Photocatalyst-Free Visible-Light-Promoted C(sp2)-S Coupling: A Strategy for the Preparation of S-Aryl Dithiocarbamates

Article abstract of DOI:10.1021/acs.orglett.9b02921

We have successfully developed a green and efficient multicomponent reaction protocol to synthesize S-aryl dithiocarbamates under visible light. Most appealingly, the reaction can proceed smoothly without adding any transition-metal catalysts, ligands, or photocatalysts while minimizing chemical wastes and metal residues in the end products. The advantages of this method meet the requirements of sustainable and green synthetic chemistry, and it provides a straightforward way to create valuable S-aryl dithiocarbamates.

Full text of DOI:10.1021/acs.orglett.9b02921

Letter
pubs.acs.org/OrgLett
Cite This: Org. Lett. XXXX, XXX, XXX−XXX
Photocatalyst-Free Visible-Light-Promoted C(sp2)−S Coupling:
A Strategy for the Preparation of S‑Aryl Dithiocarbamates
Guoqing Li,†,‡ Qiuli Yan,† Ziyu Gan,‡ Qin Li,‡ Xiaomeng Dou,§ and Daoshan Yang*,†,‡
†Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, State Key Laboratory Base of
Eco-Chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology,
Qingdao, 266042, P. R. China
‡School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, 273165, P. R. China
§School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan, 411201, P. R. China
S
* Supporting Information
ABSTRACT: We have successfully developed a green and
efficient multicomponent reaction protocol to synthesize S-
aryl dithiocarbamates under visible light. Most appealingly, the
reaction can proceed smoothly without adding any transition-
metal catalysts, ligands, or photocatalysts while minimizing
chemical wastes and metal residues in the end products. The
advantages of this method meet the requirements of
sustainable and green synthetic chemistry, and it provides a
straightforward way to create valuable S-aryl dithiocarbamates.
arbon−sulfur bonds are well-known in natural products,
Cpharmacologically active molecules, and organic materi-
als.1 The development of novel and efficient approaches for the
construction of C−S bonds has always been an ongoing
curiosity in organic chemistry.2 The traditional methods for the
construction of C−S bonds include the transition-metal-
catalyzed cross-couplings of thiols or disulfides with aryl
halides, arylboronic acids, or pseudo halides.3 Despite having
great benefits, these reactions could possess some limitations
such as requirement of high temperature, specially designed
ligands, high catalyst loading, and toxic metal salt catalysts
which could not meet the requirements of sustainable and
green chemistry. Thus, it remains a thought-provoking and
attractive task to develop simpler, more efficient, and
environmentally benign strategies for the construction of C−
S bonds.
Figure 1. Representative organic dithiocarbamates with pharmaceut-
ical activity.
approaches for the formation of aryl dithiocarbamates are quite
limited and the available methods involved the Wittig reaction
of aldehydes with phosphonium ylides9 and the reaction of the
sodium salt of dithiocarbamic acid with hypervalent iodine
compounds.10 Recently, transition-metal-catalyzed approaches
for the formation of aryl dithiocarbamates have been
developed.5e,11 For example, very recently, Dong and Bolm
developed an efficient route utilizing copper-catalyzed coupling
reactions for the synthesis of aryl dithiocarbamates using
inexpensive thiuram disulfide reagents (Scheme 1a).11a
Although some achievements have been made, these reactions
could come across certain limitations, including harsh reaction
conditions, toxic metal salt catalysts, and unavailability of the
precursors.
As important sulfur-containing compounds, organic dithio-
carbamates are ubiquitous in a variety of biologically active
compounds (Figure 1).4 For example, they are commonly used
in medicinal chemistry and have found application in the
treatment of cancer.5 Importantly, their biological properties
and critical roles in agriculture have led to the development of
synthetic methods for these compounds. Moreover, they also
function as useful synthetic intermediates, linkers in solid
phase organic synthesis,6 and protecting groups in peptide
synthesis.7 As a result, development of efficient and novel
methods for the synthesis of this kind of significant sulfur-
containing compounds will be of great value for the screening
of biologically active molecules. Traditionally, one-pot
procedures by reaction of amines with carbon disulfide and
alkyl halides have been demonstrated to be convenient
methods for the synthesis of alkyl dithiocarbamates.8 However,
Received: August 16, 2019
© XXXX American Chemical Society
A
DOI: 10.1021/acs.orglett.9b02921
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Organic Letters
Letter
a
Scheme 1. Strategies for the Synthesis of S-Aryl
Table 1. Optimization of the Reaction Conditions
Dithiocarbamates
b
entry
base
photoredox catalyst
solvent
DMSO
DMSO
DMSO
DMSO
DMSO
DMF
yield (%)
1
2
3
4
5
6
7
8
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
KOH
A
B
C
D
79
45
51
23
78
24
Trace
12
Trace
Trace
Trace
54
45
49
Trace
7
5
As a greener substitute to the transition-metal-catalyzed
strategies in organic synthesis chemistry, photochemical
reactions have the advantage of avoiding the excessive use of
expensive and toxic metal catalysts, ultimately avoiding the
metal residues in target products.12 Recently, diverse and
efficient light-induced organic transformations have been
widely used to construct C−C and C−heteroatom bonds.
Recenlty, many studies on the light-promoted C−S bond
forming reactions have been reported.13 In 2016, Oderinde,
Johannes and co-workers developed an efficient photoinduced
Ni-catalyzed method for the cross-coupling of thiols with aryl
and heteroaryl iodides.13d In 2017, Miyake et al. developed an
efficient visible-light-induced protocol for the C−S cross-
coupling of thiols and aryl halides in the absence of photoredox
catalysts.13f In the same year, Fu and co-workers developed an
elegant visible-light photoredox arylation of thiols with aryl
halides at room temperature.13g As an important organic
synthesis means, multicomponent reactions (MCRs) have
attracted extensive attention since complex and diverse
structures are generated in a single operation which improves
the atom economy of the reaction procedure and reduces the
pollution to the greatest extent possible.14 However, studies on
the construction of C−S bonds based on light-induced MCRs
strategies are rare. As a part of our continuing studies on the
photochemical reactions15 and synthesis of sulfur-containing
molecules,16 herein, we report an efficient, innovative, and
simple visible-light-promoted method for the construction of
S-aryl dithiocarbamates through MCRs of aryl halides, carbon
disulfide, and amines at room temperature without using
transition metals or other photocatalysts (Scheme 1b).
Initially, we selected 1-(4-iodophenyl) ethan-1-one (1a),
carbon disulfide (2), and N-methylaniline (3a) as the model
substrates to explore the optimal reaction conditions, including
the bases, photocatalysts, and solvents under an atmosphere of
nitrogen and an irradiation of visible light with a 23 W
compact fluorescent light (CFL). As shown in Table 1, four
photoredox catalysts were screened in DMSO with the use of
2.0 equiv of Cs2CO3 (relative to amount of 1a) as the base,
and Rose Bengal provided the maximum yield (79%) (entries
1−6, Table 1). Notably, the yield also reached 78% without a
photocatalyst (entry 5, Table 1). Encouraged by this result, we
next screened the solvents such as DMF, DMSO, THF,
CH3CN, and 1,4-dioxane in order to improve the trans-
formation efficiency, and the results showed that DMSO was
the ideal solvent for this procedure (comparing the entry 5
with entries 6−9). Other bases tested (entries 10−18) were
found to be inferior to Cs2CO3. No reaction occurred without
the irradiation of visible light (entry 19). Highly pure Cs2CO3
(99.995% purity, trace metals <55.0 ppm) was used to avoid
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
CH3CN
THF
9
1,4-Dioxane
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
10
11
12
13
14
15
16
17
18
19
20
NaOH
K2CO3
DBU
DBN
Pyridine
DABCO
t-BuOK
Et3N
Cs2CO3
Cs2CO3
6
NR
78
c
d
a
Reaction conditions: 1-(4-iodophenyl)ethan-1-one 1a (0.3 mmol),
carbon disulfide 2 (0.8 mmol), N-methylaniline 3a (0.4 mmol), base
(0.6 mmol), solvent (1.5 mL), temperature (rt, ∼25 °C), time (24 h).
b
c
d
Isolated yield. No light. Use of highly pure Cs2CO3 from Sigma-
Aldrich Company (99.995% purity). NR = No reaction. CFL =
compact fluorescent light.
the involvement of other transition metals in the present
transformation, and the reaction gave a 78% yield (entry 20),
which was the same when the analytically pure Cs2CO3 (99%)
was used.
Using the optimized conditions, we next began to explore
the generality and scope of the visible-light-promoted C(sp2)−
S coupling process, and the results are summarized in Scheme
2. To our delight, a variety of aryl halides reacted smoothly
with CS2 and amines, affording the analogous S-aryl
dithiocarbamates in moderate to good yields. Various aryl
halides including aryl iodides and bromides were successfully
coupled with CS2 and amines. Undoubtedly, the reactivity
followed in the order of aryl iodides > aryl bromides, while aryl
chlorides did not work in the present transformation. For aryl
iodides, the electronic effects of substituents exerted obvious
influence on the reaction. Although aryl iodides bearing the
electron-withdrawing groups displayed high reactivity, those
bearing electron-donating ones were found to be poor
substrates (see the Supporting Information (SI) for details).
Further exploration on the scopes and limits of the synthetic
application are in progress. It is worth noting that aromatic
amines showed good reactivity compared to alkyl amines.
B
DOI: 10.1021/acs.orglett.9b02921
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Organic Letters
Letter
a b
,
(4z′) was obtained in 92% yield. This result indicates the
secondary amines are crucial for the present transformation.
The visible-light-promoted domino multicomponent reactions
could tolerate quite a few functional groups such as ketone,
aldehyde, methyl group, ester, nitro group, and cyano group,
leaving ample room for further modification.
Scheme 2. Substrate Scope of Aryl halides with Amines
To further demonstrate the synthetic application of this
method, a gram-scale synthesis of 4a using 1-(4-iodophenyl)-
ethan-1-one (1a), CS2 (2), and N-methylaniline (3a) was
performed. Under the irradiation of two 23 W CFLs, the
desired product (4a) could be formed with a yield of 72% (5.0
mmol scale) (Scheme 3a). This transformation can be also
Scheme 3. Synthetic Applications
applied to the late-stage functionalization of a pharmaceutically
relevant molecule (Scheme 3b). A L-menthol derivative with a
iodine motif could be readily converted to the corresponding
dithiocarbamate product (4aa) in moderate yields (63%).
In order to explore the probable mechanism of this visible-
light-promoted C(sp2)−S coupling, several control experi-
ments were conducted (Figure 2 and Figure 3). We initially
performed UV−vis spectroscopic measurements on various
combinations of 1a, 2, 3a, and Cs2CO3 in DMSO for each
species. As shown in Figure 2a, when 1a, 2, and 3a were mixed
in DMSO, the color of the solution transformed from pale
yellow to brown, and its optical absorption spectrum showed a
bathochromic shift in the visible region, demonstrating the
formation of an electron donor−receptor EDA complex.17
Subsequently, a Job plot using UV/vis absorption experiments
was drawn to evaluate the stoichiometry of the EDA complex
between 1a and 7, where 7 was formed through reaction of 2
and 3a. The maximal absorption obtained at 50% molar
fraction of [2 + 3a] suggested a 1:1 ratio of 1a and 7 (Figure
3). In addition, reactivity was also suppressed in the presence
of TEMPO (2 equiv) and under an aerobic atmosphere (see
the SI for details).
a
Reaction conditions: aryl halides 1 (0.3 mmol), CS2 2 (0.8 mmol),
amines 3 (0.4 mmol), Cs2CO3 (0.6 mmol), DMSO (1.5 mL),
b
Additionally, in order to investigate the effect of photo-
irradiation on the system, an on/off visible light irradiation
experiment was performed. The graph preliminarily points
toward the requirement of continuous visible-light irradiation
for the onset as well as continuity of the reaction (Figure 4).
On the basis of the preliminary results reported above and in
combination with the previous reports,13,17 a plausible
reaction time (24 h). Isolated yield. Unless otherwise noted, all
products were obtained from aryl iodides.
Finally, a primary amine was also investigated under the
standard conditions. Interestingly, when p-toluidine (3l) was
used, no dithiocarbamate (4z) was observed, and the thiourea
C
DOI: 10.1021/acs.orglett.9b02921
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Organic Letters
Letter
Figure 4. “Light/dark” experiments over the time.
Scheme 4. Possible Reaction Pathway
Figure 2. UV−vis spectroscopic measurements on various combina-
tions of 1a, 2, 3a, and Cs2CO3 in DMSO.
tolerance. Through this protocol, one new C−N bond and one
C−S bond are constructed simultaneously in a single step. This
method provides a sustainable and straightforward way to
construct valuable S-aryl dithiocarbamates. Further investiga-
tion of the detailed mechanism and further exploration
regarding the scopes and limits of the synthetic application
are ongoing in our laboratory.
ASSOCIATED CONTENT
* Supporting Information
■
S
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.or-
glett.9b02921.
Figure 3. Job’s plot for ratio between 1a and 7.
Experimental details and compound characterization
(PDF)
Accession Codes
mechanism is herein presented (Scheme 4). Initially, CS2 (2)
would react with amines (3) in the presence of Cs2CO3 to give
the corresponding thiolate (A). Then, an aryl halide and a
thiolate anion first associate, forming an EDA complex. This
EDA complex is subsequently activated by visible-light
irradiation to induce a SET (single electron transfer) from
the thiolate anion to the aryl halide to generate a thiyl radical, a
halide anion, and an aryl radical (B). Finally, the aryl radical
coupled with the thiyl radical, forming the coupling product
(4).
In conclusion, a green and efficient MCR protocol has been
developed for the synthesis of S-aryl dithiocarbamates under
visible light conditions. A series of S-aryl dithiocarbamates
could be conveniently obtained with good functional group
CCDC 1943687−1943689 contain the supplementary crys-
tallographic 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
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: yangdaoshan@tsinghua.org.cn.
ORCID
Daoshan Yang: 0000-0002-3047-5416
D
DOI: 10.1021/acs.orglett.9b02921
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138, 2985−2988. (e) Tan, Y. C.; Munoz-Molina, J. M.; Fu, G. C.;
Peters, J. C. Chem. Sci. 2014, 5, 2831−2835. (f) Chen, J.-R.; Hu, X.-
Q.; Lu, L.-Q.; Xiao, W.-J. Acc. Chem. Res. 2016, 49, 1911−1923.
(g) Xie, L.-Y.; Fang, T.-G.; Tan, J.-X.; Zhang, B.; Cao, Z.; Yang, L.-H.;
He, W.-M. Green Chem. 2019, 21, 3858−3863. (h) Terrett, J. A.;
Cuthbertson, J. D.; Shurtleff, V. W.; MacMillan, D. W. C. Nature
2015, 524, 330−334. (i) Romero, N. A.; Nicewicz, D. A. Chem. Rev.
2016, 116, 10075−10166. (j) Shang, T.-Y.; Lu, L.-H.; Cao, Z.; Liu, Y.;
He, W.-M.; Yu, B. Chem. Commun. 2019, 55, 5408−5419. (k) Li, L.;
Liu, W.; Zeng, H.; Mu, X.; Cosa, G.; Mi, Z.; Li, C.-J. J. Am. Chem. Soc.
2015, 137, 8328−8331. (l) Xie, L.-Y.; Jiang, L.-L.; Tan, J.-X.; Wang,
Y.; Xu, X.-Q.; Zhang, B.; Cao, Z.; He, W.-M. ACS Sustainable Chem.
Eng. 2019, 7, 14153−14163.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the Natural Science Foundation
of Shandong Province (ZR2016JL012), the National Natural
Science Foundation of China (21302110), and the Scientific
Research Foundation of Qingdao University of Science and
Technology.
REFERENCES
■
(13) For selected examples, see: (a) Uyeda, C.; Tan, Y. C.; Fu, G.
C.; Peters, J. C. J. Am. Chem. Soc. 2013, 135, 9548−9552. (b) Bunnett,
J. F.; Creary, X. J. Org. Chem. 1974, 39, 3173−3174. (c) Johnson, M.
W.; Hannoun, K. I.; Tan, Y.; Fu, G. C.; Peters, J. C. Chem. Sci. 2016,
7, 4091−4100. (d) Oderinde, M. S.; Frenette, M.; Robbins, D. W.;
Aquila, B.; Johannes, J. W. J. Am. Chem. Soc. 2016, 138, 1760−1763.
(e) Chen, L.; Liang, J.; Chen, Z.-Y.; Chen, J.; Yan, M.; Zhang, X.-J.
Adv. Synth. Catal. 2018, 361, 956−960. (f) Liu, B.; Lim, C.-H.;
Miyake, G. M. J. Am. Chem. Soc. 2017, 139, 13616−13619. (g) Jiang,
M.; Li, H.; Yang, H.; Fu, H. Angew. Chem., Int. Ed. 2017, 56, 874−
879. (h) Jouffroy, M.; Kelly, C. B.; Molander, G. A. Org. Lett. 2016,
18, 876−879.
(1) (a) Li, N. S. Acc. Chem. Res. 2011, 44, 1257−1269. (b) Haruki,
H.; Pedersen, M. G.; Gorska, K. I.; Pojer, F.; Johnsson, K. Science
2013, 340, 987−991. (c) Shen, C.; Zhang, P.; Sun, Q.; Bai, S.; Hor, T.
S. A.; Liu, X. Chem. Soc. Rev. 2015, 44, 291−314.
(2) (a) Hartwig, J. F. Acc. Chem. Res. 2008, 41, 1534−1544.
(b) Beletskaya, I. P.; Ananikov, V. P. Chem. Rev. 2011, 111, 1596−
1636.
(3) For selected examples, see: (a) Kondo, T.; Mitsudo, T.-a. Chem.
Rev. 2000, 100, 3205−3220. (b) Wu, C.; Lu, L.-H.; Peng, A.-Z.; Jia,
G.-K.; Peng, C.; Cao, Z.; Tang, Z.; He, W.-M.; Xu, X. Green Chem.
2018, 20, 3683−3688. (c) Sun, K.; Shi, Z.; Liu, Z.; Luan, B.; Zhu, J.;
Xue, Y. Org. Lett. 2018, 20, 6687−6690. (d) Xie, L.-Y.; Peng, S.; Tan,
J.-X.; Sun, R.-X.; Yu, X.; Dai, N.-N.; Tang, Z.-L.; Xu, X.; He, W.-M.
ACS Sustainable Chem. Eng. 2018, 6, 16976−16981. (e) Bates, C. G.;
Saejueng, P.; Doherty, M. Q.; Venkataraman, D. Org. Lett. 2004, 6,
5005−5008. (f) Ma, D.; Cai, Q. Acc. Chem. Res. 2008, 41, 1450−
1460. (g) Bao, W.-H.; He, M.; Wang, J.-T.; Peng, X.; Sung, M.; Tang,
Z.; Jiang, S.; Cao, Z.; He, W.-M. J. Org. Chem. 2019, 84, 6065−6071.
(h) Lu, L.-H.; Wang, Z.; Xia, W.; Cheng, P.; Zhang, B.; Cao, Z.; He,
W.-M. Chin. Chem. Lett. 2019, 30, 1237−1240. (i) Kwong, F. Y.;
Buchwald, S. L. Org. Lett. 2002, 4, 3517−3520.
(4) (a) Fernandez, J. M. G.; Mellet, C. O.; Blanco, J. L. J.; Mota, J.
F.; Gadelle, A.; Coste-Sarguet, A.; Defaye, J. Carbohydr. Res. 1995,
268, 57−71. (b) D'hooghe, M.; De Kimpe, N. Tetrahedron 2006, 62,
513−535.
(5) (a) Ronconi, L.; Marzano, C.; Zanello, P.; Corsini, M.; Miolo,
G.; Macca, C.; Trevisan, A.; Fregona, D. J. Med. Chem. 2006, 49,
1648−1657. (b) Hou, X.; Ge, Z.; Wang, T.; Guo, W.; Cui, J.; Cheng,
T.; Lai, C.; Li, R. Bioorg. Med. Chem. Lett. 2006, 16, 4214−4219.
(c) Huang, W.; Ding, Y.; Miao, Y.; Liu, M.-Z.; Li, Y.; Yang, G.-F. Eur.
J. Med. Chem. 2009, 44, 3687−3696. (d) Li, R.-D.; Zhang, X.; Li, Q.-
Y.; Ge, Z.-M.; Li, R.-T. Bioorg. Med. Chem. Lett. 2011, 21, 3637−3640.
(e) Gao, M.-Y.; Xu, W.; Zhang, S.-B.; Li, Y.-S.; Dong, Z.-B. Eur. J. Org.
Chem. 2018, 2018, 6693−6698.
(14) Selective reviews, see: (a) D’ Souza, D.; Muller, T. Chem. Soc.
̈
̀
Rev. 2007, 36, 1095−1108. (b) Toure, B. B.; Hall, D. G. Chem. Rev.
2009, 109, 4439−4486.
(15) (a) Yang, D.; Li, G.; Xing, C.; Cui, W.; Li, K.; Wei, W. Org.
Chem. Front. 2018, 5, 2974−2979. (b) Yang, D.; Huang, B.; Wei, W.;
Li, J.; Lin, G.; Liu, Y.; Ding, J.; Sun, P.; Wang, H. Green Chem. 2016,
18, 5630−5634. (c) Sun, P.; Yang, D.; Wei, W.; Jiang, M.; Wang, Z.;
Zhang, L.; Zhang, H.; Zhang, Z.; Wang, Y.; Wang, H. Green Chem.
2017, 19, 4785−4791. (d) Li, G.; Yan, Q.; Gong, X.; Dou, X.; Yang,
D. ACS Sustainable Chem. Eng. 2019, 7, 14009−14015.
(16) (a) Yang, D.; Sun, P.; Wei, W.; Liu, F.; Zhang, H.; Wang, H.
Chem. - Eur. J. 2018, 24, 4423−4427. (b) Sun, P.; Jiang, M.; Wei, W.;
Min, Y.; Zhang, W.; Li, W.; Yang, D.; Wang, H. J. Org. Chem. 2017,
82, 2906−2913. (c) Gong, X.; Li, G.; Gan, Z.; Yan, Q.; Dou, X.; Yang,
D. Asian J. Org. Chem. 2019, 8, 1472−1478. (d) Li, G.; Gan, Z.; Kong,
K.; Dou, X.; Yang, D. Adv. Synth. Catal. 2019, 361, 1808−1814.
(17) (a) Rosokha, S. V.; Kochi, J. K. Acc. Chem. Res. 2008, 41, 641−
653. (b) Lima, C. G. S.; Lima, T. d. M.; Duarte, M.; Jurberg, I. D.;
Paixao, M. W. ACS Catal. 2016, 6, 1389−1407. (c) Arceo, E.; Jurberg,
̃
́
́
I. D.; A lvarez-Fernandez, A.; Melchiorre, P. Nat. Chem. 2013, 5,
750−756. (d) Zhang, J.; Li, Y.; Xu, R.; Chen, Y. Angew. Chem., Int. Ed.
2017, 56, 12619−12623. (e) Nappi, M.; Bergonzini, G.; Melchiorre,
P. Angew. Chem., Int. Ed. 2014, 53, 4921−4925. (f) Davies, J.; Booth,
S. G.; Essafi, S.; Dryfe, R. A. W.; Leonori, D. Angew. Chem., Int. Ed.
2015, 54, 14017−14021. (g) Kandukuri, S. R.; Bahamonde, A.;
Chatterjee, I.; Jurberg, I. D.; Escudero-Adan, E. C.; Melchiorre, P.
Angew. Chem., Int. Ed. 2015, 54, 1485−1489. (h) Song, S.; Zhang, Y.;
Yeerlan, A.; Zhu, B.; Liu, J.; Jiao, N. Angew. Chem., Int. Ed. 2017, 56,
2487−2491.
(6) Morf, P.; Raimondi, F.; Nothofer, H.-G.; Schnyder, B.; Yasuda,
A.; Wessels, J. M.; Jung, T. A. Langmuir 2006, 22, 658−663.
(7) Greene, T. W.; Wuts, P. G. M. Protecting Groups in Organic
Synthesis, 3rd ed.; Wiley Interscience: New York, 1999; p 484.
(8) (a) Azizi, N.; Aryanasab, F.; Torkiyan, L.; Ziyaei, A.; Saidi, M. R.
J. Org. Chem. 2006, 71, 3634−3635. (b) Azizi, N.; Aryanasab, F.;
Saidi, M. R. Org. Lett. 2006, 8, 5275−5277. (c) Peng, H.-Y.; Dong, Z.-
B. Eur. J. Org. Chem. 2019, 2019, 949−956.
(9) Huang, Z.-Z.; Wu, L. L. Synth. Commun. 1996, 26, 509−514.
(10) Chen, Z.-C.; Jin, Y.-Y.; Stang, P. J. J. Org. Chem. 1987, 52,
4117−4118.
(11) (a) Dong, Z.-B.; Liu, X.; Bolm, C. Org. Lett. 2017, 19, 5916−
5919. (b) Liu, Y.; Bao, W. Tetrahedron Lett. 2007, 48, 4785−4788.
(c) Bhadra, S.; Saha, A.; Ranu, B. C. Green Chem. 2008, 10, 1224−
1230. (d) Aryanasab, F. RSC Adv. 2016, 6, 32018−32024. (e) Qi, C.;
Guo, T.; Xiong, W. Synlett 2016, 27, 2626−2630.
(12) For selected examples, see: (a) Prier, C. K.; Rankic, D. A.;
MacMillan, D. W. C. V. Chem. Rev. 2013, 113, 5322−5363. (b) Li, L.;
Fan, S.; Mu, X.; Mi, Z.; Li, C.-J. J. Am. Chem. Soc. 2014, 136, 7793−
7796. (c) Li, L.; Mu, X.; Liu, W.; Wang, Y.; Mi, Z.; Li, C.-J. J. Am.
Chem. Soc. 2016, 138, 5809−5812. (d) Mfuh, A. M.; Doyle, J. D.;
Chhetri, B.; Arman, H. D.; Larionov, O. V. J. Am. Chem. Soc. 2016,
E
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