KI as iodine source for the synthesis of E-iodovinyl sulfones via metal-free iodosulfonylation of terminal alkynes

Full text of DOI:10.1080/10426507.2017.1359596

Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: http://www.tandfonline.com/loi/gpss20
KI as iodine source for the synthesis of E-iodovinyl
sulfones via metal-free iodosulfonylation of
terminal alkynes
Lu Yang, Deqing Hu, Li Wei & Yunyun Liu
To cite this article: Lu Yang, Deqing Hu, Li Wei & Yunyun Liu (2017): KI as iodine source for the
synthesis of E-iodovinyl sulfones via metal-free iodosulfonylation of terminal alkynes, Phosphorus,
Sulfur, and Silicon and the Related Elements, DOI: 10.1080/10426507.2017.1359596
To link to this article: http://dx.doi.org/10.1080/10426507.2017.1359596
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Date: 03 November 2017, At: 22:47

PHOSPHORUS, SULFUR, AND SILICON
https://doi.org/./..
KI as iodine source for the synthesis of E-iodovinyl sulfones via metal-free
iodosulfonylation of terminal alkynes
Lu Yang, Deqing Hu, Li Wei, and Yunyun Liu
College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, P.R. China
ABSTRACT
ARTICLE HISTORY
Received  June 
Accepted  July 
The E-selective iodosulfonylation of terminal alkynes has been achieved by employing sulfonyl hydrazines
and potassium iodide as sulfonyl and iodine sources, respectively. Besides using simple and cheap reactants,
the present method requires no metal catalyst and proceeds well at room temperature. A broad array of
iodovinyl sulfones have been efficiently synthesized via the alkyne difunctionalization in the presence of
benzoic peroxyanhydride (BPO).
KEYWORDS
Alkyne; E-selective;
iodosulfonylation; potassium
iodide; transition metal-free
GRAPHICAL ABSTRACT
Introduction
difunctionalization-based synthesis of β-iodovinyl sulfones,
the main challenge with most of the known methods is that a
transition metal salt is employed as either the catalyst or halogen
source. Considering the current in devising transition metal-
free organic synthesis20–22 as well as their usefulness in alkyne
difunctionalization reaction,23,24 developing alternative routes
of alkyne halosulfonylation reactions to access β-halovinyl
sulfones is still an important task. In continuation of our
research interest in the alkyne difunctionalization reaction, we
report herein the selective iodosulfonylation of alkynes for the
synthesis of E-β-iodovinyl sulfones under transition metal-free,
room temperature conditions by employing potassium iodide
as iodine source and sulfonyl hydrazines as sulfonyl precursors.
Owing to their significance as synthetic building blocks
and as the structural fragment of many biologically relevant
molecules,1–4 β-iodovinyl sulfones have been attracting high
interest as target molecules of organic synthesis. Over the past
decade, different types of synthetic tactics toward β-iodovinyl
sulfones and analogous halogenated alkenes have been reported.
While synthetic methods such as the halogenation of vinyl zir-
conium reagents functionalized with sulfonyl5,6 and the oxi-
dation of β-halogenated vinyl sulfides7,8 are all documented
in the literature, the direct halosulfonylation of alkynes is
presently amongst the most popular strategies in the synthesis
of these alkene derivatives. In this kind of synthetic strategy, sul-
fonyl halides,9,11 sodium sulfinates,12–15 sulfonyl hydrazines,16
sulfinic acids17 have been found as practical sulfonyl donors to
provide the target products in the presence or absence of halo-
gen atom source.
Recently, our group have identified CuX (X = Cl, Br, I) to
mediate and take part in the halosulfonylation of alkynes in the
presence of sulfonyl hydrazines and BPO to yield β-iodovinyl
sulfones with novel Z-selectivity.18 In addition, simply mod-
ifying the reaction conditions by using catalytic loading of
CuI enables the chemoselective synthesis of sulfonyl alkenes.19
Despite of the number of approaches developed for the alkyne
Results and discussion
To start the exploration, the reaction of phenylacetylene 1a,
tosylhydrazine 2a and potassium iodide was firstly conducted
as blank entry or in the presence of various peroxide additives
including BPO, TBHP and hydrogen peroxide at room temper-
ature. The results from these entries indicated that BPO was
particularly efficient in promoting the synthesis of product 3a
(entries 1–4, Table 1). On the other hand, entries conducted in
different reaction media suggested that and DMSO was the best
CONTACT Yunyun Liu and Li Wei
Nanchang , P.R. China.
chemliuyunyun@jxnu.edu.cn; wl@jxnu.edu.cn
College of Chemistry and Chemical Engineering, Jiangxi Normal University,
Color versions of one or more of thei figures in the article can be found online at www.tandfonline.com/gpss.
Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/./..
©  Taylor & Francis Group, LLC

2
L. YANG ET AL.
Table . Optimization of reaction conditionsa .
Entry
Additive
Solvent
Yield(%)b








no
BPO
TBHP
HO
BPO
BPO
BPO
BPO
BPO
BPO
BPO
BPO
BPO
BPO
DMSO
DMSO
DMSO
DMSO
DMF
ethyl lactate
EtOH
nr

trace
trace

trace
trace
trace
trace





Scheme . The proposed mechanism.
terminal alkynes as well as sulfonyl hydrazines to the stan-
dard conditions proved that aromatic alkynes and aromatic
sulfonyl hydrazines were generally tolerated for the synthe-
sis of the corresponding β-iodovinyl sulfones 3. While most
entries in this section afforded the corresponding products
with good to excellent yields, relatively inferior yields were
observed in the reactions involving electron withdrawing group
functionalized alkynes (3j, 3l, Table 2) or sulfonyl hydrazine
(3o, Table 2). When the alkyl alkyne 1-hexyne was employed
to react with tosyl hydrazine under the standard condition,
no target iodovinyl sulfone product was observed. The reac-
tions employing potassium bromide or chloride as alternative
halogen sources failed to provide the expect halovinyl sulfone
products probably because of the lower reactivity of the bro-
mide and chloride species, demonstrating the unique function
of potassium iodide in this kind of alkyne halosulfonylation
reactions.
Based on the known literature on the sulfonylation-based
alkyne difunctionalization,6b,8 a possible mechanism for the
present reaction is proposed as outlined in Scheme 1. First, the
sulfonyl hydrazine 2 could be converted to the sulfonyl radical
4 in the presence of peroxide species. This radical then incor-
porates to the terminal alkyne to afford the vinyl sulfone radi-
cal 5 via radical addition to the triple bond. On the other hand,
the oxidation of the iodine anion gives molecular iodine which
is able to capture the radical intermediate 5 to provide product
3 and release an iodine radical. The dimerization of the iodine
radical generates molecular iodine to continuously take part in
the formation of 3 until the completion of the reaction.
HO

CHCN
DMSO
DMSO
DMSO
DMSO
DMSO
c
d
e
f
g
aGeneral conditions: phenylacetylene 1a (. mmol), tosylhydrazine 2a (. mmol),
KI (. mmol), additive (. mmol), stirred for  h in . mL solvent.
bYield of isolated product based on 1a.
cThe amount of KI was . mmol.
dThe loading of additive was . mmol.
eThe loading of additive was . mmol.
f The amount of 2a was . mmol.
gThe amount of 2a was . mmol.
one among the test candidates (entries 2 and 5–9, Table 1). Sub-
sequent examination on the effect of reactant loading, includ-
ing the loading of potassium iodide, phenylacetylene and the
additive led to the discovery that increasing the amount of 2a to
1.5 eq (0.3 mmol) could assist the formation of 3a with higher
yield, and further increase didn’t lead to significant improve-
ment (entries 10–14, Table 1).
With the results from the optimization experiments, the
scope on the synthesis of iodovinyl sulfones was subsequently
studied. As shown in Table 2, the employment of various
Table . Scope of the halosulfonylation of alkynesa .
Ar
Ar
Product
Yield(%)b
Conclusions
Ph
Ph
-CHCH
Ph
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p














In conclusion, we have established a new synthetic route for
the synthesis of E-iodovinyl sulfones via the iodosulfonylation
of terminal alkynes. By employing potassium iodide and sul-
fonyl hydrazine as reaction partners, the synthesis of the tar-
get products with a broad structural scope have been smoothly
achieved at room temperature in the presence of only BPO.
The simple operation, mild conditions, as well easy access
of the reactants/reagents make the present method a use-
ful complement to the known methods of halovinyl sulfone
synthesis.
-CHCH
-CHOCH
-FCH
-ClCH
-CHCH
-CHCH
-CHOCH
-ClCH
-CHCH
-FCH
Ph
Ph
Ph
Ph
Ph
-CHCH
-CHCH
-CHCH
-CHCH
-CHCH
-CHOCH
-ClCH
-CNCH
-naphthyl
-CHCH
-CHCH
-CHCH
Ph


Experimental section
aGeneral conditions: alkyne 1 (. mmol), sulfonyl hydrazine 2 (. mmol), KI (.
mmol), BPO (. mmol) in DMSO ( mL), stirred at rt for  h.
bYield of isolated product based on 2.
General procedure for the alkyne iodosulfonylation giving
products 3. A 25 mL round-bottom flask was charged with

PHOSPHORUS, SULFUR, AND SILICON
3
13C NMR: 144.5, 140.7, 140.2, 137.5, 136.9, 129.6, 128.6, 127.9,
127.8, 114.7, 21.6, 21.5.
alkynes 1 (0.2 mmol), sulfonylhydrazides 2 (0.3 mmol), KI
(0.2 mmol), BPO (0.2 mmol, benzoyl peroxide), and DMSO
(2 mL). Then the mixture was stirred at room temperature in
air over night. Upon completion (TLC), the reaction mixture
was mixed with water (10 mL), and the resulting suspension
was extracted with ethyl acetate (3 × 10 mL). The combined
organic phase was dried over anhydrous Na2SO4 and filtrated.
The solution was evaporated under reduced pressure to remove
the solvent. Purification of the residue by flash silica column
chromatography using ethyl acetate (EA)/and petroleum ether
(PET) mixtures as eluent (VEA: VPET = 1: 15) afforded pure
product. NMR Spectra were measured in CDCl3 at 400 MHz
(1H) and 100 MHz (13C). The Supplemental Materials file
(E)-1-[2-Iodo-2-(4-methoxyphenyl)vinylsulfonyl]-4-
methylbenzene (3i).17 White solid; m.p. 121 °C;1H NMR: δ
7.49 (d, J = 8.0 Hz, 2 H), 7.29 (s, 1 H), 7.24 (d, J = 8.4 Hz, 2 H),
7.18 (d, J = 8.0 Hz, 2 H), 6.78 (d, J = 8.8 Hz, 2 H), 3.80 (s, 3 H),
2.37 (s, 3 H); 13C NMR: 160.8, 144.5, 140.4, 137.5, 131.9, 130.0,
129.7, 127.8, 115.0, 113.3, 55.4, 21.7.
(E)-1-Chloro-4-(1-iodo-2-tosylvinyl)benzene(3j).17 White
1
solid; m.p. 58 °C; H NMR: δ 7.50 (d, J = 8.4 Hz, 2 H), 7.34
(s, 1 H), 7.27 (d, J = 8.4 Hz, 2 H), 7.24 (d, J = 8.0 Hz, 2 H), 7.19
(d, J = 8.4 Hz, 2 H), 2.42 (s, 3 H); 13C NMR: 144.9, 141.8, 138.1,
137.2, 135.9, 129.8, 129.1, 128.2, 127.9, 112.0, 21.7.
1
contains sample H and 13C NMR of the products 3 (Figures
(E)-1-(1-Iodo-2-tosylvinyl)-3-methylbenzene(3k). White
1
S2–S33).
solid;m.p. 112 °C; H NMR: δ 7.44 (d, J = 8.4 Hz, 2 H), 7.35
(E)-1-(2-Iodo-2-phenylvinylsulfonyl)-4-methylbenzene
(3a).17 White solid; m.p. 69 °C; 1H NMR: δ 7.44 (d, J = 8.0 Hz,
2 H), 7.36 (s, 1 H), 7.31–7.25 (m, 3 H), 7.22 (d, J = 6.0 Hz, 2 H),
7.17 (d, J = 7.6 Hz, 2 H), 2.37 (s, 3 H); 13C NMR: 144.6, 141.3,
139.7, 137.2, 129.8, 129.7, 127.95, 127.88, 127.7, 114.3, 21.7.
(s, 1 H), 7.16 (t, J = 6.0 Hz, 3 H), 7.10 (d, J = 6.8 Hz, 1
H), 7.04 (d, J = 7.2 Hz, 1 H), 6.91 (s, 1 H), 2.39 (s, 3 H), 2.27
(s, 3 H); 13C NMR (100 MHz, CDCl3): 144.5, 141.2, 139.6, 137.7,
137.3, 130.6, 129.6, 128.0, 127.93, 127.86, 124.8, 114.6, 21.6,
21.3; ESI-HRMScalcd.for C16H15IO2SNa[M+Na]+ 420.9730,
found 420.9723.
(E)-[1-Iodo-2-(phenylsulfonyl)vinyl]benzene
(3b).17
7.58–7.53
Yellow solid; m.p. 63 °C; 1H NMR:
δ
(E)-1-Fluoro-2-(1-iodo-2-tosylvinyl)benzene(3l). Brown
1
(m, 3 H), 7.41 (s, 1 H), 7.39 (s, 2 H), 7.33–7.27 (m, 3 H),
7.21 (d, J = 6.4 Hz, 2 H); 13C NMR: 141.1, 140.2, 139.6, 133.5,
129.9, 129.0, 128.0, 127.8, 127.7, 114.8.
solid; m.p. 116°C; H NMR: δ 7.53 (d, J = 8.0 Hz, 2 H), 7.40
(s, 1 H), 7.32 (m, 1 H), 7.23 (t, J = 8.4 Hz, 3 H), 7.15 (t, J =
7.2 Hz, 1 H), 6.95 (t, J = 8.8 Hz, 1 H), 2.41 (s, 3 H); 13C NMR:
157.3 (d, J = 248.9 Hz), 145.0, 142.9, 136.7, 131.7 (d, J = 8.8
Hz), 129.9, 129.3, 127.9, 127.6 (d, J = 14.9 Hz), 123.9 (d, J =
3.5 Hz), 115.7 (d, J = 20.6 Hz), 104.6, 21.7; ESI-HRMScalcd.for
C15H12FIO2SNa[M+Na]+ 424.9479, found 424.9475.
(E)-1-[1-Iodo-2-(phenylsulfonyl)vinyl]-4-methylbenzene
(3c).17 Yellow solid; m.p. 97 °C; 1H NMR: δ 7.60 (d, J = 7.2 Hz,
2 H), 7.53 (t, J = 7.6 Hz, 1 H), 7.38 (t, J = 7.6 Hz, 2 H), 7.33 (s, 1
H), 7.13 (d, J = 7.6 Hz, 2 H), 7.06 (d, J = 7.6 Hz, 2 H), 2.34 (s, 3
H); 13C NMR: 140.65, 140.57, 140.2, 136.9, 133.4, 128.9, 128.6,
127.84, 127.82, 115.2, 21.4.
(E)-1-(1-Iodo-2-(4-methoxyphenylsulfonyl)vinyl)-4-
methylbenzene (3m). Yellow solid; m.p. 91 °C; 1H NMR: δ 7.51
(d, J = 8.0 Hz, 2 H), 7.31 (s, 1 H), 7.15 (d, J = 7.2 Hz, 2 H), 7.08
(d, J = 7.2 Hz, 2 H), 6.84 (d, J = 7.6 Hz, 2 H), 3.82 (s, 3 H),
2.34 (s, 3 H); 13C NMR: 163.6, 141.1, 140.1, 136.9, 131.7, 130.1,
128.6, 127.8, 114.31, 114.25, 55.8, 21.5; ESI-HRMScalcd.for
C16H15IO3SNa[M+Na]+ 436.9679, found 436.9660.
(E)-1-[1-Iodo-2-(phenylsulfonyl)vinyl]-4-
methoxybenzene (3d).17 Yellow solid; m.p. 94 °C; 1H NMR: δ
7.61 (d, J = 7.6 Hz, 2 H), 7.54 (t, J = 3.6 Hz, 1 H), 7.42–7.39
(m, 2 H), 7.32 (s, 1 H), 7.24 (d, J = 8.4 Hz, 2 H), 6.79 (d, J =
8.8 Hz, 2 H), 3.83 (s, 3 H); 13C NMR: 160.8, 140.4, 140.1, 133.5,
131.8, 130.0, 129.0, 127.8, 115.5, 113.3, 55.4.
(E)-1-Chloro-4-(2-iodo-2-p-tolylvinylsulfonyl)benzene
(3n). White solid; m.p. 105 °C; 1H NMR: δ 7.49 (d, J =
8.8 Hz, 2 H), 7.34 (d, J = 7.6 Hz, 3 H), 7.13-7.07 (m, 4 H),
2.36 (s, 3 H); 13C NMR: 140.5, 140.4, 140.2, 138.8, 136.7,
129.3, 129.2, 128.7, 127.8, 115.9, 21.5; ESI-HRMScalcd.for
C15H12ClIO2SNa[M+Na]+ 440.9183, found 440.9186.
(E)-4-(2-Iodo-2-p-tolylvinylsulfonyl)benzonitrile(3o).
White solid; m.p. 179 °C; 1H NMR: δ 7.65 (s, 4 H), 7.36
(s, 1 H), 7.09 (s, 4 H), 2.37 (s, 3 H); 13C NMR: 144.6, 140.8,
139.8, 136.6, 132.5, 128.7, 128.5, 127.8, 117.2, 117.1, 117.0,
21.3; ESI-HRMScalcd.for C16H12INO2SNa[M+Na]+ 431.9526,
found 431.9525.
(E)-1-Fluoro-4-[1-iodo-2-(phenylsulfonyl)vinyl]benzene
(3e).17 Yellow solid; m.p. 74 °C; 1H NMR: δ 7.61–7.54 (m, 3 H),
7.42 (t, J = 8.0 Hz, 2 H), 7.38 (s, 1 H), 7.25–7.22 (m, 2 H), 6.97
(t, J = 8.8 Hz, 2 H); 13C NMR: 163.2 (d, J = 250 Hz), 141.5,
140.2, 135.6 (d, J = 3.3 Hz), 133.7, 130.0 (d, J = 8.6 Hz), 129.2,
127.8, 115.2 (d, J = 21.6 Hz), 113.2.
(E)-1-Chloro-4-[1-iodo-2-(phenylsulfonyl)vinyl]benzene
(3f).17 White solid; m.p. 65 °C;1H NMR: δ 7.62 (d, J = 7.2 Hz,
2 H), 7.58 (d, J = 7.6 Hz, 1 H), 7.44 (t, J = 8.0 Hz, 2 H), 7.37
(s, 1 H), 7.26 (d, J = 8.8 Hz, 2 H), 7.17 (d, J = 8.4 Hz, 2 H);
13C NMR: 141.6, 140.2, 138.0, 136.0, 133.7, 129.2, 129.1, 128.3,
127.8, 112.6.
(E)-2-(2-Iodo-2-phenylvinylsulfonyl)naphthalene(3p).17
1
(E)-1-[1-Iodo-2-(phenylsulfonyl)vinyl]-3-methylbenzene
(3g).17 Yellow liquid; 1H NMR: δ 7.53 (d, J = 8.4 Hz, 2 H), 7.49
(d, J = 7.6 Hz, 2 H), 7.37 (s, 1 H), 7.34 (t, J = 7.6 Hz, 2 H), 7.14
(t, J = 7.6 Hz, 1 H), 7.07 (d, J = 7.6 Hz, 1 H), 7.01 (d, J = 7.2 Hz,
1 H), 6.89 (s, 1 H), 2.24 (s, 3 H); 13C NMR: 141.1, 140.3, 139.5,
137.7, 133.4, 130.7, 128.9, 128.0, 127.9, 127.8, 124.8, 115.2, 21.4.
(E)-1-(2-Iodo-2-p-tolylvinylsulfonyl)-4-methylbenzene
(3h).17 White solid; m.p. 113 °C;1H NMR: δ 7.49 (d, J = 8.0 Hz,
2 H), 7.30 (s, 1 H), 7.20 (d, J = 8.0 Hz, 2 H), 7.16 (d, J = 8.0 Hz,
2 H), 7.09 (d, J = 8.4 Hz, 2 H), 2.40 (s, 3 H), 2.36 (s, 3 H);
Yellow solid; m.p. 83 °C; H NMR: δ 8.00 (s, 1 H), 7.87 (d, J
= 7.6 Hz, 1 H), 7.78 (d, J = 7.6 Hz, 1 H), 7.67–7.56 (m, 3 H),
7.46 (s, 1 H), 7.24-7.20 (m, 1 H), 7.18 (d, J = 4.0 Hz, 4 H);
13C NMR: 141.3, 139.5, 136.9, 135.1, 132.0, 130.0, 129.9, 129.4,
129.3, 127.9, 127.7, 127.6, 122.4, 114.8.
Acknowledgment
This work was financially supported by National Natural Science Founda-
tion of China (21562024).

4
L. YANG ET AL.
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