Electrochemical Scalable Sulfoxidation of Sulfides with Molecular Oxygen and Water

Article abstract of DOI:10.1002/ejoc.202100610

An efficient and chemoselective synthesis of sulfoxides through the electrooxidation of sulfides has been well developed. This protocol takes advantage of electricity as the terminal oxidant and of molecular oxygen and water as the oxygen atom sources. A variety of structurally diverse sulfoxide compounds are assembled in moderate to excellent yields. The scaled-up reactions at 6–20 mmol show the good practicability and application potential of this methodology. A possible free radical mechanism has been proposed to rationalize the reaction procedure.

Full text of DOI:10.1002/ejoc.202100610

Communications
doi.org/10.1002/ejoc.202100610
Electrochemical Scalable Sulfoxidation of Sulfides with
Molecular Oxygen and Water
Zhen Cheng,[a] Xinglian Gao,[a] Lingling Yao,[a] Zhaoxin Wei,[a] Guohui Qin,[a]
Yonghong Zhang,[a] Bin Wang,[a] Yu Xia,[a] Ablimit Abdukader,[a] Fei Xue,[a] Weiwei Jin,*[a] and
Chenjiang Liu*[a]
systems including classical transition metal catalysis,[8] organic
An efficient and chemoselective synthesis of sulfoxides through
catalysis,[9] and the resurgent and cutting-edge visible light
the electrooxidation of sulfides has been well developed. This
photoredox catalysis.[10]
protocol takes advantage of electricity as the terminal oxidant
In recent years, organic electrosynthesis which using
electrons as the ideal oxidizing and reducing agents and
possessing many inherent requirement of green sustainable
chemistry has emerged as an important alternative to conven-
and of molecular oxygen and water as the oxygen atom
sources. A variety of structurally diverse sulfoxide compounds
are assembled in moderate to excellent yields. The scaled-up
reactions at 6–20 mmol show the good practicability and
application potential of this methodology. A possible free
radical mechanism has been proposed to rationalize the
reaction procedure.
tional
thermochemical
methods
and
photochemical
strategies.[11] In this context, electrosynthesis of oxygen-contain-
ing organic compounds including the construction of diverse
XÀ O (X=C, N, P etc.) bonds[12] and heterocyclic compounds[13]
have made a great deal of progress. Nowadays, several pioneer-
ing works on the sulfoxidation of sulfides under electrolytic
conditions have also been well established. In 2017, Noël and
collaborators developed an electrochemical selective oxidation
of sulfides in water with the strategy of flow chemistry in an
acidic aqueous CH3CN/H2O/HCl mixed solvents.[14] Recently, an
electrochemical anodic oxidation system employing a CoFe
layered double hydroxide anode was successfully reported to
the synthesis of pharmaceutical significant sulfoxide related
compounds by Duan group.[15] More recently, during the
preparation of this article, Jiao and co-workers demonstrated a
novel and meaningful cascade activation strategy combining
classic nickel catalysis and electrochemical process for the
selective sulfoxidation of sulfides.[16] Based on these progress
mentioned as above, water is regarded as the source of oxygen
atom. The in situ generated O2, originating from the electrolytic
water process, is the real source of oxygen. Although the good
performance in this field, there are still some remarkable
drawbacks need to be addressed including narrow substrate
scope, harsh reaction conditions, and specialized instruments
and so on.
Sulfoxides are among the most important oxygen-containing
organosulfur chemicals.[1] They are commonly used as versatile
reaction intermediates and sulfur-based ligands in organic
synthetic chemistry,[2] as well as applications in the manufacture
of potential bioactive medicines and natural products.[3] More-
over, the oxidation of sulfur to harmless and easily purified
sulfoxides and sulfones is one kind of key technology in the
field of sulfur-containing environmental wastewater treatment[4]
and sulfur-rich fuel oil oxidative desulfurization.[5] Among the
sulfoxides prepared approaches in existence, the direct oxida-
tion of sulfides is one of the most convenient and efficient
method for the selective transformation of raw materials into
high-value-added fine chemicals. In view of the apparent
drawbacks of traditional thioether oxygenation processes with
excessive amounts of toxic or hazardous organic oxidants or
inorganic metal salts, the development of clean and mild
chemical oxidative procedure comply with the basic principles
of “green chemistry” is of great significance.[6] During the past
few decades, molecular oxygen has been considered as a
readily available, ecologically friendly, and ideal “green” oxidant
and aroused wide concern in aerobic oxygenation oxidation.[7]
Actually, the oxidizing processes of sulfides with molecular
oxygen have been studied extensively with different catalytic
In 2019, we developed a tunable synthesis of aryl sulfones
and sulfoxides via the reaction temperature controlled chemo-
selective aerobic oxygenation of sulfides in a high boiling point
ether reaction medium under thermal conditions.[17] Inspired by
recent advances of electrochemical anodic oxidation and as an
expansion of our long-standing research interest on eco-friendly
green chemical processes including aerobic oxygenation[18] and
organic photo/electrosynthesis,[19] we present herein our pre-
liminary studies about the electrochemical aerobic oxidation of
sulfides with molecular oxygen and water at room temperature
for selective synthesis of sulfoxide derivatives.
[a] Z. Cheng, X. Gao, L. Yao, Z. Wei, G. Qin, Prof. Dr. Y. Zhang, B. Wang,
Prof. Dr. Y. Xia, Prof. Dr. A. Abdukader, F. Xue, Prof. Dr. W. Jin,
Prof. Dr. C. Liu
Urumqi Key Laboratory of Green Catalysis and Synthesis Technology,
Key Laboratory of Oil and Gas Fine Chemicals,
Ministry of Education & Xinjiang Uygur Autonomous Region,
State Key Laboratory of Chemistry and Utilization of Carbon Based
Energy Resources, College of Chemistry,
Xinjiang University,
Urumqi 830046, P. R. China
Firstly, the electrooxidation of diphenyl sulfide 1a installed
with an oxygen balloon at 0.1 MPa was selected as the model
reaction (Table 1). Under constant current of 7 mA, the desired
E-mail: wwjin0722@xju.edu.cn
pxylcj@126.com
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Table 1. Optimization of reaction conditions for the electrochemical
sulfoxidation of sulfides.[a]
Table 2. Substrate scope for the electrochemical sulfoxidation of sulfide-
s.[a,b]
Entry
Variation from the standard conditions
None
2 h instead of 3 h
Under air
Without LiClO4 ·3H2O
Without current
N2
Yield of 2a [%][b,c]
97 (84)
74
1
2
3
4
5
6
7
54
n.r.
n.r.
51
N2 and 10 equiv. H2O
92
[a] Reaction conditions: 1a (0.3 mmol), O2 balloon, LiClO4 ·3H2O
(0.03 mmol), DMF (4 mL), C anode (immersed surface area 8×5 mm2), Ni
cathode (immersed surface area 8×5 mm2), the distance between the
electrodes (5 mm), room temperature, constant current=7 mA, 3 h, 2.6 F/
mol, undivided cell. [b] Determined by GC analysis. [c] Isolated yield in
parentheses. n.r.: no reaction.
oxygenation product diphenyl sulfoxide 2a was obtained in
highest 84% isolated yield in DMF with LiClO4 ·3H2O as the
electrolyte employing a carbon plate anode and a nickel plate
cathode at ambient temperature for 3 h, 2.6 F/mol in an
undivided cell (entry 1). With the decrease of the reaction time
to 2 h, 1.7 F/mol, the yield of 2a was reduced to 74% (entry 2).
Instead of air with oxygen atmosphere, the yield was reduced
to 54% (entry 3). The utmost importance of electrolyte and
electricity was demonstrated by the blank experiments, no
reaction happened under these conditions (entries 4–5). The
oxidizing product 2a also could be generated in the presence
of trace water or additional water (entries 6–7) An investigation
of various supporting electrolytes, various solvents, and currents
allowed to define the best conditions see Tables S1–S3 of the
Supporting Information for details.
With the best reaction conditions established, the generality
and limitations of this electrochemical aerobic oxidation of
sulfides were explored, as illustrated in Table 2. Substituted
diphenyl sulfides 2a–2d with electron-donating and/or elec-
tron-withdrawing groups were smoothly transformed into the
desired sulfoxidation products in moderate to excellent yields.
An obvious decrease in the yield of product 2d was observed, a
possible reason is the strong inactivation of the nitro group.
Condensed sulfur-containing aromatic hydrocarbon substrates
dibenzo[b,d]thiophene, thianthrene, and 2-chloro-9H-thioxanth-
en-9-one were also suitable sulfide substrates, affording
respective oxidative products 2e–2g in 65–96% yields. A series
of monosubstituted aryl methyl sulfoxides 2h–2t anchored
with electron-rich and -deficient substituents at ortho- and
para-positions on the phenyl ring were assembled in moderate
to good yields. The oxidation of the polychlorinated methyl
phenyl thioethers 1u–1x gave higher yields of the correspond-
ing sulfoxides 2u–2x (81–98%) than that of the monohalo-
genated aryl methyl thioethers 1l–1q (38%–83% of 2l–2q).
The potential derivatization of these products could be realized
[a] Reaction conditions:
1
(0.3 mmol), O2 balloon, LiClO4 ·3H2O
(0.03 mmol), DMF (4 mL), C anode (immersed surface area 8×5 mm2), Ni
cathode (immersed surface area 8×5 mm2), the distance between the
electrodes (5 mm), room temperature, constant current=7 mA, 5 h, 4.3 F/
mol, undivided cell; for 2a and 2ab, 3 h, 2.6 F/mol; for 2c, 8 h, 6.9 F/mol.
[c] Isolated yields. [c] Bu4NPF6 (0.05 mmol), EtOH (4 mL), constant
current=10 mA, 3 h, 3.7 F/mol. [d] dr=1:1.75.
through subsequent cross coupling reactions for the prepara-
tion of synthetically important functional molecules. Interest-
ingly, cyclopropane derived starting materials were tolerated
and delivered the corresponding products 2y–2z in 57% and
85% yields, respectively. Polycyclic aryl sulfides 2aa and 2ab
afforded the sulfoxides 2aa and 2ab in good yields (79% and
70%), and heteroaryl sulfides 1ac and 2ad gave the sulfoxides
2ac and 2ad in satisfactory yields (56% and 45%).
The high practicability and good reliability of this electro-
chemical methodology were demonstrated firmly by the scale-
up oxygenation experiments of various surveyed sulfide
compounds at 6–20 mmol scale (Table 3). These large scale
reactions were carried out under slightly modified standard
conditions with constant current continuous electrolysis at
16 mA. To our delight, the yield for product 2a was increased
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Table 3. Large-scale reactions.[a,b]
Entry
Substrate
Product
t (h)
Yield
1
2
3
4
5
6
7
8
1a
1a
1e
1f
1g
1l
2a
2a
2e
2f
2g
2l
30
120
34
28
52
45
19
24
98
98c
76
95
77
29d
96
78
1w
1aa
2w
2aa
[a] Reaction conditions: 1 (6 mmol), O2 balloon, LiClO4 (1 mmol), DMF
(20 mL),
C
anode (immersed surface area 8×12 mm2), Ni cathode
(immersed surface area 8×12 mm2), the distance between the electrodes
(5 mm), room temperature, constant current=16 mA, 24–30 h, 2.4–3.0 F/
mol, undivided cell. [b] Isolated yields. [c] 20 mmol, 3.6 F/mol. [d] 8 mmol,
3.4 F/mol.
to 98% under scale-up preparation (Table 3, entries 1–2). The
yields for other investigated substrates at large scale (2e–g, 2l,
2w, and 2aa) were similar as standard condition scale in
Table 2 (Table 3, entries 3–8).
Although the sulfoxides could not be oxidized to the
corresponding sulfones under the best conditions developed
for the oxidation of sulfides, a change of the electrolyte and
solvent as shown in Scheme 1 allowed the preparation of the
sulfones 3a–3c in good yields (64–74%)(Scheme 1).
To gain a deeper insight into the mechanism of the
electrochemical oxidation of sulfides to sulfoxides, the experi-
ments described in Scheme 2 were carried out. The incorpo-
ration of 18O into the sulfoxide 2a, as shown by the results of
Scheme 2a–2b (see also pages S7–S9) when the electrolysis of
1a was carried out in the presence of 18O2 and H218O, confirms
Scheme 2. Mechanistic studies.
that dioxygen is involved in the formation of sulfoxide 2a[16]
.
The obvious inhibiting effects of radical scavengers such as
TEMPO and BHT to the oxidizing reaction activities of diphenyl
sulfide were observed, demonstrating a potential free radical
process of this electrosynthetic reaction (Scheme 2c). The
results of electron paramagnetic resonance (EPR) experiments
also backed up the involvement of the free radical in this
protocol (see S12, Figure S2). On the one hand, the intermedi-
ate probe experiment under standard conditions in Table 1,
showing the absolute chemoselectivity of this electrooxidation
method for sulfoxidation products of sulfides (Scheme 2d). On
the other hand, according to the result of the same reaction
under standard conditions in Scheme 1, diphenyl sulfoxide 2a
was demonstrated to be a possible reactive intermediate for
the sulfonation process of thioethers (Scheme 2e). In order to
demonstrate the release of H2 during this electrochemical
oxidation procedure, the resulted hydrogen gas collected in a
balloon was monitored by a H2 detector (see S12, Figure S3).
The cyclic voltammetry (CV) experiments indicated that 1a is
prone to be oxidized (Figure 1). The result of on/off current
experiment about the model reaction ruled out the autocata-
lytic process of this reaction (Figure 2).
Mechanistically, according to the above experimental
results, the sulfide 1a was firstly oxidized in the electrochemical
anodic oxidation system to generate a sulfur radical cation
intermediate A[20]
. Secondly, the sulfur radical cation A
combined with molecular oxygen which come from O2 balloon
and/or electrolytic water at anode to produce the persulfoxide
species B, which was immediately captured by another sulfide
1a to generate the final sulfoxide product 2a. The hydrogen
gas was released by the reduction of H+ at cathode (Scheme 3).
In summary, we have reported a concise, safe, efficient, and
scalable method for electrochemical oxygenation of sulfides to
synthesize of sulfoxide compounds. By avoiding the use of
conventional poisonous and costly oxidants, this method
utilizes electricity as a green oxidant. The protocol features
wide substrate scope, good functional compatibility, mild
Scheme 1. Electrochemical sulfonation of sulfides.
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and renewable hydrogen energy preparation in one electrolytic
bath will be a promising and potent tactics. The similar strategy
using water as the indirect O2 source in electrochemical aerobic
oxygenation reactions is still ongoing in our laboratory and will
be reported in due course.
Experimental Section
General procedure for the synthesis of 2a: A mixture of diphenyl
sulfide 1a (0.30 mmol), LiClO4 ·3H2O (0.03 mmol) and DMF (4 mL)
were added to an undivided bottle (10 mL). The bottle was
equipped with graphite rod as the anode (immersed surface area
8×5 mm2) and nickel plate as the cathode (immersed surface area
8×5 mm2), the distance between the electrodes was 5 mm. The
undivided bottle was flushed with O2 for 1.0 minute and then
equipped with a O2 balloon. The reaction was stirred and electro-
lyzed at a constant current of 7 mA at room temperature for 3–8 h.
After the reaction was finished, the resulting mixture was extracted
with EtOAc (3×10 mL). The combined organic phase was dried
over anhydrous MgSO4, filtered, and all the volatiles were
evaporated under reduced pressure. The resultant residue was
purified by silica gel column chromatography (eluent: petroleum
Figure 1. Cyclic voltammetry experiments of 1a and background. Cyclic
voltammograms were recorded with a CHI660E electrochemical workstation
at room temperature in DMF. A glassy carbon-disk (R=5.5 mm, h=10 mm)
was used as the working electrode. The Ni disk (R=5.5 mm, h=10 mm) and
Ag/AgCl (R=5.0 mm, h=10 mm) was used as counter and reference
electrode, respectively. The scan rate was 100 mV/s.
°
ether (60–90 C)/EtOAc=25:1, v/v) to afford the desired product
2a.
Acknowledgements
We are grateful to the National Natural Science Foundation of
China (Grant Nos. 21572195, 21702175, 21961037 and 22061040)
for support of this research.
Figure 2. On/off current experiment.
Conflict of Interest
The authors declare no conflict of interest.
Keywords: Electrooxidation · Free radical mechanism · Scale-up
reactions · Sulfides · Sulfoxides
[1] R. J. Cremlyn, An Introduction to Organosulfur Chemistry, John Wiley &
Sons, Ltd, 1996.
[2] a) T. Toru, C. Bolm, Organosulfur Chemistry in Asymmetric Synthesis,
Wiley-VCH, Weinheim, 2008; b) S. M. Roberts, J. Whittall, Regio- and
Stereo- Controlled Oxidations and Reductions, Volume 5, John Wiley &
Sons, Ltd, 2007; c) M. C. Carreno, Chem. Rev. 1995, 95, 1717–1760.
[3] a) N. Xu, J. Zhu, Y.-Q. Wu, Y. Zhang, J.-Y. Xia, Q. Zhao, G.-Q. Lin, H.-L. Yu,
J.-H. Xu, Org. Process Res. Dev. 2020, 24, 1124–1130; b) K. A. Scott, J. T.
Njardarson, Top. Curr. Chem. 2018, 376, 5–34; c) N. Wang, P. Saidhar-
eddy, X. Jiang, Nat. Prod. Rep. 2020, 37, 246–275.
Scheme 3. Putative mechanism for the electrochemical aerobic oxygenation
of sulfides to sulfoxides.
[4] T. Reemtsma, B. Zywicki, M. Stueber, A. Kloepfer, M. Jekel, Environ. Sci.
Technol. 2002, 36, 1102–1106.
[5] F. Liu, J. Yu, A. B. Qazi, L. Zhang, X. Liu, Environ. Sci. Technol. 2021, 55,
1419–1435.
[6] a) B. Liu, F. Jin, T. Wang, X. Yuan, W. Han, Angew. Chem. Int. Ed. 2017, 56,
12712–12717; Angew. Chem. 2017, 129, 12886–12891; b) P. Hu, M. Tan,
L. Cheng, H. Zhao, R. Feng, W.-J. Gu, W. Han, Nat. Commun. 2019, 10,
2425–2434.
[7] a) C. Bian, A. K. Singh, L. Niu, H. Yi, A. Lei, Asian J. Org. Chem. 2017, 6,
386–396; b) Y.-F. Liang, N. Jiao, Acc. Chem. Res. 2017, 50, 1640–1653;
c) Y. Liang, J. Wei, X. Qiu, N. Jiao, Chem. Rev. 2018, 118, 4912–4945.
reaction conditions, and excellent chemoselectivity. Dioxygen
and water both are demonstrated as the source of oxygen
atom by control experiments. Given that the electrochemical
water splitting is a well-studied process in energy and materials
chemistry, we believe that the combination of fine chemical
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[8] a) B. Li, A.-H. Liu, L.-N. He, Z.-Z. Yang, J. Gao, K.-H. Chen, Green Chem.
[11] a) S.-H. Shi, Y. Liang, N. Jiao, Chem. Rev. 2021, 121, 485–505; b) S. Tang,
L. Zeng, A. Lei, J. Am. Chem. Soc. 2018, 140, 13128–13135; c) T.
Fuchigami, S. Inagi, Acc. Chem. Res. 2020, 53, 322–334; d) F. Wang, S. S.
Stahl, Acc. Chem. Res. 2020, 53, 561–574; e) K.-J. Jiao, Y.-K. Xing, Q.-L.
Yang, H. Qiu, T.-S. Mei, Acc. Chem. Res. 2020, 53, 300–310; f) P. Xiong, H.-
C. Xu, Acc. Chem. Res. 2019, 52, 3339–3350; g) C. Kingston, M. D.
Palkowitz, Y. Takahira, J. C. Vantourout, B. K. Peters, Y. Kawamata, P. S.
Baran, Acc. Chem. Res. 2020, 53, 72–83; h) J. C. Siu, N. Fu, S. Lin, Acc.
Chem. Res. 2020, 53, 547–560; i) M. Yan, Y. Kawamata, P. S. Baran, Chem.
Rev. 2017, 117, 13230–13319.
[12] a) P. Xiong, H.-B. Zhao, X.-T. Fan, L.-H. Jie, H. Long, P. Xu, Z.-J. Liu, Z.-J.
Wu, J. Cheng, H.-C. Xu, Nat. Commun. 2020, 11, 2706–2714; b) X. Sun,
H.-X. Ma, T.-S. Mei, P. Fang, Y. Hu, Org. Lett. 2019, 21, 3167–3171; c) T.-T.
Zhang, M.-J. Luo, Y. Li, R.-J. Song, J.-H. Li, Org. Lett. 2020, 22, 7250–7254;
d) S. Guo, S. Li, W. Yan, Z. Liang, Z. Fu, H. Cai, Green Chem. 2020, 22,
7343–7347; e) K. Sun, J. Lei, Y. Liu, B. Liu, N. Chen, Adv. Synth. Catal.
2020, 362, 3709–3726; f) Y. Li, Q. Yang, L. Yang, N. Lei, K. Zhang, Chem.
Commun. 2019, 55, 4981–4984; g) Q.-Y. Li, T. R. Swaroop, C. Hou, Z.-Q.
Wang, Y.-M. Pan, H.-T. Tang, Adv. Synth. Catal. 2019, 361, 1761–1765;
h) L. Deng, Y. Wang, H. Mei, Y. Pan, J. Han, J. Org. Chem. 2019, 84, 949–
956; i) E. J. Horn, B. R. Rosen, Y. Chen, J. Tang, K. Chen, M. D. Eastgate,
P. S. Baran, Nature 2016, 533, 77–81.
2012, 14, 130–135; b) M. Liu, S. Shi, L. Zhao, M. Wang, G. Zhu, X. Zheng,
J. Gao, J. Xu, ACS Catal. 2018, 8, 683–691; c) K. Nakatsuka, K. Mori, S.
Okada, S. Ikurumi, T. Kamegawa, H. Yamashita, Chem. Eur. J. 2014, 20,
8348–8354; d) A. Haimov, R. Neumann, Chem. Commun. 2002, 876–877;
e) L. Chen, Y. Yang, D. Jiang, J. Am. Chem. Soc. 2010, 132, 9138–9143;
f) I. Klement, H. Lütjens, P. Knochel, Angew. Chem. Int. Ed. 1997, 36,
1454–1456; Angew. Chem. 1997, 109, 1605–1607; g) S. Chatterjee, T. K.
Paine, Angew. Chem. Int. Ed. 2015, 54, 9338–9342; Angew. Chem. 2015,
127, 9470–9474; h) X.-D. Li, R. Ma, L.-N. He, Chin. Chem. Lett. 2015, 26,
539–542; i) A. Rezaeifard, M. Jafarpour, A. Naeimi, R. Haddad, Green
Chem. 2012, 14, 3386–3394.
[9] a) K.-J. Liu, J.-H. Deng, J. Yang, S.-F. Gong, Y.-W. Lin, J.-Y. He, Z. Cao, W.-
M. He, Green Chem. 2020, 22, 433–438; b) M. V. Gómez, R. Caballero, E.
Vázquez, A. Moreno, A. de la Hoz, A. Díaz-Ortiz, Green Chem. 2007, 9,
331–336; c) H. Togo, T. Nabana, K. Yamaguchi, J. Org. Chem. 2000, 65,
8391–8394; d) N. Shapiro, M. Kramer, I. Goldberg, A. Vigalok, Green
Chem. 2010, 12, 582–584; e) H. Yu, Z. Li, C. Bolm, Org. Lett. 2018, 20,
7104–7106; f) T. Chinnusa, O. Reiser, ChemSusChem 2010, 3, 1040–1042;
g) E. Baciocchi, C. Chiappe, T. D. Giacco, C. Fasciani, O. Lanzalunga, A.
Lapi, B. Melai, Org. Lett. 2009, 11, 1413–1416.
[10] a) Y. Li, S. A. Rizvi, D. Hu, D. Sun, A. Gao, Y. Zhou, J. Li, X. Jiang, Angew.
Chem. Int. Ed. 2019, 58, 13499–13560; Angew. Chem. 2019, 131, 13633–
13640; b) Q. Liu, L. Wang, H. Yue, J.-S. Li, Z. Luo, W. Wei, Green Chem.
2019, 21, 1609–1613; c) H. Cui, W. Wei, D. Yang, Y. Zhang, H. Zhao, L.
Wang, H. Wang, Green Chem. 2017, 19, 3520–3524; d) X. Lang, W. Hao,
W. R. Leow, S. Li, J. Zhao, X. Chen, Chem. Sci. 2015, 6, 5000–5005; e) W.
Iali, P.-H. Lanoe, S. Torelli, D. Jouvenot, F. Loiseau, C. Lebrun, O. Hamelin,
S. Ménage, Angew. Chem. Int. Ed. 2015, 54, 8415–8419; Angew. Chem.
2015, 127, 8535–8539; f) X. Lang, J. Zhao, X. Chen, Angew. Chem. Int. Ed.
2016, 55, 4697–4700; Angew. Chem. 2016, 128, 4775–4778; g) K.-J. Liu, Z.
Wang, L.-H. Lu, J.-Y. Chen, F. Zeng, Y.-W. Lin, Z. Cao, X. Yu, W.-M. He,
Green Chem. 2021, 23, 496–500; h) X. Gu, X. Li, Y. Chai, Q. Yang, P. Li, Y.
Yao, Green Chem. 2013, 15, 357–361; i) Q. Li, X. Lan, G. An, L. Ricardez-
Sandoval, Z. Wang, G. Bai, ACS Catal. 2020, 10, 6664–6675; j) T. Nevesely,
E. Svobodová, J. Chudoba, M. Sikorski, R. Cibulka, Adv. Synth. Catal.
2016, 358, 1654–1663; k) L. Liu, B. Zhang, X. Tan, D. Tan, X. Cheng, B.
Han, J. Zhang, Chem. Commun. 2020, 56, 4567–4570; l) X. Lang, W. R.
Leow, J. Zhao, X. Chen, Chem. Sci. 2015, 6, 1075–1082; m) H. Hao, Z.
Wang, J.-L. Shi, X. Li, X. Lang, ChemCatChem 2018, 10, 4545–4554; n) J.
Wang, X. Xu, Y. Liu, Z. Wang, P. Wang, Z. Zheng, H. Cheng, Y. Dai, B.
Huang, ChemSusChem 2020, 13, 3488–3494; o) W. Zhao, C. Yang, J.
Huang, X. Jin, Y. Deng, L. Wang, F. Su, H. Xie, P. K. Wong, L. Ye, Green
Chem. 2020, 22, 4884–4889.
[13] Y. Jiang, K. Xu, C. Zeng, Chem. Rev. 2018, 118, 4485–4540.
[14] G. Laudadio, N. J. W. Straathof, M. D. Lanting, B. Knoops, V. Hessel, T.
Noël, Green Chem. 2017, 19, 4061–4066.
[15] L. Ma, H. Zhou, M. Xu, P. Hao, X. Kong, H. Duan, Chem. Sci. 2021, 12,
938–945.
[16] Y. Liang, S.-H. Shi, R. Jin, X. Qiu, J. Wei, H. Tan, X. Jiang, X. Shi, S. Song, N.
Jiao, Nat. Catal. 2021, 4, 116–123.
[17] Z. Chen, W. Jin, Y. Xia, Y. Zhang, M. Xie, S. Ma, C. Liu, Org. Lett. 2020, 22,
8261–8266.
[18] a) W. Jin, P. Zheng, W.-T. Wong, G.-L. Law, Adv. Synth. Catal. 2017, 359,
1588–1593; b) Z. Cheng, W. Jin, C. Liu, Org. Chem. Front. 2019, 6, 841–
845.
[19] a) X. Dong, R. Wang, W. Jin, C. Liu, Org. Lett. 2020, 22, 3062–3066; b) Z.
Cheng, P. Sun, A. Tang, W. Jin, C. Liu, Org. Lett. 2019, 21, 8925–8929.
[20] H. Ishii, N. Yamada, T. Fuchigami, Chem. Commun. 2000, 1617–1618..
Manuscript received: May 19, 2021
Revised manuscript received: June 24, 2021
Accepted manuscript online: June 25, 2021
Eur. J. Org. Chem. 2021, 3743–3747
www.eurjoc.org
3747
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