Potassium iodide-mediated radical arylsulfonylation/1,2-carbon migration sequences for the synthesis of β-sulfonated cyclic ketones

Article abstract of DOI:10.1016/j.tetlet.2018.09.027

Potassium iodide-mediated radical sulfonylation/1,2-carbon migration sequences of alkenylcyclobutanols has been developed. The reaction was effectively accelerated using potassium iodide as a catalyst under mild reaction conditions without other metal oxi

Full text of DOI:10.1016/j.tetlet.2018.09.027

Tetrahedron Letters xxx (2018) xxx–xxx
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Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Potassium iodide-mediated radical arylsulfonylation/1,2-carbon
migration sequences for the synthesis of b-sulfonated cyclic ketones
⇑
Yeon Joo Kim, Mi Hyeon Choo, Dae Young Kim
Department of Chemistry, Soondhunhyang University, Asan, Chungnam 31538, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
Potassium iodide-mediated radical sulfonylation/1,2-carbon migration sequences of alkenylcyclobu-
tanols has been developed. The reaction was effectively accelerated using potassium iodide as a catalyst
under mild reaction conditions without other metal oxidant. This approach is environmentally benign by
use of shelf-stable arylsulfonyl hydrazides as arylsulfonyl radical precursor and water as solvent. This
approach offers a facile way to prepare b-sulfonated cyclic ketone derivatives.
Received 12 July 2018
Revised 25 August 2018
Accepted 11 September 2018
Available online xxxx
Ó 2018 Published by Elsevier Ltd.
Keywords:
Sulfonation
1,2-Carbon migration
Radical process
Alkenylcyclobutanols
b-Sulfonated cyclic ketones
The sulfone moiety serves as valuable building blocks for the
synthesis of a large number of biologically active compounds and
pharmaceuticals [1]. Therefore, the development of novel and
practical methods for the installation of sulfonyl group into organic
frameworks has been a subject of intense study [2]. The addition of
sulfonyl radicals to unsaturated carbon-carbon bonds represents a
general route to synthesis of sulfone compounds. Recently, sulfonyl
hydrazides have emerged as valuable sulfonyl radical sources via
various oxidation processes [3]. Compared to other sulfonylation
reagents [4] including sulfonyl halides, sulfinic selenides, and sul-
finates, sulfonyl hydrazides are regarded as favorable sulfonyl rad-
ical precursors due to its stability for air and moisture, high
reactivity, and eco-friendly byproducts. Recently, several groups
reported the syntnesis of b-funtionalized ketones by radical addi-
tion and 1,2-carbon migration sequences of allylic alcohol deriva-
tives with various radicals including acyl, aryl, phosphoryl,
difluoromethyl, trifluoromethyl, and amine radicals [5]. Narasaka
and co-workers reported an oxidative sulfonylation reaction and
pinacol-type rearrangement of 1-vinyl cyclic alcohols with sodium
2-naphthalenesulfinate promoted by cerium (IV) tetrabutylammo-
nium nitrate [6]. However, there are some imperfections to the
previous work, such as narrow substrates scope and use of metal
oxidant. We envisioned the transformation of the alkenylcyclobu-
tanols to the b-sulfonated cyclopentanones by transition
metal-free sulfonylation/1,2-alkyl migration sequence with
sulfonyl hydrazides as sulfonyl radical source.
In connection with our ongoing research program related to
redox reaction and ring closure sequences, we recently reported
the intramolecular redox reaction via C–H bond functionalization
[7] and radical addition reaction to alkenes with several radical
sources under redox conditions [5c–5g]. Herein, we report
potassium iodode catalyzed oxidative sulfonylation and 1,2-alkyl
migration of alkenylcyclobutanol derivatives.
To determine suitable reaction conditions for the catalytic rad-
ical arylsulfonylation/1,2-alkyl migration sequences of alkenylcy-
clobutanol derivatives, we examined the copper-catalyzed radical
arylsulfonylation of 1-(1-phenylvinyl)cyclobutanol (1a) with p-
toluenesulfonyl hydrazide (2a) as arylsulfonyl radical source.
Treatment of 1-(1-phenylvinyl)cyclobutanol (1a) with p-toluene-
sulfonyl hydrazide (2a) and 20 mol % of copper salts in water at
80 °C gave the radical addition/1,2-alkyl migration product 3a in
low yields (Table 1, entries 1–2). Various iodide ion catalysts, such
as tetrabutylammonium iodide (TBAI), sodium iodide, and potas-
sium iodide were screened (Table 1, entries 5–7), potassium iodide
was the most efficient catalyst for this transformation (Table 1,
entry 5). A survey of the reaction media indicated that common
solvents, such as acetonitrile, ethyl acetate, DMF, DMSO, and co-
solvents of acetonitrile and water were also tested, which did not
give improved results (Table 1, entries 6–11). To our delight, the
addition of 18-crown-6 as an additive significantly improved the
yield to 90% (Table 1, entry 12). In the absence of potassium iodide,
no reaction occurred (Table 1, entry 13).
⇑
Corresponding author.
E-mail address: dyoung@sch.ac.kr (D.Y. Kim).
https://doi.org/10.1016/j.tetlet.2018.09.027
0040-4039/Ó 2018 Published by Elsevier Ltd.
Please cite this article in press as: Y.J. Kim et al., Tetrahedron Lett. (2018), https://doi.org/10.1016/j.tetlet.2018.09.027

2
Y.J. Kim et al. / Tetrahedron Letters xxx (2018) xxx–xxx
Table1
Table 2
Optimization of the reaction conditions.a
Substrate scope.a,b
Entry
Cat.
Solvent
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
CuBr
CuCl2
TBAI
NaI
KI
KI
KI
KI
KI
KI
KI
KI
–
H2O
H2O
H2O
H2O
H2O
CH3CN
EtOAc
DMF
DMSO
CH3CN:H2O (2:1)
CH3CN:H2O (1:2)
H2O
H2O
H2O
5
5
5
4
5
5
6
6
6
5
5
4
4
4
5
13
45
45
67
46
23
trace
trace
50
48
90
9
10
11
12c
13d
14e
trace
trace
KI
a
Reaction conditions: 1a (0.2 mmol), 2a (0.4 mmol), catalyst (0.04 mmol), TBHP
(0.6 mmol) in solvent (3.0 mL) at 80 °C.
b
Isolated yield.
18-crown-6 (0.04 mmol) was added.
Without catalyst.
TEMPO (3 equiv) was added.
c
d
e
With the optimal reaction conditions in hand, we investigated
the scope of substrates for potassium iodide catalyzed radical aryl-
sulfonylation/1,2-alkyl migration sequences of alkenylcyclobu-
tanols 1 with arylsulfonyl hydrazides 2 in the presence of 20 mol
% of potassium iodide and 18-crown-6 in water at 80 °C. As shown
in Table 2, various alkenylcyclobutanols 1 with electron-donating
or electron-withdrawing substituted-aryl and naphthyl groups fur-
nished the corresponding ring expansion products with moderate
to high yields (45–95%, Table 2, 3a–3h). To further examine the
scope of this reaction, a range of sulfonyl hydrazide derivatives 2,
such as benzenesulfonyl hydrazide and 2-naphthylsulfonyl hydra-
zide, were exposed to the optimal reaction conditions to react with
1-(1-arylvinyl)cyclobutanols 1. It was found that the correspond-
ing products 3a0–3e0 and 3a00–3e00 were obtained in moderate to
high yields (52–90%, Table 2). Notably, this potassium iodide-
mediated radical sulfonation/1,2-carbon migration reaction with
alkyl-substituted vinylcyclobutanol, 1-(3-phenylprop-1-en-2-yl)-
cyclobutanol, gave 50% yield of desired product 3i under the opti-
mal reaction conditions. The present method is operationally
simple and efficient and, thus, may be valuable for practical chem-
ical synthesis. As shown in Scheme 1, when 1-(1-phenylvinyl)cy-
clobutanol (1a) with p-toluenesulfonyl hydrazide (2a) under the
optimum reaction conditions, the reaction proceeded smoothly to
afford the desired tosyl-substituted cyclopentanone 3a on a gram
scale with 88% yield (Scheme 1). To illustrate synthetic utility,
we also carried out reductive removal of the sulfone group to
afford cyclopentanone derivative 4 in moderate yield (Scheme 2).
To gain mechanistic insights into this transformation, some pre-
liminary experiments were performed. The absence of potassium
iodide as catalyst shut down the reactivity (Table 1, entry 13). A
trace of the product was detected in the presence of a radical scav-
enger, 2,2,6,6-tetramethylpiperidin-1-yloxyl (TEMPO) (Table 1,
entry 14). We propose the reaction mechanism shown in Fig. 1
based on our results and previously reported work [3,8]. Initially,
potassium iodide interacts with TBHP to generate tert-buthoxyl
and tert-butylperoxy radicals which then react with arylsulfonyl
a
Reaction conditions: 1 (0.2 mmol), 2 (0.4 mmol), KI (0.04 mmol), 18-crown-
6 (0.04 mmol), TBHP (0.6 mmol) in H2O (3.0 mL) at 80 °C.
b
Isolated yield.
Scheme 1. Gram scale sulfonation/1,2-alkyl migration of 1a.
Scheme 2. Desulfonation of compound 3c0.
hydrazide 2 to generate an arylsulfonyl radical I with the release
of N2. Next, the arylsulfonyl radical I inserts to alkenylcyclobu-
tanols 1, yielding radical intermediate II, which is oxidized by
the TBHP to afford the cation III. 1,2-Alkyl migration of cation III
leads to a ring expansion that yields the product 3.
Please cite this article in press as: Y.J. Kim et al., Tetrahedron Lett. (2018), https://doi.org/10.1016/j.tetlet.2018.09.027

Y.J. Kim et al. / Tetrahedron Letters xxx (2018) xxx–xxx
3
(e) S.-Y. Lin, T.-K. Yeh, C.-C. Kuo, J.-S. Song, M.-F. Cheng, F.-Y. Liao, M.-W. Chao,
H.-L. Huang, Y.-L. Chen, C.-Y. Yang, M.-H. Wu, C.-L. Hsieh, W. Hsiao, Y.-H. Peng,
J.-S. Wu, L.-M. Lin, M. Sun, Y.-S. Chao, C. Shih, S.-Y. Wu, S.-L. Pan, M.-S. Hung, S.-
H. Ueng, J. Med. Chem. 59 (2016) 419.
[2] (a) For selected recent examples, see: F.-L. Yang, S.-K. Tian Angew. Chem. Int.
Ed. 52 (2013) 4929;
(b) Q. Lu, J. Zhang, F. Wei, Y. Qi, H. Wang, Z. Liu, A. Lei, Angew. Chem. Int. Ed. 52
(2013) 7156;
(c) E.J. Emmett, B.R. Hayter, M.C. Willis, Angew. Chem. Int. Ed. 52 (2013) 12679;
(d) K. Xu, V. Khakyzadeh, T. Bury, B. Breit, J. Am. Chem. Soc. 136 (2014) 16124;
(e) Y. Xi, B. Dong, E.J. McClain, Q. Wang, T.L. Gregg, N.G. Akhmedov, J.L. Petersen,
X. Shi, Angew. Chem. Int. Ed. 53 (2014) 4657;
(f) Z. Yuan, H.-Y. Wang, X. Mu, P. Chen, Y.-L. Guo, G. Liu, J. Am. Chem. Soc. 137
(2015) 2468.
[3] (a) For review, see: F.-L. Yang, S.-K. Tian Tetrahedron Lett. 58 (2017) 487;
(b) , For a selection of recent works on arylsulfonyl hydrizes, see:P.-Y. Ji, M.-Z.
Zhang, J.-W. Xu, Y.-F. Liu, C.-C. Guo J. Org. Chem. 81 (2016) 5181;
(c) G.C. Senadi, B.-C. Guo, W.-P. Hu, J.-J. Wang, Chem. Commun. 52 (2016)
11410;
(d) W.-J. Hao, Y. Du, D. Wang, B. Jiang, Q. Gao, S.-J. Tu, G. Li, Org. Lett. 18 (2016)
1884;
(e) Y.-L. Zhu, B. Jiang, W.-J. Hao, A.-F. Wang, J.-K. Qiu, P. Wei, D.-C. Wang, G.
Licd, S.-J. Tu, Chem. Commun. 2016 (1907) 52;
(f) Y. Wang, L. Ma, M. Ma, H. Zheng, Y. Shao, X. Wan, Org. Lett. 18 (2016) 5082;
(g) L. Zheng, Z.-Z. Zhou, Y.-T. He, L.-H. Li, J.-W. Ma, Y.-F. Qiu, P.-X. Zhou, X.-Y. Liu,
P.-F. Xu, Y.-M. Liang, J. Org. Chem. 81 (2016) 66;
(h) Y. Su, X. Zhou, C. He, W. Zhang, X. Ling, X. Xiao, J. Org. Chem. 81 (2016)
4981;
(i) J. Meesin, M. Pohmakotr, V. Reutrakul, D. Soorukram, P. Leowanawat, S.
Saithong, C. Kuhakarn, Org. Lett. 19 (2017) 6546;
(j) J. Meesin, M. Pohmakotr, V. Reutrakul, D. Soorukram, P. Leowanawat, C.
Kuhakarn, Org. Biomol. Chem. 15 (2017) 3662;
(k) X. Yang, L. Zhao, B. Yuan, Z. Qi, R. Yan, Adv. Synth. Catal. 359 (2017) 3248;
(l) A.O. Terent’ev, O.M. Mulina, D.A. Pirgach, A.I. Ilovaisky, M.A. Syroeshkin, N.I.
Kapustina, G.I. Nikishin, Tetrahedron 73 (2017) 6871;
(m) P. Zhang, Y. Gao, S. Chen, G. Tang, Y. Zhao, Org. Chem. Front. 4 (2017) 1350;
(n) R. Rahaman, P. Barman, Synlett 28 (2017) 684;
(o) W. Chen, X. Liu, E. Chen, B. Chen, J. Shao, Y. Yu, Org. Chem. Front. 4 (2017)
1162;
(p) R. Fu, W.-J. Hao, Y.-N. Wu, N.-N. Wang, S.-J. Tu, G. Lib, B. Jiang, Org. Chem.
Front. 3 (2016) 1452;
(q) B. Jiang, Y.-N. Wu, Z.-Z. Chen, X. Wen, W.-J. Hao, S.-L. Wang, S.-J. Tu,
Tetrahedron Lett. 57 (2016) 4246.
Fig. 1. Proposed reaction mechanism.
[4] (a) N. Mantrand, P. Renaud, Tetrahedron 64 (2008) 11860;
(b) R.P. Nair, T.H. Kim, B.J. Frost, Organometallics 28 (2009) 4681;
(c) N. Taniguchi, Synlett (2011) 1308;
In conclusion, we have presented a new and efficient synthesis
of b-sulfonated cyclic ketone derivatives via the potassium iodide-
catalyzed radical arylsulfonylation/ring expansion sequences
through 1,2-alkyl migration of alkenylcyclobutanol derivatives 1
with arylsulfonyl hydrazides 2. This approach is environmentally
benign by use of shelf-stable arylsulfonyl hydrazids as arylsulfonyl
radical precursor and water as solvent. The presented protocol is
an efficient option for synthesizing b-sulfonated cyclic ketone
derivatives.
(d) Q. Lu, J. Zhang, G. Zhao, Y. Qi, H. Wang, A. Lei, J. Am. Chem. Soc. 135 (2013)
11481;
(e) T. Shen, Y. Yuan, S. Song, N. Jiao, Chem. Commun. 50 (2014) 4115;
(f) N. Taniguchi, Tetrahedron 2014 (1984) 70;
(g) A. Kariya, T. Yamaguchi, T. Nobuta, N. Tada, T. Miura, A. Itoh, RSC Adv. 4
(2014) 13191;
(h) H.-S. Li, G. Liu, J. Org. Chem. 79 (2014) 509;
(i) A.U. Meyer, S. Jager, D.P. Hari, B. Konig, Adv. Synth. Catal. 357 (2015) 2050;
(j) D. Zheng, J. Yu, J. Wu, Angew. Chem. Int. Ed. 55 (2016) 11925;
(k) Z.-J. Shen, Y.-N. Wu, C.-L. He, L. He, W.-J. Hao, A.-F. Wang, Tu. Shu-J, B. Jiang,
Chem. Commun. 54 (2018) 445;
(l) F. Liu, J.-Y. Wang, P. Zhou, G. Li, W.-J. Hao, S.-J. Tu, B. Jiang, Angew. Chem., Int.
Ed. 56 (2017) 15570.
Acknowledgment
[5] (a) X.-Z. Shu, M. Zhang, Y. He, H. Frei, F.D. Toste, J. Am. Chem. Soc. 136 (2014)
5844;
This research was supported by Soonchunhyang University
Research Fund and Basic Science Research Program through
the National Research Foundation of Korea (NRF-2016
R1D1A1B03933723).
(b) B. Sahoo, J.-L. Li, F. Glorius, Angew. Chem. Int. Ed. 54 (2015) 11577;
(c) C.W. Suh, D.Y. Kim, Tetrahedron Lett. 56 (2015) 5661;
(d) S.B. Woo, D.Y. Kim, J. Fluorine Chem. 178 (2015) 214;
(e) S.J. Kwon, Y.J. Kim, D.Y. Kim, Tetrahedron Lett. 57 (2016) 4371;
(f) S.J. Kwon, D.Y. Kim, Org. Lett. 18 (2016) 4562;
(g) Y.J. Kim, D.Y. Kim, J. Fluorine Chem. 211 (2018) 119;
(h) G. Bergonzini, C. Cassani, H.L. Olsson, J. Hörberg, C.-J. Wallentin, Chem. Eur.
J. 22 (2016) 3292;
Appendix A. Supplementary data
(i) R. Honeker, R.A.G. Sanchez, M.N. Hopkinson, F. Glorius, Chem. Eur. J. 22
(2016) 4395;
(j) W.-Z. Weng, J.-G. Sun, P. Li, B. Zhang, Chem. Eur. J. 23 (2017) 9752;
(k) J.-J. Zhang, Chin. J. Chem. 35 (2017) 311;
(l) H. Wu, Q. Wang, J. Zhu, Chem. Eur. J. 23 (2017) 13037;
(m) S. Yao, K. Zhang, Q.-Q. Zhou, Y. Zhao, D.-Q. Shi, W.-J. Xiao, Chem. Commun.
54 (2018) 8096.
Supplementary data (Experimental procedures, characteriza-
tions, 1H NMR, 13C, and 19F NMR spectra, HPLC traces) to this article
can be found online at https://doi.org/10.1016/j.tetlet.2018.09.027.
References
[6] T. Mochizaki, S. Hayakawa, K. Narasaka, Bull. Chem. Soc. Jpn. 69 (1996) 2317.
[7] (a) For a selection of our recent works on C-H activation, see: Y.K. Kang, S.M.
Kim, D.Y. Kim J. Am. Chem. Soc. 132 (2010) 11847;
[1] (a) N.S. Simpkins, Sulfones in Organic Synthesis, Pergamon Press, Oxford, 1993;
(b) M. Artico, R. Silvestri, E. Pagnozzi, B. Bruno, E. Novellino, G. Greco, S. Massa,
A. Ettorre, A.G. Loi, F. Scintu, P.J. La Colla, Med. Chem. 43 (2000) 1886;
(c) R.A. Hartz, A.G. Arvanitis, C. Arnold, J.P. Rescinito, K.L. Hung, G. Zhang, H.
Wong, D.R. Langley, P.J. Gilligan, G.L. Trainor, Bioorg. Med. Chem. Lett. 16 (2006)
934;
(b) M.H. Kim, D.Y. Kim, Bull. Korean Chem. Soc. 34 (2013) 3891;
(c) Y.K. Kang, D.Y. Kim, Adv. Synth. Catal. 355 (2013) 3131;
(d) C.W. Suh, S.B. Woo, D.Y. Kim, Asian J. Org. Chem. 3 (2014) 399;
(e) Y.K. Kang, D.Y. Kim, Chem. Commun. 50 (2014) 222;
(f) C.W. Suh, H.J. Jeong, D.Y. Kim, Bull. Korean Chem. Soc. 36 (2015) 406;
(g) C.W. Suh, D.Y. Kim, Org. Lett. 16 (2014) 5374;
(d) K.G. Petrov, Y. Zhang, M. Carter, G.S. Cockerill, S. Dickerson, C.A. Gauthier, Y.
Guo, R.A. Mook, D.W. Rusnak, A.L. Walker, E.R. Wood, K.E. Lackey, Bioorg. Med.
Chem. Lett. 16 (2006) 4686;
(h) S.J. Kwon, D.Y. Kim, Chem. Rec. 16 (2016) 1191;
Please cite this article in press as: Y.J. Kim et al., Tetrahedron Lett. (2018), https://doi.org/10.1016/j.tetlet.2018.09.027

4
Y.J. Kim et al. / Tetrahedron Letters xxx (2018) xxx–xxx
(j) G. Chen, X. Zhang, Z. Zeng, W. Peng, Q. Liang, J. Liu, ChemistrySelect 2017
(i) T.H. Yoon, D.Y. Kim, Synth. Commun. 47 (2017) 2109;
(j) T.H. Kim, M.K. Gil, D.Y. Kim, Bull. Korean Chem. Soc. 38 (2017) 1499;
(k) H.I. Jeong, T.H. Yoon, D.Y. Kim, Bull. Korean Chem. Soc. 38 (2017) 421;
(l) S.J. Kwon, M.G. Gil, D.Y. Kim, Tetrahedron Lett. 58 (2017) 1592;
(m) C.W. Suh, S.J. Kwon, D.Y. Kim, Org. Lett. 19 (2017) 1334;
(n) Y.J. Kim, Y. Kim, D.Y. Kim, Bull. Korean Chem. Soc. 38 (2017) 578;
(o) H.J. Jeong, D.Y. Kim, Org. Lett. 20 (2018) 2944;
(p) H.J. Jeong, Y.H. Kim, D.Y. Kim, Bull. Korean Chem. Soc. 39 (2018) 12;
(q) J.H. Kim, D.Y. Kim, Bull. Korean Chem. Soc. 39 (2018) 1007;
(r) H.I. Jung, J.H. Lee, D.Y. Kim, Bull. Korean Chem. Soc. 39 (2018) 1003;
(s) S.J. Kwon, D.Y. Kim, ChemistrySelect 3 (2018) 5824.
(1979) 2;
(k) X.-Y. Zhu, M. Li, Y.-P. Han, S. Chen, X.-S. Li, Y.-M. Liang, J. Org. Chem. 82
(2017) 8761;
(l) W. Li, L. Gao, W. Zhuge, X. Sun, G. Zheng, Org. Biomol. Chem. 15 (2017)
7819;
(m) P. Chen, C. Zhu, R. Zhu, W. Wu, H. Jiang, Chem. Asian J. 2017 (1875) 12;
(n) G.-Y. Zhang, S.-S. Lv, A. Shoberu, J.-P. Zou, J. Org. Chem. 82 (2017) 9801;
(o) B. Wang, L. Tang, L. Liu, Y. Li, Y. Yang, Z. Wang, Green Chem. 19 (2017)
5794;
(p) Y. Yang, Y. Bao, Q. Guan, Q. Sun, Z. Zha, Z. Wang, Green Chem. 19 (2017)
112;
(q) D. Cheng, T. Chen, X. Xu, J. Yan, Adv. Synth. Catal. 360 (2018) 901;
(r) Z. Peng, X. Zheng, Y. Zhang, D. An, W. Dong, Green Chem. 20 (2018) 1760;
(s) J. Ni, Y. Xue, L. Sun, A. Zhang, J. Org. Chem. 83 (2018) 4598;
(t) Y. Hou, L. Zhu, H. Hu, S. Chen, Z. Li, Y. Liu, P. Gong, New J. Chem. 42 (2018)
8752;
(u) T. Liu, J. Liu, S. Xia, J. Meng, X. Shen, X. Zhu, W. Chen, C. Sun, F. Cheng, ACS
Omega 3 (2018) 1409;
(v) X. Cao, X. Cheng, J. Xuan, Org. Lett. 20 (2018) 449;
(w) S. Kumar, R. Singh, K.N. Singh, Asian J. Org. Chem. 7 (2018) 359.
[8] (a) For a selection of recent works on sulfonyl radicals, see: V. Khakyzadeh, Y.-
H. Wang, B. Breit Chem. Commun. 53 (2017) 4966;
(b) K. Sun, X. Wang, F. Fu, C. Zhang, Y. Chen, L. Liu, Green Chem. 19 (2017) 1490;
(c) J.-P. Wan, S. Zhong, Y. Guo, L. Wei, Eur. J. Org. Chem. 2017 (2017) 4401;
(d) X. Li, C. Zhou, P. Diao, Y. Ge, C. Guo, Tetrahedron Lett. 58 (2017) 1296;
(e) B. Li, Y. Li, L. Yu, X. Wu, W. Wei, Tetrahedron 73 (2017) 2760;
(f) K. Choudhuri, T.K. Achar, P. Mal, Adv. Synth. Catal. 359 (2017) 3566;
(g) P.-G. Li, Y.-C. Li, T. Zhu, L.-H. Zou, Wu, Z, Eur. J. Org. Chem. 2017 (2017) 6081;
(h) K. Xu, L. Li, W. Yan, Y. Wu, Z. Wang, S. Zhang, Green Chem. 19 (2017) 4494;
(i) Y. Zhao, W.-L. Lai, K.-S. Du, D.-Z. Lin, J.-M. Huang, J. Org. Chem. 82 (2017)
9655;
Please cite this article in press as: Y.J. Kim et al., Tetrahedron Lett. (2018), https://doi.org/10.1016/j.tetlet.2018.09.027