Electrochemically enabled sulfonylation of alkynes with sodium sulfinates

Article abstract of DOI:10.1021/acs.orglett.0c02341

An electrochemical sulfonylation of alkynes with sodium sulfinates was achieved for the first time at room temperature. Employing this electrolysis strategy, the reaction occurs efficiently under transition-metal-free, external oxidant-free, and base-free conditions and furnishes diverse alkynyl sulfones in satisfactory yield with broad functional group tolerance.

Full text of DOI:10.1021/acs.orglett.0c02341

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Letter
Electrochemically Enabled Sulfonylation of Alkynes with Sodium
Sulfinates
Xiangtai Meng, Hehua Xu, Xiaoji Cao, Xu-Min Cai, Jinyue Luo, Fei Wang, and Shenlin Huang*
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ABSTRACT: An electrochemical sulfonylation of alkynes with
sodium sulfinates was achieved for the first time at room
temperature. Employing this electrolysis strategy, the reaction
occurs efficiently under transition-metal-free, external oxidant-free,
and base-free conditions and furnishes diverse alkynyl sulfones in
satisfactory yield with broad functional group tolerance.
Scheme 1. Coupling Reaction of Alkynes
ulfones, one of the important organosulfur compounds, are
S
frequently found in natural products,1 pharmaceuticals,2
and drug candidates.3 Among them, alkynyl sulfones are
valuable synthetic intermediates in cycloadditions,4 conjugated
additions,5 cross-coupling reactions,6 and others;7 meanwhile,
many alkynyl sulfone molecules exhibit remarkable biological
activities. Thus several classical synthetic methods, including
the oxidation of alkynyl sulfides,8 oxidation−elimination of
selenides,9 and dehydrohalogenation of vinyl sulfones,10 have
been well established for the preparation of these alkynyl
sulfones. However, these protocols generally require predeco-
rated substrates or multiple synthetic steps.
Nowadays, C−S coupling reactions have become a reliable
and direct approach to produce alkynyl sulfones. For example,
the reactions of alkyl halides or acetylenic acids with sodium
sulfinates or sulfonyl hydrazides afforded alkynyl sulfone
compounds, which typically use transition-metal catalysts and
excess oxidants.11 In addition, several difunctionalizations of
alkynes with sodium sulfonates have been known. In 2014,
Lipshutz et al.12 reported a reaction between arylalkynes and
sodium arylsulfinates, providing β-ketosulfones in nanomicelles
(Scheme 1a). Jiang13 and Liu14 developed a mild iodosulfo-
nylation reaction of alkynes with sodium sulfinates promoted
by stoichiometric N-iodosuccinimide (NIS) or I2, respectively
(Scheme 1b). In contrast, iodoalkenyl sulfides were isolated
from the reaction of alkynes and sodium sulfinates in the
presence of excess I2 and PPh3, which was discovered by Lu
and coworkers (Scheme 1c).15 In 2016, Kuhakarn and
coworkers described an iodine-catalyzed sulfonylation of
arylacetylenes with sodium sulfinates using stoichiometric
tert-butyl hydroperoxide (TBHP) as the oxidant (Scheme
1d).16 However, electron-deficient arylacetylenes and arylsulfi-
nates were proved to be ineffective substrates. Despite these
advances, the development of a direct approach to access
alkynyl sulfones from terminal alkynes and sodium sulfinates
under mild conditions is still strongly desired. To date, organic
electrosynthesis, as an environmentally friendly method, has
recently been applied to cross-coupling reactions.17 Very
recently, an elegant electrochemical approach for the
sulfonylation of arylalkynes with arylsulfinates was reported
by Tang and Huang (Scheme 1e).18 Whereas this report
reflects an external oxidant-free sulfonylation, it requires a
reference electrode, an external base, and high reaction
temperature. Therefore, we would like to find a very simple
electrochemical synthetic protocol to produce alkynyl sulfones
Received: July 14, 2020
https://dx.doi.org/10.1021/acs.orglett.0c02341
© XXXX American Chemical Society
Org. Lett. XXXX, XXX, XXX−XXX
A

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a b
,
under a design philosophy that is free of metal, external
oxidant, and base and has a broad substrate scope.
Scheme 2. Scope of Terminal Alkynes
Herein we report an electrochemically enabled direct
sulfonylation of alkynes with sodium sulfinates as the sulfonyl
reagent (Scheme 1f). This electrochemical synthesis19 occurs
in an undivided cell under constant current conditions at room
temperature. Our method offers efficient access to diverse
alkynyl sulfones without any oxidizing reagents, bases, or
transition metals. Moreover, sodium sulfinates, which are
commercially available, bench-stable, and easily handled, are
regarded as a sustainable sulfonyl source for the direct coupling
reaction.
Initially, phenylacetylene 1a and sodium p-toluenesulfinate
2a were chosen as the model substrates to optimize the
sulfonylation in an undivided cell, as shown in Table 1.
a
Table 1. Reaction Optimization
b
entry
variation from standard conditions
none
graphite as the cathode
graphite as the anode
C (+) | Ni (−) instead of Pt (+) | Pt (−)
TBAI instead of KI
NaI instead of TBAI
n-Bu4NBF4 instead of KI
without H2O
DMSO instead of CH3CN
MeOH instead of CH3CN
5 mA, 10 h
yield
1
2
3
4
5
6
7
8
93%
22%
74%
48%
52%
36%
0
trace
0
9
10
11
12
0
60%
73%
15 mA, 4 h
a
Standard conditions: 1 (0.3 mmol), 2a (3.0 equiv), KI (1 equiv),
a
Standard conditions: 1a (0.3 mmol), 2a (3.0 equiv), KI (1 equiv),
b
H2O (0.1 mL), and MeCN (10.0 mL), 10 mA, rt, 7 h. Isolated yield.
H2O (0.1 mL), and MeCN (10.0 mL), undivided cell, 10 mA, rt, 7 h.
b
HPLC yields were determined with naphthalene as the internal
standard.
with sodium p-toluenesulfinate 2a, the reaction showed broad
compatibility with various substituents on the benzene ring
(3aa−oa). A range of functional groups, including alkyl (3ba−
da), methoxyl (3ea and 3fa), halogen (3ga−ja), aldehyde
(3ka), ester (3la), nitrile (3ma), nitro (3na), silane (3oa), and
ketone (3pa), were all left intact under the reaction conditions.
In general, terminal phenylacetylenes bearing electron-
donating groups were more efficient than those bearing
electron-withdrawing groups, and ortho-, meta-, and para-
position patterns had little effect on the reaction performance.
Notably, natural product estrone could be converted into 3pa
with the developed protocol. Finally, 2-ethynylthiophene 1q
could also be an appropriate candidate, furnishing the
corresponding alkynyl sulfone 3qa in good yield.
Next, we tested a variety of sodium sulfinates under our
conditions (Scheme 3). Sodium benzenesulfinate 2b and
sodium p-(tert-butyl)benzenesulfinate 2c were found to be
effective for the conversion of phenylacetylene 1a to alkynyl
sulfones 3ab and 3ac. The reaction of sodium 2,4,6-
trimethylbenzenesulfinate 2d with 1a afforded the sulfonyla-
tion product 3ad in a lower yield, likely as a result of the
increased steric effect. Sodium arenesulfinates bearing halogens
(F, Cl, Br), trifluoromethyl (CF3), and nitrile (CN) were all
tolerated in this sulfonylation reaction, affording 3ae−ai in
moderate to good yields. Besides arylsulfinates, it was
Gratifyingly, the desired acetylenic sulfone 3aa was indeed
isolated in 93% yield with two platinum electrodes under 10
mA current electrolysis at room temperature using KI as the
electyrolyte and MeCN/H2O as the solvent (Table 1, entry 1).
A significant decrease in yields was observed when we replaced
the platinum electrode with graphite or a nickel electrode
(Table 1, entries 2−4). Other iodide salts, such as
tetrabutylammonium iodide (TBAI) and NaI, were then
examined as the electrolyte. Unfortunately, a lower reaction
efficiency was observed (Table 1, entries 5 and 6). No reaction
was observed with n-Bu4NBF4 as the supporting electrolyte
(Table 1, entry 7), suggesting that the iodide could also be a
redox mediator in this transformation. Only a trace amount of
3aa could be obtained when the reaction was conducted in
anhydrous CH3CN (Table 1, entry 8), indicating that H2O was
necessary, as it might participate in the reaction process and
also increase the solubility of the salts. The sulfonylation did
not occur when DMSO or MeOH was used instead of CH3CN
(Table 1, entries 9 and 10). Changing the current was found to
reduce the reaction performance (Table 1, entries 11 and 12).
With the optimized electrochemical sulfonylation conditions
in hand, we then investigated the scope of terminal alkynes
(Scheme 2). When terminal phenylacetylenes 1 was reacted
B
https://dx.doi.org/10.1021/acs.orglett.0c02341
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Letter
a b
,
Scheme 3. Scope of Sodium Sulfinates
Scheme 4. Control Experiments
a
Standard conditions: 1a (0.3 mmol), 2 (3.0 equiv), KI (1 equiv),
b
H2O (0.1 mL), and MeCN (10.0 mL), 10 mA, rt, 7 h. Isolated yield.
interesting to discover that sodium ethanesulfinate 2j was also
a suitable substrate, leading to acetylenic alkylsulfone 3aj,
which cannot be prepared using a previous electrochemical
approach.18
To shed light on the reaction mechanism of this electro-
chemical sulfonylation, several control experiments were
carried out (Scheme 4). First, when 2.0 equiv of 2,2,6,6-
tetramethyl-1-piperidinoxy (TEMPO) or 2,6-di-tert-butyl-p-
toluenol (BHT) was added to the reaction of 1a and 2a under
the standard conditions, the desired product 3aa could not be
detected (Scheme 4a), indicating that the sulfonylation might
involve a radical pathway. Consequently, phenylethynyl iodide
was prepared and subsequently treated with 2a under the
standard conditions, and no reaction was observed (Scheme
4b). This result suggests that phenylethynyl iodide is not
involved in this reaction. As expected, only (E)-β-iodo
vinylsulfone 4aa was isolated from the reaction of 1a and 2a
in the presence of stoichiometric I2 without electricity (Scheme
4c), which is consistent with Liu’s work14 (Scheme 1c). In
contrast, with electrolysis of the same reaction mixture,
acetylenic sulfone 3aa was furnished in high yield (Scheme
4d). These results indicate that electrolysis is still required after
the generation of I2. Finally, 4aa was converted to 3aa in 89%
isolated yield under the standard conditions (Scheme 4e),
thereby suggesting that it might be an intermediate in this
transformation.
On the basis of the previously described experiments and
cyclic voltammetric (CV) results (see the Supporting
Information), a plausible pathway for this sulfonylation is
proposed in Scheme 5. Initially, molecular iodine is formed
from the anodic oxidation of iodide anion,19g which is
confirmed by two oxidation peaks of KI at 1.10 and 1.65 V
vs Ag/AgCl (I− to I3− to I2, red curve, Figure S1). At the same
time, sodium sulfinate 2a does not undergo anodic oxidation
(blue curve, Figure S1). Afterward, the in situ-generated I2
reacts with sodium sulfinate 2 to afford sulfonyl iodide 5,
which readily undergoes homolytic cleavage to produce the
Scheme 5. Possible Mechanism
sulfur-centered sulfonyl radical A. The subsequent addition of
A to alkyne 1 affords vinyl radical B, which is then oxidized at
the anode, giving vinyl cation C.20 The desired product 3 is
finally obtained by a deprotonation of intermediate C or D.
Simultaneously, the cathodic reduction of H2O produces
hydrogen gas and a hydroxide ion.
In conclusion, we have reported an electrochemically direct
coupling of terminal alkynes and sodium aryl or alkyl sulfinates
at room temperature for the first time. The reaction was
performed under mild reaction conditions and does not
require any exogenous oxidants, bases, or transition metals. In
addition, a range of valuable alkynyl sulfones can be
constructed using this eco-friendly protocol, and this protocol
tolerated many functional groups.
C
https://dx.doi.org/10.1021/acs.orglett.0c02341
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ASSOCIATED CONTENT
ACKNOWLEDGMENTS
■
■
sı
We acknowledge the financial support from the Natural
Science Foundation of China (21502094, 21601087, and
21602200), the Natural Science Foundation of Jiangsu
Province (BK20181401), as well as the Natural Science
Foundation of the Jiangsu Higher Education Institutions of
China (17KJA220003). We are also grateful for support from
the advanced analysis and testing center of Nanjing Forestry
University.
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.orglett.0c02341.
Experimental procedures and characterization data
(PDF)
AUTHOR INFORMATION
■
REFERENCES
■
Corresponding Author
(1) Dunbar, K. L.; Scharf, D. H.; Litomska, A.; Hertweck, C.
Enzymatic Carbon-Sulfur Bond Formation in Natural Product
Biosynthesis. Chem. Rev. 2017, 117, 5521.
(2) (a) Zhao, C.; Rakesh, K. P.; Ravidar, L.; Fang, W.-Y.; Qin, H.-L.
Pharmaceutical and medicinal significance of sulfur (SVI)-Containing
motifs for drug discovery: A critical review. Eur. J. Med. Chem. 2019,
162, 679. (b) Ilardi, E. A.; Vitaku, E.; Njardarson, J. T. Data-Mining
for Sulfur and Fluorine: An Evaluation of Pharmaceuticals To Reveal
Opportunities for Drug Design and Discovery. J. Med. Chem. 2014,
57, 2832.
Shenlin Huang − Jiangsu Provincial Key Lab for the Chemistry
and Utilization of Agro-Forest Biomass, College of Chemical
Engineering, Jiangsu Key Lab of Biomass-Based Green Fuels and
Chemicals, Jiangsu Co-Innovation Center of Efficient Processing
and Utilization of Forest Resources, Nanjing Forestry University,
Nanjing 210037, P. R. China; orcid.org/0000-0001-7322-
6981; Email: shuang@njfu.edu.cn
Authors
(3) (a) Aranapakam, V.; Grosu, G. T.; Davis, J. M.; Hu, B.;
Ellingboe, J.; Baker, J. L.; Skotnicki, J. S.; Zask, A.; DiJoseph, J. F.;
Sung, A.; Sharr, M. A.; Killar, L. M.; Walter, T.; Jin, G.; Cowling, R.
Synthesis and Structure-Activity Relationship of α-Sulfonylhydroxa-
mic Acids as Novel, Orally Active Matrix Metalloproteinase Inhibitors
for the Treatment of Osteoarthritis. J. Med. Chem. 2003, 46, 2361.
(b) Artico, M.; Silvestri, R.; Pagnozzi, E.; Bruno, B.; Novellino, E.;
Greco, G.; Massa, S.; Ettorre, A.; Loi, A. G.; Scintu, F.; La Colla, P.
Structure-Based Design, Synthesis, and Biological Evaluation of Novel
Pyrrolyl Aryl Sulfones: HIV-1 Non-Nucleoside Reverse Transcriptase
Inhibitors Active at Nanomolar Concentrations. J. Med. Chem. 2000,
43, 1886.
(4) (a) Zhou, X.; Yu, S.; Qi, Z.; Li, X. Rhodium(III)-catalyzed [3 +
2] annulative coupling between oximes and electron-deficient alkynes.
Sci. China: Chem. 2015, 58, 1297. (b) Todoroki, H.; Iwatsu, M.;
Urabe, D.; Inoue, M. Total Synthesis of (−)-4-Hydroxyzinowol. J.
Org. Chem. 2014, 79, 8835. (c) Kawai, H.; Yuan, Z.; Tokunaga, E.;
Shibata, N. Regioselective Synthesis of Pyrazole Triflones Based on
Triflyl Alkyne Cycloadditions. Org. Lett. 2012, 14, 5330. (d) Riddell,
N.; Tam, W. Ruthenium-Catalyzed [2 + 2] Cycloadditions of Alkynyl
Sulfides and Alkynyl Sulfones. J. Org. Chem. 2006, 71, 1934.
(e) Paquette, L. A.; Fischer, J. W.; Browne, A. R.; Doecke, C. W.
Synthesis of [4]peristylane and functionalized derivatives of this
hemispherical ring system. J. Am. Chem. Soc. 1985, 107, 686.
(f) Paquette, L. A.; Browne, A. R.; Doecke, C. W.; Williams, R. V.
Short, stereocontrolled synthesis of [4]peristylane. J. Am. Chem. Soc.
1983, 105, 4113.
(5) (a) Huang, X.; Duan, D.; Zheng, W. Studies on Hydro-
zirconation of 1-Alkynyl Sulfoxides or Sulfones and the Application
for the Synthesis of Stereodefined Vinyl Sulfoxides or Sulfones. J. Org.
Chem. 2003, 68, 1958. (b) Xie, M.; Wang, J.; Gu, X.; Sun, Y.; Wang,
S. Highly Regio- and Stereoselective Synthesis of Tetrasubstituted
Olefins by the Three-Component Tandem Reaction of Allylzinc
Bromide, Acetylenic Sulfone, and Halohydrocarbon. Org. Lett. 2006,
8, 431.
(6) (a) Guo, A.; Han, J.-B.; Zhu, L.; Wei, Y.; Tang, X.-Y. Site-
Selective α-Alkoxyl Alkynation of Alkyl Esters Mediated by Boryl
Radicals. Org. Lett. 2019, 21, 2927. (b) Jin, W.; Wu, M.; Xiong, Z.;
Zhu, G. Visible-light induced three-component alkynyl-difluoroalky-
lation of unactivated alkenes. Chem. Commun. 2018, 54, 7924.
Xiangtai Meng − Jiangsu Provincial Key Lab for the Chemistry
and Utilization of Agro-Forest Biomass, College of Chemical
Engineering, Jiangsu Key Lab of Biomass-Based Green Fuels and
Chemicals, Jiangsu Co-Innovation Center of Efficient Processing
and Utilization of Forest Resources, Nanjing Forestry University,
Nanjing 210037, P. R. China
Hehua Xu − Jiangsu Provincial Key Lab for the Chemistry and
Utilization of Agro-Forest Biomass, College of Chemical
Engineering, Jiangsu Key Lab of Biomass-Based Green Fuels and
Chemicals, Jiangsu Co-Innovation Center of Efficient Processing
and Utilization of Forest Resources, Nanjing Forestry University,
Nanjing 210037, P. R. China
Xiaoji Cao − College of Chemical Engineering, Zhejiang
University of Technology, Hangzhou, Zhejiang 310014, P. R.
China
Xu-Min Cai − Jiangsu Provincial Key Lab for the Chemistry and
Utilization of Agro-Forest Biomass, College of Chemical
Engineering, Jiangsu Key Lab of Biomass-Based Green Fuels and
Chemicals, Jiangsu Co-Innovation Center of Efficient Processing
and Utilization of Forest Resources, Nanjing Forestry University,
Nanjing 210037, P. R. China; orcid.org/0000-0003-2567-
213X
Jinyue Luo − Jiangsu Provincial Key Lab for the Chemistry and
Utilization of Agro-Forest Biomass, College of Chemical
Engineering, Jiangsu Key Lab of Biomass-Based Green Fuels and
Chemicals, Jiangsu Co-Innovation Center of Efficient Processing
and Utilization of Forest Resources, Nanjing Forestry University,
Nanjing 210037, P. R. China
Fei Wang − Jiangsu Provincial Key Lab for the Chemistry and
Utilization of Agro-Forest Biomass, College of Chemical
Engineering, Jiangsu Key Lab of Biomass-Based Green Fuels and
Chemicals, Jiangsu Co-Innovation Center of Efficient Processing
and Utilization of Forest Resources, Nanjing Forestry University,
Nanjing 210037, P. R. China; orcid.org/0000-0001-6428-
5111
Complete contact information is available at:
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̈
(c) Schwarz, J.; Konig, B. Decarboxylative Alkynylation of Biomass-
Derived Compounds by Metal-Free Visible Light Photocatalysis.
ChemPhotoChem. 2017, 1, 237. (d) Fang, K.; Xie, M.; Zhang, Z.;
Ning, P.; Shu, G. Nickel-catalyzed cross-coupling reaction of
acetylenic sulfones with alkynyl Grignard reagents: a facile method
Notes
The authors declare no competing financial interest.
D
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Letter
for the preparation of unsymmetrical 1,3-diynes. Tetrahedron Lett.
2013, 54, 3819.
(7) Chen, H.; Zhang, L. A Desulfonylative Approach in Oxidative
Gold Catalysis: Regiospecific Access to Donor-Substituted Acyl Gold
Carbenes. Angew. Chem., Int. Ed. 2015, 54, 11775.
(8) Guerrero-Robles, M. A.; Vilchis-Reyes, M. A.; Ramos-Rivera, E.
M.; Alvarado, C. Synthesis of Alkynyl Sulfones. ChemistrySelect 2019,
4, 13698.
Electrochemical Oxidative Cross-Coupling with Hydrogen Evolution
Reactions. Acc. Chem. Res. 2019, 52, 3309. (c) Jiang, Y.; Xu, K.; Zeng,
C. Use of Electrochemistry in the Synthesis of Heterocyclic
Structures. Chem. Rev. 2018, 118, 4485. (d) Yan, M.; Kawamata, Y.;
Baran, P. S. Synthetic Organic Electrochemical Methods Since 2000:
On the Verge of a Renaissance. Chem. Rev. 2017, 117, 13230.
(e) Francke, R.; Little, R. D. Redox catalysis in organic electrosyn-
thesis: basic principles and recent developments. Chem. Soc. Rev.
2014, 43, 2492. (f) Frontana-Uribe, B. A.; Little, R. D.; Ibanez, J. G.;
Palma, A.; Vasquez-Medrano, R. Organic electrosynthesis: a
promising green methodology in organic chemistry. Green Chem.
2010, 12, 2099.
(9) (a) Qian, H.; Huang, X. Polystyrene-supported selenosulfonates:
efficient reagents for the synthesis of acetylenic sulfones. Tetrahedron
Lett. 2002, 43, 1059. (b) Bhaskar reddy, D.; Chandrasekhar babu, N.;
Padmavathi, V.; Padmaja, A. A Simple Strategy for Styryl Sulfonyl
Ethynylogues and 1,4-Diarylbut-l-en-3-ynes. Tetrahedron 1997, 53,
17351. (c) Back, T. G.; Muralidharan, K. R. Free-Radical
Selenosulfonation of Vinylcyclopropanes, a Cyclopropylidene, and
Cyclopropylacetylene. Relative Rates of Chain-Transfer, Ring-Open-
ing, and Inversion in Radical Intermediates. J. Org. Chem. 1989, 54,
121. (d) Back, T. G.; Collins, S.; Kerr, R. G. Selenosulfonation of
Acetylenes: Preparation of Novel β-(Phenylseleno)vinyl Sulfones and
Their Conversion to Acetylenic and β-Functionalized Sulfones. J. Org.
Chem. 1983, 48, 3077.
(10) (a) Wei, W.; Wen, J.; Yang, D.; Jing, H.; You, J.; Wang, H.
Direct difunctionalization of alkynes with sulfinic acids and molecular
iodine: a simple and convenient approach to (E)-β-iodovinyl sulfones.
RSC Adv. 2015, 5, 4416. (b) Nair, V.; Augustine, A.; Suja, T. D. CAN
Mediated Reaction of Aryl Sulfinates with Alkenes and Alkynes:
Synthesis of Vinyl Sulfones, β-Iodovinyl Sulfones and Acetylenic
Sulfones. Synthesis 2002, 2259. (c) Corey, E. J.; Da Silva Jardine, P. A
short and efficient enantioselective route to a key intermediate for the
total synthesis of forskolin. Tetrahedron Lett. 1989, 30, 7297.
(11) (a) Wang, L.; Wei, W.; Yang, D.; Cui, H.; Yue, H.; Wang, H.
Direct cross-coupling of aryl alkynyliodines with arylsulfinic acids
leading to alkynyl sulfones under catalyst-free conditions. Tetrahedron
Lett. 2017, 58, 4799. (b) Chen, P.; Zhu, C.; Zhu, R.; Wu, W.; Jiang,
H. MnO2 -Promoted Oxidative Radical Sulfonylation of Haloalkynes
with Sulfonyl Hydrazides: C(sp)-S Bond Formation towards Alkynyl
Sulfones. Chem. - Asian J. 2017, 12, 1875. (c) Singh, R.; Allam, B. K.;
Singh, N.; Kumari, K.; Singh, S. K.; Singh, K. N. A Direct Metal-Free
Decarboxylative Sulfono Functionalization (DSF) of Cinnamic Acids
to α, β-Unsaturated Phenyl Sulfones. Org. Lett. 2015, 17, 2656.
(d) Hamnett, D. J.; Moran, W. J. Improving alkynyl(aryl)iodonium
salts: 2-anisyl as a superior aryl group. Org. Biomol. Chem. 2014, 12,
4156.
(18) Mo, Z.-Y.; Zhang, Y.-Z.; Huang, G.-B.; Wang, X.-Y.; Pan, Y.-M.;
Tang, H.-T. Electrochemical Sulfonylation of Alkynes with Sulfonyl
Hydrazides: A Metal- and Oxidant-Free Protocol for the Synthesis of
Alkynyl Sulfones. Adv. Synth. Catal. 2020, 362, 2160.
(19) (a) Yavari, I.; Shaabanzadeh, S. Electrochemical Synthesis of β-
Ketosulfones from Switchable Starting Materials. Org. Lett. 2020, 22,
464. (b) Wu, Y.-C.; Jiang, S.-S.; Luo, S.-Z.; Song, R.-J.; Li, J.-H.
Transition-metal- and oxidant-free directed anodic C-H sulfonylation
of N,N-disubstituted anilines with sulfinates. Chem. Commun. 2019,
55, 8995. (c) Wang, Y.; Deng, L.; Wang, X.; Wu, Z.; Wang, Y.; Pan, Y.
Electrochemically Promoted Nickel-Catalyzed Carbon−Sulfur Bond
Formation. ACS Catal. 2019, 9, 1630. (d) He, T.-J.; Ye, Z.; Ke, Z.;
Huang, J.-M. Stereoselective synthesis of sulfur-containing β-
enaminonitrile derivatives through electrochemical Csp3-H bond
oxidative functionalization of acetonitrile. Nat. Commun. 2019, 10,
833. (e) Wen, J.; Shi, W.; Zhang, F.; Liu, D.; Tang, S.; Wang, H.; Lin,
X.-M.; Lei, A. Electrooxidative Tandem Cyclization of Activated
Alkynes with Sulfinic Acids To Access Sulfonated Indenones. Org.
Lett. 2017, 19, 3131. (f) Wang, P.; Tang, S.; Huang, P.; Lei, A.
Electrocatalytic Oxidant-Free Dehydrogenative C-H/S-H Cross-
Coupling. Angew. Chem., Int. Ed. 2017, 56, 3009. (g) Jiang, Y.-Y.;
Wang, Q.-Q.; Liang, S.; Hu, L.-M.; Little, R. D.; Zeng, C.-C.
Electrochemical Oxidative Amination of Sodium Sulfinates: Synthesis
of Sulfonamides Mediated by NH4I as a Redox Catalyst. J. Org. Chem.
2016, 81, 4713.
(20) (a) Meng, X.; Zhang, Y.; Luo, J.; Wang, F.; Cao, X.; Huang, S.
Electrochemical Oxidative Oxydihalogenation of Alkynes for the
Synthesis of α, α-Dihaloketones. Org. Lett. 2020, 22, 1169. (b) Wille,
U. Radical Cascades Initiated by Intermolecular Radical Addition to
Alkynes and Related Triple Bond Systems. Chem. Rev. 2013, 113, 813.
(12) Handa, S.; Fennewald, J. C.; Lipshutz, B. H. Aerobic Oxidation
in Nanomicelles of Aryl Alkynes, in Water at Room Temperature.
Angew. Chem., Int. Ed. 2014, 53, 3432.
(13) Gao, Y.; Wu, W.; Huang, Y.; Huang, K.; Jiang, H. NBS-
promoted halosulfonylation of terminal alkynes: highly regio- and
stereoselective synthesis of (E)-β-halo vinylsulfones. Org. Chem. Front.
2014, 1, 361.
(14) Sun, Y.; Abdukader, A.; Lu, D.; Zhang, H.; Liu, C. Synthesis of
(E)-β-iodo vinylsulfones via iodine-promoted iodosulfonylation of
alkynes with sodium sulfinates in an aqueous medium at room
temperature. Green Chem. 2017, 19, 1255.
(15) (a) Lin, Y.-M.; Lu, G.-P.; Wang, G.-X.; Yi, W.-B. Acid/
Phosphide-Induced Radical Route to Alkyl and Alkenyl Sulfides and
Phosphonothioates from Sodium Arylsulfinates in Water. J. Org.
Chem. 2017, 82, 382. (b) Lin, Y.-M.; Lu, G.-P.; Cai, C.; Yi, W.-B.
Odorless, One-Pot Regio- and Stereoselective Iodothiolation of
Alkynes with Sodium Arenesulfinates under Metal-Free Conditions
in Water. Org. Lett. 2015, 17, 3310.
(16) Meesin, J.; Katrun, P.; Pareseecharoen, C.; Pohmakotr, M.;
Reutrakul, V.; Soorukram, D.; Kuhakarn, C. Iodine-catalyzed
Sulfonylation of Arylacetylenic Acids and Arylacetylenes with Sodium
Sulfinates: Synthesis of Arylacetylenic Sulfones. J. Org. Chem. 2016,
81, 2744.
(17) (a) Kingston, C.; Palkowitz, M. D.; Takahira, Y.; Vantourout, J.
C.; Peters, B. K.; Kawamata, Y.; Baran, P. S. A Survival Guide for the
″Electro-curious″. Acc. Chem. Res. 2020, 53, 72. (b) Yuan, Y.; Lei, A.
E
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