An Iodide-Mediated Transition-Metal-Free Strategy towards Unsymmetrical Diaryl Sulfides via Arylhydrazines and Thiols

Article abstract of DOI:10.1055/s-0039-1690757

A mild, scalable iodine-mediated oxidative cross-coupling reaction of arylhydrazines and thiols for construction of thioethers (sulfides) in the absence of any transition metals or photocatalysts is disclosed. A variety of unsymmetrical diaryl sulfides with broad substrate scope both on thiols and hydrazines were synthesized in high yields in water at room temperature. Furthermore, to demonstrate the utility of the protocol, the above C-S bond formation was applied in the synthesis of the key structure of vortioxetine as an antidepressant drug. The gram-scale outcome also added to the potential utility of this protocol.

Full text of DOI:10.1055/s-0039-1690757

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2019, 51, A–H
paper
A
en
F. Jafarpour et al.
Paper
Synthesis
An Iodide-Mediated Transition-Metal-Free Strategy towards
Unsymmetrical Diaryl Sulfides via Arylhydrazines and Thiols
Farnaz Jafarpour*
H
N
NHNH2
SH
Ar2
Mohammad Asadpour
Meysam Azizzade
S
TBHP,
Base
H2O
I
Ar1
+
Ar1
Ar2
N
Mehran Ghasemi
S
rt
21 examples
up to 88% yield
Saideh Rajai-Daryasarei
gram scale
water compatible
mild
no metals
no photocatalyst
no light
School of Chemistry, College of Science, University of Tehran,
P.O. Box 14155-6455, Tehran, Iran
jafarpur@khayam.ut.ac.ir
Vortioxetine
Received: 03.10.2019
Accepted after revision: 11.11.2019
Published online: 25.11.2019
sary to deactivate transition metals strongly coordinated to
thiolates, which largely limits functional group tolerance.
To address these issues photoredox-mediated coupling of
thiols and haloarenes have emerged as a powerful alterna-
tive tool (Scheme 1A).10q,z,11 However these methods are as-
sociated with expensive Ru, Ir, and other metal-based photo-
sensitizers which introduce a bar in terms of the sustain-
ability and scalability of these methods. Some progress
made by Paul and co-workers very recently, employing
DOI: 10.1055/s-0039-1690757; Art ID: ss-2019-t0567-op
Abstract A mild, scalable iodine-mediated oxidative cross-coupling re-
action of arylhydrazines and thiols for construction of thioethers (sul-
fides) in the absence of any transition metals or photocatalysts is dis-
closed. A variety of unsymmetrical diaryl sulfides with broad substrate
scope both on thiols and hydrazines were synthesized in high yields in
water at room temperature. Furthermore, to demonstrate the utility of
the protocol, the above C–S bond formation was applied in the synthe-
sis of the key structure of vortioxetine as an antidepressant drug. The
gram-scale outcome also added to the potential utility of this protocol.
H
N
Key words catalysis, iodine, metal-free, thioethers, vortioxetine
OH
Cl
N
O
N
S
Cl
S
Cl
S
COOH
OH
Organosulfur compounds are prevalent in a wide range
of functional materials,1 natural products,2 pharmaceuti-
cals,3 agrochemicals,4 and even food.5 In particular, aryl
thioethers are a highly useful class of sulfur-containing
compounds which are presented in numerous drugs with a
broad range of therapeutic activities for the treatment of
various diseases such as asthma, inflammation, Alzheimer’s
disease, cancer, depression, HIV infections, etc. (Scheme 1).6
In addition, diaryl sulfides can be employed as precursors
to other higher oxidation state sulfur-containing com-
pounds that have similar important bioactive properties.7
In light of their importance, the development of straightfor-
ward and efficient approaches for the construction of the
carbon–sulfur (C–S) bond has been a research focus up to
now.8
Most synthetic disconnections for the synthesis of aryl
thioethers heavily rely on nucleophilic aromatic substitu-
tion9 and transition-metal-catalyzed coupling of aryl ha-
lides or pseudohalides with thiols (Scheme 1A).10 Despite
the advantages, in most approaches strong bases are need-
ed to generate thiolates from thiols, and elevated reaction
temperatures and/or specially designed ligands are neces-
HO
Cl
HIV-1 integrase inhibitor
Vortioxetine
Bithionol
(A) Classic cross-coupling reactions:
HS
X
S
TM = Pd, Ir, Ni etc.
Ar1
Ar1
Ar2
+
Ar2
or
[M]/photoredox catalysis
or visible light
or Ni/electrochemistry
X = Cl, Br, I, B(OH)2, OTf
(B) Oxidative cross-coupling reactions:
Pd/ligands
Cu/Ag salts
S
X
HS
Ar2
Ar1
Ar1
X = CO2H, NHNH2
(C) This work:
+
Ar2
or
photocatalyst/visible-light
S
NHNH2
+
HS
I
TBHP,
Ar2
Ar1
Ar1
Ar2
base, H2O, rt
gram scale
water compatible
mild
no metals
no photocatalyst
no light
Scheme 1 Biologically active thioethers and approaches to unsym-
metrical diaryl sulfides
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
F. Jafarpour et al.
Paper
Synthesis
Ni(II) catalysts bearing redox noninnocent ligands, allowed
the catalytic reaction to be performed at room tempera-
ture.12
Mei and co-workers also developed an electrochemical
thiolation of heteroaryl halides employing a Ni catalyst.13
Furthermore, regarding environmental concerns of organo
halides particularly on an industrial scale, some Pd(II)-cata-
lyzed oxidative cross-coupling reactions of arenecarboxylic
acids with thiols or disulfides using Ag or Cu salts as oxi-
dant also have been developed (Scheme 1B).14
Recently, much attention has been paid to use of arylhy-
drazines as an effective coupling partner for the formation
of carbon–carbon and carbon–heteroatom bonds in cross-
coupling reactions.15 Arylhydrazines are considered as envi-
ronmentally friendly arylating agents for cross-coupling re-
actions, because nitrogen gas and water are the only by-
products of C–N bond cleavage. In this regard, Zhao and co-
workers as well as Hajra and co-workers have developed the
synthesis of some unsymmetrical diaryl sulfides via oxida-
tive cross-coupling reactions of arylhydrazines and aren-
ethiols in the presence of metals and visible light (Scheme
1B).16,17
Despite the associated advantages, to simplify the tran-
sition of the system to industrial processes and to improve
on cost, toxicity, simplicity of reaction setup, and expand
the scope to light-sensitive adducts, it would be a signifi-
cant progress if these thiolation reactions could do away
with requiring any transition metals, light irradiation, pho-
tocatalysts, and electrical energy.
In light of recent progresses and continuing our research
on cross-coupling reactions,18 herein we report our prog-
ress in the development of an improved iodine-mediated
oxidative C–S cross-coupling reaction between arylhydra-
zines and thiols in water at room temperature for the con-
struction of unsymmetrical diaryl and aryl alkyl sulfides
(Scheme 1C). Iodine as an excellent candidate in non-metal-
catalyzed cross-coupling reactions,19 is an inexpensive, safe,
and environmentally benign reagent to undergo the elec-
tron-transfer process. Furthermore, this transformation is
carried out in the absence of any transition metals, photo-
catalysts, or light under mild reaction conditions and is
scalable.
We commenced our study on the cross-coupling of 4-
methylphenylhydrazine hydrochloride (1b) and benzen-
ethiol (2a) in the presence of DTBP (2.0 equiv) as oxidant, a
10 mol% of TBAI as catalyst and K2CO3 (1.0 equiv) as base at
room temperature for 20 h. Initial solvent screening
showed that H2O provided the desired product 3b in 43%
yield (Table 1, entries 1–5). Then, the effect of other oxi-
dants such as TBHP, (NH4)2S2O8, K2S2O8, and BPO on the effi-
ciency of the reaction was studied. Screening of the oxi-
dants showed that TBHP is the best choice of oxidant and
gave the desired product 3b in 55% isolated yield (Table 1,
entries 6–9). Interestingly, when the reaction was tested in
the presence of KI instead of TBAI, coupling product 3b was
obtained in 61% yield (Table 1, entry 10). However, conduct-
ing the reaction in the presence of other additives such as
KBr, KIO3, and I2 led to a decrease in the yield (Table 1, en-
tries 11–13). The effect of the base to improve of the effi-
ciency of the reaction was tested by use of different bases
such as Na2CO3, Cs2CO3, NaOH, and t-BuONa. Replacement
of K2CO3 with Na2CO3 and Cs2CO3 as bases, gave the corre-
sponding adduct in 51% and 68% yields, respectively (en-
tries 14 and 15); NaOH and t-BuONa were inert in this reac-
tion (entries 16 and 17).
Table 1 Optimization of the Reaction Conditions for the Thiolation of
Hydrazine 1ba
S
NHNH2·HCl
HS
oxidant, additive
+
solvent, base
20 h, rt
1b
2a
3b
Entry
Oxidant
Additive
Base
K2CO3
Solvent
Yield (%)b
1
DTBPc
DTBP
DTBP
DTBP
DTBP
TBHPe
TBAId
TBAI
TBAI
TBAI
TBAI
TBAI
TBAI
TBAI
TBAI
KI
PhCl
DMSO
DCE
H2O
MeCN
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
15
21
14
43
38
55
2
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Na2CO3
Cs2CO3
NaOH
t-BuONa
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
3
4
5
6
f
7
(NH4)2S2O8
K2S2O8
BPOg
–
f
8
–
f
9
–
10
11
12
13
14
15
16
17
18h
19i
20i,j
21
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
61
39
10
47
51
68
KBr
KIO3
I2
KI
KI
f
KI
–
f
KI
–
KI
74
80
85
KI
KI
f
–
–
a Reaction conditions: 1b (0.1 mmol), 2a (0.2 mmol), oxidant (2.0 equiv),
additive (10 mol%), base (1.0 equiv), solvent (0.3 mL), rt, 20 h.
b Isolated yield.
c Di-tert-butyl peroxide.
d Tetrabutylammonium iodide.
e tert-Butyl hydroperoxide.
f No reaction.
g Benzoyl peroxide.
h KI (30 mol%).
i KI (50 mol%).
j TBHP (4.0 equiv).
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

C
F. Jafarpour et al.
Paper
Synthesis
Hence, Cs2CO3 was chosen as the most appropriate base,
giving the highest yield of the reaction product. Adjusting
the amount of additive showed that increasing the amount
of KI from 10 to 50 mol% increased the yield of 3b from 68%
to 80% (entries 18 and 19). Increasing the amount of TBHP
to 4.0 equivalents improved the yield further to 85% (entry
20). When the reaction temperature was raised up to 60 °C,
the yield of 3b was reduced to 51%. Finally, when the reac-
tion was conducted in the absence of KI, the reaction did
not proceed at all (entry 21). The results showed that prop-
er base, solvent, and reaction temperature and an appropri-
ate amount of iodide/TBHP, are essential to achieve the
most efficient reaction.
With the optimized reaction conditions in hand, we in-
vestigated the scope of the transition-metal-free cross-cou-
pling reaction between various arylhydrazines and thiols
where the desired products 3a–t were obtained in 63–88%
isolated yields (Scheme 2). Arylhydrazines bearing elec-
tron-neutral and electron-donating groups such as methyl
and methoxy groups on the arenes were treated with vari-
ous arenethiols such as benzenethiol, p-toluenethiol, 3-me-
thoxybenzenethiol, and 4-bromobenzenethiol to afford the
corresponding products 3a–f in 83–88% yields. Halogen-
substituted (2-F, 4-F, 4-Cl) arylhydrazines were also applied
in this reaction successfully to provide the desired products
3g–k in 63–84% yields. In addition, the reaction of electron-
deficient arylhydrazines having a strong electron-with-
drawing nitro group in the para or ortho positions of the
aryl ring proceeded well and provided 3l, 3m, and 3n in
65%, 76%, and 72% yields, respectively.
TBHP (4 equiv)
KI (50 mol%)
Cs2CO3
NHNH2·HCl HS
+
S
R1
R2
R1
R2
1
2
3
H2O , rt, 20 h
S
OMe
S
S
OMe
3a, 87%
3b, 85%
3c, 83%
S
S
S
Br
MeO
MeO
F
3d, 84%
3f, 88%
3e, 86%
F
S
S
S
Cl
Cl Cl
OMe
NO2
3g, 82%
3h, 84%
3i, 63%
NO2
S
S
S
Cl
Cl
3j, 83%
3k, 81%
3l, 65%
NO2
NO2
S
S
S
Cl
O2N
O2N
3m, 76%
3n, 72%
3o, 75%
S
S
F
3p, 80%
3q, 70%
S
S
S
3r, 82%
3t, 80%
3s, 83%
Scheme 2 Scope of the iodine-mediated C–S bond formation; all reac-
tions were run under the optimized reaction conditions
It should be noted that 2,4-dinitrophenylhydrazine was
also tested under the optimum conditions and gave 3o in
high yield yet. Furthermore, when 2-naphthalenethiol was
used in the cross-coupling reaction with 4-methylphenyl-
hydrazine and 4-fluorophenylhydrazine, the corresponding
products 3p and 3q were prepared in 80% and 70% yields,
respectively. Phenylmethane- and 4-methylphenylmethan-
ethiol were also employed in this C–S coupling reaction,
and gave the desired products 3r and 3s in 82% and 83%
yields, respectively. Finally, the cross-coupling reaction be-
tween phenylhydrazine and butanethiol was examined,
and fortunately the desired aryl alkyl sulfide 3t was ob-
tained in 80% yield.
ether 3b was collected in 81% isolated yield which high-
lights the utility and operational simplicity of this proce-
dure (Scheme 3B).
(A) Synthesis of key structure of Vortioxetine
NHNH2·HCl
SH
Cl
TBHP (4 equiv)
KI (50 mol%)
Cs2CO3
Cl
+
S
H
N
H2O, rt, 20 h
3u, 65%
N
HN
NH
S
t-BuONa, CuI
toluene
(B) Gram scale reaction
To illustrate potential pharmaceutical applications and
preparative utility of this thiolation reaction, we first ap-
plied our protocol in the synthesis of the key structure of
vortioxetin as a novel piperazine-based antidepressant
drug20 (Scheme 3A). The desired key structure 3u was ob-
tained in 65% isolated yield under the standard reaction
conditions which compared with reported methods, our
transformation involved milder conditions and proceeded
without the need for any transition metals, ligands, or addi-
tives at room temperature. Furthermore, performing the
gram-scale reaction containing 7 mmol of hydrazine sub-
strate 1b under the optimized conditions, the desired thio-
Vortioxetine
[Ref 17]
SH
NHNH2·HCl
TBHP (4 equiv)
KI (50 mol%)
Cs2CO3
S
+
H2O, rt, 20 h
7 mmol
14 mmol
3b, 1.1 g, 81%
Scheme 3 Synthetic applications
To get insight into the mechanism of this reaction,
2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) (3.0 equiv) as
a radical scavenger was added to the reaction mixture of 4-
chlorophenylhydrazine and 2-methylbenzenethiol and only
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

D
F. Jafarpour et al.
Paper
Synthesis
traces of the desired product 3j were collected [Scheme 4,
(1)]. Accordingly, a radical pathway for this cross-coupling
may be suggested. Furthermore, when the reaction of thiol
and 4-methylphenylhydrazine was ceased after 3 hours of
stirring, the presence of diphenyl disulfide in the reaction
mixture was evidenced. So, the reaction of thiol was con-
ducted under the standard conditions, in the absence of any
hydrazine and the related diphenyl disulfide was obtained
in 80% yield [Scheme 4, (2)]. Moreover, when di-p-tolyl di-
sulfide was reacted with 4-methoxyphenylhydrazine under
the standard conditions, the related diaryl sulfide 3f was
obtained in 69% yield [Scheme 4, (3)].
t-BuOOH
t-BuO
OH
+
A
1/2 I2
I
I
+
t-BuOO
B
H2O
+
t-BuOOH OH
NHNH2·HCl
NHNH2
Ar
t-BuOH
or t-BuOOH
t-BuO
or t-BuOO
N
NH2
base
Ar
Ar
t-BuOH
or t-BuOOH
t-BuO
or t-BuOO
N
N
N
NH
Ar
Ar
Ar
N2
t-BuO
or t-BuOO
t-BuOH
or t-BuOOH
C
D
SH
NHNH2·HCl
+
R
SH
RS SR
R
S
E
TBHP (4 equiv)
KI (50 mol%)
Cs2CO3
TEMPO (3 equiv)
H2O, rt, 20 h
S
2
F
(1)
S
R
Cl
3j, trace
Ar
+
Ar
RS SR
Cl
R
S
SH
D
F
3
TBHP (4 equiv)
KI (50 mol%)
Cs2CO3
S
S
Scheme 5 Proposed mechanism of KI/TBHP-mediated C–S bond for-
(2)
(3)
mation
80%
H2O, rt, 20 h
NHNH2·HCl
TBHP (4 equiv)
KI (50 mol%)
Cs2CO3
S
S
S
+
All reagents were commercially available and used as received. Col-
umn chromatography was carried out on silica gel (230–400 mesh).
TLC was conducted on silica gel 250 micron, F254 plates. 1H NMR
spectra were recorded at room temperature on Bruker 500 MHz spec-
trometer, using DMSO-d6 and CDCl3 as solvent. Chemical shifts are
with TMS as an internal standard (TMS:  = 0.0). 13C NMR spectra are
referenced from the solvent central peak ( = 77.23). Elemental analy-
ses (CHN) were recorded on a Thermo Finnigan Flash EA 1112 ele-
mental analyzer.
MeO
3f, 69%
H2O, rt, 20 h
OMe
Scheme 4 Control experiments
On the basis of control experiments and the related lit-
erature reports,21 we proposed a plausible mechanism for
the transition-metal-free thiolation of arylhydrazines
(Scheme 5). At the beginning of this reaction, tert-butoxy A
and/or tert-butylperoxy B radicals may be formed from de-
composition of TBHP with the assistance of the catalytic
amount of iodide anion. Subsequently, hydrogen abstrac-
tion from arylhydrazine 1 and thiol 2 by whether tert-bu-
toxy or tert-butylperoxy radicals generates aryldiazenyl
radical C and thiyl radical E, respectively. Then, the aryldia-
zenyl radical is converted into the aryl radical D through
elimination of molecular nitrogen. Also, thiyl radical E may
undergo homocoupling reaction to afford disulfide F. Final-
ly, the reaction of the aryl radical D with disulfide F leads to
the formation of the desired diaryl sulfide 3.
In summary, we have successfully developed a mild and
efficient iodine/peroxide mediated thiolation of hydrazines
for construction of unsymmetrical diaryl sulfides. A wide
range of thioethers were constructed at room temperature
in water under metal-, photocatalyst-, and light-free condi-
tions, making this protocol more practicable in synthetic
organic chemistry. We have also demonstrated that this
cost-effective and sustainable protocol is scalable and can
be applied for construction of the key structure of vortioxe-
tine as an antidepressant drug, which makes this practice
more interesting in medicinal chemistry.
(3-Methoxyphenyl)(phenyl)sulfane (3a); Typical Procedure
A vial equipped with a stir bar was charged with thiol 2 (0.2 mmol, 2
equiv), arylhydrazine hydrochloride 1 (0.1 mmol, 1 equiv), Cs2CO3
(0.1 mmol, 1 equiv), KI (50 mol%), and TBHP (0.4 mmol, 4 equiv). H2O
(0.3 mL) was added and the vial was capped. The resulting mixture
was stirred at rt for 20 h. Upon completion of the reaction, the result-
ing mixture was extracted with EtOAc. The combined organic layer
was dried (anhyd Na2SO4). After the removal of the solvent under re-
duced pressure, the crude product was purified by column chroma-
tography (silica gel, EtOAc/hexane gradient) to provide the desired
product 3a as a pale yellow oil; yield: 19 mg (87%).
1H NMR (CDCl3, 500 MHz):  = 3.78 (s, 3 H), 6.82 (dd, J = 8.3, 2.5 Hz, 1
H), 6.91–6.93 (m, 1 H), 6.94–6.97 (m, 1 H), 7.24 (t, J = 7.9 Hz, 1 H), 7.30
(d, J = 7.1 Hz, 1 H), 7.35 (t, J = 8.0 Hz, 2 H), 7.42 (d, J = 7.4 Hz, 2 H).
13C NMR (CDCl3, 125 MHz):  = 55.2, 112.8, 115.9, 123.0, 127.2, 129.2,
129.9, 131.4, 135.3, 137.2, 160.1.
Anal. Calcd for C13H12OS: C, 72.19; H, 5.59. Found: C, 71.83; H, 5.50.
Phenyl(p-tolyl)sulfane (3b)
White solid; yield: 17 mg (85%); mp 88–90 °C (Lit.22 90–93 °C(.
1H NMR (CDCl3, 500 MHz):  = 2.4 (s, 3 H), 7.32 (d, J = 8.0 Hz, 2 H),
7.50 (t, J = 7.3 Hz, 2 H), 7.56 (t, J = 7.4 Hz, 1 H), 7.84 (d, J = 8.0 Hz, 2 H),
7.32 (d, J = 7.6 Hz, 2 H).
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

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F. Jafarpour et al.
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Synthesis
13C NMR (CDCl3, 125 MHz):  = 21.54, 127.5, 127.7, 129.2, 129.9,
(4-Chlorophenyl)(4-nitrophenyl)sulfane (3i)
Yellow solid; yield: 17 mg (63%); mp 86–88 °C (Lit.26 90 °C).
133.0, 138.7, 142.0, 144.2.
1H NMR (CDCl3, 500 MHz):  = 7.20 (d, J = 8.9 Hz, 2 H), 7.44 (d, J = 8.5
Hz, 2 H), 7.48 (d, J = 8.5 Hz, 2 H), 8.09 (d, J = 8.9 Hz, 2 H).
Anal. Calcd for C13H12S: C, 77.95; H, 6.04. Found: C, 78.25; H, 6.13.
(3-Methoxyphenyl)(p-tolyl)sulfane (3c)
13C NMR (CDCl3, 125 MHz):  = 124.1, 126.9, 129.1, 130.3, 135.9,
Colorless oil; yield: 19 mg (83%).
136.1, 145.6, 147.6.
1H NMR (CDCl3, 500 MHz):  = 2.39 (s, 3 H), 3.78 (s, 3 H), 6.75–6.79
(m, 1 H), 6.86 (t, J = 1.8 Hz, 1 H), 6.87–6.91 (m, 1 H), 7.16–7.24 (m, 3
H), 7.36–7.40 (m, 2 H).
Anal. Calcd for C12H8ClNO2S: C, 54.24; H, 3.03; N, 5.27. Found: C,
54.64; H, 3.18; N, 5.57.
13C NMR (CDCl3, 125 MHz):  = 21.2, 55.2, 112.1, 114.8, 121.8, 129.8,
(4-Chlorophenyl)(o-tolyl)sulfane (3j)
130.1, 130.8, 132.6, 137.8, 138.6, 160.0.
White oil; yield: 20 mg (83%).
1H NMR (DMSO-d6, 500 MHz):  = 2.29 (s, 3 H), 7.13 (d, J = 8.5 Hz, 2
H), 7.21 (t, J = 7.7 Hz, 1 H), 7.28–7.31 (m, 2 H), 7.34 (d, J = 7.7 Hz, 1 H),
7.36 (d, J = 8.5 Hz, 2 H).
Anal. Calcd for C14H14OS: C, 73.01; H, 6.13. Found: C, 72.83; H, 6.02.
(4-Bromophenyl)(p-tolyl)sulfane (3d)
White solid; yield: 24 mg (84%); mp 75–77 °C (Lit.23 75–77 °C).
13C NMR (DMSO-d6, 125 MHz):  = 20.6, 127.7, 129.2, 129.8, 130.8,
1H NMR (CDCl3, 500 MHz):  = 2.38 (s, 3 H), 7.13 (d, J = 8.5 Hz, 2 H),
7.18 (d, J = 7.9 Hz, 2 H), 7.33 (d, J = 7.9 Hz, 2 H), 7.39 (d, J = 8.5 Hz, 2 H).
131.4, 131.4, 132.4, 133.7, 135.1, 140.2.
Anal. Calcd for C13H11ClS: C, 66.52; H, 4.72. Found: C, 66.92; H, 4.87.
13C NMR (CDCl3, 125 MHz):  = 21.2, 120.1, 130.2, 130.9, 132.0, 132.7,
136.8, 138.2.
(4-Chlorophenyl)(3-methoxyphenyl)sulfane (3k)
Yellow oil; yield: 20 mg (81%).
Anal. Calcd for C13H11BrS: C, 55.93; H, 3.97. Found: C, 56.33; H, 4.13.
1H NMR (CDCl3, 500 MHz):  = 23.79 (s, 3 H), 6.84 (dd, J = 8.3, 2.7 Hz, 1
H), 6.91 (d, J = 2.3 Hz, 1 H), 6.95 (d, J = 7.1 Hz, 1 H), 7.23–7.27 (m, 1 H),
7.28–7.34 (m, 4 H).
13C NMR (CDCl3, 125 MHz):  = 55.3, 113.1, 116.3, 123.2, 129.3, 130.1,
132.4, 133.2, 134.2, 136.5, 160.1.
(4-Methoxyphenyl)(phenyl)sulfane (3e)
Yellow oil; yield: 19 mg (86%).
1H NMR (CDCl3, 500 MHz):  = 3.85 (s, 3 H), 6.94–6.96 (m, 2 H), 7.17–
7.24 (m, 3 H), 7.27–7.30 (m, 2 H), 7.46–7.48 (m, 2 H).
13C NMR (CDCl3, 125 MHz):  = 55.4, 115.1, 124.4, 125.8, 128.3, 129.0,
Anal. Calcd for C13H11ClOS: C, 62.27; H, 4.42. Found: C, 61.95; H, 4.30.
135.4, 138.7, 159.9.
(2-Nitrophenyl)(phenyl)sulfane (3l)
Yellow solid; yield: 15 mg (65%); mp 79–81 °C (Lit.27 80–82 °C).
Anal. Calcd for C13H12OS: C, 72.19; H, 5.59. Found: C, 72.59; H, 5.68.
(4-Methoxyphenyl)(p-tolyl)sulfane (3f)
White solid; yield: 20 mg (88%); mp 47–49 °C (Lit.24 48–50 °C).
1H NMR (CDCl3, 500 MHz):  = 2.35 (s, 3 H), 3.84 (s, 3 H), 6.92 (d, J =
8.7 Hz, 2 H), 7.12 (d, J = 8.1 Hz, 2 H), 7.20 (d, J = 8.1 Hz, 2 H), 7.42 (d, J =
8.8 Hz, 2 H).
1H NMR (CDCl3, 500 MHz):  = 6.88 (d, J = 8.2 Hz, 1 H), 7.23 (t, J = 7.7
Hz, 1 H), 7.35 (t, J = 7.8 Hz, 1 H), 7.48–7.53 (m, 3 H), 7.58–7.62 (m, 2
H), 8.24 (d, J = 8.3 Hz, 1 H).
13C NMR (CDCl3, 125 MHz):  = 125.0, 125.7, 128.3, 130.1, 130.2,
131.0, 133.5, 136.0, 139.5, 144.9.
13C NMR (CDCl3, 125 MHz):  = 21.0, 55.3, 114.9, 125.7, 129.4, 129.8,
134.4, 134.4, 136.1, 159.5.
Anal. Calcd for C12H9NO2S: C, 62.32; H, 3.92; N, 6.06. Found: C, 62.63;
H, 4.01; N, 6.26.
Anal. Calcd for C14H14OS: C, 73.01; H, 6.13. Found: C, 73.33; H, 6.23.
(4-Chlorophenyl)(2-nitrophenyl)sulfane (3m)
Yellow solid; yield: 21 mg (76%); mp 93–95 °C (Lit.27 94–96 °C).
(4-Chlorophenyl)(2-fluorophenyl)sulfane (3g)
1H NMR (CDCl3, 500 MHz):  = 6.87 (d, J = 8.2 Hz, 1 H), 7.25 (t, J = 7.8
Hz, 1 H), 7.38 (t, J = 7.6 Hz, 1 H), 7.46 (d, J = 8.2 Hz, 2 H), 7.52 (d, J = 8.2
Hz, 2 H), 8.22 (d, J = 8.2 Hz, 1 H).
13C NMR (CDCl3, 125 MHz):  = 125.3, 125.8, 128.2, 129.6, 130.4,
133.6, 136.5, 137.1, 138.7, 145.0.
Pale yellow oil; yield: 20 mg (82%).
1H NMR (CDCl3, 500 MHz):  = 7.10–7.16 (m, 2 H), 7.25–7.30 (m, 4 H),
7.30–7.35 (m, 2 H).
13C NMR (CDCl3, 125 MHz):  = 116.1 (d, J = 21.2 Hz), 122.0 (d, J = 17.5
Hz), 124.8 (d, J = 3.7 Hz), 129.4, 129.9 (d, J = 7.5 Hz), 131.9, 133.1 (d, J =
2.5 Hz), 133.3, 133.8, 161.3 (d, J = 246.2 Hz).
Anal. Calcd for C12H8ClNO2S: C, 54.24; H, 3.03; N, 5.27; Found: C,
54.64; H, 3.18; N, 5.57.
Anal. Calcd for C12H8ClFS: C, 60.38; H, 3.38. Found: C, 60.63; H, 3.49.
(4-Nitrophenyl)(phenyl)sulfane (3n)
Yellow solid; yield: 17 mg (72%); mp 55–57 °C (Lit.28 55–56 °C).
1H NMR (CDCl3, 500 MHz):  = 7.18 (d, J = 9.0 Hz, 2 H), 7.43–7.49 (m, 3
H), 7.52–7.57 (m, 2 H), 8.05 (d, J = 9.0 Hz, 2 H).
13C NMR (CDCl3, 125 MHz):  = 124.0, 126.7, 129.7, 130.0, 130.5,
(4-Chlorophenyl)(4-fluorophenyl)sulfane (3h)
White solid; yield: 20 mg (84%); mp 38–40 °C (Lit.25 34 °C).
1H NMR (DMSO-d6, 500 MHz):  = 7.21–7.26 (m, 4 H), 7.37 (d, J = 8.6
Hz, 2 H), 7.43– 7.46 (m, 2 H).
13C NMR (DMSO-d6, 125 MHz):  = 117.3 (d, J = 22.5 Hz), 129.4 (d, J =
3.7 Hz), 129.8, 131.4, 132.2, 134.0, 135.0 (d, J = 8.7 Hz), 162.5 (d, J =
243.7 Hz).
134.7, 145.4, 148.5.
Anal. Calcd for C12H9NO2S: C, 62.32; H, 3.92; N, 6.06. Found: C, 62.72;
H, 4.07; N, 6.36.
Anal. Calcd for C12H8ClFS: C, 60.38; H, 3.38. Found: C, 60.68; H, 3.47.
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

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Synthesis
(2,4-Dinitrophenyl)(phenyl)sulfane (3o)
Yellow solid; yield: 21 mg (75%); mp 118–120 °C (Lit.29 120–121 °C).
1H NMR (CDCl3, 500 MHz):  = 7.01 (d, J = 9.0 Hz, 1 H), 7.55–7.64 (m, 5
H), 8.13 (dd, J = 9, 2.5 Hz, 1 H), 9.07 (d, J = 2.5 Hz, 1 H).
13C NMR (CDCl3, 125 MHz):  = 121.4, 126.9, 128.9, 129.0, 130.7,
1H NMR (CDCl3, 500 MHz):  = 2.28 (s, 3 H), 2.48 (s, 3 H), 6.57 (d, J =
8.1 Hz, 1 H), 6.86 (d, J = 8.0 Hz, 1 H), 6.93 (s, 1 H), 7.03 (dd, J = 905,
1.65 Hz, 2 H), 7.12 (dd, J = 9.3, 1.3 Hz, 1 H), 7.30 (t, J = 8.1 Hz, 1 H).
13C NMR (CDCl3, 125 MHz):  = 20.0, 20.1, 113.8, 116.5, 122.0, 125.8,
127.6, 129.6, 131.4, 131.8, 135.8, 136.0, 140.4, 158.9.
Anal. Calcd for C14H13ClS: C, 67.59; H, 5.27. Found: C, 67.99; H, 5.36.
131.1, 135.9, 143.8, 144.3, 148.4.
Anal. Calcd for C12H8N2O4S: C, 52.17; H, 2.92; N, 10.14. Found: C,
52.47; H, 3.01; N, 10.34.
Funding Information
Naphthalen-2-yl(p-tolyl)sulfane (3p)
White solid; yield: 20 mg (80%); mp 68–70 °C (Lit.30 67–69 °C).
We acknowledge financial support from the University of Tehran.()
1H NMR (DMSO-d6, 500 MHz):  = 2.30 (s, 3 H), 7.21–7.23 (m, 2 H),
7.30–7.33 (m, 3 H), 7.48–7.52 (m, 2 H), 7.81–7.83 (m, 2 H), 7.86–7.89
(m, 2 H).
13C NMR (DMSO-d6, 125 MHz):  = 21.1, 126.7, 127.3, 127.7, 128.0,
128.5, 129.5, 130.8, 131.0, 132.1, 132.2, 133.8, 133.9, 138.0.
Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/s-0039-1690757.
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Anal. Calcd for C17H14S: C, 81.56; H, 5.64. Found: C, 81.96; H, 5.79.
References
(4-Fluorophenyl)(naphthalen-2-yl)sulfane (3q)
White solid; yield: 18 mg (70%); mp 67–68 °C (Lit.31 66–68 °C).
1H NMR (CDCl3, 500 MHz):  = 7.10–7.12 (m, 2 H), 7.43–745 (m, 1 H),
7.48–7.56 (m, 4 H), 7.78–7.87 (m, 4 H).
13C NMR (CDCl3, 125 MHz):  = 116.57 (d, J = 21.2 Hz), 126.3, 126.8,
127.4, 127.8, 127.9, 128.7, 129.0, 132.2, 133.8, 133.9, 134.0 (d, J = 7.5
Hz), 162.4 (d, J = 246.2 Hz).
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Benzyl(phenyl)sulfane (3r)
White solid; yield: 16 mg (82%); mp 40–42 °C (Lit.32 42 °C).
1H NMR (CDCl3, 500 MHz):  = 4.15 (s, 2 H), 7.20–7.23 (m, 1 H), 7.27–
7.35 (m, 9 H).
13C NMR (CDCl3, 125 MHz):  = 39.1, 126.4, 127.2, 128.5, 128.90,
128.91, 129.9, 136.5, 137.5.
Anal. Calcd for C13H12S: C, 77.95; H, 6.04. Found: C, 78.25; H, 6.13.
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(4-Methylbenzyl)(phenyl)sulfane (3s)
White solid; yield: 18 mg (83%); mp 66–67 °C (Lit.33 66–67 °C).
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1H NMR (DMSO-d6, 500 MHz):  = 7.26 (s, 3 H), 4.20 (s, 2 H), 7.09 (d,
J = 7.5 Hz, 2 H), 7.17 (t, J = 7.25 Hz, 1 H), 7.24 (d, J = 7.6 Hz, 2 H), 7.28
(t, J = 7.65 Hz, 2 H), 7.34 (d, J = 7.65 Hz, 2 H).
13C NMR (DMSO-d6, 125 MHz):  = 25.9, 41.7, 130.1, 133.5, 133.9,
134.1, 134.1, 139.6, 141.4, 141.6.
Anal. Calcd for C14H14S: C, 78.46; H, 6.58. Found: C, 78.76; H, 6.67.
Butyl(phenyl)sulfane (3t)
Yellow oil; yield: 14 mg (80%).
1H NMR (CDCl3, 500 MHz):  =  .94 (t, J = 7.2 Hz, 3 H), 1.42–1.51 (m, 2
H), 1.61–1.69 (m, 2 H), 2.94 (t, J = 7.3 Hz, 2 H), 7.15–7.20 (m, 1 H),
7.26–7.31 (m, 2 H), 7.32–7.36 (m, 2 H).
13C NMR (CDCl3, 125 MHz):  = 13.6, 21.9, 31.2, 33.2, 125.6, 128.8,
128.8, 137.0.
Anal. Calcd for C10H14S: C, 72.23; H, 8.49. Found: C, 71.92; H, 8.38.
(2-Chlorophenyl)(2,4-dimethylphenyl)sulfane (3u)
Brown oil; yield: 16 mg (65%).
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

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Synthesis
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