Direct C(sp2)-H Arylsulfonylation of Enamides via Iridium(III)-Catalyzed Insertion of Sulfur Dioxide with Aryldiazonium Tetrafluoroborates

Article abstract of DOI:10.1002/adsc.201900257

An iridium(III)-catalyzed three-component reaction of enamides, aryldiazonium tetrafluoroborates, and 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) (DABSO) for the direct C(sp²)?H arylsulfonylation of enamides is developed. This transformation provides a robust and straightforward approach for preparing a diverse array of β-amidovinyl sulfones in moderate to excellent yields and high stereoselectivities without Light-emitting diode (LED) radiation. This transformation also features mild conditions, broad substrate scopes, and excellent functional group tolerance. (Figure presented.).

Full text of DOI:10.1002/adsc.201900257

Title: Direct C(sp²)−H Arylsulfonylation of Enamides
<i>via</i> Iridium(III)-Catalyzed Insertion of Sulfur Dioxide with
Aryldiazonium Tetrafluoroborates
Authors: Tong-Hao Zhu, Xiao-Chen Zhang, Xian-Lu Cui, Ze-Yu Zhang,
Hui Jiang, Shan-Shan Sun, Li-Li Zhao, KAI ZHAO, and Teck-
Peng Loh
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Adv. Synth. Catal. 10.1002/adsc.201900257
Link to VoR: http://dx.doi.org/10.1002/adsc.201900257

10.1002/adsc.201900257
Advanced Synthesis & Catalysis
UPDATE
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Direct C(sp2)−H Arylsulfonylation of Enamides via
Iridium(III)-Catalyzed Insertion of Sulfur Dioxide with
Aryldiazonium Tetrafluoroborates
Tong-Hao Zhu,a Xiao-Chen Zhang,a Xian-Lu Cui,a Ze-Yu Zhang,a Hui Jiang,a Shan-
Shan Sun,a Li-Li Zhao,a Kai Zhao,a* Teck-Peng Loh a,b*
a
Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic
Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing 211816, China.
[E-mail: ias_kzhao@njtech.edu.cn]
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang
b
Technological University, Singapore 637371, Singapore.
[E-mail: teckpeng@ntu.edu.sg]
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.((Please
delete if not appropriate))
Abstract. An iridium(III)-catalyzed three-component
reaction of enamides, aryldiazonium tetrafluoroborates, and
1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) (DABSO)
for the direct C(sp2)−H arylsulfonylation of enamides is
developed. This transformation provides a robust and
straightforward approach for preparing a diverse array of β-
amidovinyl sulfones in moderate to excellent yields and
high stereoselectivities without Light-emitting diode (LED)
radiation. This transformation also features mild conditions,
broad substrate scopes, and excellent functional group
tolerance.
1a). Notwithstanding those advance attained, the
development of novel synthetic approaches which
could streamline the preparation of β-sulfonylated
enamides by expanding the substrate scopes and
avoiding the use of expensive catalysis or hazardous
and polluting additives, would still be of significant
importance in both organic synthetic chemistry and
pharmaceuticals development.
Keywords: Organic catalysis; C−H functionalization;
Insertion of sulfur dioxide; Enamides; β-Amido sulfones.
β-Amido sulfones served as privileged scaffolds in a
plethora of biologically and pharmaceutically
attractive molecules and natural products, they also
played crucial roles as pivotal building blocks to
access various alkaloids, amino acids, carbohydrate
and other useful amino derivatives. Therefore, they
have gathered increasing attention among the
chemical community.[1] Especially, β-amidovinyl
sulfones have been considered as synthetic targets of
particular interest, because they could be easily
hydrolyzed to α-sulfonyl ketones[2] or be reduced to
bioactive chiral β-amido sulfones through asymmetric
hydrogenation.[3] Thus, the development of efficient
and straightforward protocols to access β-amidovinyl
sulfones is highly desirable. In principle, the direct β-
sulfonylation of enamides represents one of the most
straightforward methods to access β-amidovinyl
sulfones, with several significant breakthroughs
established by the groups of Yu,[4] Zhang,[5] and our
group,[6] by using arylsulfonyl chlorides or sodium
sulfinates as sulfonating agents, respectively (Scheme
Scheme 1. Arylsulfonylation reactions of enamides.
1,4-Diazabicyclo[2.2.2]octane bis(sulfur dioxide)
(DABSO), which was firstly demonstrated by Santos
and Mello,[7] has been considered as a readily
applicable and stable surrogate of sulfur dioxide,[8] as
1
This article is protected by copyright. All rights reserved.

10.1002/adsc.201900257
Advanced Synthesis & Catalysis
witnessed by several remarkable achievements
established by the groups of Wills,[9] Wu,[10] Tu,[11]
and many others.[12] As pioneeringly disclosed by Wu
and coworkers, the arylsulfonyl radicals generated in-
situ through the combination of DABSO and
aryldiazonium salts, could serve as an efficient
intermediate for sp2-arylsulfonylation.[13] Recently,
this synthetic strategy has been employed by our
group to access the geometrically-defined β-
sulfonylated enamides (Scheme 1b).2 Nevertheless,
stoichiometric amount of copper(II) triflate was
required to increase the reaction efficiency. In order
to overcome this limitation, we herein reported an
was observed in 87% yield (Table 1, entry 1).
However,
other
photocatalysts
such
as
.
Ru(bpy)2Cl2 6H2O, Eosin Y and Mes-AcrClO4 were
not as efficient as fac-Ir(ppy)3 (Table 1, entries 2-4).
The screening of solvents (For details, see ESI†:
Table S1, entries 1, 5-13) showed that DCE was still
the solvent of choice. Further optimization revealed
that the optimal loading of fac-Ir(ppy)3 was 2.5 mol%
in view of the cost and efficiency (Table 1, entry 5 vs
entries 1 and 6). To our surprise, the desired product
3aa could be obtained in 89% yield in the presence of
2.5 mol% fac-Ir(ppy)3 in DCE in the dark, indicating
that illumination was not essential for this
transformation. Moreover, the control experiment in
the absence of fac-Ir(ppy)3 gave 3aa in 21% yield
with 68% enamide 1a recovered , showing the critical
iridium-catalyzed
C(sp2)–H
sulfonylation
of
enamides with DABSO and diazonium salts to
furnish synthetically valuable β-amidovinyl sulfones
in excellent yields and stereoselectivities (Scheme 1c). role of an iridium catalyst for the arylsulfonylation
(Table 1, entry 8). Various Ir-catalysts were also
Table 1. Screening of the optimal reaction conditions.[a]
screened without blue LED illumination (Table 1,
entries 9-13), and it was found that the optimum yield
was given in the presence of 2.5 mol% fac-Ir(ppy)3
in DCE at room temperature (91% yield, Table 1,
entry 9). Other sulfonating agents such as 4-
dimethylaminopyridine sulfur dioxide (DMAP.SO2)
and sodium metabisulfite were less efficient in
contrast to DABSO, giving the desired product 3aa in
34% and 71% yield respectively (Table 1, entries 14
and 15).
Yield of
Recovery
Entry
Catalyst (mol%)
3aa[b](%) of 1a[b] (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
fac-Ir(ppy)3 (5)
Ru(bpy)2Cl2.6H2O (5)
Eosin Y (5)
87
17
27
35
90
0
49
31
24
0
0
0
68
0
0
13
55
56
trace
0
Table
2.
Substrate
scope
of
aryldiazonium
tetrafluoroborates 2a-2s.[a,b]
Mes-AcrClO4 (5)
fac-Ir(ppy)3 (2.5)
fac-Ir(ppy)3 (1)
fac-Ir(ppy)3 (2.5)
fac-Ir(ppy)3 (0)
fac-Ir(ppy)3 (2.5)
[Ir(COD)Cl]2 (1.25)
[IrCp*Cl2]2 (1.25)
IrCl3 (2.5)
69
89[c]
21[d]
91[d]
84[d]
82[d]
14[d]
37[d]
34[d],[e]
71[d],[f]
Ir(acac)3 (2.5)
fac-Ir(ppy)3 (2.5)
fac-Ir(ppy)3 (2.5)
[a] Reaction conditions: enamide 1a (0.2 mmol), diazonium
salt 2a (0.3 mmol, 1.5 equiv.), DABSO (0.3 mmol, 1.5
equiv.), catalyst, DCE (1.0 mL), room temperature, N2,
[b]
under blue LED irradiation (14.5 W) for 12 hours.
Determined by NMR analysis of the crude using
[c]
mesitylene as the internal standard.
The reaction was
performed in the dark. [d] In the absence of blue LED.
DMAP.SO2 (1.5 equiv.) was used as SO2 source.
Na2S2O5 was used as SO2 source.
[e]
[f]
[a] Reaction conditions: enamide 1a (0.3 mmol), diazonium
salts 2 (0.45 mmol, 1.5 equiv.), DABSO (0.45 mmol, 1.5
equiv.), and fac-Ir(ppy)3 (0.0075 mmol, 2.5 mol%) in DCE
(1.5 mL) at room temperature for 12 hours under nitrogen.
[b] Isolated yields.
Our
arylsulfonylation began with the reaction of N-
benzyl-N-(1-phenylvinyl)acetamide (1a),
investigation
into
this
C(sp2)−H
phenyldiazonium tetrafluoroborate (2a) and DABSO
in the presence of a photocatalyst fac-Ir(ppy)3 (5
mol%) in 1,2-dichloroethane (DCE) at room
temperature under blue LED irradiation. Fortunately,
the desired product (E)-β-amidovinyl sulfone 3aa
With the optimized reaction conditions in hand, we
commenced to investigate the substrate scopes of
various aryldiazonium tetrafluoroborates 2a-2s
(Table 2). Generally, the electronic variation of
aryldiazonium tetrafluoroborates did not attenuate the
2
This article is protected by copyright. All rights reserved.

10.1002/adsc.201900257
Advanced Synthesis & Catalysis
reaction efficiency, and substrates bearing either
electron-donating groups (2b-2f) or electron-
withdrawing groups (2k-2o) were both amenable to
this transformation to attain desired products in
moderate to good yields. Halogen substituted
aryldiazonium salts (2g-2j) were also suitable
substrates to forge 3ag-3aj in 54-86% yields. It was
worth noting that various sensitive functional groups
including CN, NO2, CO2Et, COMe, COPh were
compatible to standard conditions to furnish target
product 3ak-3ao in 56-83% yields. Substrate
containing an alkyne moiety could also be tolerated
to give desired product 3ap in synthetically useful
yield. Notably, substrates bearing relatively bulkly
naphthyl group were also viable in this
transformation, affording the desired products 3aq,
3ar in 79% and 62% yields, respectively.
Aryldiazonium salts bearing 2-thienyl skeleton also
proved to be an eligible substrate, attaining expected
product 3as in 54% yield. Notably,this
transformation proceeded in a highly stereoselective
manner, which afforded geometrically-defined (E)-
variation of electronic or steric peculiarities on the α-
phenyl group of enamides did not show dramatic
effect to the reaction efficiency and stereoselectivity,
allowing the formation of geometrically-defined β-
amidovinyl sulfones 3ba-3ja in 57-91% yields.
Sterically hindered N-benzyl-N-(1-(naphthalen-2-
yl)vinyl)acetamide (1k) also reacted with enamide 2a
smoothly to give the desired product 3ka in excellent
yield. Notably, 2-thienyl substituted enamides was
also viable in this transformation to give 3la in 54%
yields. Gratifyingly, enamides 1m 2-bromobenzyl as
the N-protecting group proved to be suitable substrate
to give 3ma in 88% yields, which enabled the
preparation of isoquinoline derivative 4 through
intramolecular Heck coupling. Importantly, when
cyclic enamides 1n and 1o were subjected to standard
conditions, the desired products 3na and 3oa were
attained in 38% and 45% yields, respectively. A Boc-
substituted enecarbamate 1q was proved to be viable
to this transformation to generate the desired product
3qa in synthetically useful yield. However, the
reactions of secondary enamide 1r and enecarbamate
1s failed to give the desired products. It should be
noted that N-vinylpyrrolidone could also participate
in the reaction to forge E-configured β-sulfonylated
enamide 3pa in 81% yield. In order to showcase the
potential synthetic utility of this transformation, a
gram-scale arylsulfonylation of enamides 1a was
performed, delivering 3aa in 85% yield (Scheme 2).
configured
β-amidovinyl
sulfones.
The
stereochemistry of 3aa could be further confirmed
by X-ray crystallography.[2]
Table 3. Substrate scope of enamides and
enecarbamates 1b-1s.[a,b]
Scheme 2. Gram-scalable synthesis of 3aa.
A number of preliminary mechanistic studies were
conducted to shed more light on the plausible
reaction pathway. The transformation was found to
be completely inhibited in the presence of a radical
scavenger
2,2,6,6-tetramethyl-1-piperidinyloxy
(TEMPO), indicating the involvement of a radical
species in the reaction (Scheme 3a, eq. 1), which was
further proved through the interception of an
arylsulfonyl radical by ethene-1,1-diyldibenzene 5 to
forge (2-(phenylsulfonyl)ethene-1,1-diyl)dibenzene 6
(Scheme 3a, eq. 2). Noteworthily, the yield of 6
dramatically increased from 28% to 72% in the
presence of fac-Ir(ppy)3, which indicated its essential
role to promote the generation of arylsulfonyl radical
species (Scheme 3a, eq. 2). The control experiments
of 1b and 2a in the absence of DABSO were also
conducted, it was observed that 11% of arylated
enamide 7 was given with the aid of fac-Ir(ppy)3,
while no phenyl addition product was observed in the
absence of fac-Ir(ppy)3, showing that the iridium
catalyst might serve as an electron-shuttle in the
[a]
Reaction conditions: enamides or enecarbamates 1b-1s
(0.3 mmol), diazonium salt 2a (0.45 mmol, 1.5 equiv.),
DABSO (0.45 mmol, 1.5 equiv.), and fac-Ir(ppy)3 (0.0075
mmol, 2.5 mol%) in DCE (1.5 mL) at room temperature
for 12 hours under nitrogen. [b] Isolated yields.
Next, we started to investigate the substrate scopes
with respect to enamides. As shown in Table 3, the
3
This article is protected by copyright. All rights reserved.

10.1002/adsc.201900257
Advanced Synthesis & Catalysis
single electron transfer (SET)-reduction of diazonium
salt 2a to form a phenyl radical (Scheme 3a, eq. 3).
The intermolecular kinetic isotope effect (KIE)
between 1a and the dideuterated 1a-d2 was also
performed, with a calculated KH/KD = 0.67, which
showed that the C-H bond cleavage was unlikely to
be the rate-determining step (Scheme 3b).
and the free energy change is predicted to be -2.8
kcal/mol at 298.15 K (For details, see ESI†, Figure SI,
a), implying a thermodynamically feasible process.
Then, the arylradical is rapidly trapped by sulfur
dioxide (a good n-donor) generated in-situ from
DABSO to afford
a more stable S-centered
arylsulfonyl radical (as compared to an aryl
radical),[16] which is intercepted by the alkene moiety
of enamides 1, giving rise to a radical intermediate A.
Subsequently, the radical intermediate A is oxidized
by iridium(IV) species into a cation B through SET,
along with the regeneration of iridium(III) catalyst to
complete the catalytic cycle. Notably, this step is
exoergic by -12.1 kcal/mol in free energy (For details,
see ESI†, Figure SI, a), which indicates the existence
of a thermodynamic driving force in this process.
Finally, the deprotonation of β-H from cation B by
basic DABCO produces the final arylsulfonylation
product.
Scheme 4. Proposed mechanism.
In summary, we have demonstrated a robust and
readily applicable iridium(III)-catalyzed direct
C(sp2)-H arylsulfonylation of enamides via the
insertion of sulfur dioxide with aryldiazonium
tetrafluoroborates. In the presence of a catalytic
amount of iridium catalyst under mild conditions, this
transformation proceeded efficiently to afford the
synthetically valuable and geometrically-defined β-
amidovinyl sulfones bearing a broad array of
functional groups in excellent yields and
Scheme 3. Control experiments.
Based on the above results and previous
literatures,[2],[10k],[14] as well as DFT theoretical
calculations, a plausible reaction mechanism was
proposed (Scheme 4). Initially, diazonium salt 2
reacts with an iridium(III) complex to produce an
arylradical and an iridium(IV) species through a SET-
reduction process, which is similar to the mechanism
as previously demonstrated by Jacobi von Wangelin
and cowokers in an aromatic chlorosulfonylation of
diazonium salt.[15] The SET-reduction process has
been further rationalized by the DFT calculations,
stereoselectivities.
A plausible radical reaction
pathway is proposed to rationalize the transformation.
This new synthetic method served as a crucial
complement to previous approaches in view of cost
4
This article is protected by copyright. All rights reserved.

10.1002/adsc.201900257
Advanced Synthesis & Catalysis
[7] P. S. Santos, M. T. S. Mello, J. Mol. Struc. 1988, 178,
121−133.
and efficiency, which also paved a new avenue to
access β-amidovinyl sulfones.
[8] For reviews of the insertion of sulfur dioxide, see: a) P.
Vogel, M. Turks, L. Bouchez, D. Marković, A. Varela-
Alvarez, J. A. Sordo, Acc. Chem. Res. 2007, 40,
931−942; b) P. Bisseret, N. Blanchard, Org. Biomol.
Chem. 2013, 11, 5393−5398; c) A. S. Deeming, E. J.
Emmett, C. S. Richards-Taylor, M. C. Willis, Synthesis
2014, 46, 2701−2710; d) G. Liu, C.-B. Fan, J. Wu, Org.
Biomol. Chem. 2015, 13, 1592−1599; e) E. J. Emmett,
M. C. Willis, Asian J. Org. Chem. 2015, 4, 602−611; f)
D.-Q. Zheng, J. Wu, “Sulfur Dioxide Insertion
Reactions for Organic Synthesis”, Nature Springer:
Berlin, 2017; g) G. Qiu, K.-D. Zhou, L. Gao, J. Wu,
Org. Chem. Front. 2018, 5, 691−705; h) K. Hofman,
N.-W. Liu, G. Manolikakes, Chem. Eur. J. 2018, 24,
11852−11863; i) K. Sutal, M. Turks, Chem. Heterocycl.
Compd. 2018, 54, 584−586; j) G. Qiu, L.-F. Lai, J.
Cheng, J. Wu, Chem. Commun. 2018, 54,
10405−10414; k) G. Qiu, K.-D. Zhou, J. Wu, Chem.
Commun. 2018, 54, 12561−12569; l) S.-Q. Ye, G. Qiu,
J. Wu, Chem. Commun. 2019, 55, 1013−1019.
Experimental Section
Enamides 1 (0.3 mmol), aryldiazonium salts 2 (0.45 mmol,
1.5 equiv.), DABSO ( 0.45 mmol, 1.5 equiv.), and fac-
Ir(ppy)3 (0.0075 mmol, 2.5 mol%) were added sequentially
into Schlenk tube under nitrogen. Then DCE (1.5 mL) was
added rapidly by syringe. The resulting mixture was
allowed to stir at room temperature for 12 hours as
monitored by TLC. Upon completion, solvent was
removed under vacuum and the residue was purified by
flash silica gel column chromatography using petroleum
ether/ethyl acetate as eluent to afford pure products 3.
Acknowledgements
We gratefully acknowledge the financial support from Nanjing
Tech University (Start-up Grant No. 39837137, 39837101 and
3827401739), and National Natural Science Foundation of China
(21372210, 21672198, 21801129), the State Key Program of
National Natural Science Foundation of China (21432009),
Natural science research projects in Jiangsu higher education
institutions (18KJB150018) for generous financial support.
[9] For selected examples, see: a) B. Nguyen, E. J. Emmett,
M. C. Willis, J. Am. Chem. Soc. 2010, 132,
16372−16373; b) Y.-D. Chen, M. C. Willis, Chem. Sci.
2017, 8, 3249−3253; c) A. T. Davies, J. M. Curto, S. W.
Bagley, M. C. Willis, Chem. Sci. 2017, 8, 1233−1237;
d) Y.-D. Chen, P. R. D. Murray, A. T. Davies, M. C.
Willis, J. Am. Chem. Soc. 2018, 140, 8781−8787; e) V.
Vedovato, E. P. A. Talbot, M. C. Willis, Org. Lett.
2018, 20, 5493−5496.
References
[1] a) C. Reading, M. Cole, J. Enzyme Inhib. 1986, 1,
83−104; b) V. P. Sandanayaka, A. S. Prashad, Y. Yang,
R. T. Williamson, Y. I. Lin, T. S. Mansour, J. Med.
Chem. 2003, 46, 2569−2571; c) Y.-M. Zhang, S.
Cockerill, S. B. Guntrip, D. Rusnak, K. Snith, D.
Vanderwall, E. Wood, K. Lackey, Bioorg. Med. Chem.
Lett. 2004, 14, 111−114; d) J. M. Sanfrutos, A. M.
Fernandez, F. H. Mateo, D. G. Gonzalez, R. S.
Gonzalez, F. S. Gonzalez, Org. Biomol. Chem. 2011, 9,
851−864; e) M. Nottingham, C. R. Bethel, S. R. R.
Pagadala, E. Harry, A. Pinto, Z. A. Lemons, S. M.
Drawz, F. van den Akker, P. R. Carey, R. A. Bonomo,
J. D. Buynak, Bioorg. Med. Chem. Lett. 2011, 21,
387−393; f) W. F. Annes, A. Long, J. W. Witcher, M.
A. Ayan-Oshodi, M. P. Knadler, W. Zhang, M. I.
Mitchell, K. Cornelissen, S. D. Hall, J. Pharm. Sci.
2015, 104, 207−214; g) R. E. Salmas, P. Seeman, B.
Aksoydan, I. Erol, I. Kantarcioglu, M. Stein, M.
Yurtsever, S. Durdagi, ACS Chem. Neurosci. 2017, 8,
1404−1415.
[10] For recent selected examples, see: a) T. Liu, Y.-C.
Ding, X.-N. Fan, J. Wu, Org. Chem. Front. 2018, 5,
3153−3157; b) F.-S. He, Y.-Q. Wu, J. Zhang, H.-G. Xia,
J. Wu, Org. Chem. Front. 2018, 5, 2940−2944; c) X.-F.
Wang, Y.-W. Li, G. Qiu, J. Wu, Org. Chem. Front.
2018, 5, 2555−2559; d) F.-S. He, X.-F. Cen, S.-Y.
Yang, J. Zhang, H.-G. Xia, J. Wu, Org. Chem. Front.
2018, 5, 2437−2441; e) J. Zhang, K.-D. Zhou, J. Wu,
Org. Chem. Front. 2018, 5, 813−816; f) K.-D. Zhou, M.
Chen, L.-Q. Yao, J. Wu, Org. Chem. Front. 2018, 5,
371−375; g) H.-G. Xia, Y.-Y. An, X.-C. Zeng, J. Wu,
Org. Chem. Front. 2018, 5, 366−370; h) K.-D. Zhou, J.
Zhang, L.-F. Lai, J. Cheng, J.-T. Sun, J. Wu, Chem.
Commun. 2018, 54, 7459−7462; i) J. Zhang, F. Zhang,
L.-F. Lai, J. Cheng, J.-T. Sun, J. Wu, Chem. Commun.
2018, 54, 3891−3894; j) T. Liu, Y.-W. Li, L.-F. Lai, J.
Cheng, J.-T. Sun, J. Wu, Org. Lett. 2018, 20,
3605−3608. k) T. Liu, D.-P. Zheng, Z.-H. Li, J. Wu
Adv. Synth. Catal. 2018, 360, 865−869; l) K.-D. Zhou,
J. Zhang, G. Qiu, J. Wu, Org. Lett. 2019, 21, 275−278;
m) H.-J. Chen, M.-L. Liu, G. Qiu, J. Wu, Adv. Synth.
Catal. 2019, 361, 146−150; m) F. Zhang, D.-Q. Zheng,
L.-F. Lai, J. Cheng, J.-T. Sun, J. Wu, Org. Lett. 2018,
20, 1167−1170.
[2] T.-H. Zhu, X.-C. Zhang, K. Zhao, T.-P. Loh, Org.
Chem. Front. 2019, 6, 94−98.
[3] a) J. Jiang, Y. Wang, X.-M. Zhang, ACS Catal. 2014, 4,
1570-1573; b) J. Long, W.-C. Gao, Y.-Q. Guan, H. Lv,
X.-M. Zhang, Org. Lett. 2018, 20, 5914−5917.
[4] H. Jiang, X.-J. Chen, Y. Zhang, S.-Y. Yu, Adv. Synth.
Catal. 2013, 355, 809−813.
[5] D.-L. Sun, R.-H. Zhang, Org. Chem. Front. 2018, 5,
92−97.
[11] For recent selected examples, see: a) F. Liu, J.-Y.
Wang, P. Zhou, G. Li, W.-J. Hao, S.-J. Tu, B. Jiang,
Angew. Chem., Int. Ed. 2017, 56, 15570−15574; b) Z.-J.
Shen, Y.-N. Wu, C.-L. He, L. He, W.-J. Hao, A.-F.
Wang, S.-J. Tu, B. Jiang, Chem. Commun. 2018, 54,
[6] Y.-H. Xu, M. Wang, P. Lu, T.-P. Loh, Tetrahedron
2013, 69, 4403−4407.
5
This article is protected by copyright. All rights reserved.

10.1002/adsc.201900257
Advanced Synthesis & Catalysis
445−448; c) A.-F. Wang, W.-J. Hao, Y.-L. Zhu, G.-G.
Li, P. Zhou, S.-J. Tu, B. Jiang, ACS Omega 2018, 3,
1482−1491.
[13] D.-Q. Zheng, Y. An, Z. Li, J. Wu, Angew. Chem., Int.
Ed. 2014, 53, 2451−2454.
[14] D.-Q. Zheng, J.-Y. Yu, J. Wu, Angew. Chem., Int. Ed.
2016, 55, 11925−11929.
[12] For recent selected examples, see: a) D.-S. Yang, P.-F.
Sun, W. Wei, F.-J. Liu, H. Zhang, H. Wang, Chem. Eur.
J. 2018, 24, 4423−4427; b) N.-W. Liu, S. Liang, G.
Manolikakes, Adv. Synth. Catal. 2017, 359,
1308−1319; c) N. Wolff, J. Char, X. Frogneux, T.
Cantat, Angew. Chem., Int. Ed. 2017, 56, 5616−5619;
d) D.-L. Sun, K. Yin, R.-H. Zhang, Chem. Commun.
2018, 54, 1335−1338; e) H.-B. Zhu, Y.-J. Shen, Q.-Y.
Deng, C.-Y. Huang, T. Tu, Chem. Asian J. 2017, 12,
706−712; f) J. Sheng, Y.-W. Li, G. Qiu, Org. Chem.
Front. 2017, 4, 95−100; g) K. Wang, G.-D. Wang, G.-
Y. Duan, C.-C. Xia, RSC Adv. 2017, 7, 51313−51317;
h) H. Wang, S. Sun, J. Cheng, J. Org. Lett. 2017, 19,
5844−5847; i) Y. Wang, L.-L. Deng, J. Zhou, X.-C.
Wang, H.-B. Mei, J.-L. Han, Y. Pan, Adv. Synth. Catal.
2018, 360, 1060−1065; j) H.-P. Wang, B.-B. Wang, S.
Sun, J. Cheng, Org. Chem. Front. 2018, 5, 2547−2551.
[15] a) M. Májek, M. Neumeier, Jacobi von Wangelin, A.
ChemSusChem. 2017, 10, 151−155; For review, see: b)
M. Májek, Jacobi von Wangelin, A. Acc. Chem. Res.
2016, 49, 2316−2327.
[16] A. U. Meyer, S. Jäger, D. P. Hari, B. Kӧnig, Adv.
Synth. Catal. 2015, 357, 2050−2054.
6
This article is protected by copyright. All rights reserved.

10.1002/adsc.201900257
Advanced Synthesis & Catalysis
UPDATE
Direct C(sp2)−H Arylsulfonylation of Enamides via
Iridium(III)-Catalyzed Insertion of Sulfur Dioxide
with Aryldiazonium Tetrafluoroborates
Adv. Synth. Catal. Year, Volume, Page – Page
Tong-Hao Zhu,a Xiao-Chen Zhang,a Xian-Lu Cui,a
Ze-Yu Zhang,a Hui Jiang,a Shan-Shan Sun,a Li-Li
Zhao,a Kai Zhao,a* Teck-Peng Loh a,b*
7
This article is protected by copyright. All rights reserved.