Visible-Light-Catalyzed in Situ Denitrogenative Sulfonylation of Sulfonylhydrazones

Article abstract of DOI:10.1021/acs.orglett.1c02369

A photocatalyzed in situ denitrogenative sulfonylation of N-arylsulfonyl hydrazones has been developed. This transformation provides a low-carbon strategy to assemble arylalkyl sulfones in a stepwise denitrogenation/sulfonylation manner.

Full text of DOI:10.1021/acs.orglett.1c02369

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Letter
Visible-Light-Catalyzed in Situ Denitrogenative Sulfonylation of
Sulfonylhydrazones
Xiang Huang, Xing Chen, Haisheng Xie,* Zheng Tan, Huanfeng Jiang, and Wei Zeng*
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ABSTRACT: A photocatalyzed in situ denitrogenative sulfonylation of N-arylsulfonyl
hydrazones has been developed. This transformation provides a low-carbon strategy to
assemble arylalkyl sulfones in a stepwise denitrogenation/sulfonylation manner.
denitrogenative process of aza-compounds provides an
efficient strategy to produce carbenoids and radicals,
Scheme 1. Synthetic Strategies of Aryl-Alkyl Sulfones
A
which are active species often encountered in modern
synthetic chemistry.1 Traditionally, transition-metal-catalyzed
denitrogenation−coupling of multinitrogen compounds with
arenes,2 alkanes,3 alkenes,4 alkynes,5 amines,6 aldehydes,7 and
others8 have been widely explored to assemble complex
molecules. In comparison, photocatalyzed denitrogenation
transformations were still not well-established. To date, only
diazo compounds and sulfonylazides were reported to be
converted to carbenoids,9 ketenes,10 nitrenes,11 and radicals12
via denitrogenation under visible light conditions, and the
corresponding intermediates could be further trapped by
ketoimines, indoles, and alkenes. Few protocols of photo-
catalyzed denitrogenation of hydrazones have been developed
for synthetic transformations.
The sulfonyl moiety generally endows the corresponding
sulfone molecules with distinctive reactivities, biological
activities, and photophysical properties.13 Exploring efficient
strategies to access different sulfones have recently aroused
increasing interest in the field of pharmaceutical industry and
material chemistry.14 Although the oxidation of sulfides can
deliver arylsulfone compounds,15 this method requires large
amounts of strong oxidants which still limit functional group
tolerance. To surmount these drawbacks, transition-metal-
catalyzed sulfonylation of “SO2” sources with various coupling
partners has been successively developed in the past decades.16
For examples, Willis reported a Pd-catalyzed one-pot three-
component sulfonylation of arylhalides with benzyl bromides
and a SO2-surrogate (DABSO), in which N′,N′-dialkyl
aminosulfonamides belong to key intermediates (Scheme
1a).17 Meanwhile, a photocatalytical strategy further provides
a more environment-friendly approach to sulfones under mild
conditions. In this regard, Li employed 4CzIPN/Cu(OTf)2 as
a combinated catalysis system to achieve a visible-light-
catalyzed decarboxylative radical sulfonylation of sulfinates
with redox-active aliphatic carboxylic esters (Scheme 1b).18
More recently, we still described a photocatalyzed coupling−
cyclization of sulfonylazides with vinylethers and vinylsilanes to
furnish complex oxa- and sila-cycles via denitrogenation,
respectively.19 Based on the fact that diazo esters, sulfonyla-
zides, and sulfonylhydrazones possess similar multinitrogen
skeletons, we therefore envisioned that sulfonylhydrazones
could also possibly undergo photocatalytical denitrogenation
to directly afford arylsulfones under mild conditions (Scheme
1c).
To verify this hypothesis, we employed tosylhydrazide (1a)
as a model substrate for screening various reaction parameters
and finally found that the treatment of 1a with [Ir(dtbbpy)-
(ppy)2][PF6] (2 mol %) and K2HPO4 (3.0 equiv) in DMF
(0.13 M, 1.5 mL) for 24 h at room temperature under blue
light-emitting diode (LED) radiation (30 W) and an Ar
atmosphere led to the formation of 1-methyl-4-((4-
methylbenzyl)sulfonyl)benzene 2a in 82% yield (Table 1,
entry 1). On the contrary, other photocatalysts such as Eosin
Y, TPT, Ir(ppy)3, [Mes-Acr]ClO4, and Ru(bpy)3Cl2 gave very
poor reaction conversions (entries 2−6, 0−23%). Evaluation of
different bases under the standard conditions indicated that
inorganic bases such as K2CO3 and K3PO4 could afford
Received: July 15, 2021
https://doi.org/10.1021/acs.orglett.1c02369
© XXXX American Chemical Society
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A

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a
a b
,
Table 1. Optimization of the Reaction Parameters
Scheme 2. Diazo Compound Scope
b
entry
changes to standard conditions
2a yield (%)
1
none
82
2
3
4
5
6
7
Eosin Y
TPT
Ir(ppy)3
[Mes-Acr]ClO4
Ru(bpy)3Cl2
K2CO3
trace
trace
12
0
23
56
8
K3PO4
61
9
Et3N
9
10
11
12
13
14
15
16
17
THF
DMSO
toluene
air
trace
60
13
61
c
O2
7
green LED light
no light
no photocatalysts
27
0
0
a
Reaction conditions: 0.2 mmol of 4-methyl-N′-(4-methylbenzyli-
dene) phenylsulfonohydrazide 1a, [Ir(dtbbpy)(ppy)2][PF6] (2 mol
%), and K2HPO4 (3.0 equiv) in DMF (0.2 M, 1.5 mL) under Ar
atmosphere at room temperature for 24 h, blue LED light (30 W).
b
c
Isolated yield. O2 atmosphere still led to 64% yield 4-
methylbenzaldehyde 2a-1.
moderate yields of 2a (entries 7−8, 56−61%), and organobase
Et3N only delivered a 9% yield of 2a (entry 9). Meanwhile,
replacing the solvent with THF, DMSO, and toluene did not
exhibit corresponding improvement (entries 10−12). More-
over, performing this denitrogenative coupling reaction of 1a
under an air and O2 atmosphere resulted in 61% and 7% yields
of 2a, respectively (entries 13 and 14), implying that molecular
oxygen could inhibit this transformation to some degree.20
Also, irradiating this transformation by using green LED light
gave a 27% yield of 2a (entry 15). It should be noted that this
in situ denitrogenative coupling of sulfonylhydrazone 1a did
not occur without light or the photocatalysts (entries 16 and
17).
Subsequently, we measured the substrate scope of the
visible-light-catalyzed in situ denitrogenative coupling of 4-
methylphenylsulfonyl hydrazones. As shown in Scheme 2, the
substituent on the phenyl ring (Ar1) of sulfonylhydrazones had
great influence on this transformation. Among them, electron-
rich substituents (Me− and MeO−) gave good to excellent
yields of the corresponding sulfones (2a−2f: 66−83%),
regardless of the ortho-, meta-, and para-position (2a vs 2b
and 2c). Meanwhile, weak electron-withdrawing halo group-
substituted phenyl rings (Ar1) could also afford good yields of
halobenzyl sulfones 2g−2j (61−77%). However, stronger
electron-deficient NO2-, NC-, and CF3-substituted phenyl
rings (Ar1) only generated poorer yields of products 2k−2m
(33−39%). To our delight, 1-naphthaldehyde-, 4-phenyl-
benzaldehyde-, thiophene-3-carbaldehyde-, cinnamaldehyde-,
and isonicotinaldehyde-derived N′-sulfonylhydrazones were
also well-tolerated in the reaction conditions, providing 55−
63% yields of arylalkyl sulfones 2n−2r. Again, acetophenone-,
benzophenone-, and benzocycloketone-derived sulfonylhydra-
a
All the reactions were performed using 0.2 mmol of 4-methyl-N’-(4-
methylbenzylidene) phenylsulfonohydrazide 1a, [Ir(dtbbpy)(ppy)2]-
[PF6] (2 mol %), and K2HPO4 (3.0 equiv) in DMF (0.2 M, 1.5 mL)
under an Ar atmosphere at room temperature for 24 h, blue LED light
b
c
(30 W). Isolated yield. 1.0 mmol of tosylhydrazide (1a) was used.
zones were still allowed to give the complex arylalkyl sulfones
(2s−2u) with 49−65% yields.
To examine the functional group tolerance from the
sulfonylaryl ring of hydrazones, the substituent effect from
the sulfonylaryl ring (Ar2) has been further evaluated
systematically. It was found that arylsulfonyl hydrazones
including electron-rich (MeO−) and electron-deficient
(halo-, CF3-) phenylsulfonyl hydrazones could be smoothly
converted to 63−82% yields of the corresponding products
2v−2aa. In comparison, stronger electron-withdrawing group-
substituted arylsulfonyl hydrazones easily suffered from
deprotonation, leading to excellent reaction conversions (2y,
2z, and 2aa), but switching arylsulfonylhydrazones to
methylsulfonylhydrazone did not deliver the desired alkyl/
alkylketone 2ab. The present procedure could still rapidly
B
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assemble 2-(((4-chlorophenyl)sulfonyl)methyl)-1,4-difluoro-
benzene 2ac which belongs to an important γ-secretase
inhibitor.14c Interestingly, when 2-pyridylaldehyde- and 2-
pyridylketone-derived sulfonylhydrazones were subjected to
the reaction conditions, unexpected coupling−cyclization
instead of denitrogenative coupling occurred, giving [1,2,3]-
triazolo[1,5-a]pyridines 2ad (62%) and 2ae (60%) via
intramolecular nucleophilic substitution.21 Besides, cyclo-
hexanone-derived sulfonylhydrazone was not a suitable
substrate to make 1-(cyclohexylsulfonyl)-4-methylbenzene
2af possibly due to the weak stability of cyclohexyl radicals.
The postsynthetic conversions of the sulfones indicated that
Pd(II)-catalyzed α-Csp3−H bond arylation of arylalkylsulfones
with iodobenzene could easily introduce a phenyl group into
the α-position of sulfone 2d to give diphenylmethyl p-tolyl
sulfone 2t (60%) which smoothyl underwent a cross-coupling
with 2-methylthiephenol in the presence of Sc(OTf)3 catalysts,
furnishing 2-diphenylmethyl-5-methylthiophene 3 (65% yield)
through C−S bond cleavage. Meanwhile, (CH2O)n and
alkylsulfones could be employed as electrophilic reagents to
react with arylalkylsulfone under base conditions to give
vinylsulfones 4 (70%) and 5 (63%), respectively (Scheme 3).
data suggested that carbon anion intermediates were also
involved in this reaction (Scheme 4b). Finally, merging of the
cross-coupling of hydrazones 1f and 1v synchronously led to
the formation of sulfones 2ag (20%) and 2a (17%) (Scheme
4c),23 indicating that the denitrogenative sulfonylation possibly
proceeded via a stepwise rather than concerted process.
Based on the above-menionted mechanistic investigations, a
possible reaction mechanism was proposed, shown in Scheme
5. The deprotonation of arylsulfonyl hydrazones under base
Scheme 5. Proposed Mechanism
Scheme 3. Synthetic Applications
conditions first occurred to produce nitrogen anion inter-
mediates A, followed by detosylation to deliver α-diazo-p-
xylene B,5f and denitrogenation of B could afford the
corresponding benzyl carbenoids C. Subsequently, a photo-
catalyzed single electron transfer (SET) between the excited
state *IrIII-catalysts and benzyl carbenoids C gave cationic
radicals D and Ir(II)-catalysts.12b D suffered from a
nucleophilic attack by Ts− to produce radicals E which further
underwent an SET with Ir(II)-catalysts to give the benzyl
anions F with release of Ir(III)-catalysts. Finally, the
protonation of anions F furnished the desired sulfone products
2. Also, cationic radicals D could still be trapped by TEMPO
to afford benzyl cations G which were nucelophilically attacked
by nitrogen anion intermediates A to produce the TEMPO-
tethered hydrazine 6 (Scheme 4a).
In summary, we have developed an efficient visible-light-
catalyzed in situ denitrogenative sulfonylation of sulfonylhy-
drazones. This method provides a green and low-carbon
approach to access arylalkyl sulfones under mild conditions.
Mechanistic studies indicate that a stepwise denitrogenative
sulfonylation is involved in this transformation.
To gain better insight into the mechanism of this
transformation, the treatment of 4-methylphenylsulfonyl
hydrazide 1a with TEMPO (2.0 equiv) under our standard
conditions did not give sulfone 2a, and the in situ
denitrogenative coupling of 1a was completely inhibited. On
the contrary, an unexpected hydrazone-tethered O-benzyl-
hydroxylamine 622 (57%) was formed possibly via the benzyl
carbenoids which were trapped by TEMPO (Scheme 4a). On
the other hand, when the denitrogenative sulfonylation of
hydrazone 1a was performed in the D2O/DMF system, the
incorporation of deuterium into the α-position (85% D) of
sulfone d2-2a (79% yield) was observed; this H/D exchange
ASSOCIATED CONTENT
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* Supporting Information
Scheme 4. Preliminary Mechanism Studies
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.orglett.1c02369.
Detailed experimental procedures, characterization data,
copies of 1H NMR and 13C NMR spectra for all isolated
compounds (PDF)
Accession Codes
CCDC 2095523 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cam-
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
C
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annulation/C(sp2)−H Amination of 1,2,3,4-Tetrazoles by Electro-
cyclization. J. Am. Chem. Soc. 2018, 140, 8429−8433.
AUTHOR INFORMATION
■
Corresponding Authors
(3) For selected examples, see: (a) Xiao, X. S.; Hou, C.; Zhang, Z.
H.; Ke, Z. F.; Lan, J. Y.; Jiang, H. F.; Zeng, W. Ir(III)-Catalyzed
Regioselective Intermolecular Unactivated Secondary Csp3-H Bond
Amidation. Angew. Chem., Int. Ed. 2016, 55, 11897. (b) Xie, H. S.; Ye,
Z. R.; Ke, Z. F.; Lan, J. Y.; Jiang, H. F.; Zeng, W. Rh(III)-Catalyzed
Regioselective Intermolecular N-Methylene Csp3-H Bond Carbenoid
Insertion. Chem. Sci. 2018, 9, 985. (c) Lv, L.; Li, C. J. Palladium-
Catalyzed Defluorinative Alkylation of gem-Difluorocyclopropanes:
Switching Regioselectivity via Simple Hydrazones. Angew. Chem., Int.
Ed. 2021, 60, 13098−13104. (d) Shen, H.; Fu, J.; Yuan, H.; Gong, J.;
Yang, Z. Synthesis of 2,3-Disubstituted Indoles and Benzofurans by
the Tandem Reaction of Rhodium(II)-Catalyzed Intramolecular C−
H Insertion and Oxygen-Mediated Oxidation. J. Org. Chem. 2016, 81,
10180−10192. (e) Roy, S.; Das, S. K.; Khatua, H.; Das, S.; Singh, K.
N.; Chattopadhyay, B. Iron-Catalyzed Radical Activation Mechanism
for Denitrogenative Rearrangement over C(sp 3)−H Amination.
Angew. Chem., Int. Ed. 2021, 60, 8772−8780. (f) Das, S. K.; Roy, S.;
Khatua, H.; Chattopadhyay, B. Iron-Catalyzed Amination of Strong
Aliphatic C(sp3)−H Bonds. J. Am. Chem. Soc. 2020, 142, 16211−
16217.
(4) For selected examples, see: (a) Nakamuro, T.; Hagiwara, K.;
Miura, T.; Murakami, M. Enantioselective Denitrogenative Annula-
tion of 1H-Tetrazoles with Styrenes Catalyzed by Rhodium. Angew.
Chem., Int. Ed. 2018, 57, 5497−5500. (b) Wang, Q. L.; Zhou, Q.;
Liao, J.; Chen, Z.; Xiong, B. Q.; Deng, G. J.; Tang, K. W.; Liu, Y. Cu-
Catalyzed Oxidative Dual Arylation of Active Alkenes: Preparation of
Cyanoarylated Oxindoles through Denitrogenation of 3-Amino-
indazoles. J. Org. Chem. 2021, 86, 2866−2875. (c) Teng, J.; Sun,
S.; Yu, J. T.; Cheng, J. Copper-Catalyzed Cascade Denitrogenative
Transannulation/Hydrolyzation of 3-Aminoindazoles toward 2,2-
Disubstituted Indanones. J. Org. Chem. 2019, 84, 15669−15676.
(d) Wang, Y. H.; Li, Y. H.; Fan, Y. J.; Wang, Z. G.; Tang, Y. F.
Palladium-catalyzed denitrogenative functionalizations of benzotria-
zoles with alkenes and 1,3-dienes. Chem. Commun. 2017, 53, 11873−
11876.
Wei Zeng − Key Laboratory of Functional Molecular
Engineering of Guangdong Province, School of Chemistry and
Chemical Engineering, South China University of Technology,
Guangzhou 510641, China; orcid.org/0000-0002-6113-
2459; Email: zengwei@scut.edu.cn
Haisheng Xie − Key Laboratory of Functional Molecular
Engineering of Guangdong Province, School of Chemistry and
Chemical Engineering, South China University of Technology,
Guangzhou 510641, China; Email: xiehs@scut.edu.cn
Authors
Xiang Huang − Key Laboratory of Functional Molecular
Engineering of Guangdong Province, School of Chemistry and
Chemical Engineering, South China University of
Technology, Guangzhou 510641, China
Xing Chen − Key Laboratory of Functional Molecular
Engineering of Guangdong Province, School of Chemistry and
Chemical Engineering, South China University of
Technology, Guangzhou 510641, China
Zheng Tan − Key Laboratory of Functional Molecular
Engineering of Guangdong Province, School of Chemistry and
Chemical Engineering, South China University of
Technology, Guangzhou 510641, China
Huanfeng Jiang − Key Laboratory of Functional Molecular
Engineering of Guangdong Province, School of Chemistry and
Chemical Engineering, South China University of
Technology, Guangzhou 510641, China; orcid.org/
0000-0002-4355-0294
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.orglett.1c02369
(5) For selected examples, see: (a) Chuprakov, S.; Hwang, F. W.;
Gevorgyan, V. Rh-Catalyzed Transannulation of Pyridotriazoles
withAlkynes and Nitriles. Angew. Chem., Int. Ed. 2007, 46, 4757−
4759. (b) Miura, T.; Funakoshi, Y.; Morimoto, M.; Biyajima, T.;
Murakami, M. Synthesis of Enaminones by Rhodium-Catalyzed
Denitrogenative Rearrangement of 1-(N-Sulfonyl-1,2,3-triazol-4-yl)-
Alkanols. J. Am. Chem. Soc. 2012, 134, 17440−17443. (c) Wang, Y.
H.; Wang, Z. G.; Chen, X. W.; Tang, Y. F. Org. Chem. Front. 2018, 5,
2815−2819. (d) Li, W. Y.; Zhou, L. Org. Lett. 2021, 23, 4279−4283.
(e) Le, P. Q.; May, J. A. Hydrazone-initiated carbene/alkyne cascades
to form polycyclic products: ring-fused cyclopropenes as mechanistic
intermediates. J. Am. Chem. Soc. 2015, 137, 12219−12222. (f) Xiao,
Q.; Xia, Y.; Li, H.; Zhang, Y.; Wang, J. Coupling of N-
Tosylhydrazoneswith Terminal Alkynes Catalyzed by Copper(I):
Synthesis of Trisubstituted Allenes. Angew. Chem., Int. Ed. 2011, 50,
1114−1117. (g) Roy, S.; Das, S. K.; Chattopadhyay, B. Cobalt(II)-
based Metalloradical Activation of 2-(Diazomethyl)-pyridines for
Radical Transannulation and Cyclopropanation. Angew. Chem., Int.
Ed. 2018, 57, 2238−2243. (h) Roy, S.; Khatua, H.; Das, S. K.;
Chattopadhyay, B. Iron(II)-Based Metalloradical Activation: Switch
from Traditional Click Chemistry to Denitrogenative Annulation.
Angew. Chem., Int. Ed. 2019, 58, 11439−11443. (i) Khatua, H.; Das, S.
K.; Roy, S.; Chattopadhyay, B. Dual Reactivity of 1,2,3,4-Tetrazole:
Manganese-Catalyzed Click Reaction and Denitrogenative Annula-
tion. Angew. Chem., Int. Ed. 2021, 60, 304−312.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
The authors thank the NSFC (No. 21871097), CPSF (No.
2019M662887), NSFGP (No. 2019A1515011790), STPG
(No. 201904010113, No. 202102020659), and the FRFCU
(No. 2020ZYGXZR044) for financial support.
REFERENCES
■
(1) For selected review, see: (a) Yadagiri, D.; Rivas, M.; Gevorgyan,
V. Denitrogenative Transformations of Pyridotriazoles and Related
Compounds: Synthesis of N-Containing Heterocyclic Compounds
and Beyond. J. Org. Chem. 2020, 85, 11030−11046. (b) Li, W. B.
Synthesis of Heterocycles through Denitrogenative Cyclization of
Triazoles and Benzotriazoles. Chem. - Eur. J. 2020, 26, 11931−11945.
(c) Chattopadhyay, B.; Gevorgyan, V. Transition-Metal-Catalyzed
Denitrogenative Transannulation: Converting Triazoles into other
Heterocyclic Systems. Angew. Chem., Int. Ed. 2012, 51, 862−872.
(2) For selected examples, see: (a) Pal, K.; Volla, C. Rh(II)-
catalyzed Denitrogenative Cascade of 1,2,3-Triazolyl Propiolates and
Indoles: Access to Butenolide Tethered Homotryptamines. Org. Lett.
2021, 23, 4294−4299. (b) Zhou, Y.; Lin, L.; Wang, Y.; Zhu, J.; Song,
Q. L. Cu-Catalyzed Aromatic Metamorphosis of 3-Aminoindazoles.
Org. Lett. 2019, 21, 7630−7634. (c) Zhou, Y.; Deng, S.; Mai, S.; Song,
Q. L. Cu-Catalyzed Denitrogenative Ring-Opening of 3-Amino-
indazoles for the Synthesis of Aromatic Nitrile-Containing (Hetero)-
Arenes. Org. Lett. 2018, 20, 6161−6165. (d) Das, S. K.; Roy, S.;
Khatua, H.; Chattopadhyay, B. Ir-Catalyzed Intramolecular Trans-
(6) Gevondian, A. G.; Kotovshchikov, Y. N.; Latyshev, G. V.;
Lukashev, N. V.; Beletskaya, I. P. Domino Construction of
Benzoxazole-Derived Sulfonamides via Metal-Free Denitrogenation
of 5-Iodo-1,2,3-triazoles in the Presence of SO2 and Amines. J. Org.
Chem. 2021, 86, 5639−5650.
(7) Shrestha, R.; Khanal, H. D.; Rubio, P. Y. M.; Mohandoss, S.; Lee,
Y. R. Base-Mediated Denitrogenative Sulfonylation/Benzannulation
D
https://doi.org/10.1021/acs.orglett.1c02369
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pubs.acs.org/OrgLett
Letter
of Conjugated N-Sulfonylhydrazones with 3-Formylchromones for
the Construction of Polyfunctionalized Biaryl Sulfones. Org. Lett.
2020, 22, 7531−7536.
inhibitors. Bioorg. Med. Chem. Lett. 2005, 15, 2685−2688. (d) Liu, T.;
Zhou, W.; Wu, J. Palladium-catalyzed direct C−H functionalization of
indoles with the insertion of sulfur dioxide: synthesis of 2-sulfonated
indoles. Org. Lett. 2017, 19, 6638−6641. (e) Liu, T.; Li, Y.; Lai, L.;
Cheng, J.; Sun, J. T.; Wu, J. Photocatalytic reaction of potassium
alkyltrifluoroborates and sulfur dioxide with alkenes. Org. Lett. 2018,
20, 3605−3608.
(15) For selected examples, see: (a) Reddy, T. I.; Varma, R. S. Ti-
beta-catalyzed selective oxidation of sulfides to sulfoxides using urea−
hydrogen peroxide adduct. Chem. Commun. 1997, 471−472.
(b) Aldea, R.; Alper, H. Selective Aerobic Oxidation of Sulfides
Using a Novel Palladium Complex as the Catalyst Precursor. J. Org.
Chem. 1995, 60, 8365−8366. (c) Rostami, A.; Akradi, J. A highly
efficient, green, rapid, and chemoselective oxidation of sulfides using
hydrogen peroxide and boric acid as the catalyst under solvent-free
conditions. Tetrahedron Lett. 2010, 51, 3501−3503.
(16) For selected examples, see: (a) Feng, X. W.; Wang, J.; Zhang, J.;
Yang, J.; Wang, N.; Yu, X. Q. Copper-Catalyzed Nitrogen Loss of
Sulfonylhydrazones: A Reductive Strategy for the Synthesis of
Sulfones from Carbonyl Compounds. Org. Lett. 2010, 12, 4408−
4411. (b) Barluenga, J.; Tomas-Gamasa, M.; Aznar, F.; Valdes, C.
Synthesis of sulfones by iron-catalyzed decomposition of sulfonylhy-
drazones. Eur. J. Org. Chem. 2011, 2011, 1520−1526.
(17) Richards-Taylor, C. S.; Blakemore, D. C.; Willis, M. C. One-Pot
Three-Component Sulfone Synthesis Exploiting Palladium-Catalysed
Aryl Halide Aminosulfonylation. Chem. Sci. 2014, 5, 222−228.
(18) He, J. Y.; Chen, G. L.; Zhang, B. X.; Li, Y.; Chen, J. R.; Xiao, W.
J.; Liu, F.; Li, C. Z. Catalytic Decarboxylative Radical Sulfonylation.
Chem. 2020, 6, 1149−1159.
(19) Chen, F. J.; Shao, Y. X.; Li, M. K.; Yang, C.; Su, S. J.; Jiang, H.
F.; Ke, Z. F.; Zeng, W. Photocatalyzed Cycloaromatization of
Vinylsilanes with Arylsulfonyl Azides. Nat. Nat. Commun. 2021, 12,
3304.
(20) Most of the starting material 1a could be oxidized by molecular
oxygen to 4-methylbenzaldehyde 2a-1 in 64% yield via a
denitrogenation process.
(21) Jones, G.; Pitman, M. A.; Lunt, E.; Lythgoe, D. J.; Abarca, B.;
Ballesteros, R.; Elmasnaouy, M. Triazolopyridines. 18.1 Nucleophilic
Substitution Reactions on Triazolopyridines; A New Route to 2,2’-
Bipyridines. Tetrahedron 1997, 53, 8257−8268.
(22) Please see the single crystal data for 6 (CCDC 2095523) in the
Supporting Information.
(8) (a) Koronatov, A. N.; Rostovskii, N. V.; Khlebnikov, A. F.;
Novikov, M. S. Synthesis of 3-Alkoxy-4-Pyrrolin-2-ones via Rhodium-
(II) Catalyzed Denitrogenative Transannulation of 1H-1,2,3-Triazoles
with Diazo Esters. Org. Lett. 2020, 22, 7958−7963. (b) Zhou, Z.; Liu,
Y.; Chen, J.; Yao, E.; Cheng, J. Multicomponent Coupling Reactions
of Two N-Tosyl Hydrazones and Elemental Sulfur: Selective
Denitrogenation Pathway toward Unsymmetric 2,5-Disubstituted
1,3,4-Thiadiazoles. Org. Lett. 2016, 18, 5268−5271. (c) Xie, S. M.;
Su, L. B.; Mo, M.; Zhou, W.; Zhou, Y. B.; Dong, J. Y. Cu-Catalyzed
Oxidative Thioesterification of Aroylhydrazides with Disulfides. J. Org.
Chem. 2021, 86, 739−749. (d) Wang, X.; Huang, Y.; Xu, Y.; Tang, X.;
Wu, W.; Jiang, H. J. Palladium-Catalyzed Denitrogenative Synthesis of
Aryl Ketones from Arylhydrazines and Nitriles Using O2 as Sole
Oxidant. J. Org. Chem. 2017, 82, 2211−2218. (e) Yang, D.; Shan, L.;
Xu, Z. F.; Li, C. Y. Metal-free synthesis of imidazole by BF3·Et2O
promoted denitrogenative transannulation of N-sulfonyl-1,2,3-triazole.
Org. Biomol. Chem. 2018, 16, 1461−1464.
(9) (a) Pastor-Perez, L.; Wiebe, C.; Perez-Prieto, J.; Stiriba, S. E. A.
Tetramethoxybenzophenone as Efficient Triplet Photocatalyst for the
Transformation of Diazo Compounds. J. Org. Chem. 2007, 72, 1541−
1544. (b) Jurberg, I. D.; Davies, H. M. L. Blue light-promoted
photolysis of aryldiazoacetates. Chem. Sci. 2018, 9, 5112−5118.
(c) Hommelsheim, R.; Guo, Y.; Yang, Z.; Empel, C.; Koenigs, R. M.
Blue-Light-Induced Carbene-Transfer Reactions of Diazoalkanes.
Angew. Chem., Int. Ed. 2019, 58, 1203−1207. (d) Yang, J.; Duan, J.;
Wang, G.; Zhou, H.; Ma, B.; Wu, C.; Xiao, J. Visible-Light-Promoted
Site-Selective N1-Alkylation of Benzotriazoles with α-Diazoacetates.
Org. Lett. 2020, 22, 7284−7289. (e) He, F.; Koenigs, R. M. Visible
light mediated, metal-free carbene transfer reactions of diazoalkanes
with propargylic alcohols. Chem. Commun. 2019, 55, 4881−4884.
(f) Xiao, T.; Mei, M.; He, Y.; Zhou, L. Blue light-promoted cross-
coupling of aryldiazoacetates and diazocarbonyl compounds. Chem.
Commun. 2018, 54, 8865−8868.
(10) For selected examples, see: (a) Wang, C.; Wang, Z.; Yang, J.;
Shi, S. H.; Hui, X. P. Sequential Visible-Light and N-Heterocyclic
Carbene Catalysis: Stereoselective Synthesis of Tetrahydropyrano-
[2,3-b]indoles. Org. Lett. 2020, 22, 4440−4443. (b) Wei, Y.; Liu, S.;
Li, M. M.; Li, Y.; Lan, Y.; Lu, L. Q.; Xiao, W. J. Enantioselective
Trapping of Pd-Containing 1,5-Dipoles by Photogenerated Ketenes:
Access to 7-MemberedLactones Bearing Chiral Quaternary Stereo-
centers. J. Am. Chem. Soc. 2019, 141, 133−137.
(23) Sulfones 2f (41%) and 2v (45%) were also isolated.
(11) Brachet, E.; Ghosh, T.; Ghosh, I.; König, B. Visible light C−H
amidation of heteroarenes with benzoyl azides. Chem. Sci. 2015, 6,
987−992.
(12) (a) Zhu, S.; Pathigoolla, A.; Lowe, G.; Walsh, D. A.; Cooper,
M.; Lewis, W.; Lam, H. W. Sulfonylative and Azidosulfonylative
Cyclizations by Visible-Light Photosensitization of Sulfonyl Azides in
THF. Chem. - Eur. J. 2017, 23, 17598−17604. (b) Huang, X.;
Webster, R. D.; Harms, K.; Meggers, E. Asymmetric catalysis with
organic azides and diazo compounds Initiated by photoinduced
electron transfer. J. Am. Chem. Soc. 2016, 138, 12636−12642.
(c) Ciszewski, L. W.; Durka, J.; Gryko, D. Photocatalytic Alkylation of
Pyrroles and Indoles with α-Diazo Esters. Org. Lett. 2019, 21, 7028−
7032.
(13) Hickner, M. A.; Ghassemi, H.; Kim, Y. S.; Einsla, B. R.;
McGrath, J. E. Alternative Polymer Systems for Proton Exchange
Membranes (PEMs). Chem. Rev. 2004, 104, 4587−4612.
(14) (a) Isoherranen, N.; Lutz, J. D.; Chung, S. P.; Hachad, H.;
Levy, R. H. Ragueneau-Majlessi, Importance of Multi-P450 Inhibition
in Drug−Drug Interactions: Evaluation of Incidence, Inhibition
Magnitude, and Prediction from in Vitro Data. Chem. Res. Toxicol.
2012, 25, 2285−2300. (b) Bharate, S. S.; Bharate, S. B. Modulation of
Thermoreceptor TRPM8 by Cooling Compounds. ACS Chem.
Neurosci. 2012, 3, 248−267. (c) Teall, M.; Oakley, P.; Harrison, T.;
Shaw, D.; Kay, E.; Elliott, J.; Gerhard, U.; Castro, J. L.; Shearman, M.;
Ball, R. G.; Tsou, N. N. Aryl sulfones: a new class of γ-secretase
E
https://doi.org/10.1021/acs.orglett.1c02369
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