A Novel Method for the Direct Synthesis of Symmetrical and Unsymmetrical Sulfides and Disulfides from Aryl Halides and Ethyl Potassium Xanthogenate

Article abstract of DOI:10.1055/s-0037-1609081

An efficient and new method for the synthesis of disulfides and sulfides via the reaction of aryl halides with ethyl potassium xanthogenate in the presence of MOF-199 is described. O -Ethyl- S -aryl carbonodithioate has a key role as an intermediate in this procedure; it was converted into symmetrical diaryl disulfides in DMF. Additionally, this could be applied to the synthesis of unsymmetrical aryl alkyl(aryl′) disulfides by the reaction with S -alkyl(aryl) sulfurothioates (Bunte salts) as well as unsymmetrical aryl alkyl(aryl′) sulfides in DMSO.

Full text of DOI:10.1055/s-0037-1609081

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© Georg Thieme Verlag Stuttgart · New York
2018, 29, A–G
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M. Soleiman-Beigi, Z. Arzehgar
Letter
Synlett
A Novel Method for the Direct Synthesis of Symmetrical and
Unsymmetrical Sulfides and Disulfides from Aryl Halides and Ethyl
Potassium Xanthogenate
M. Soleiman-Beigi*
S
R
Ar
S
Z. Arzehgar
60–81%
Department of Chemistry, Basic of Sciences Faculty,
Ilam University, PO Box 69315-516, Ilam, Iran
SoleimanBeigi@yahoo.com
1) MOF-199, DMSO, 80 °C, 12 h
2) K2CO3, RSSO3Na, 80 °C, 12 h
S
MOF-199, K2CO3
DMF, 120 °C, 8 h
1) MOF-199, DMSO, 80 °C
2) K2CO3, R-X, 80 °C, 12 h
EtO
SK
+
Ar-X
S
S
Ar
S
R
Ar
Ar
R = aryl or alkyl
50–90%
58–98%
Received: 06.11.2017
Accepted after revision: 24.12.2017
Published online: 31.01.2018
reagents and procedures that can afford, in particular, un-
symmetrical disulfides. Hence, sodium S-alkyl (S-aryl) sul-
furothioates6 (Bunte salts reported in 1897 by Hans Bunte)
and ethyl potassium xanthogenate5f–h have been successful-
ly used as the sulfur source for the synthesis of aryl
alky(aryl′) disulfides in the presence of metal–organic
frameworks (MOF-199). Bunte salts were previously used
as a thiolate source in the synthesis of disulfides and tri-
sulfides by the reactions with thiols, Na2S, and sulfinates.7
Metal–organic frameworks (MOFs) are important crys-
talline materials in heterogeneous catalysis that are used
for a variety of transformations including cross-coupling
reactions.8,9 Important features of MOFs when used as hetero-
geneous catalysts are their high internal surface area, high
activity, microporosity, ease of product separation, stabili-
ty, diffusion, and high metal content.10
Herein, in an extension of our previous studies on the
synthesis of disulfides,11 we report a novel method for the
synthesis of unsymmetrical aryl alkyl(aryl′) disulfides by
reaction of aryl halides, ethyl potassium xanthogenate, and
Bunte salts in the presence of MOF-199. The procedure was
also extended to the synthesis of unsymmetrical organic
sulfides and symmetrical disulfides.
The MOF-199 was prepared in 87% yield using the reac-
tion of benzenetricarboxylic acid and Cu(OAc)2·H2O in a
1:1:1 mixture of DMF/EtOH/H2O following the literature.12
The structures of MOF-199 were deduced from their FT-IR,
EDX, X-ray, and SEM analytical data.13
Initially, we commenced our study with a model reac-
tion of iodobenzene 1, ethyl potassium xanthogenate 2, and
a catalytic amount of MOF-199 at 80 °C, in order to opti-
mize conditions for forming the key intermediate O-ethyl-
S-phenyl carbonodithioate (3), because this project was
DOI: 10.1055/s-0037-1609081; Art ID: St-2017-d0819-l
Abstract An efficient and new method for the synthesis of disulfides
and sulfides via the reaction of aryl halides with ethyl potassium xantho-
genate in the presence of MOF-199 is described. O-Ethyl-S-aryl
carbonodithioate has a key role as an intermediate in this procedure; it
was converted into symmetrical diaryl disulfides in DMF. Additionally,
this could be applied to the synthesis of unsymmetrical aryl alkyl(aryl′)
disulfides by the reaction with S-alkyl(aryl) sulfurothioates (Bunte salts)
as well as unsymmetrical aryl alkyl(aryl′) sulfides in DMSO.
Key words MOF-199, unsymmetrical disulfides, ethyl potassium
xanthogenate, sulfides
Organosulfur derivatives represent an important class of
compounds with applications in the pharmaceutical indus-
try, materials science, food chemistry, and synthetic chem-
istry.1,2 The most common methods used to synthesize
these compounds include the use of thiols.3 Consequently,
the thioalkylation of thiols–thiolysis is appropriate for the
synthesis of unsymmetrical disulfides and sulfides.4
Although thiols are readily available they have significant
drawbacks such as being toxic and having unpleasant odors
with associated environmental issues. Furthermore, the
ready overoxidation of thiols to their corresponding sym-
metrical disulfides during the synthesis of unsymmetrical
disulfides or sulfides is another drawback of using these
compounds. In order to overcome these difficulties signifi-
cant attention has been directed towards the search for
alternative pathways. Nowadays, C–S cross-coupling reac-
tions of aryl halides with S-transfer reagents have attracted
a lot of attention for the direct syntheses of organosulfur
derivatives.5 As such, interest continues in finding new
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–G

B
M. Soleiman-Beigi, Z. Arzehgar
Letter
Synlett
aimed towards applying O-ethyl-S-phenyl carbonodithioate
as an aryl thiolate (ArS–) source. The desired product 3 was
obtained using DMSO as the reaction solvent in 92% yield
and was the only product. When using PEG and DMF as the
reaction solvent, diphenyl disulfide was formed as the
major product in 60% and 74% yields, respectively (Scheme 1).
bromides) and benzyl bromide. However, in the case of aryl
sec-butyl disulfide products the reaction yield was lower
when compared to the others (Table 1, 5l–n). The procedure
could also be applied to the synthesis of unsymmetrical
diaryl disulfides from sodium aryl sulfurothioates. In this
regard, sodium phenyl sulfurothioate was examined un-
der the optimal reaction conditions; 1-(4-methoxyphe-
nyl) 2-phenyl disulfide and 1-phenyl 2-(p-tolyl) disulfide
were obtained in 71% and 63% 1-phenyl 2-(p-tolyl) disul-
fide and 1-(4-methoxyphenyl) 2-phenyl disulfide were
obtained in 63% and 71% yields, respectively (Table 1, 5o
and 5p)
The procedure was also extended to the synthesis of
unsymmetrical sulfides by the addition of aryl (alkyl) ha-
lides to the reaction mixture after the first step was com-
plete (Table 2). In this way, a range of diaryl and aryl alkyl
sulfides was synthesized in good to excellent yield (Table 2).
S
MOF-199, K2CO3
S
OEt
S
Ph
+
Ph-I
+
Ph
Ph
S
solvent, 80 °C
EtO
SK
S
1
2
3
4
Solvent
DMSO
DMF
3 (%) 4 (%)
92
10
23
–
74
60
PEG
Scheme 1 Synthesis of O-ethyl-S-phenyl carbonodithioate as an aryl
thiolate (ArS–) source. Reagents and conditions: PhI (2.0 mmol), ethyl
potassium xanthogenate (2, 3.0 mmol), MOF-199 (8.0 mg), DMF
(3.0 mL), K2CO3 (1.0 mmol) 80 °C, and 8 h.
We were able to extend these reaction conditions as a
novel and efficient method for the synthesis of symmetrical
disulfides using potassium ethyl xanthogenate 2 (S source)
by increasing the temperature to 120 °C in DMF in the pres-
ence of K2CO3 (Scheme 2).
1) MOF-199
DMSO, 80 °C
S
I
S
S
+
2) K2CO3, BnSSO3Na
EtO
SK
1
2
5
Next, we focused on the major aim of this project;
namely the one-pot synthesis of unsymmetrical disulfides
5 from aryl halides and potassium ethyl xanthogenate 2 in
the presence of MOF-199. After, conversion of potassium
ethyl xanthogenate (2) into O-ethyl-S-aryl carbonodithioate
(3) and K2CO3, a range of sodium S-alkyl(benzyl,aryl)sulfu-
rothioates was added to the reaction mixture and heating
was continued for 12 h to give the corresponding unsym-
metrical disulfides in moderate to good yields (Table 1).
The procedure was successful with sec-butyl, benzyl,
and n-butyl sulfurothioates with various aryl iodides (and
MOF-199
BnSSO3Na
SK
S
OEt
K2CO3
S
hydrolysis
3
7
Scheme 3 Purposed mechanism for the unsymmetrical disulfide
formation
S
MOF-199, K2CO3
S
Ar
Ar-I
+
Ar
S
EtO
SK
DMF, 120 °C
8 h
2
4
S
S
S
S
S
S
4a: 98%, X=I
4b: 58%, X=Br
4c: 89%, X=I
NO2
OMe
S
S
S
S
S
S
OMe
O2N
4d: 93%, X=I
4e: 60%, X=Br
4f: 88%, X=I
Scheme 2 Scope for the synthesis of symmetrical disulfides.a a Reagents and conditions: ArI (2.0 mmol), ethyl potassium xanthogenate 2 (3.0 mmol),
MOF-199 (8.0 mg), DMF (3.0 mL), K2CO3 (1.0 mmol) 120 °C, 8 h. b Isolated yield.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–G

C
M. Soleiman-Beigi, Z. Arzehgar
Letter
Synlett
Mechanistically, the coupling reaction for the formation
of the C–S bond between iodobenzene (1) and potassium ethyl
xanthogenate (2, xanthate coupling) gives the key inter-
mediate O-ethyl-S-phenyl carbonodithioate (3). Hydrolysis
using K2CO3 gives the corresponding thiolate 7, which
reacts with sodium S-benzyl sulfurothioate to give unsym-
metrical disulfide 5 (Scheme 3).
In the case of diaryl and aryl alkyl sulfides, according to
a possible mechanistic pathway based on the one suggested
by Akkilagunta et al., thiolate 7 undergoes a second cross-
coupling reaction with alkyl or aryl halides to form the un-
symmetrical sulfides 6 (Scheme 4).5f
Table 1 Scope for the Synthesis of Unsymmetrical Disulfidesa
1) MOF-199
DMSO, 80 °C, 12 h
S
S
R
+
Ar-I
Ar
S
EtO
SK
2) K2CO3, RSSO3Na
80 °C, 12 h
2
5
R = Aryl or Alkyl
Entry
1
ArI
RSSO3Na
Product
Yield of 5 (%)b
I
S
S
BnSSO3Na
BnSSO3Na
BnSSO3Na
5a
5b
5c
81
I
S
S
2
3
80
74
I
S
S
I
S
S
S
4
5
6
BnSSO3Na
BnSSO3Na
BnSSO3Na
5d
5e
5f
75
70
79
MeO
MeO
Br
S
Br
S
S
F3C
F3C
I
S
S
S
7
8
9
n-BuSSO3Na
n-BuSSO3Na
n-BuSSO3Na
5g
5h
5i
71
68
67
I
S
I
S
S
MeO
F3C
MeO
F3C
Br
S
S
10
11
n-BuSSO3Na
n-BuSSO3Na
5j
67
80
S
Br
S
5k
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–G

D
M. Soleiman-Beigi, Z. Arzehgar
Letter
Synlett
Table 2 (continued)
Entry
ArI
RSSO3Na
Product
Yield of 5 (%)b
I
S
S
12
s-BuSSO3Na
S
S
5l
65
I
13
14
s-BuSSO3Na
5m
5n
63
60
I
S
S
s-BuSSO3Na
MeO
MeO
Br
S
15
16
PhSSO3Na
PhSSO3Na
5o
5p
63
71
S
S
I
S
MeO
MeO
a Reagents and conditions: (1) aryl halide (1.0 mmol), ethyl potassium xanthogenate (2, 1.5 mmol), MOF-199 (4.0 mg), DMSO (2.0 mL), 80 °C, 12 h.
(2) RS2O3Na (1.0 mmol), K2CO3 (1.0 mmol), reflux, 12 h.
b Isolated yields.
Table 2 Scope for the Synthesis of Unsymmetrical Sulfidesa
1) MOF-199, DMSO
80 °C, 12 h
S
S
Ar
R
+
Ar-I
EtO
SK
2) K2CO3, R-X
80 °C, 12 h
2
6
R = Aryl or Alkyl
Entry
1
ArI
RX
Product
Yield of 6 (%)b
I
Br
Br
Br
S
6a
6b
90
I
S
2
81
I
I
S
S
3
4
6c
85
84
Br
6d
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–G

E
M. Soleiman-Beigi, Z. Arzehgar
Letter
Synlett
Table 2 (continued)
Entry
ArI
RX
Product
Yield of 6 (%)b
I
Br
Br
S
5
6e
6f
80
I
I
S
6
7
85
73
OMe
OMe
I
S
S
6g
Br
I
I
8
9
6h
6i
72
75
I
S
S
S
I
I
I
10
11
6j
84
50
Br
6k
O2N
NO2
I
I
S
12
6l
66
MeO
OMe
a Reagents and conditions: (1) aryl halide (1.0 mmol), ethyl potassium xanthogenate (2, 1.5 mmol), MOF-199 (4.0 mg), DMSO (2.0 mL), 80 °C, 12 h.
(2) RX (1.0 mmol), K2CO3 (1.0 mmol), reflux, 12 h.
b Isolated yields.
To confirm the recyclability of the MOF-199,
the fresh and reused catalyst was characterized by FT-IR,
XRD, EDX, and SEM spectroscopy. All of the data are similar
to that of other MOF-199 samples previously described in
the literature.13 It was found that MOF-199 could
be reused for further runs (demonstrated for up to five
cycles) without decrease in activity.
In conclusion, an efficient and novel method is de-
scribed for the synthesis of various organosulfur com-
pounds from aryl halides and ethyl potassium xantho-
genate in the presence of MOF-199.14–18 This procedure is
not only applicable to the synthesis of O-ethyl-S-aryl xantho-
genate as the reaction intermediate, but can also be used for
synthesis of unsymmetrical disulfides and sulfides on add-
ing K2CO3, Bunte salts, and organic halides to the previously
generated intermediate. The procedure was also extended
to synthesize symmetrical diaryl disulfides in good to ex-
cellent yields by changing the reaction solvent to DMF. In
this work, MOF-199 as an affective heterogeneous, porous,
and recyclable catalyst, and O-ethyl-S-aryl xanthogenate as
a new, stable, solid, and odorless sulfurating reagent were
successfully investigated.
I
S
S
1) MOF-199, DMSO
80 °C
R
+
EtO
SK
2) K2CO3, R-X
80 °C, 12 h
6
2
1
MOF-199
R-X
S
OEt
SK
K2CO3
hydrolysis
S
3
7
Scheme 4 Proposed pathway for unsymmetrical sulfide formation
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–G

F
M. Soleiman-Beigi, Z. Arzehgar
Letter
Synlett
Dalton Trans. 2011, 40, 6344. (d) Deria, P.; Mondloch, J. E.;
Karagiaridi, O.; Bury, W.; Hupp, J. T.; Farha, O. K. Chem. Soc. Rev.
2014, 43, 5896.
Funding Information
Financial support from the Ilam University Research Council is grate-
fully acknowledged.
)(
(9) Furukawa, H.; Cordova, K. E.; O’Keeffe, M.; Yaghi, O. M. Science
2013, 341, 974.
(10) Dhakshinamoorthy, A.; Asiric, A. M.; Garcia, H. Chem. Soc. Rev.
2015, 44, 1922.
Supporting Information
(11) (a) Soleiman-Beigi, M.; Arzehgar, Z. Heteroat. Chem. 2015, 26,
355. (b) Soleiman-Beigi, M.; Yavari, I.; Sadeghizadeh, F. RSC Adv.
2015, 5, 87564. (c) Soleiman-Beigi, M.; Sadeghizadeh, F.;
Basereh, A. J. Sulfur Chem. 2017, 38, 572. (d) Soleiman-Beigi, M.;
Yavari, I.; Sadeghizadeh, F. Phosphorus, Sulfur Silicon Relat. Elem.
2018, 193, 41. (e) Soleiman-Beigi, M.; Mohammadi, F. J. Sulfur
Chem. 2016, 38, 134.
(12) Savegnago, L. Environ. Toxicol. Pharmacol. 2006, 21, 86.
(13) Britt, D.; Tranchemontagne, D.; Yaghi, O. M. Proc. Natl. Acad. Sci.
U.S.A. 2008, 105, 11623.
Supporting information for this article is available online at
https://doi.org/10.1055/s-0037-1609081.
S
u
p
p
ortiInfogrmoaitn
S
u
p
p
ortioInfgrmoaitn
References and Notes
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N.; Khan, A. T. ACS Comb. Sci. 2015, 17, 671. (d) Bodanszky, M.
Principles of Peptide Synthesis; Springer: Berlin, 1984.
(3) (a) Jones, R. C.; Katritzky, A. R. Comprehensive Organic Func-
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Heteroatoms with at Least One Carbon-to-heteroatom Multiple
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Adv. 2014, 4, 13854. (c) Witt, D. Synthesis 2008, 2491.
(d) Rayner, C. M. Contemp. Org. Synth. 1995, 2, 409.
(14) General Procedure for the Synthesis of S-Alkyl Sulfurothio-
ates
The requisite alkyl halide (10.0 mmol) and sodium thiosulfate
pentahydrate (2.98 g, 12.0 mmol) dissolved in methanol–water
(3:1, 20 mL). The reaction mixture was stirred and heated to 65 °C.
Upon completion of the reaction, the mixture was cooled to
room temperature, and then concentrated at 40–45 °C. The
resultant solid was treated with methanol (50 mL), heated to 50 °C
(most solid dissolved), and filtered. This removed the excess
sodium thiosulfate and sodium chloride. The filtrate was con-
centrated to a white solid. The mixture was washed with n-
hexane, filtered, and dried under vacuum at 50 °C.
(15) General Procedure for the Synthesis of S-Aryl Sulfurothio-
ates
To a stirred mixture of iodobenzene (1.02 g, 5.0 mmol), sodium
thiosulfate pentahydrate (1.88 g, 7.5 mmol) and CuI (0.09 g, 0.5
mmol, 10 mol%) in DMSO (5 mL) was added 1,10-phenanthro-
line (0.18 g, 1.0 mmol, 20 mol%), and the mixture was stirred for
5 min at room temperature and then heated to 80 °C for 4 h
under a nitrogen atmosphere until completion of reaction. The
reaction mixture was cooled to room temperature, brine (15
mL) was added, and the mixture was stirred vigorously at room
temperature for 1 h. The mixture was filtered, and the solid was
washed successively with brine and n-hexanes. The solid was
dried under vacuum at 50 °C for 3 h.
(4) (a) Fernández-Rodríguez, M. A.; Shen, Q.; Hartwig, J. F. J. Am.
Chem. Soc. 2006, 128, 2180. (b) Bastug, G.; Nolan, S. P. J. Org.
Chem. 2013, 78, 9303. (c) Murata, M.; Buchwald, S. L. Tetrahe-
dron 2004, 60, 7397. (d) Oderinde, M. S.; Frenette, M.; Robbins,
D. W.; Aquila, B.; Johannes, J. W. J. Am. Chem. Soc. 2016, 138,
1760. (e) Xu, H.-J.; Zhao, Y.-Q.; Feng, T.; Feng, Y.-S. J. Org. Chem.
2012, 77, 2649. (f) Uyeda, C.; Tan, Y.; Fu, G. C.; Peters, J. C. J. Am.
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Soc. 2013, 135, 9548. (g) Hunter, R.; Caira, M.;
Stellenboom, N. J. Org. Chem. 2006, 71, 8268. (h) Antoniow, S.;
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(k) Mukherjee, N.; Chatterjee, T.; Ranu, B. C. J. Org. Chem. 2013,
78, 11110.
(16) General Procedure for the Synthesis of Unsymmetrical
Disulfides
The requisite alkyl (aryl) halide (1.0 mmol), potassium O-ethyl-
carbonodithioate (0.24 g, 1.5 mmol) and MOF-199 (4.0 mg)
were added to DMSO (2.0 mL) and the mixture heated to 80 °C
for 12 h. After complete conversion of the alkyl (aryl) halide into
O-ethyl-S-phenyl carbonodithioate, RS2O3Na (1.0 mmol) and
K2CO3 (0.14 g, 1.0 mmol) were added and the mixture heated to
80 °C for a further 12 h. The progress of reaction was monitored
by TLC. Upon completion of the reaction, the mixture was
cooled to room temperature and then filtered. The filtrate was
evaporated under vacuum, CH2Cl2 (20 mL) was added, and the
mixture was washed with H2O (2 × 15 mL). The combined
organic layers were dried over Na2SO4, filtered, and evaporated
to afford the crude unsymmettrical alkyl (aryl) disulfide, which
was purified by thick-layer chromatography (silica gel, eluting
wth n-hexane–ethyl acetate, 20:1; in the case of 5d,f,i,j,n,p,
4:1).
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Singh, R.; Raghuvanshi, D. S.; Singh, K. N. Org. Lett. 2013, 15,
5874. (e) Qiao, Z.; Wei, J.; Jiang, X. Org. Lett. 2014, 16, 1212.
(f) Akkilagunta, V. K.; Kakulapati, R. R. J. Org. Chem. 2011, 76,
6819. (g) Prasad, D. J. C.; Sekar, G. Org. Lett. 2011, 13, 1008.
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(c) Dhakshinamoorthy, A.; Alvaro, M.; Corma, A.; Garcia, H.
O-Ethyl-S-phenyl Carbonodithioate (3)
Oil.1H NMR (300 MHz, CDCl3): δ = 7.76 (d, 2 HAr), 7.37–7.12 (m,
3 HAr), 3.26 (q, 2 HOEt), 1.14 (t, 3 HOEt) ppm.13C NMR (100
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–G

G
M. Soleiman-Beigi, Z. Arzehgar
Letter
Synlett
MHz, CDCl3): δ = 210.2 (C=S), 138.7, 136.4, 131.4, 126.4 (CAr),
66.0 (CH2), 13.7 (CH3) ppm. GC–MS (EI): m/z = 198.3 [M+].
1-Benzyl -2-(naphthalen-2-yl)disulfide (5b)
(18) General Procedure for the Synthesis of Unsymmetrical Sul-
fides
The aryl halide (1.0 mmol), potassium O-ethylcarbonodithioate
(0.24 g, 1.5 mmol) and MOF-199 (4.0 mg) were added to DMSO
(2 mL) and the mixture heated to 80 °C for 12 h. After complete
conversion of the alkyl (aryl) halide into O-ethyl-S-phenyl car-
bonodithioate, the requisite alkyl (aryl) halide (1.0 mmol) and
K2CO3(0.058 g, 1.0 mmol) were added and the mixture heated at
80 °C for a further 12 h. The progress of reaction was monitored
by TLC. Upon completion of the reaction, the mixture was
cooled to room temperature and filtered. The filtrate was evap-
orated under vacuum, CH2Cl2 (20 mL) was added, and the
mixture was washed with H2O (2 × 15 mL). The combined
organic layers were dried over Na2SO4, filtered, and evaporated
to afford the crude unsymmetrical alkyl (aryl) sulfide, which
was purified by thick-layer chromatography (silica gel, n-
hexane–ethyl acetate, 20:1; in the case of 6g,k,l, 4:1).
Phenyl(o-tolyl)sulfide (6i)
Oil. 1H NMR (300 MHz, CDCl3): δ = 5.82–7.55 (m, 12 HAr), 2.32
(s, 2 HCH2) ppm. 13C NMR (100 MHz, CDCl3): δ = 162.3, 158.4,
147.1, 136.1, 130.4, 129.5, 129.0, 128.8, 127.9, 127.3, 125.2,
124.9, 122. 6, 115.8, 31.4 ppm.
1-(4-Methoxyphenyl)-2-phenyldisulfide (5p)
White solid. 1H NMR (300 MHz, CDCl3): δ = 7.73–7.09 (m, 9
HAr), 3.80 (s, 3 HOMe) ppm. 13C NMR (100 MHz, CDCl3): δ =
136.1, 132.5, 129.8, 127.9, 125.2, 123.2, 115.9, 127.2, 31.9 ppm.
For other compounds, see the Supporting Information.
(17) General Procedure for the Synthesis of Symmetrical Disul-
fides
A mixture of the requisite alkyl (aryl) halide (2.0 mmol), potas-
sium O-ethylcarbonodithioate (0.48 g, 3.0 mmol) and MOF-199
(8 mg) in DMF (15.0 mL) in a 25 mL round-bottom flask was
stirred at 120 °C for 8 h. The reaction was monitored by TLC
analysis. Upon completion of the reaction, the mixture was
cooled to room temperature and then filtered. The filtrate was
evaporated under vacuum, CH2Cl2 (20 mL) was added, and the
mixture was washed with H2O (2 × 15 mL). The combined
organic layers were dried over Na2SO4, filtered, and solvent was
removed in vacuo. The residue was purified by thick-layer chro-
matography on silica gel (eluting with n-hexane–ethyl acetate,
20:1; in the case of 4e and 4f, 4:1 and 2:1, respectively) to give
the corresponding products.
The product was obtained as a oil.1H NMR (300 MHz, CDCl3):
δ = 7.85–7.00 (m, 9 HAr), 2.34 (s, 3 HMe) ppm. 13C NMR (100
MHz, CDCl3): δ = 138.4, 137.8, 136.4, 131.4, 131.3, 130.8, 129.1,
128.4, 127.2, 127.1, 29.1 ppm. GC–MS (EI): m/z = 200.0 [M+].
Benzyl(o-tolyl)sulfide (6c)
The product was obtained as a oil.1H NMR (400 MHz, CDCl3): δ =
7.39–7.28 (m, 9 H), 4.23 (s, 2 H), 2.31 (s, 3 HMe) ppm.13C NMR
(100 MHz, CDCl3): δ = 130.0, 129.5, 129.2, 128.8, 128.0, 127.9,
127.6, 127.5, 126.1, 39.6, 21.6 ppm. GC–MS (EI): m/z = 214.0
[M+].
Diphenyl Disulfide (4a)
White solid.1H NMR (400 MHz, CDCl3): δ = 7.24–7.36 (m, 6 H),
7.54 (m, 4 H) ppm.13C NMR (100 MHz, CDCl3): δ = 137.0, 129.1,
127.5, 127.2 ppm. GC–MS (EI): m/z = 218.0 [M+].
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–G