Synthesis of Benzo[b]thiophenes through Rhodium-Catalyzed Three-Component Reaction using Elemental Sulfur

Article abstract of DOI:10.1002/adsc.202000112

A benzo[b]thiophene synthesis by Rh-catalyzed three-component coupling reaction of arylboronic acids, alkynes, and elemental sulfur (S₈) is developed. A notable feature of this protocol is that the thienannulation (thiophene annulation) proceeds with high regioselectivity via the sequential alkyne insertion, C?H activation, and then sulfur atom transfer to the metallacycle intermediate. In a similar manner, dibenzothiophenes can be synthesized from the parent biarylboronic acids and S₈. (Figure presented.).

Full text of DOI:10.1002/adsc.202000112

Title: Synthesis of Benzo[b]thiophenes through Rhodium-Catalyzed
Three-Component Reaction using Elemental Sulfur
Authors: Sanghun Moon, Moena Kato, Yuji Nishii, and Masahiro Miura
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To be cited as: Adv. Synth. Catal. 10.1002/adsc.202000112
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10.1002/adsc.202000112
Advanced Synthesis & Catalysis
COMMUNICATION
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Synthesis of Benzo[b]thiophenes through Rhodium-Catalyzed
Three-Component Reaction using Elemental Sulfur
Sanghun Moon,a Moena Kato,a Yuji Nishii,b* and Masahiro Miuraa*
a
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
Phone: (+81)-6-6879-7360, FAX: (+81)-6-6879-7362, e-mail: miura@chem.eng.osaka-u.ac.jp
Frontier Research Base for Global Young Researchers, Graduate School of Engineering, Osaka University, Suita,
b
Osaka 565-0871, Japan
Phone: (+81)-6-6879-7361, FAX: (+81)-6-6879-7362, e-mail: y_nishii@chem.eng.osaka-u.ac.jp
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######.
substituent, whereas the polyaromatic scaffold is
essential to trigger the thienannulation.
Abstract. A benzo[b]thiophene synthesis by Rh-
catalyzed three-component coupling reaction of
arylboronic acids, alkynes, and elemental sulfur (S8) is
developed. A notable feature of this protocol is that the
thienannulation (thiophene annulation) proceeds with
high regioselectivity via the sequential alkyne insertion,
C–H activation, and then sulfur atom transfer to the
Meanwhile,
transition-metal-catalyzed
C–H
activation[7] and the subsequent oxidative carbon-
carbon as well as carbon-heteroatom bond forming
reactions have been of versatile synthetic tool over the
past decades.[8] A number of catalytic protocols for the
C–S bond formation have been established mainly
adopting disulfides as the sulfur source.[9] In contrast,
the use of elemental sulfur in the direct C–H
functionalization strategy have rarely been achieved
despite the fact that sulfur atom transfer from S8 into
the metal-carbon linkage of a Ni(II) metallacycle
species was realized by Hillhouse more than 20 years
ago.[10] To the best of our knowledge, there have been
only two reports for the thia-heterocycle construction
through the transition-metal-mediated C–H activation.
Shi achieved a Cu-mediated benzoisothiazolone
synthesis using the (pyridin-2-yl)isopropylamine (PIP-
amine) bidentate directing group.[11] Afterward, Gong
and Song developed a catalytic variant adopting a Ni
complex with the aid of 2-amino alkylbenzimidazole
(MBIP-amine) directing group.[12,13]
metallacycle intermediate. In
a
similar manner,
dibenzothiophenes can be synthesized from the parent
biarylboronic acids and S8.
Keywords: Rhodium; C-H activation; Thiophene;
Elemental sulfur; Multicomponent reactions
Benzo[b]thiophene skeleton is frequently found as
a core component of many bioactive compounds and
drug candidates.[1] Additionally, densely-fused
benzo[b]thiophene derivatives have been of vital use
in organic electronic devices such as field-effect
transistors (OFETs), light-emitting diodes (OLEDs),
and photovoltaics (OPVs).[2] To meet the increasing
demand in these research fields, the development of
efficient synthetic methods for benzo[b]thiophene and
their analogues has been a substantial topic in recent
years. Conventional approaches to the thiophene ring
closure (thienannulation) require the appropriate pre-
functionalized compounds bearing sulfur-containing
substituents (thiol, thioether, disulfide, etc.) (Scheme
1a).[3] In some cases, the sulfur functionalities can be
installed in situ from the parent haloarenes via
halogen-lithium exchange reaction or substitution with
Na2S; however, cumbersome multi-step synthesis of
ortho-disubstituted precursors is inevitable. Recently,
Itami and coworkers developed an excellent method
for the construction of thiophene-fused π-conjugated
scaffolds using elemental sulfur (S8) (Scheme 1b),[4]
which is inexpensive, readily available, and highly
user-friendly (stable, non-toxic, non-volatile, non-
hygroscopic, and non-odorous) sulfur source.[5,6] This
reaction calls for the presence of only one alkynyl
Scheme 1. Representative Synthetic Methods for
Benzo[b]thiophene Derivatives.
1
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10.1002/adsc.202000112
Advanced Synthesis & Catalysis
We previously reported a Rh-catalyzed oxidative
solubility of S8 in PhCF3. This reaction could be
conducted in 1.0 mmol scale to give 3aa in 66%
isolated yield (entry 17).
coupling of arylboronic acids with two equivalents of
alkynes, leading to the formation of 1,2,3,4-
tetrasubstituted naphthalenes (Scheme 2a).[14,15] As a
consequence of our research interest in this area, we
assumed that the sulfur atom migration to the
corresponding metallacycle intermediate would result
in the assembly of benzo[b]thiophene skeletons
(Scheme 2b). In this manuscript, a Rh-catalyzed three-
component coupling reaction[16] of arylboronic acids,
alkynes, and elemental sulfur is described. This
reaction proceeds with high regio-selectivity since the
sulfur atom migration takes place only after the
insertion of alkynes, achieving the first successful use
of elemental sulfur in thiophen ring formation via the
C–H activation under transition-metal catalysis.
Table 1. Optimization Study a)
entry deviation from the standard conditions yield b)
1
2
AgOAc (2.0 equiv)
AgOAc (2.0 equiv)
PhBpin instead of 1a
AgOAc (2.0 equiv)
PhBnep instead of 1a
AgOAc (2.0 equiv)
PhBF3K instead of 1a
AgOCOCF3 (2.0 equiv) instead of
AgOAc
54% c)
n.d.
3
4
5
n.d.
trace
4%
6
Ag2CO3 (1.0 equiv) instead of AgOAc 7%
7
--
64%
8
9
[Cp*RhCl2] (2.0 mol%) as catalyst
ethanol solvent
n.d.
38%
10
11
12
13
14
15
16
2-propanol solvent
acetone solvent
DMPU solvent
S8 (0.5 equiv)
S8 (0.25 equiv)
S8 (0.125 equiv)
DMF (0.1 mL)/PhCF3 (0.2 mL)
solvent
DMF (0.1 mL)/PhCF3 (0.2 mL)
solvent
41%
36%
41%
66%
57%
28%
Scheme 2. Rh-Catalyzed Oxidative Annulation of
Arylboronic Acids with Alkynes.
81%c)
(75%)
(66%)d)
At the outset, we carried out an optimization study
for the model reaction utilizing phenylboronic acid
(1a), diphenylacetylene (2a), and elemental sulfur
17
(Table
1).
The
desired
product
(2,3-
a)
Standard conditions: 1a (0.4 mmol), S8 (0.2 mmol), 2a
diphenylbenzo[b]thiophene, 3aa) was obtained in 54%
yield in the presence of [Cp*Rh(MeCN)3][SbF6]2 (4.0
mol %) catalyst and AgOAc (2.0 equiv) oxidant in
DMF solvent (entry 1). Intriguingly, 1,2,3,4-
tetraphenylnaphthalene, a 1:2 coupling product of 1a
with 2a, was not detected during the course of the
study. Boronic esters (entries 2 and 3) as well as a
phenyl(trifluoro)borate salt (entry 4) failed to trigger
the reaction. AgOCOCF3 and Ag2CO3 were not
suitable oxidants for the present transformation
(entries 5 and 6). We also examined other oxidants
such as Cu(II), Mn(IV), and I(III) reagents, but no
productive result was obtained (not shown). The
productivity was slightly improved with an increased
amount of AgOAc (entry 7). An analogous neutral
Rh(III) catalyst was totally inactive (entry 8). Ethanol,
(0.2 mmol), [Cp*Rh(MeCN)3][SbF6]2 (4.0 mol%), AgOAc
(0.4 mmol), DMF (0.5 mL). b) Determined by GC analysis.
Isolated yield in parentheses. c) Average of two runs. d) 1.0
mmol scale. n.d. = not detected, pin = pinacolato, nep =
neopentyl glycolato.
With the optimized reaction conditions of entry 16
in Table 1, we then examined the applicability of a
series of alkynes (Scheme 3). Para-substituted alkynes
bearing electron donating groups gave the desired
products (3ab–3ad) in high yields, whereas electron-
withdrawing functionalities considerably retarded the
reaction (3ae–3ag). A meta-substituted alkyne 2h as
well as a 2-naphthyl alkyne 2i were successfully
transformed. For alkynes with low product yield, the
corresponding naphthalene derivatives were not
detected, and the unreacted alkynes were recovered. It
was notable that the catalytic protocol was applicable
to the reaction of 2-thienyl alkynes 2j and 2k to afford
3aj and 3ak, respectively, of which terthiophene
skeleton is of precursors for benzo[1,2-b:3,4-b':6,5-
b'']trithiophene derivatives.[17] Actually, 3ak could be
converted to the corresponding trithiophene 4 in 61%
yield upon treatment with FeCl3 (Scheme 4). The
present method was not applicable to terminal alkynes
and aliphatic alkynes (not shown). The reaction of 1-
2-propanol,
acetone,
and
DMPU
(N,N'-
dimethylpropyleneurea) were also suitable solvents,
but the yields were lower than that in DMF (entries 9-
12). The amount of S8 could be decreased to 0.25 equiv
(2.0 equiv as S) without significant drop of the
reactivity (entries 13,14), but lower yield was given
with 0.125 equiv of sulfur (1.0 equiv as S) (entry 15).
Although non-polar solvents (toluene, PhCF3, DCE)
alone were not effective (not shown), a mixed solvent
system of DMF and PhCF3 gave a considerably high
81% yield of 3aa (entry 16), probably due to the higher
2
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10.1002/adsc.202000112
Advanced Synthesis & Catalysis
phenyl-1-hexyne (2l) produced the desired product 3al
in 72% yield with considerably high regioselectivity
(3al:3al’ = 88:12).
boronic acid to generate the corresponding aryl
complex A. The following alkyne insertion and the
proximal C–H activation give a five-membered
rhodacycle B. This is consistent with the reaction
outcome described in Scheme 5, where the
substituents at the para-position placed at the C6
position of the benzo[b]thiophene ring. Sulfur atom
migration into one of the Rh–C bonds leads to the
formation of six-membered metallacycle complexes C
or D.[19] Thereafter, C–S reductive elimination is
affected to liberate the coupling product 3 along with
the Rh(I) species, which is then oxidized by AgOAc to
regenerate the reactive Rh(III) complex, closing the
catalytic cycle.
Scheme 3. Substrate Scope for Alkynes.
Scheme 5. Substrate Scope for Boroxines.
Scheme 4. Synthesis of a Benzotrithiophene through FeCl3-
Mediated Oxidative Cyclization.
Next, we evaluated the scope for arylboronic acids.
Because of the better reproducibility, boroxines 1 were
used (Scheme 5).[18] Phenylboroxine afforded a
comparable 66% yield for the production of 3aa. The
para-substituted boroxines 1b and 1c were
respectively converted to the C6-substituted
benzo[b]thiophenes 3ba and 3ca, indicating that the
alkyne firstly reacted with the aryl-rhodium species
before the sulfur atom insertion (see below). In a
similar manner, the substituents at the meta position
(1d–1f) fell into the C5 position (3da–3fa) where the
sterically more accessible C–H bond preferentially
reacted, while 1f gave a mixture of isomers. A
naphtho[2,3-b]thiophene core could be constructed in
the single step to give 3ga. The reaction of ortho-Br
boroxine remained unsuccessful (<5% product yield).
A proposed reaction mechanism for the three-
component coupling is illustrated in Scheme 6. A
catalytically active Rh(III) species, probably
[Cp*RhOAc][SbF6], undergo transmetalation with the
Scheme 6. Proposed Reaction Mechanism.
On the basis of the proposed reaction mechanism,
we assumed that the reaction of 2-biphenylboronic
acid (5a)[20] with elemental sulfur would produce
dibenzothiophene (6a) through the formation of
similar metallacycle intermediates.[21] As expected, 6a
was isolated in 86% yield under the slightly modified
reaction conditions at ambient temperature (Scheme 7).
Higher reaction temperature did not improve the yield
due to the competing protodeboronation. Subsequently,
we examined the reaction with various biarylboronic
acids 5. A series of functional groups such as alkyl
(5b), alkoxy (5c), trifluoromethyl (5d), and chloro (5e)
3
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10.1002/adsc.202000112
Advanced Synthesis & Catalysis
References
were compatible to the present method, giving the
corresponding dibenzothiophenes in moderate to good
yields. For a meta-substituted substrate, 6f was
obtained in 76% yield as a sole product. This reaction
system was also applicable to the boronic acids with
ortho-methyl (5g) and 2-naphthyl (5h) substituents.
[1] For selected reviews, see: a) D. A. Horton, G. T. Bourne,
M. L. Smythe, Chem. Rev. 2003, 103, 893-930; b) G. H.
Veeneman, Curr. Med. Chem. 2005, 12, 1077-1136; c)
H. Brown, P. Thomas, C. Lindsley, Nat. Rev. Drug
Discov. 2017, 16, 351-367; d) R. S. Keri, K. Chand, S.
Budagumpi, S. B. Somappa, S. A. Patil, B. N. Nagaraja,
Eur. J. Med. Chem. 2017, 138, 1002-1033.
In
summary,
we
have
introduced
a
benzo[b]thiophene synthesis by rhodium-catalyzed
three-component coupling reaction of arylboronic
acids, alkynes, and elemental sulfur. The reaction
proceeds high regio-selectivity via the sequential
alkyne insertion, C–H activation, and then sulfur atom
transfer. Thus, this report represents the first
successful use of elemental sulfur for the
thienannulation relying on the transition-metal-
catalyzed C–H activation technique.
[2] For selected reviews, see: a) J. E. Anthony, Chem. Rev.
2006, 106, 5028-5048; b) S. Allard, M. Forster, B.
Souharce, H. Thiem, U. Scherf, Angew. Chem., Int. Ed.
2008, 47, 4070-4098; Angew. Chem. 2008, 120, 4138-
4167; c) K. Takimiya, S. Shinamura, I. Osaka, E.
Miyazaki, Adv. Mater. 2011, 23, 4347-4370; d) J. Mei,
Y. Diao, A. L. Appleton, L. Fang, Z. Bao, J. Am. Chem.
Soc. 2013, 135, 6724-6746; f) W. Jiang, Y. Li, Z. Wang,
Chem. Soc. Rev. 2013, 42, 6113-6127.
[3] See the reviews and the references therein: a) K.
Takimiya, M. Nakano, M. J. Kang, E. Miyazaki, I.
Osaka, Eur. J. Org. Chem. 2013, 217-227; b) M. E.
Cinar, T. Ozturk, Chem. Rev. 2015, 115, 3036-3140; c)
B. Wu, N. Yoshikai, Org. Biomol. Chem. 2016, 14,
5402-5416.
[4] L. Meng, T. Fujikawa, M. Kuwayama, Y. Segawa, K.
Itami, J. Am. Chem. Soc. 2016, 138, 10351-10355.
[5] For a comprehensive review, see: T. B. Nguyena, Adv.
Synth. Catal. 2017, 359, 1066-1130.
[6] For recent examples of thienannulation using elemental
sulfur, see: a) T. B. Nguyen, P. Retailleau, Org. Lett.
2017, 19, 4858-4860; b) T. B. Nguyen, P. Retailleau,
Org. Lett. 2018, 20, 186-189; c) H. Huang, Z. Xu, X. Ji,
B. Li, G.-J. Deng, Org. Lett. 2018, 20, 4917-4920; d) Z.
Liu, R. Gao, J. Lou, Y. He, Z. Yua, Adv. Synth. Catal.
2018, 360, 3097-3108; e) J. R. Zhang, L. Z. Zhan, L. Wei,
Y.-Y. Ning, X.-L. Zhong, J.-X. Lai, L. Xu, R.-Y. Tang,
Adv. Synth. Catal. 2018, 360, 533-543; f) L. Chen, H.
Min, W. Zeng, X. Zhu, Y. Liang, G. Deng, Y. Yang, Org.
Lett. 2018, 20, 7392-7395; g) J. Liu, Y. Zhang, Y. Yue,
Z. Wang, H. Shao, K. Zhuo, Q. Lv, Z. Zhang, J. Org.
Chem. 2019, 84, 12946-12959; h) P. Zhou, Y. Huang, W.
Wu, W. Yu, J. Li, Z. Zhu, H. Jiang, Org. Biomol. Chem.
2019, 17, 3424-3432; i) H. Huang, Q. Wang, Z. Xu, G.
J. Deng, Adv. Synth. Catal. 2019, 361, 591-596; j) T. T.
T. Nguyen, Z. A. Le, P. Retailleau, T. B. Nguyen, Adv.
Synth. Catal. 2019, 361, 160-165.
Scheme 7. Dibenzothiophene Synthesis using Elemental
Sulfur.
Experimental Section
Synthesis of 3aa through the three-component coupling: To
an oven-dried glass tube were added phenylboronic acid (1a,
0.4 mmol, 2.0 equiv), diphenylacetylene (2a, 0.2 mmol, 1.0
equiv), sulfur powder (51 mg, 0.2 mmol, 1.0 equiv as S8),
[Cp*Rh(MeCN3)][SbF6]2 (4.0 mol%), and AgOAc (0.6
mmol, 3.0 equiv). The tube was refilled with N2 and sealed.
DMF (0.1 mL) and PhCF3 (0.2 mL) were added to the tube
via a syringe, and the mixture was stirred for 4 h at 100 °C
with an oil bath. After cooling to room temperature, the
resulting mixture was diluted with ethyl acetate and filtered
through a pad of Celite and activated alumina. The filtrate
was concentrated in vacuo, and the residue was purified by
column chromatography (eluent: hexane) and GPC (CHCl3)
1
to give the 3aa as white solid (43.0 mg, 75% yield). H
NMR (400 MHz, CDCl3) δ 7.78-7.76 (m, 1H), 7.51-7.49 (m,
1H), 7.31-7.23 (m, 9H), 7.14-7.13 (m, 3H); 13C NMR (100
MHz, CDCl3) δ 141.0, 139.7, 139.0, 135.6, 134.4, 133.4,
130.6, 129.7, 128.8, 128.5, 127.8, 127.5, 124.7, 124.6, 123.5,
122.2. These values were identical to those reported in the
literature.[22] For other compounds, see the Supporting
Information.
[7] For a recent comprehensive review, see: C. Sambiagio,
D. Schönbauer, R. Blieck, T. Dao-Huy, G. Pototschnig,
P. Schaaf, T. Wiesinger, M. F. Zia, J. Wencel-Delord, T.
Besset, B. U. W. Maes, M. Schnürch, Chem. Soc. Rev.
2018, 47, 6603-6743.
[8] For selected reviews, see: a) T. Satoh, M. Miura, Chem.
–Eur. J. 2010, 16, 11212-11222; b) D. A. Colby, R. G.
Bergman, J. A. Ellman, Chem. Rev. 2010, 110, 624-655;
c) V. P. Boyarskiy, D. S. Ryabukhin, N. A. Bokach, A.
V. Vasilyev, Chem. Rev. 2016, 116, 5894-5986; d) R.
Santhoshkumar, C.-H. Cheng, Chem. –Eur. J. 2019, 25,
9366-9384.
Acknowledgements
This work was supported by JSPS KAKENHI Grant No. JP
19K15586 (Grant-in-Aid for Young Scientists) to Y.N. and JP
17H06092 (Grant-in-Aid for Specially Promoted Research) to
M.M.
4
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10.1002/adsc.202000112
Advanced Synthesis & Catalysis
[9] For selected examples, see: a) X. Chen, X.-S. Hao, C. E.
Goodhue, J.-Q. Yu, J. Am. Chem. Soc. 2006, 128, 6790-
6791; b) L. D. Tran, I. Popov, O. Daugulis, J. Am. Chem.
Soc. 2012, 134, 18237-18240; c) Y. Yang, W. Hou, L.
Qin, J. Du, H. Feng, B. Zhou, Y. Li, Chem. Eur. J. 2014,
20, 416-420; d) M. Iwasaki, M. Iyanaga, Y. Tsuchiya, Y.
Nishimura, W. Li, Z. Li, Y. Nishihara, Chem. Eur. J.
2014, 20, 2459-2462; e) V. P. Reddy, R. Qiu, T. Iwasaki,
N. Kambe, Org. Biomol. Chem. 2015, 13, 6803-6813; f)
S.-Y. Yan, Y.-J. Liu, B. Liu, Y. H. Liu, B.-F. Shi, Chem.
Commun. 2015, 51, 4069-4072; g) K. Yang, Y. Wang,
X. Chen, A. A. Kadi, H.-K. Fun, H. Sun, Y. Zhang, H.
Lu, Chem. Commun. 2015, 51, 3582-3585; h) W. Xie, B.
Li, B. Wang, J. Org. Chem. 2016, 81, 396-403; i) T.
Müller, L. Ackermann, Chem. –Eur. J. 2016, 22, 14151-
14154.
2224-2232; c) D. Dang, M. Xiao, P. Zhou, J. Zhong, J.
Fan, N. Su, W. Xiong, C. Yang, Q. Wang, Y. Wang, Y.
Pei, R. Yang, W. Zhu, Eur. J. Org. Chem. 2015, 2015,
820-827; d) M. L. Keshtov, Y. Geng, S. A. Kuklin, A. R.
Khokhlov, E. N. Koukaras, G. D. Sharma, Org. Electron.
2015, 17, 167-177; e) H. Y. Cho, L. T. Scott,
Tetrahedron Lett. 2015, 56, 3458-3462; f) F. Magnan, B.
Gabidullin, J. L. Brusso, RSC Advances 2016, 6, 97420-
97429; g) I. García-Benito, I. Zimmermann, J. Urieta-
Mora, J. Aragó, A. Molina-Ontoria, E. Ortí, N. Martín,
M. K. Nazeeruddin, J. Mater. Chem. A 2017, 5, 8317-
8324; h) S.-Y. Chen, Y.-C. Pao, S. K. Sahoo, W.-C.
Huang, Y.-Y. Lai, Y.-J. Cheng, Chem. Commun. 2018,
54, 1517-1520; i) J. Urieta-Mora, I. Zimmermann, J.
Aragó, A. Molina-Ontoria, E. Ortí, N. Martín, M. K.
Nazeeruddin, Chem. Mater. 2019, 31, 6435-6442.
[10] R. Han, G. L. Hillhouse, J. Am. Chem. Soc. 1998, 120,
[18] One of the possible reasons for the reproducibility issue
of the reaction with arylboronic acids is due to the
inhibition by varying amount of water in the medium.
Actually, addition of H2O (1.0 equiv) to the reaction of
1a with 2a under the standard conditions significantly
decreased the yield of 3aa (<5% yield). However,
addition of desiccants such as molecular sieves and
calcium sulfate could not improve the product yield.
7657-7658.
[11] F.-G. Chen, G. Liao, X. Li, J. Wu, B.-F. Shi, Org. Lett.
2014, 16, 5644-5647.
[12] J.-R. Guo, J.-F. Gong, M.-P. Song, Org. Biomol. Chem.
2019, 17, 5029-5037.
[13] For a related example of the use of elemental selenium
in C–H activation strategy, see: M. Iwasaki, N. Miki, Y.
Tsuchiya, K. Nakajima, Y. Nishihara, Org. Lett. 2017,
19, 1092-1095.
[19] Sulfur atom transfer from polysulfide to the Rh(III)-C
bond was reported: a) M. Arisawa, M. Ashikawa, A.
Suwa, M. Yamaguchi, Tetrahedron Lett. 2005, 46,
1727-1729; b) M. Arisawa, K. Tanaka, M. Yamaguchi,
Tetrahedron Lett. 2005, 46, 4797-4800; c) M. Arisawa,
T. Ichikawa, M. Yamaguchi, Org. Lett. 2012, 14, 5318-
5321.
[14] T. Fukutani, K. Hirano, T. Satoh, M. Miura, J. Org.
Chem. 2011, 76, 2867-2874.
[15] A similar reaction was reported under electro-catalytic
conditions: W.-J. Kong, L. H. Finger, J. C. A. Oliveira,
L. Ackermann, Angew. Chem. Int. Ed. 2019, 58, 6342-
6346; Angew. Chem. 2019, 131, 6408-6412.
[20] a) T. Nagata, T. Satoh, Y. Nishii, M. Miura, Synlett
2016, 27, 1707-1710; b) S.; Xu, B. Huang, G. Qiao, Z.
Huang, Z. Zhang, Z. Li, P. Wang, Z. Zhang, Org. Lett.
2018, 20, 5578-5582.
[16] For related benzo[b]thiophene synthesis via formal
three-component reactions, see: a) S. L. Buchwald, Q.
Fang, J. Org. Chem. 1989, 54, 2793-2797; b) B. Wu, N.
Yoshikai, Angew. Chem. Int. Ed. 2013, 52, 10496-
10499; Angew. Chem. 2013, 125, 10690-10693.
[21] Cyclic hypervalent iodonium reagents were reported to
react with elemental sulfur to give dibenzothiophenes: a)
M. Shimizu, M. Ogawa, T. Tamagawa, R. Shigitani, M.
Nakatani, Nakano, Y. Eur. J. Org. Chem. 2016, 2785-
2788; b) M. Wang, Q. Fan, X. Jiang, Org. Lett. 2016, 18,
5756-5759.
[17] For recent examples, see: a) Y. Wang, S. Zou, J. Gao,
H. Zhang, G. Lai, C. Yang, H. Xie, R. Fang, H. Li, W.
Hu, Chem. Commun. 2015, 51, 11961-11963; b) D.
Dang, J. Fan, X. Wang, M. Xiao, J. Shi, P. Zhou, X.
Duan, G. Lei, Y. Liu, W. Zhu, New J. Chem. 2015, 39,
[22] Y. Masuya, M. Tobisu, N. Chatani, Org. Lett. 2016, 18,
4312-4315.
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10.1002/adsc.202000112
Advanced Synthesis & Catalysis
COMMUNICATION
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6
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