. A reaction containing
1
mmol of 1a was performed under the standard reaction
conditions; the desired product 3a was obtained in 86% yield
after 8 h (Scheme 4).
Scheme 2 Control experiments.
yields of 75–98%. At last, substrates with functional groups
such as alcohol and ether groups were also investigated, which
afforded the desired products 3x and 3y in 71% and 68% yields,
respectively. To examine the tolerance of this reaction, a reac-
tion with a Br-containing substrate was carried out under the
standard reaction conditions, which afforded the product 3z in
71% yield after 4 h. Later, we repeated this reaction and
prolonged the reaction time to 10 h and found that 3z was still
obtained as the single product.
In order to understand the mechanism of this thiocyanation
reaction, a series of control experiments were performed and
the results are presented in Scheme 2. When KSCN was not
employed, the starting material 1a could react with HBr generated
19
in situ from NBS and H O in the presence of PdCl , which
2
2
afforded the 3-bromo-2-phenyl-1H-indole
E
in 51% yield
(
Scheme 2a). Later, we found that E could react with KSCN in
the presence of PdCl to give 2-phenyl-3-thiocyanato-1H-indole 3a
in 79% yield (Scheme 2b). However, the PdCl -catalyzed reaction
of 1a with KSCN did not form the desired product 3a without NBS
Scheme 2c). These results indicated that NBS was a key reagent
2
2
(
for the formation of 3a. Furthermore, the reaction of E with KSCN
was carried out in the absence of PdCl , where no reaction was
2
observed and most of the starting material E was left unused
(Scheme 2d). Finally, we found that a trace amount of 2-phenyl-
1
H-indole 4 was observed under the standard reaction conditions Scheme 3 Proposed mechanism.
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H. Batra, N. Rani, S. P. Singh and R. M. Moriarty, J. Org.
Chem., 2001, 66, 2019; (c) T. Castanheiro, J. Suffert,
M. Donnard and M. Gulea, Chem. Soc. Rev., 2016, 45, 494;
(
d) Q. Chen, Y. Lei, Y. Wang, C. Wang, Y. Wang, Z. Xu,
H. Wang and R. Wang, Org. Chem. Front., 2017, 4, 369;
e) J. Qiu, D. Wu, P. G. Karmaker, H. Yin and F. Chen,
(
Org. Lett., 2018, 20, 1600; ( f ) D. Zhang, H. Wang and
C. Bolm, Chem. Commun., 2018, 54, 5772.
Scheme 4 A large-scale experiment.
3
(a) S. Rezayati and A. Ramazani, Tetrehedron, 2020,
7
6, 131382; (b) K. Jouvin, C. Matheis and L. J. Goossen,
Conclusions
Chem. – Eur. J., 2015, 21, 14324; (c) I. Kamiya, J. Kawakami,
S. Yano, A. Nomoto and A. Ogawa, Organometallics, 2006,
2
Org. Lett., 2015, 17, 1716; (e) B. Bayarmagnai, C. Matheis,
K. Jouvin and L. J. Goossen, Angew. Chem., Int. Ed., 2015,
In summary, we have described a novel and efficient synthetic
method for obtaining 3-thiocyanindoles via a NBS-assisted PdCl -
2
5, 3562; (d) M. Pawliczek, L. K. B. Garve and D. B. Werz,
catalyzed bromination/cross-coupling reaction of 2-alkynyl arylazides
with KSCN. The reaction was shown to be applicable to a structurally
diverse set of 2-alkynyl arylazides. The desired products 3-thio-
cyanindoles were obtained in good to excellent yields under mild
reaction conditions. Further studies on the application reactions of
5
4, 5753; ( f ) R. Chandran, P. Ashwini, K. S. Suraj, D. Rahul,
V. Suman and N. T. Keshri, Org. Lett., 2020, 22, 6557;
g) A. Houmam, E. M. Hamed and I. W. J. Still, J. Am. Chem.
(
Soc., 2003, 125, 7258.
(a) T. B. Johnson and I. B. Douglass, J. Am. Chem. Soc., 1939,
6
J. Am. Chem. Soc., 1951, 73, 5905; (c) S. P. Brown and
A. B. Smith, J. Am. Chem. Soc., 2015, 137, 4034.
(a) Z. P. Demko and K. B. Sharpless, Org. Lett., 2001, 3, 4091;
3-thiocyanindoles are underway.
4
5
1, 2548; (b) R. Riemschneider, F. Wojahn and G. Orlick,
Conflicts of interest
There are no conflicts to declare.
(b) S. P. Brown and A. B. Smith, J. Am. Chem. Soc., 2015,
1
37, 4034; (c) X. Chen, X. Wang, J. Song, Q. Yang, C. Huang
Acknowledgements
and W. Liu, Org. Biomol. Chem., 2017, 15, 3611; (d) W. He,
L. Gao, X. Chen, Z. Wu, Y. Huang, Z. Cao, X. Xu and W. He,
Chin. Chem. Lett., 2020, 31, 1895; (e) X. Duan, X. Liu,
X. Cuan, L. Wang, K. Liu, H. Zhou, X. Chen, H. Li and
J. Wang, J. Org. Chem., 2019, 84, 12366.
This work was supported by the National Natural Science
Foundation of China, Grants (21302096), and the Natural
Science Foundation of Jiangsu Province-Grants (BK20171449),
Qing Lan Project. We are also grateful for support from the
advanced analysis and testing center of Nanjing Forestry
University.
6
(a) S. Rezayati and A. Ramazani, Tetrahedron, 2020,
76, 131382; (b) C. Wu, L. Lu, A. Peng, G. Jia, C. Peng,
Z. Cao, Z. Tang, W. He and X. Xu, Green Chem., 2018,
2
2
0, 3683; (c) T. Kittikool and S. Yotphan, Eur. J. Org. Chem.,
020, 961; (d) T. B. Johnson and I. B. Douglass, J. Am. Chem.
Notes and references
1
(a) S. Dutta, H. Abe, S. Aoyagi, C. Kibayashi and K. S. Gates,
J. Am. Chem. Soc., 2005, 127, 15004; (b) E. Elhalem,
B. N. Bailey, R. Docampo, I. Ujv ´a ry, S. H. Szajnman and
J. B. Rodriguez, J. Med. Chem., 2002, 45, 3984; (c) P. Jimonet,
F. Audiau, M. Barreau, J. Blanchard, A. Boireau, Y. Bour,
M. Col ´e no, A. Doble, G. Doerflinger, C. D. Huu, M. Donat,
J. M. Duchesne, P. Ganil, C. Gu ´e r ´e my, E. Honor ´e , B. Just,
R. Kerphirique, S. Gontier, P. Hubert, P. M. Laduron,
J. Blevec, M. Meunier, J. Miquet, C. Nemecek, M. Pasquet,
O. Piot, J. Pratt, J. Rataud, M. L. Reibaud, J. Stutzmann and
S. Mignani, J. Med. Chem., 1999, 42, 2828; (d) R. J. Capon,
C. Skene, E. H. Liu, E. Lacey, J. H. Gill, K. Heiland and
T. Friedel, J. Org. Chem., 2001, 66, 7765; (e) Q. Guan, C. Han,
D. Zuo, M. Zhai, Z. Li, Q. Zhang, Y. Zhai, X. Jiang, K. Bao,
Y. Wu and W. Zhang, Eur. J. Med. Chem., 2014, 87, 306;
Soc., 1939, 61, 2548; (e) Qumruddeen, A. Yadav, R. Kant and
C. B. Tripathi, J. Org. Chem., 2020, 85, 2814; ( f ) Z. Liang,
F. Wang, P. Chen and G. Liu, Org. Lett., 2015, 17, 2438.
7 (a) C. Wang, Z. Wang, L. Wang, Q. Chen and M. He, Chin.
J. Chem., 2016, 34, 1081; (b) A. Ye, Y. Zhang, Y. Xie, H. Luo,
J. Dong, X. Liu, X. Song, T. Ding and Z. Chen, Org. Lett.,
2019, 21, 5106; (c) V. A. Kokorekin, R. R. Yaubasarova,
S. V. Neverov and V. A. Petrosyan, Eur. J. Org. Chem., 2019,
4233; (d) P. Ghosh, G. Chhetri, A. Kumar, N. S. Sarkar,
T. Saha and S. Das, New J. Chem., 2019, 43, 10959; (e) X. Mao,
J. Ni, B. Xu and C. Ding, Org. Chem. Front., 2020, 7, 350;
( f ) C. Li, P. Long, H. Wu, H. Yin and F. Chen, Org. Biomol.
Chem., 2019, 17, 7131; (g) L. Mandic, I. Dzeba, D. Jadresko,
B. Mihaljevic, L. Biczok and N. Basari, New J. Chem., 2020,
44, 17252; (h) H. Wu, K. Yang, S. Luo, X. Wu, N. Wang,
S. Chen and Z. Wang, Eur. J. Org. Chem., 2019, 4572.
(
f ) M. P. Fortes, P. B. Silva, T. G. Silva, T. S. Kaufman,
G. C. Militao and C. C. Silveira, Eur. J. Med. Chem., 2016,
18, 21.
8 (a) V. Nair, T. G. George, L. G. Nair and S. B. Panicker,
Tetrahedron Lett., 1999, 40, 1195; (b) G. Wu, Q. Liu, Y. Shen,
W. Wu and L. Wu, Tetrahedron Lett., 2005, 46, 5831;
(c) X. Pan, M. Lei, J. Zou and W. Zhang, Tetrahedron Lett.,
1
2
(a) A. D. Mico, R. Margarita, A. Mariania and G. Piancatelli,
Chem. Commun., 1997, 1237; (b) O. Prakash, H. Kaur,
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021
New J. Chem., 2021, 45, 3828À3832 | 3831

View Article Online
NJC
Paper
2009, 50, 347; (d) Z. Wang, L. Wang, Q. Chen and M. He, 15 (a) I. Nakamura, U. Yamagishi, D. Song, S. Konta and
Synth. Commun., 2018, 48, 76; (e) J. Wu, G. Wu and L. Wu,
Synth. Commun., 2008, 38, 2367; ( f ) T. B. Mete, T. M. Khopade
and R. G. Bhat, Tetrahedron Lett., 2017, 58, 415.
Y. Yamamoto, Angew. Chem., Int. Ed., 2007, 46, 2284;
(b) B. J. Stokes, S. Liu and T. G. Driver, J. Am. Chem. Soc.,
2011, 133, 4702; (c) D. Susanti, L. L. R. Ng and
P. W. H. Chan, Adv. Synth. Catal., 2014, 356, 353;
(d) S. R. Mothe, P. Kothandaraman, S. J. L. Lauw,
S. M. W. Chin and P. W. H. Chan, Chem. – Eur. J., 2012,
18, 6133; (e) P. Kothandaraman, S. R. Mothe, S. S. M. Toh
and P. W. H. Chan, J. Org. Chem., 2011, 76, 7633.
9
(a) W. Fan, Q. Yang, F. Xu and P. Li, J. Org. Chem., 2014,
7
9, 10588; (b) W. Zhang, J. Tang, W. Yu, Q. Huang, Y. Fu,
G. Kuang, C. Pan and G. Yu, ACS Catal., 2018, 8, 8084;
c) V. Rathore and S. Kumar, Green Chem., 2019, 21, 2670.
0 (a) L. Sun, X. Zhang, Z. Li, J. Ma, Z. Zeng and H. Jiang,
(
1
Eur. J. Org. Chem., 2018, 4949; (b) X. Zhang, C. Wang, 16 L. He and X. Li, Tetrahedron, 2017, 73, 6138.
H. Jiang and L. Sun, RSC Adv., 2018, 8, 22042.
1 (a) S. Yang, T. He, D. Lin and J. Huang, Org. Lett., 2019,
17 (a) X. Zhang, P. Li, C. Lyu, W. Yong, J. Li, X. Zhu and W. Rao,
Org. Biomol. Chem., 2017, 15, 6080; (b) P. Li, W. Yong,
R. Sheng, W. Rao, X. Zhu and X. Zhang, Adv. Synth. Catal.,
2019, 361, 201; (c) X. Zhang, P. Li, C. Lyu, W. Yong, J. Li,
X. Pan, X. Zhu and W. Rao, Adv. Synth. Catal., 2017,
359, 4147; (d) P. Li, B. Zhu, Y. Xu, Z. Zhou, G. Hu,
F. Yang, S. Xu and X. Zhang, Org. Chem. Front., 2020,
7, 3480.
18 (a) C. Feng, Y. Peng, G. Ding, X. Li, C. Cui and Y. Yan, Chem.
Commun., 2018, 54, 13367; (b) H. Jiang, W. Yu, X. Tang, J. Li
and W. Wu, J. Org. Chem., 2017, 82, 9312; (c) D. Wu, J. Qiu,
P. G. Karmaker, H. Yin and F. Chen, J. Org. Chem., 2018,
83, 1576; (d) Z. Li, S. Han, C. Li, P. Shao, H. Xia, H. Li,
X. Chen, X. Feng and X. Liu, J. Mater. Chem. A, 2020, 8, 8706;
(e) Z. Zhang and L. S. Liebeskind, Org. Lett., 2006, 8,
4331; ( f ) S. D. Tambe, M. S. Jadhav, R. S. Rohokale and
U. A. Kshirsagar, Eur. J. Org. Chem., 2018, 4867;
(g) M. Koohgard, Z. Hosseinpour, A. M. Sarvestani and
M. Hosseini-Sarvari, Catal. Sci. Technol., 2020, 10, 1401;
(h) Q. Wang, P. Tian, Z. Cao, H. Zhang and C. Jiang,
Adv. Synth. Catal., 2020, 362, 3851.
1
21, 1958; (b) F. Wang, C. Chen, G. Deng and C. Xi, J. Org.
Chem., 2012, 77, 4148; (c) F. Meng, H. Zhang, H. He, N. Xu,
Q. Fang, K. Guo, S. Cao, Y. Shi and Y. Zhu, Adv. Synth. Catal.,
2020, 362, 248; (d) Y. Chen, S. Wang, Q. Jiang, C. Cheng,
X. Xiao and G. Zhu, J. Org. Chem., 2018, 83, 716; (e) N. Sun,
L. Che, W. Mo, B. Hu, Z. Shen and X. Hu, Org. Biomol.
Chem., 2015, 13, 691.
2 (a) N. Li, X. Lian, Y. Li, T. Wang, Z. Han, L. Zhang and
L. Gong, Org. Lett., 2016, 18, 4178; (b) L. Gu, C. Jin, W. Wang,
Y. He, G. Yang and G. Li, Chem. Commun., 2017, 53, 4203;
1
(c) Z. Zhang, F. Xiao, B. Huang, J. Hu, B. Fu and Z. Zhang,
Org. Lett., 2016, 18, 908; (d) F. Chen, Q. Meng, S. Han and
B. Han, Org. Lett., 2016, 18, 3330; (e) C. Gronnier,
G. Boissonnat and F. Gagosz, Org. Lett., 2013, 15, 4234;
(
2
f ) Z. Y. Yan, Y. Xiao and L. Zhang, Angew. Chem., Int. Ed.,
012, 51, 8624.
1
3 D. J. Gorin, N. R. Davis and F. D. Toste, J. Am. Chem. Soc.,
005, 127, 11260.
4 (a) A. Wetzel and F. Gagosz, Angew. Chem., Int. Ed., 2011,
2
1
50, 7354; (b) B. Lu, Y. Luo, L. Liu, L. Ye, Y. Wang and 19 X. Duan, X. Liu, X. Cuan, L. Wang, K. Liu, H. Zhou, X. Chen,
L. Zhang, Angew. Chem., Int. Ed., 2011, 50, 8358. H. Li and J. Wang, J. Org. Chem., 2019, 84, 12366.
3832 | New J. Chem., 2021, 45, 3828À3832
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