Solvent-free synthesis of alkyl and fluoroalkyl sulfonium salts from sulfides and fluoroalkyl trifluoromethanesulfonates

Article abstract of DOI:10.1016/j.jfluchem.2016.10.020

A series of diaryl(fluoroalkyl)sulfonium salts were synthesized from electron-rich diaryl sulfides and fluoroalkyl trifluoromethanesulfonates under solvent-free conditions. Unlike diaryl sulfides, dialkyl and alkyl(aryl) sulfides reacted with fluoroalkyl

Full text of DOI:10.1016/j.jfluchem.2016.10.020

Accepted Manuscript
Title: Solvent-Free Synthesis of Alkyl and Fluoroalkyl
Sulfonium Salts from Sulfides and Fluoroalkyl
Trifluoromethanesulfonates
Author: Hai-Xia Song Shi-Meng Wang Xiao-Yan Wang
Jia-Bin Han Ying Gao Su-Jiao Jia Cheng-Pan Zhang
PII:
S0022-1139(16)30325-6
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.jfluchem.2016.10.020
FLUOR 8885
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28-10-2016
28-10-2016
Please cite this article as: Hai-Xia Song, Shi-Meng Wang, Xiao-Yan Wang, Jia-Bin
Han, Ying Gao, Su-Jiao Jia, Cheng-Pan Zhang, Solvent-Free Synthesis of Alkyl and
FluoroalkylSulfoniumSaltsfromSulfidesandFluoroalkylTrifluoromethanesulfonates,
Journal of Fluorine Chemistry http://dx.doi.org/10.1016/j.jfluchem.2016.10.020
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<AT>Solvent-Free Synthesis of Alkyl and Fluoroalkyl Sulfonium Salts from Sulfides
and Fluoroalkyl Trifluoromethanesulfonates
<AU>Hai-Xia Song, Shi-Meng Wang, Xiao-Yan Wang, Jia-Bin Han, Ying Gao,
Su-Jiao Jia, Cheng-Pan Zhang* ##Email##cpzhang@whut.edu.cn##/Email##,
##Email##zhangchengpan1982@hotmail.com##/Email##
<AU>
<AFF>School of Chemistry, Chemical Engineering and Life Science, Wuhan
University of Technology, 205 Luoshi Road, Wuhan, 430070, China
<PA>*Corresponding author Graphic.
<ABS-HEAD>Abstract►
<ABS-HEAD>Highlights► Solvent-free facile synthesis of alkyl and fluoroalkyl
sulfonium salts. ► Fluoroalkyl trifluoromethanesulfonates were used as fluoroalkyl
sources. ► The reaction could selectively afford alkyl- or fluoroalkylsulfonium salts.
► The reactants and reaction temperature dramatically affected the reaction.
<ABS-HEAD>Abstract
<ABS-P>A series of diaryl(fluoroalkyl)sulfonium salts were synthesized from
electron-rich diaryl sulfides and fluoroalkyl trifluoromethanesulfonates under
solvent-free conditions. Unlike diaryl sulfides, dialkyl and alkyl(aryl) sulfides reacted
with fluoroalkyl trifluoromethanesulfonates (e.g. CF3SO3CH2CF3, CF3SO3CH2CF2H)
to provide trialkyl- and aryl(dialkyl)sulfonium trifluoromethanesulfonates in good
yields, wherein dialkyl- and alkyl(aryl)(fluoroalkyl)sulfonium salts were formed,
respectively, and nucleophilically attacked by a second sulfide to yield the
non-fluorinated sulfoniums. The SN2-type reaction could stop at the first step and
exclusively afford dialkyl- and alkyl(aryl)(fluoroalkyl)sulfonium salts, which was
dramatically dependent upon the structure of sulfides, the nature of fluoroalkyl
trifluoromethanesulfonates, the reactant ratio, and/or the reaction temperature. This
protocol allows for an efficient and convenient access to a variety of alkyl and
fluoroalkyl sulfonium salts.
<KWD>Keywords: sulfides; fluoroalkyl trifluoromethanesulfonates; sulfonium salts.
<H1>1. Introduction
Sulfonium salts are versatile reagents in the fields of chemistry and materials science
[1,2]. Triarylsulfonium salts have been widely used as photoinitiators in cationic
polymerizations and as photoacid generators in the areas of coatings, adhesives,
photoresists, microfabrication, and patterning [2,3]. Vinylsulfoniums can in situ form
1

sulfur ylides via nucleophilic conjugate addition, leading to a variety of useful
cyclization reactions [4,5]. Alkylsulfoniums have become the most common ylide
precursors, generating sulfur ylides in the presence of appropriate bases to furnish a
great quantity of cyclopropane derivatives [6]. They can also undergo elimination and
displacement for numerous synthetic purposes [7]. Diaryl(perfluoroalkyl)sulfonium
salts are powerful electrophilic perfluoroalkylation reagents which have
perfluoroalkylated a wide range of nucleophiles and electrophiles under mild
conditions [8]. Moreover, diaryl(fluoroalkyl)sulfonium trifluoromethanesulfonates
have been used as effective fluoroalkylation and arylation reagents in
transition-metal-catalyzed cross-couplings during the past few years [9,10]. Owing to
their wide applications, the development of efficient methods to the synthesis of these
sulfonium salts is of particular importance [1,6].
In general, triarylsulfonium salts were prepared by the reactions of arylthiols or diaryl
sulfides with diaryliodonium salts, and the reactions of arenes with sulfur
monochloride, diaryl sulfoxides or sulfimides [1a,1d,1e]. Alkyl(diaryl)sulfonium salts
were synthesized from the reactions of arenes with alkyl(aryl)(halo)sulfoniums or
sodium methanesulfinate, and the reactions of diaryl sulfides or sulfoxides with
alkylation reagents [1d]. Aryl(dialkyl)sulfonium salts were derived from the reactions
of arenes with dialkyl(halo)sulfonium salts, dialkyl sulfoxides, dialkyl(aza)sulfoniums
or dialkyl(nitrosyl)sulfoniums, the reactions of aryl(alkyl)sulfoxides or sulfides with
alkylation reagents, and the reaction of dialkyl sulfides with benzyne [1d].
Trialkylsulfonium salts were simply constructed by the reactions of dialkyl sulfides
with alkylation reagents such as alkyl halides and sulfates [6]. Different from the
2

non-fluorinated sulfonium salts, diaryl(perfluoroalkyl)sulfonium salts were tediously
synthesized from arenethiols via several steps (e.g. perfluoroalkylation of thiols,
oxidation, and electrophilic aromatic substitution) [8]. The direct nucleophlic
perfluoroalkylation of diarylsulfides by RfnX failed to give the desired products
because of the strong electronegativity and huge steric hindrances of perfluoroalkyl
groups (Rfn) compared to the non-fluorinated analogues.
In contrast to diaryl(perfluoroalkyl)sulfonium salts,
diaryl(α,α-dihydroperfluoroalkyl)sulfonium trifluoromethanesulfonates including
[Ph2SCH2CF3][OTf] were successfully synthesized by the reactions of diarylsulfides
with (α,α-dihydroperfluoroalkyl)phenyliodonium salts (or 2,2,2-trifluoroethyl
trifluoromethanesulfonate) [8-10]. Their analogues such as dialkyl- and
alkyl(aryl)(polyfluoroalkyl)sulfonium salts, however, were rarely reported. To our
knowledge, there have been only few examples derived from dialkyl or alkyl(aryl)
sulfides and (α,α-dihydroperfluoroalkyl)phenyliodonium [11]. Therefore, we are
motivated in the development of an effective and practical method to the synthesis of
these sulfoniums with easily accessed reagents.
<H1>2. Results and Discussions
Diphenyl(2,2,2-trifluoroethyl)sulfonium trifluoromethanesulfonate (3aa) was readily
prepared by the reaction of diphenyl sulfides (1a) and 2,2,2-trifluoroethyl
trifluoromethanesulfonate (2a) or phenyl(2,2,2-trifluoroethyl)iodonium salt [8,9],
which was already applied as a cross-coupling partner in transition-metal-catalyzed
fluoroalkylation and phenylation [9,10]. This strategy ought to be suitable for the
synthesis of other diaryl-, dialkyl-, and alkyl(aryl)sulfonium
trifluoromethanesulfonates [10]. Since (2,2-difluoroethyl)- and
(2-fluoroethyl)phenyliodonium salts are not available at present, the use of
2,2-difluoroethyl and 2-fluoroethyl trifluoromethanesulfonates as the alkylation
reagents [12] to prepare the corresponding 2,2-difluoroethyl and 2-fluoroethyl
sulfonium salts is reasonably adopted. Here we report a solvent-free reaction of diaryl,
dialkyl, and aryl(alkyl) sulfides with 2,2,2-trifluoroethyl trifluoromethanesulfonate
(2a), 2,2-difluoroethyl trifluoromethanesulfonate (2b), 2-fluoroethyl
trifluoromethanesulfonate (2c), and 2,2,3,3,3-pentafluoropropyl
trifluoromethanesulfonate (2d), which conveniently constructed a variety of
fluoroalkyl or alkyl sulfonium salts in up to quantitative yields.
As shown in Table 1, reaction of 2a with diphenyl sulfide (1a, 5 equiv) at 150 oC for 48
h under a solvent-free condition gave 3aa in 61% yield (entry 1) [9,10], and lowering
the reaction temperature from 150 oC to 120 oC caused none of the desired product. A
mixture of 2b and 1a (3 equiv) or 2b (3 equiv) and 1a heated at 120 oC for 48 h
produced (2,2-difluoroethyl)diphenylsulfonium trifluoromethanesulfonate (3ab) in
94% or 84% yield (entries 2 and 3, Table 1). Treatment of 2c with 1a (1.5 equiv) at 60
oC for 15 h formed diphenyl(2-fluoroethyl)sulfonium trifluoromethanesulfonate (3ac)
in 84% yield (entry 4, Table 1). 2,2,3,3,3-Pentafluoropropyl trifluoromethanesulfonate
(2d) reacted with 1a at 150 oC for 72 h to provide
diphenyl(2,2,3,3,3-pentafluoropropyl)sulfonium trifluoromethanesulfonate (3ad) in
7% yield, which was tentatively attributed to the steric hindrance of perfluoroalkyl
3

group (entry 5, Table 1). These results implied that the order of fluoroalkylation ability
of 2a-d toward sulfide is 2c > 2b > 2a > 2d (from strong to weak). Although the
electronegativity of the fluoroalkyl groups of 2a and 2d is stronger than that of 2b and
2c, the steric hindrances of the former counteract the electrophilicity of the carbon
centers (adjacent to CF2H2-nX group (see Table 1)), thus leading to poor reactivity of
2a and 2d.
Moreover, the substituents on the phenyl rings of diaryl sulfides had a considerable
impact on the reaction. 4-Methoxyphenyl phenyl sulfide (1b) reacted with 2a-c under
solvent-free conditions to give the corresponding fluoroalkyl diarylsulfonium salts
(3ba, 3bb, and 3bc) in good to high yields (entries 6-8, Table 1). Reaction of
4-chlorophenyl phenyl sulfide (1c) with 2a didn’t provide the desired product (entry 9,
Table 1). When 1c was analogously treated with 2,2-difluoroethyl
trifluoromethanesulfonate (2b) and 2-fluoroethyl trifluoromethanesulfonate (2c), the
respective fluoroalkyl(diaryl)sulfonium salts (3cb and 3cc) were formed in 66% and
93% yields (entries 10 and 11, Table 1). Replacing 1c by the more electron-deficient
4-nitrophenyl phenyl sulfide (1d), only the reaction of 1d with 2c furnished the desired
product (3dc) (entry 12, Table 1). Furthermore, reaction of dibenzothiophene (1e) with
2b at 120 oC for 48 h provided 3eb in 15% yield (entry 13, Table 1) and treatment of 1e
with 2c at 100 oC for 15 h afforded 3ec in 61% yield (entry 14, Table 1). All these
results again suggested the stronger fluoroalkylation ability of 2c.
To shed light on the structure of fluoroalkyl(diaryl)sulfonium salts, the representative
crystalline 3aa and 3ab were analyzed by single crystal X-ray diffraction (Figure 1)
[13]. The study revealed that the length of S-CH2CF3 bond (1.789(5) Å) in 3aa is very
close to that of S-Ph bonds (1.779(4)‒1.789(5) Å), while the length of S-CH2CF2H
bond (1.805(3) Å) in 3ab is longer than that of S-Ph bonds (1.772(3)‒1.781(3) Å)
(Table 2). This feature (especially for 3ab) is in accordance with the previous
observation for non-fluorinated analogue that the S-Ph bond in [Ph2SCH3][OTf] is
somewhat shorter than the S-Me bond [6f]. In addition, the C-F bonds in the cations of
3aa (1.310(6)‒1.320(7) Å) are much shorter than those in 3ab (1.338(4)‒1.341(3) Å)
(Table 2). The C3-S-C9 angle in 3aa is 105.6(2)°, and that for 3ab is smaller at
103.71(7)°. The bond distance of C1-H(1A) and C1-H(1B) [0.9700 Å] is identical in
both 3aa and 3ab and is shorter than that of C2-H2 [0.9800 Å] in 3ab. All these data
hint a considerable ``fluorine effect'', which might illustrate the different stability and
phenylation power of 3aa and 3ab in Pd-catalyzed Mizoroki-Heck and Suzuki-Miyaura
cross-couplings [10].
Next, reactions of dialkyl sulfides with fluoroalkyl trifluoromethanesulfonates under
solvent-free conditions provided trialkyl- or dialkyl(fluoroalkyl)sulfonium
trifluoromethanesulfonates in up to quantitative yields (entries 1-12, Table 3). The
outcomes of the reaction were dramatically dependent upon the structure of sulfides,
the nature of fluoroalkyl trifluoromethanesulfonates, the reactant ratio, and/or the
reaction temperature. For instance, dibutyl sulfide (4a, 3 equiv.) reacted with 2a or 2b
at 100 oC for 24 h to afford tributylsulfonium trifluoromethanesulfonate (6a) in 55% or
97% yield, respectively (entries 1 and 2, Table 3). The reaction might involve
dibutyl(2,2,2-trifluoroethyl)- or dibutyl(2,2-difluoroethyl)sulfonium intermediate,
4

which was nucleophilically attacked by a second dibutyl sulfide to yield 6a due to the
strong electron-withdrawing ability of polyfluoroethyl group. If the reaction of 4a and
2b was performed at room temperature for 24 h, dibutyl(2,2-difluoroethyl)sulfonium
trifluoromethanesulfonate (5ab) was formed in 91% yield (entry 3, Table 3).
Furthermore, a mixture of 4a and 2c (2 equiv) or 4a (3 equiv) and 2c heated at 60 oC for
15 h furnished dibutyl(2-fluoroethyl)sulfonium trifluoromethanesulfonate (5ac) in
almost quantitative yields (entries 4 and 5, Table 3). Treatment of diallyl sulfide (4b, 3
or 5 equiv.) with 2a at 100 oC for 24 h, with 2b at 60 oC for 24 h, or with 2c at 60 oC for
15 h provided triallylsulfonium trifluoromethanesulfonate (6b) in 43%, 99%, or 92%
yield, respectively (entries 6-8, Table 3). If 4b reacted with 2c (2 equiv.) at room
temperature for 15 h, diallyl(2-fluoroethyl)sulfonium trifluoromethanesulfonate (5bc)
was obtained in > 99% yield (entry 9, Table 3). Besides, reaction of diethyl sulfide (4c,
5 equiv) with 2a at 100 oC for 24 h constructed triethylsulfonium
trifluoromethanesulfonate (6c) in 27% yield (entry 10, Table 3). Treatment of 4c (3
equiv) with 2b at room temperature, 60 oC, or 100 oC supplied a mixture of 5cb and 6c,
which was determined by NMR spectroscopy (entry 11, Table 3). Nonetheless, if 4c (3
equiv) was reacted with 2c at 60 oC for 15 h, diethyl(2-fluoroethyl)sulfonium
trifluoromethanesulfonate (5cc) was formed in 99% yield (entry 12, Table 3).
Likewise, the solvent-free reaction of aryl(alkyl) sulfides with fluoroalkyl
trifluoromethanesulfonates constructed a series of dialkyl(aryl)- or
alkyl(aryl)fluoroalkylsulfonium trifluoromethanesulfonates in up to > 99% yields
(entries 13-21, Table 3). The use of excess methyl phenyl sulfide (4d) to work with 2a
at 100 oC for 24 h or 2b at 60 oC for 24 h provided (dimethyl)(phenyl)sulfonium
trifluoromethanesulfonate (6d) in 21% or 98% yield (entries 13 and 14, Table 3),
whereas the reaction of 4d with 2c (2 equiv.) at 60 oC for 5 h supplied
(2-fluoroethyl)(methyl)(phenyl)sulfonium trifluoromethanesulfonate (5dc) in 97%
yield (entry 15, Table 3). The exact structure of 6d was determined by single crystal
X-ray diffraction (Figure 1) [13]. It should be mentioned that the previous methods to
the preparation of 6d required highly toxic and expensive CH3OTf or AgOTf / CH3I
mixture [1f,6f], which limited their use on large scales. Alternatively, the present
reaction provided a safe and convenient access to 6d. Similar product distributions
were also observed for ethyl phenyl sulfide (4e) and butyl phenyl sulfide (4f) when they
were treated with 2a-c under solvent-free conditions (entries 16-21, Table 3). In
addition, the reaction of tetrahydrothiophene (4g) with 2 equiv. of 2a at 100 oC for 4 h
afforded 1-(4-((2,2,2-trifluoroethyl)thio)butyl)tetrahydro-1H-thiophen-1-ium
trifluoromethanesulfonate (6ga) in 98% yield (Scheme 1). If the reaction was run at 60
oC with either excess or insufficient 2c,
1-(2-fluoroethyl)tetrahydro-1H-thiophen-1-ium trifluoromethanesulfonate (5gc) was
furnished in > 99% or 77% yield, respectively (Scheme 1). Furthermore, when the
steric hindered diisopropyl sulfide (4h) reacted with 2a or 2b at 100 oC for 24 h,
triisopropylsulfonium trifluoromethanesulfonate (6h) was formed in 31% or 87% yield
(Scheme 2). Nevertheless, if 4h was treated with 2b at 60 oC for 8 h or at room
temperature for 24 h, (2,2-difluoroethyl)diisopropylsulfonium
trifluoromethanesulfonate (5hb) was synthesized in 83% or 30% yield, respectively
5

(Scheme 2). These results suggested that the secondary alkyl substituent on 4h did not
obviously impact the reaction.
Since the fluoroalkyl groups activated dialkyl- and alkyl(aryl)(fluoroalkyl)sulfonium
salts (5), the reaction didn’t stop at the first step in some cases and finally afforded
trialkyl- and dialkyl(aryl)sulfonium trifluoromethanesulfonates (6) in good to
quantitative yields. The results indicated that fluoroalkylsulfoniums (5) with heavier
fluorine content on the alkyl groups (e.g. CFnH3-n = CF3, CF2H) might more easily
undergo a second attack by sulfide to form the overreacted products (6). In other words,
because 2a is less electrophilic than 2b and 2c, the reaction of 2a with dialkyl and
alkylaryl sulfides (4) required higher temperatures and provided non-fluorinated
alkylsulfonium salts as the final products. For 2b, the reaction with 4 gave either
difluoroalkyl sulfoniums or the overreacted products, which was dependent upon the
temperatures. Notably, if 2c was reacted with 4, monofluoroethyl sulfonium salts were
prepared in most cases.
<H1>3. Conclusion
In conclusion, we have synthesized a number of fluoroalkyl(diaryl)sulfonium salts by
SN2-type reactions of electron-rich diaryl sulfides with fluoroalkyl
trifluoromethanesulfonates under solvent-free conditions. Different from diaryl
sulfides, dialkyl and alkyl(aryl) sulfides reacted with fluoroalkyl
trifluoromethanesulfonates providing trialkyl- or dialkyl(fluoroalkyl)sulfoniums and
dialkyl(aryl)- or alkyl(aryl)(fluoroalkyl)sulfoniums in good to quantitative yields. The
formation of trialkyl- and dialkyl(aryl)sulfonium trifluoromethanesulfonates might
involve dialkyl- and alkyl(aryl)(fluoroalkyl)sulfonium intermediates, respectively,
which were attacked by a second sulfide, owing to the strong electron-withdrawing
ability of fluoroalkyl groups and leading to the overreacted products. The reaction
could stop at the first step in some cases and afforded fluoroalkylated sulfonium salts,
which was dramatically dependent upon the structure of sulfides, the nature of
fluoroalkyl trifluoromethanesulfonates, the reactant ratio, and/or the reaction
temperature. Moreover, fluoroalkyl trifluoromethanesulfonates were easily prepared
by the reaction of Tf2O with fluoroalkyl alcohols, so the accessibility of
fluoroalkylation reagents is no longer problematic. Overall, this protocol supplies an
efficient and convenient access to a variety of alkyl and fluoroalkyl sulfonium salts.
<H1>4. Experimental Section
All reactions were carried out under a nitrogen atmosphere. Unless otherwise specified,
NMR spectra were recorded in CDCl3, CD3COCD3, or CD3SOCD3 on a 500 or 400
MHz (for 1H), 471 or 376 MHz (for 19F), and 126 or 100 MHz (for 13C) spectrometer.
All chemical shifts were reported in ppm relative to TMS (1H NMR, 0 ppm) or PhCF3
(19F NMR, -63.5 ppm) as an internal or external standard. Melting points of the
products were measured and uncorrected. Diaryl and aryl(alkyl) sulfides (1b, 1c, 1d,
1e, 4e, and 4f) were synthesized according to the literature [14]. Fluoroalkyl
trifluoromethanesulfonate (2a, 2b, 2c, and 2d) were synthesized according to the
literatures [12,15]. Other reagents were all purchased from commercial sources and
used without further purification.
6

<H2>4.1. Procedures for the synthesis of 2a, 2b, 2c, and 2d [12,15]
4.1.1. Trifluoromethanesulfonic anhydride (42.3 g, 150.0 mmol) was added dropwise
to 2,2,2-trifluoroethanol (15.0 g, 150.0 mmol) in a 250 mL Schlenk flask (equipped
with a condenser) at 0 oC. Then the mixture was heated at reflux for 1.5 h, cooled to
room temperature, washed with aqueous NaHCO3 solution (30 mL) and brine (3 × 50
mL), dried over anhydrous MgSO4, and distilled to give 2,2,2-trifluoroethyl
trifluoromethanesulfonate (2a) as a colorless liquid (18.1 g, 78.0 mmol, 52%). 1H NMR
(400 MHz, CDCl3) δ 4.70 (q, J = 7.8 Hz, 2H). 19F NMR (376 MHz, CDCl3) δ -74.4 (s,
3F), -74.7 (t, J = 7.5 Hz, 3F). 13C NMR (100 MHz, CDCl3) δ 129.0 (q, J = 278.0 Hz),
118.4 (q, J = 321.4 Hz), 68.6 (q, J = 39.8 Hz).
4.1.2. Trifluoromethanesulfonic anhydride (42.3 g, 150.0 mmol) was added dropwise
to 2,2-difluoroethanol (12.3 g, 150.0 mmol) in a 250 mL Schlenk flask (equipped with a
condenser) at -20 oC. The mixture was then heated at reflux for 1.5 h, cooled to room
temperature, washed with aqueous NaHCO3 solution (30 mL) and brine (3 × 50 ml),
dried over anhydrous MgSO4, and distilled to give 2,2-difluoroethyl
trifluoromethanesulfonate (2b) as a colorless liquid (19.6 g, 91.6 mmol, 61%). 1H NMR
(400 MHz, CDCl3) δ 6.04 (tt, J = 53.8 Hz, J = 3.4 Hz, 1H), 4.58 (td, J = 12.4 Hz, J = 2.4
Hz, 2H). 19F NMR (376 MHz, CDCl3) δ -74.1 (s, 3F), -126.5 (td, J = 54.8 Hz, J = 12.8
Hz, 2F). 13C NMR (100 MHz, CDCl3) δ 118.5 (q, J = 315.8 Hz), 110.7 (t, J = 246.8 Hz),
71.0 (t, J = 31.3 Hz).
4.1.3. Trifluoromethanesulfonic anhydride (10.3 g, 55.0 mmol) was added dropwise to
a solution of 2-fluoroethanol (2.1 g, 33.3 mmol) and NEt3 (3.7 g, 36.7 mmol) in
anhydrous CH2Cl2 (40 mL) at -50 oC over a period of 20 min with vigorous stirring.
The mixture was warmed to room temperature for 2 h, quenched with H2O, neutralized
by aqueous NaHCO3 solution, washed with brine (3 × 50 mL), dried over anhydrous
MgSO4, and concentrated under reduced pressure to give 2-fluoroethyl
trifluoromethanesulfonate (2c) as pale brown liquid (4.6 g, 23.5 mmol, 71%). The
product was used without further purification. 1H NMR (400 MHz, CDCl3) δ 4.76 (q, J
= 7.6 Hz, 2H), 4.66 (dm, J = 6.8 Hz, 2H). 19F NMR (476 MHz, CDCl3) δ -75.8 (s, 3F),
-226.6 (m, 1F). 13C NMR (100 MHz, CDCl3) δ 118.6 (q, J = 321.2 Hz), 80.8 (d, J =
176.0 Hz), 74.4 (d, J = 20.6 Hz).
4.1.4. Trifluoromethanesulfonic anhydride (42.3 g, 150.0 mmol) was added dropwise
to 2,2,3,3,3-pentafluoropropanol (22.5 g, 150.0 mmol) in a 250 mL Schlenk flask
(equipped with a condenser) at 0 oC. The mixture was heated at reflux for 1.5 h, cooled
to room temperature, washed with aqueous NaHCO3 solution (30 mL) and brine (3 × 50
mL), dried over anhydrous MgSO4, and distilled to give 2,2,3,3,3-pentafluoropropyl
trifluoromethanesulfonate (2d) as a colorless liquid (13.8 g, 48.9 mmol, 33%). 1H NMR
(400 MHz, CDCl3) δ 4.77 (t, J = 12.2 Hz, 2H). 19F NMR (376 MHz, CDCl3) δ -74.2 (s,
3F), -83.7 (s, 3F), -123.9 (t, J = 11.6 Hz, 2F). 13C NMR (100 MHz, CDCl3) δ 118.4 (q,
J = 320.5 Hz), 67.7 (t, J = 29.6 Hz).
<H2>4.2. General procedure for the synthesis of alkyl and fluoroalkyl sulfonium salts
Diaryl, dialkyl, or aryl(alkyl) sulfides and fluoroalkyl trifluoromethanesulfonate were
placed in a sealed tube under a N2 atmosphere with vigorous stirring. The mixture was
reacted at a temperature for 5-72 h (see Table 1 and Table 3), cooled to room
7

temperature, washed with diethyl ether or hexane (till the excess sulfide or sulfonate
was completely removed), and dried in vacuum to give the title compounds. In some
cases (see below), the product was decolored by activated charcoal in CH2Cl2
(refluxing for 0.5 h) to afford a light color oil.
4.2.1. Diphenyl(2,2,2-trifluoroethyl)sulfonium trifluoromethanesulfonate (3aa). White
solid, 102.0 mg from 2.00 mmol of 1a and 0.400 mmol of 2a, 0.244 mmol, 61% yield.
1H NMR (500 MHz, CD3SOCD3) δ 8.34 (d, J = 7.78 Hz, 4H), 8.17 (t, J = 7.5 Hz, 2H),
8.07 (t, J = 7.8 Hz, 4H), 5.44 (q, J = 8.6 Hz, 2H). 19F NMR (376 MHz, CD3SOCD3) δ
-61.4 (t, J = 8.8 Hz, 3F), -79.3 (s, 3F). 13C NMR (126 MHz, CD3SOCD3) δ 135.0 (s),
131.3 (s), 130.7 (s), 124.4 (s), 122.5 (q, J = 280.8 Hz), 120.7 (q, J = 322.2 Hz), 43.7 (q,
J = 31.8 Hz).
4.2.2. (2,2-Difluoroethyl)diphenylsulfonium trifluoromethanesulfonate (3ab). White
solid, 225.6 mg from 1.80 mmol of 1a and 0.600 mmol of 2b, 0.564 mmol, 94% yield.
1H NMR (500 MHz, CDCl3) δ 8.06 (d, J = 7.7 Hz, 4H), 7.75 (t, J = 7.4 Hz, 2H), 7.69 (t,
J = 7.6 Hz, 4H), 6.51 (t, J = 53.7 Hz, 1H), 4.95 (t, J = 15.3 Hz, 2H). 19F NMR (376
MHz, CDCl3) δ -78.5 (s, 3F), -114.2 (dt, J = 53.8 Hz, J = 15.0 Hz, 2F). 13C NMR (126
MHz, CDCl3) δ 135.0 (s), 131.7 (s), 130.6 (s), 124.4 (s), 120.7 (q, J = 320.0 Hz), 111.6
(t, J = 244.8 Hz), 47.4 (t, J = 23.6 Hz).
4.2.3. Diphenyl(2-fluoroethyl)sulfonium trifluoromethanesulfonate (3ac). Light grey
solid, 192.5 mg from 0.900 mmol of 1a and 0.600 mmol of 2c, 0.504 mmol, 84% yield.
1H NMR (500 MHz, CDCl3) δ 8.04 (d, J = 7.1 Hz, 4H), 7.74 (t, J = 7.3 Hz, 2H), 7.69 (t,
J = 7.0 Hz, 4H), 4.86 (d, J = 46.7 Hz, 2H), 4.72 (d, J = 23.7 Hz, 2H). 19F NMR (471
MHz, CDCl3) δ -78.4 (s, 3F), -218.5 (m, 1F). 13C NMR (100 MHz, CDCl3) δ 135.0 (s),
131.7 (s), 130.9 (s), 123.6 (s), 120.7 (q, J = 320.0 Hz), 77.5 (d, J = 173.4 Hz), 46.3 (d, J
= 18.1 Hz).
4.2.4. Diphenyl(2,2,3,3,3-pentafluoropropyl)sulfonium trifluoromethanesulfonate
(3ad). White solid, 13.1 mg from 2.00 mmol of 1a and 0.400 mmol of 2d, 0.028 mmol,
7% yield. 1H NMR (500 MHz, CDCl3) δ 8.21 (d, J = 8.1 Hz, 4H), 7.77 (t, J = 7.4 Hz,
2H), 7.71 (t, J = 7.6 Hz, 4H), 5.31 (t, J = 15.1 Hz, 2H). 19F NMR (471 MHz, CDCl3) δ
-78.6 (s, 3F), -84.0 (s, 3F), -111.4 (t, J = 15.1 Hz, 2F). 13C NMR (126 MHz, CDCl3) δ
135.5 (s), 131.8 (s), 131.0 (s), 123.7 (s), 120.6 (q, J = 319.9 Hz), 44.9 (t, J = 21.8 Hz).
4.2.5. (4-Methoxyphenyl)(phenyl)(2,2,2-trifluoroethyl)sulfonium
trifluoromethanesulfonate (3ba). Brown oil, 113.4 mg from 4.00 mmol of 1b and 0.800
mmol of 2a, 0.253 mmol, 32% yield. 1H NMR (400 MHz, CDCl3) δ 8.13-8.11 (m, 4H),
7.77-7.67 (m, 3H), 7.17 (d, J = 9.3 Hz, 2H), 5.25 (q, J = 8.3 Hz, 2H), 3.88 (s, 3H). 19F
NMR (376 MHz, CDCl3) δ -60.8 (t, J = 8.6 Hz, 3F), -78.5 (s, 3F). 13C NMR (126 MHz,
CDCl3) δ 165.4 (s), 135.1 (s), 133.5 (s), 131.7 (s), 130.5 (s), 124.5 (s), 121.8 (q, J =
278.4 Hz), 120.7 (q, J = 318.5 Hz), 117.4 (s), 111.9 (s), 56.1 (s), 46.6 (q, J = 34.2 Hz).
IR (KBr): 3099, 2992, 2936, 2848, 1591, 1575, 1499, 1448, 1419, 1332, 1312, 1268,
1160, 1095, 1081, 1029, 999, 834, 750, 684, 639, 518 cm-1. ESI-MS (m/z): 298.9
([M]+). Anal. Calcd for C16H14F6O4S2: C, 42.86; H, 3.15; Found: C, 43.18; H, 3.44.
4.2.6. (2,2-Difluoroethyl)(4-methoxyphenyl)(phenyl)sulfonium
trifluoromethanesulfonate (3bb). Brown oil, 306.3 mg from 2.10 mmol of 1b and 0.700
mmol of 2b, > 99% yield. 1H NMR (500 MHz, CDCl3) δ 7.97 (d, J = 7.7 Hz, 4H), 7.64
8

(t, J = 7.3 Hz, 1H), 7.59 (t, J = 7.4 Hz, 2H), 7.08 (d, J = 8.3 Hz, 2H), 6.42 (t, J = 53.6 Hz,
1H), 4.76 (t, J = 14.9 Hz, 2H), 3.79 (s, 3H). 19F NMR (376 MHz, CDCl3) δ, -78.4 (s,
3F), -114.6 (dt, J = 53.5 Hz, J = 16.3 Hz, 2F). 13C NMR (126 MHz, CDCl3) δ 164.9 (s),
134.7 (s), 133.0 (s), 131.5 (s), 130.0 (s), 125.4 (s), 120.7 (q, J = 318.5 Hz), 117.2 (s),
113.0 (s), 111.7 (t, J = 245.9 Hz), 56.0 (s), 47.7 (t, J = 23.8 Hz). IR (KBr): 3516, 3099,
3065, 2997, 2945, 2847, 1591, 1499, 1463, 1448, 1418, 1371, 1259, 1163, 1111, 1081,
1030, 999, 944, 835, 800, 750, 684, 639, 574, 518 cm-1. ESI-MS (m/z): 281.0 ([M]+).
Anal. Calcd for C16H15F5O4S2•0.5H2O: C, 43.73; H, 3.67; Found: C, 43.77; H, 3.99.
4.2.7. (2-Fluoroethyl)(4-methoxyphenyl)(phenyl)sulfonium trifluoromethanesulfonate
(3bc). Brown oil, 1211.6 mg from 3.00 mmol of 1b and 6.00 mmol of 2c, 2.94 mmol,
98% yield. 1H NMR (500 MHz, CD3COCD3) δ 8.04 (d, J = 7.8 Hz, 4H), 7.75-7.70 (m,
3H), 7.20 (d, J = 8.4 Hz, 2H), 4.90 (dd, J = 32.4 Hz, J = 14.2 Hz, 2H), 4.63 (d, J = 23.5
Hz, 2H), 3.89 (s, 3H). 19F NMR ( 471 MHz, CD3COCD3) δ -78.5 (s, 3F), -218.9 (m,
1F). 13C NMR (126 MHz, CDCl3) δ 164.8 (s), 134.5 (s), 133.1 (s), 131.4 (s), 130.1 (s),
124.9 (s), 120.5 (q, J = 321.1 Hz), 117.1 (s), 112.4 (s), 77.4 (d, J = 173.2 Hz), 55.9 (s),
46.1 (d, J = 18.8 Hz). IR (KBr): 3492, 3098, 2995, 2947, 2847, 1591, 1575, 1499, 1465,
1447, 1418, 1267, 1225, 1163, 1063, 1030, 835, 754, 685, 639, 574, 518 cm-1. ESI-MS
(m/z): 263.0 ([M]+). Anal. Calcd for C16H16F4O4S2•2H2O: C, 42.85, H, 4.50; Found: C,
42.97; H, 4.38.
4.2.8. (4-Chlorophenyl)(2,2-difluoroethyl)(phenyl)sulfonium
trifluoromethanesulfonate (3cb). Brown oil, 288.3 mg from 3.00 mmol of 1c and 1.00
mmol of 2b, 0.664 mmol, 66% yield. 1H NMR (400 MHz, CDCl3) δ 8.06-8.04 (m, 4H),
7.75-7.60 (m, 5H), 6.48 (tt, J = 53.6 Hz, J = 2.8 Hz, 1H), 4.93 (m, 2H). 19F NMR (376
MHz, CDCl3) δ -78.5 (s, 3F), -114.2 (dt, J = 54.0 Hz, J = 15.0 Hz, 2F). 13C NMR (126
MHz, CD3COCD3) δ 141.0 (s), 135.1 (s), 132.7 (s), 131.6 (s), 131.6 (s), 130.9 (s), 124.8
(s), 123.9 (s), 121.2 (q, J = 320.2 Hz), 112.5 (t, J = 242.6 Hz), 46.5 (t, J = 23.9 Hz). IR
(KBr): 3505, 3094, 3002, 2944, 1634, 1572, 1480, 1449, 1399, 1371, 1259, 1168, 1096,
1030, 1010, 944, 827, 745, 683, 640, 575, 517 cm-1. ESI-MS (m/z): 285.0 ([M]+). Anal.
Calcd for C15H12ClF5O3S2•3H2O: C, 36.85; H, 3.71; Found: C, 36.74; H, 3.60.
4.2.9. (4-Chlorophenyl)(2-fluoroethyl)(phenyl)sulfonium trifluoromethanesulfonate
(3cc). The product derived from 2.00 mmol of 1c and 4.00 mmol of 2c was decolored
by activated charcoal in CH2Cl2 refluxing for 0.5 h to give 770.4 mg of 3cc as a light
yellow oil, 1.85 mmol, 93% yield. 1H NMR (500 MHz, CD3COCD3) δ 8.24 (t, J = 9.5
Hz, 4H), 7.86 (d, J = 7.4 Hz, 2H), 7.81 (d, J = 7.6 Hz, 3H), 5.07 (d, J = 46.9 Hz, 2H),
4.93 (d, J = 23.5 Hz, 2H). 19F NMR (471 MHz, CD3COCD3) δ -78.9 (s, 3F), -219.4 (m,
1F). 13C NMR (126 MHz, CD3COCD3) δ 140.8 (s), 134.9 (s), 132.7 (s), 131.5 (s), 131.5
(s), 130.9 (s), 124.7 (s), 123.8 (s), 121.1 (q, J = 321.4 Hz), 78.1 (d, J = 170.5 Hz), 45.8
(d, J = 18.8 Hz). IR (KBr): 3491, 3093, 2989, 2934, 1573, 1480, 1448, 1398, 1256,
1226, 1165, 1096, 1063, 1029, 1010, 826, 745, 684, 639, 516 cm-1. HRMS-ESI Calcd
for [C14H13ClFS+] (M+): 267.0405; Found: 267.0406.
4.2.10. (2-Fluoroethyl)(4-nitrophenyl)(phenyl)sulfonium trifluoromethanesulfonate
(3dc). Brown oil, 730.0 mg from 3.00 mmol of 1d and 6.00 mmol of 2c, 1.71 mmol,
57% yield. 1H NMR (500 MHz, CD3COCD3) δ 8.54 (q, 4H), 8.28 (d, J = 7.6 Hz, 2H),
7.92 (t, J = 6.8 Hz, 1H), 7.83 (t, J = 6.8 Hz, 2H), 5.21-5.09 (m, 2H), 5.04 (m, 2H). 19F
9

NMR (471 MHz, CD3COCD3) δ -79.0 (s, 3F), -219.1 (m, 1F). 13C NMR (126 MHz,
CD3COCD3) δ 153.7 (s), 151.2 (s), 135.3 (s), 132.4 (s), 131.7 (s), 131.6 (s), 125.8 (s),
123.7 (s), 121.2 (q, J = 320.5 Hz), 78.2 (d, J = 172.2 Hz), 46.1 (d, J = 18.6 Hz). IR
(KBr): 3491, 3106, 2925, 1533, 1479, 1448, 1348, 1256, 1225, 1162, 1062, 1029, 854,
755, 741, 727, 638 cm-1. HRMS-ESI Calcd for [C14H13FNO2S+] ([M]+): 278.0646;
Found: 278.0646.
4.2.11. 5-(2,2-Difluoroethyl)-5H-dibenzo[b,d]thiophen-5-ium
trifluoromethanesulfonate (3eb). Gray solid, 300.7 mg from 10.0 mmol of 1e and 5.00
mmol of 2b, 0.756 mmol, 15% yield. M.p. 120-122 oC. 1H NMR (500 MHz,
CD3COCD3) δ 8.55 (d, J = 7.3 Hz, 2H), 8.49 (d, J = 6.3 Hz, 2H), 8.03 (s, 2H), 7.87 (s,
2H), 6.56 (t, J = 53.2 Hz, 1H), 4.77 (t, J = 14.9 Hz, 2H). 19F NMR (471 MHz,
CD3COCD3) δ -78.9 (s, 3F), -114.6 (dt, J = 54.0 Hz, J = 16.4 Hz, 2F). 13C NMR (126
MHz, CD3COCD3) δ 140.1 (s), 134.5 (s), 131.3 (s), 128.9 (s), 128.3 (s), 124.5 (s), 120.7
(q, J = 321.1 Hz), 112.5 (t, J = 243.8 Hz), 50.2 (t, J = 25.4 Hz). IR (KBr): 3049, 2924,
2853, 1723, 1445, 1427, 1251, 1229, 1169, 1068, 1031, 742, 734, 709, 638, 576, 517
cm-1. HRMS-ESI Calcd for [C14H11F2S+] (M+): 249.0544; Found: 249.0544.
4.2.12. 5-(2-Fluoroethyl)-5H-dibenzo[b,d]thiophen-5-ium trifluoromethanesulfonate
(3ec). White solid, 578.1 mg from 2.50 mmol of 1e and 5.00 mmol of 2c, 1.52 mmol,
61% yield. 1H NMR (500 MHz, CD3COCD3) δ 8.53 (d, J = 8.0 Hz, 2H), 8.45 (d, J = 7.5
Hz, 2H), 8.00 (t, J = 7.4 Hz, 2H), 7.85 (t, J = 7.6 Hz, 2H), 4.86 (d, J = 45.8 Hz, 2H), 4.62
(d, J = 25.2 Hz, 2H). 19F NMR (471 MHz, CD3COCD3) δ -78.9 (s, 3F), -217.9 (m, 1F).
13C NMR (126 MHz, CD3COCD3) δ 140.2 (s), 134.1 (s), 131.1 (s), 128.8 (s), 128.6 (s),
124.3 (s), 122.3 (q, J = 321.0 Hz), 78.1 (d, J = 168.9 Hz), 50.7 (d, J = 19.4 Hz). IR
(KBr): 3491, 3051, 2925, 2839, 1719, 1450, 1427, 1249, 1228, 1172, 1030, 743, 704,
639, 576, 517 cm-1. HRMS-ESI Calcd for [C14H12FS+] (M+): 231.0638; Found:
231.0639.
4.2.13. Tributylsulfonium trifluoromethanesulfonate (6a). White solid, 77.5 mg from
2.00 mmol of 4a and 0.400 mmol of 2a, 0.220 mmol, 55% yield; 204.4 mg from 1.80
mmol of 4a and 0.600 mmol of 2b, 0.581 mmol, 97% yield. 1H NMR (400 MHz,
CDCl3) δ 3.38 (t, J = 7.8 Hz, 6H), 1.76 (m, 6H), 1.51 (m, 6H), 0.98 (t, J = 7.3 Hz, 9H).
19F NMR (376 MHz, CDCl3) δ -78.4 (s, 3F). 13C NMR (126 MHz, CDCl3) δ 120.7 (q, J
= 321.1Hz), 39.9 (s), 26.6 (s), 21.7 (s), 13.3 (s).
4.2.14. Dibutyl(2,2-difluoroethyl)sulfonium trifluoromethanesulfonate (5ab). Colorless
oil, 197.0 mg from 1.80 mmol of 4a and 0.600 mmol of 2b, 0.547 mmol, 91% yield. 1H
NMR (400 MHz, CDCl3) δ 6.41 (tt, J = 54.1 Hz, J = 2.8 Hz, 1H), 4.02 (td, J = 16.7 Hz,
J = 2.8 Hz, 2H), 3.51 (t, J = 8.0 Hz, 4H), 1.80 (m, 4H), 1.50 (m, 4H), 0.96 (t, J = 7.4 Hz,
6H). 19F NMR (376 MHz, CDCl3) δ -78.7 (s, 3F), -114.5 (dt, J = 54.6 Hz, J = 16.8 Hz,
2F). 13C NMR (126 MHz, CDCl3) δ 120.7 (q, J = 320.9 Hz), 111.9 (t, J = 242.8 Hz),
42.6 (t, J = 23.5 Hz), 45.1 (s), 26.3 (s), 21.4 (s), 13.1 (s). IR (KBr): 3501, 2968, 2940,
2880, 1645, 1468, 1418, 1375, 1259, 1227, 1166, 1070, 1031, 757, 639, 574, 518 cm-1.
ESI-MS (m/z): 211.1 ([M]+). Anal. Calcd for C11H21F5O3S2•0.5H2O: C, 35.77; H, 6.00;
Found: C, 35.87; H, 5.80.
4.2.15. Dibutyl(2-fluoroethyl)sulfonium trifluoromethanesulfonate (5ac). Brown oil,
201.6 mg from 1.80 mmol of 4a and 0.600 mmol of 2c, 0.589 mmol, 98% yield. 1H
10

NMR (400 MHz, CD3SOCD3) δ 4.94 (dt, J = 46.8 Hz, J = 4.7 Hz, 2H), 3.82 (dt, J = 27.0
Hz, J = 5.0 Hz, 2H), 3.41 (t, J = 7.8 Hz, 4H), 1.72 (m, 4H), 1.42 (m, 4H), 0.93 (t, J = 7.4
Hz, 6H). 19F NMR (471 MHz, CD3SOCD3) δ -77.8 (s, 3F), -216.6 (m, 1F). 13C NMR
(126 MHz, CD3COCD3) δ 120.7 (q, J = 320.9 Hz), 78.7 (d, J = 169.6 Hz), 40.3 (d, J =
16.9 Hz), 39.9 (s), 26.0 (s), 21.4 (s), 12.7 (s). IR (KBr): 3529, 2965, 2934, 2877, 1723,
1468, 1260, 1225, 1160, 1061, 1030, 756, 638 cm-1. ESI-MS (m/z): 193.1 ([M]+). Anal.
Calcd for C11H22F4O3S2•H2O: C, 36.66; H, 6.71; Found: C, 36.21; H, 6.41.
4.2.16. Triallylsulfonium trifluoromethanesulfonate (6b). Light yellow oil, 52.3 mg
from 2.00 mmol of 4b and 0.400 mmol of 2a, 0.172 mmol, 43% yield; 902.8 mg from
9.00 mmol of 4b and 3.00 mmol of 2b, 2.97 mmol, 99% yield; 278.9 mg from 3.00
mmol of 4b and 1.00 mmol of 2c, 0.917 mmol, 92% yield. 1H NMR (400 MHz, CDCl3)
δ 5.92 – 5.81 (m, 3H), 5.68 (dd, J = 28.9 Hz, J = 10.0 Hz, 6H), 4.08 (d, J = 7.2 Hz, 6H).
19F NMR (471 MHz, CDCl3) δ -78.4 (s, 3F). 13C NMR (126 MHz, CDCl3) δ 128.1 (s),
123.7 (s), 120.6 (q, J = 320.0 Hz), 41.5 (s). IR (KBr): 3504, 2984, 2934, 1638, 1428,
1406, 1260, 1227, 1167, 1031, 992, 951, 759, 740, 640, 575, 518 cm-1. ESI-MS (m/z):
155.1 ([M]+). Anal. Calcd for C10H15F3O3S2•0.5H2O: C, 38.33; H, 5.15; Found: C,
38.47; H, 5.07.
4.2.17. Diallyl(2-fluoroethyl)sulfonium trifluoromethanesulfonate (5bc). Brown oil,
638.2 mg from 2.00 mmol of 4b and 4.00 mmol of 2c, > 99% yield. 1H NMR (500
MHz, CD3COCD3) δ 6.11-6.05 (m, 2H), 5.78 (d, J = 16.9 Hz, 2H), 5.67 (d, J = 10.0 Hz,
2H), 5.05 (d, J = 47.1 Hz, 2H), 4.34 (d, J = 6.8 Hz, 4H), 3.88 (d, J = 25.8 Hz, 2H). 19F
NMR (471 MHz, CD3COCD3) δ -79.0 (s, 3F), -218.2 (m, 1F). 13C NMR (126 MHz,
CD3COCD3) δ 127.4 (s), 124.4 (s), 120.0 (q, J = 287.2 Hz), 78.6 (d, J = 169.3 Hz), 42.2
(s), 39.1 (d, J = 20.0 Hz). IR (KBr): 3508, 2988, 2939, 1639, 1470, 1429, 1406, 1260,
1226, 1166, 1061, 1031, 994, 956, 759, 740, 640, 575, 518 cm-1. ESI-MS (m/z): 161.1
([M]+). Anal. Calcd for C9H14F4O3S2•1.5H2O: C, 32.04; H, 5.08; Found: C, 32.07; H,
4.75.
4.2.18. Triethylsulfonium trifluoromethanesulfonate (6c). Light yellow oil, 28.9 mg
from 2.00 mmol of 4c and 0.400 mmol of 2a, 0.108 mmol, 27% yield. 1H NMR (400
MHz, CDCl3) δ 3.42 (q, J = 7.5 Hz, 6H), 1.51 (t, J = 7.5 Hz, 9H). 19F NMR (376 MHz,
CDCl3) δ -78.5 (s, 3F). 13C NMR (126 MHz, CDCl3) δ 120.6 (q, J = 320.3 Hz), 33.3 (s),
9.2 (s). IR (KBr): 3501, 2986, 2921, 2850, 1633, 1457, 1425, 1392, 1259, 1227, 1167,
1084, 1031, 978, 760, 640, 576, 518 cm-1. ESI-MS (m/z): 387.1 ({[Et3S]2[OTf]}+).
Anal. Calcd for C7H15F3O3S2•0.5H2O: C, 30.32; H, 5.82; Found: C, 30.31; H, 5.88.
4.2.19. Diethyl(2-fluoroethyl)sulfonium trifluoromethanesulfonate (5cc). Dark brown
oil, 169.6 mg from 1.80 mmol of 4c and 0.600 mmol of 2c, 0.593 mmol, 99% yield. 1H
NMR (400 MHz, CD3SOCD3) δ 4.93 (dt, J = 46.5 Hz, J = 5.0 Hz, 2H), 3.77 (dt, J = 27.1
Hz, J = 5.0 Hz, 2H), 3.41 (q, J = 7.4 Hz, 4H), 1.36 (t, J = 7.4 Hz, 6H). 19F NMR (471
MHz, CD3SOCD3) δ -77.8 (s, 3F), -216.6 (m, 1F). 13C NMR (126 MHz, CD3SOCD3) δ
121.2 (q, J = 322.5 Hz), 79.0 (d, J = 167.2 Hz), 38.9 (d, J = 19.7 Hz), 33.8 (s), 9.0 (s). IR
(KBr): 3502, 2985, 2922, 2850, 1645, 1457, 1425, 1393, 1257, 1226, 1161, 1084, 1031,
976, 758, 639, 574, 518 cm-1. ESI-MS (m/z): 137.1 ([M]+). Anal. Calcd for
C7H14F4O3S2•H2O: C, 27.63; H, 5.30; Found: C, 27.78; H, 5.30.
11

4.2.20. Dimethyl(phenyl)sulfonium trifluoromethanesulfonate (6d). White solid, 31.1
mg from 2.00 mmol of 4d and 0.400 mmol of 2a, 0.108 mmol, 27% yield; 169.3 mg
from 1.80 mmol of 4d and 0.600 mmol of 2b, 0.588 mmol, 98% yield. 1H NMR (400
MHz, CDCl3) δ 8.00 (d, J = 8.0 Hz, 2H), 7.77 (t, J = 7.4 Hz, 1H), 7.70 (t, J = 7.4 Hz,
2H), 3.40 (s, 6H). 19F NMR (471 MHz, CDCl3) δ -78.4 (s, 3F). 13C NMR (126 MHz,
CD3SOCD3) δ 133.6 (s), 130.3(s), 129.7 (s), 126.6 (s), 120.6 (q, J = 320.8 Hz), 28.1 (s).
4.2.21. (2-Fluoroethyl)(methyl)(phenyl)sulfonium trifluoromethanesulfonate (5dc).
Brown oil, 310.0 mg from 1.00 mmol of 4d and 2.00 mmol of 2c, 1.00 mmol, 97%
yield. 1H NMR (500 MHz, CD3COCD3) δ 7.69 (d, J = 7.2 Hz, 2H), 7.36 (t, J = 6.2 Hz,
1H), 7.27 (t, J = 7.4 Hz, 2H), 4.53 (dm, J = 46.1 Hz, 1H), 4.33 (dm, J = 46.7 Hz, 1H),
3.92-3.73 (m, 2H), 3.09 (s, 3H). 19F NMR (471 MHz, CD3COCD3) δ -78.9 (s, 3F),
-219.8 (m, 1F). 13C NMR (126 MHz, CD3COCD3) δ 134.8 (s), 131.1 (s), 130.9 (s),
123.7 (s), 121.2 (q, J = 320.5 Hz), 77.7 (d, J = 169.4 Hz), 46.8 (d, J = 19.0 Hz), 26.5 (s).
IR (KBr): 3051, 2925, 2852, 1715, 1449, 1256, 1225, 1159, 1068, 1029, 751, 685, 637,
516 cm-1. ESI-MS (m/z): 171.0 ([M]+). Anal. Calcd for C10H12F4O3S2•2H2O: C 33.71,
H 4.53; Found: C, 33.69; H, 4.61.
4.2.22. Diethyl(phenyl)sulfonium trifluoromethanesulfonate (6e). Light yellow oil, 8.9
mg from 2.00 mmol of 4e and 0.400 mmol of 2a, 0.028 mmol, 7% yield; 203.7 mg from
1.80 mmol of 4e and 0.600 mmol of 2b, > 99% yield). 1H NMR (400 MHz, CDCl3) δ
7.95 (d, J = 7.6 Hz, 2H), 7.76 (t, J = 7.5 Hz, 1H), 7.68 (t, J = 8.5 Hz, 2H), 3.88-3.70 (dm,
J = 34.5 Hz, 4H), 1.29 (t, J = 7.4 Hz, 6H). 19F NMR (376 MHz, CDCl3) δ -78.4 (s, 3F).
13C NMR (100 MHz, CDCl3) δ 135.1 (s), 131.6 (s), 131.5 (s), 120.7 (q, J = 320.7 Hz),
120.1 (s), 38.9 (s), 9.4 (s). IR (KBr): 3511, 3064, 2965, 2937, 2877, 1629, 1582, 1467,
1448, 1425, 1386, 1252, 1226, 1163, 1031, 1000, 927, 756, 688, 639, 574, 518 cm-1.
ESI-MS (m/z): 167.1 ([M]+). Anal. Calcd for C11H15F3O3S2•1.5H2O: C, 38.48; H, 5.28;
Found: C, 38.48; H, 5.17.
4.2.23. Ethyl(2-fluoroethyl)(phenyl)sulfonium trifluoromethanesulfonate (5ec). The
product derived from 1.00 mmol of 4e and 2.00 mmol of 2c was decolored by activated
charcoal in CH2Cl2 refluxing for 0.5 h to give 325.0 mg of 5ec as a light yellow oil,
0.973 mmol, 97% yield. 1H NMR (500 MHz, CD3COCD3) δ 8.21 (d, J = 6.2 Hz, 2H),
7.92 (t, J = 8.2 Hz, 1H), 7.82 (t, J = 7.2 Hz, 2H), 5.08 (dm, J = 46.6 Hz, 1H), 4.85 (dm,
J = 46.6 Hz, 1H), 4.40 (m, 2H), 4.06 (m, 2H),1.41 (t, J = 6.3 Hz, 3H). 19F NMR (471
MHz, CD3COCD3) δ -78.9 (s, 3F), -219.3 (m, 1F). 13C NMR (126 MHz, CD3COCD3) δ
135.1 (s), 131.8 (s), 131.3 (s), 121.3 (q, J = 321.4 Hz), 121.2 (s), 78.3 (d, J = 169.8 Hz),
44.7 (d, J = 19.2 Hz), 39.5 (s), 8.8 (s). IR (KBr): 2921, 2849, 1712, 1449, 1254, 1225,
1163, 1029, 751, 685, 638 cm-1. HRMS-ESI Calcd for [C10H14FS+] (M+): 185.0795;
Found: 185.0795.
4.2.24. Dibutyl(phenyl)sulfonium trifluoromethanesulfonate (6f). Light yellow oil, 17.5
mg from 2.00 mmol of 4f and 0.400 mmol of 2a, 0.047 mmol, 12% yield; 226.1 mg
from 1.80 mmol of 4f and 0.600 mmol of 2b, > 99% yield. 1H NMR (400 MHz, CDCl3)
δ 7.98 (d, J = 7.5 Hz, 2H), 7.76 (t, J = 7.6 Hz, 1H), 7.69 (t, J = 7.8 Hz, 2H), 3.78 (m,
4H), 1.66-1.36 (m, 8H), 0.85 (t, J = 7.2 Hz, 6H). 19F NMR (376 MHz, CDCl3) δ -78.4
(s, 3F).13C NMR (100 MHz, CDCl3) δ 134.9 (s), 131.4 (s), 131.4 (s), 120.7(s), 120.6 (q,
J = 320.5 Hz), 43.7 (s), 26.3 (s), 21.0 (s), 13.1 (s). IR (KBr): 3502, 2983, 2921, 2849,
12

1645, 1449, 1386, 1259, 1226, 1160, 1084, 1030, 753, 688, 638, 574, 518 cm-1.
ESI-MS (m/z): 223.1 ([M]+). Anal. Calcd for C15H23F3O3S2•0.5H2O: C, 47.23; H, 6.34;
Found: C, 46.75; H, 6.16.
4.2.25. Butyl(2-fluoroethyl)(phenyl)sulfonium trifluoromethanesulfonate (5fc). Dark
brown oil, 356.7 mg from 1.00 mmol of 4f and 2.00 mmol of 2c, 0.985 mmol, 99%
yield. 1H NMR (500 MHz, CD3COCD3) δ 8.23 (d, J = 7.5 Hz, 2H), 7.91 (t, J = 6.9 Hz,
1H), 7.81 (t, J = 7.4 Hz,2H), 5.06 (dm, J = 45.5 Hz, 1H), 4.82 (dm, J = 47.4 Hz, 1H),
4.39 (m, 2H), 4.04 (t, J = 7.4 Hz, 2H), 1.70 (tm, J = 27.3 Hz, 2H), 1.50 (m, 2H), 0.89 (t,
J = 6.7 Hz, 3H). 19F NMR (471 MHz, CD3COCD3) δ -78.9 (s, 3F), -219.4 (m, 1F). 13C
NMR (126 MHz, CD3COCD3) δ 135.1 (s), 131.8 (s), 131.3 (s), 121.4 (s), 121.2 (q, J =
321.9 Hz), 78.3 (d, J = 169.7 Hz), 45.2 (d, J = 19.0 Hz), 44.0 (s), 26.2 (s), 21.0 (s), 12.7
(s). IR (KBr): 3492, 2967, 2926, 2875, 1645, 1468, 1449, 1389, 1257, 1225, 1162,
1062, 1030, 754, 686, 638, 518 cm-1. ESI-MS (m/z): 213.0 ([M]+). Anal. Calcd for
C13H18F4O3S2•2.5H2O: C, 38.32; H, 5.69; Found: C, 37.94; H, 5.18.
4.2.26. 1-(4-((2,2,2-Trifluoroethyl)thio)butyl)tetrahydro-1H-thiophen-1-ium
trifluoromethanesulfonate (6ga). Colorless oil, 160.0 mg from 2.00 mmol of 4g and
0.400 mmol of 2b, 0.392 mmol, 98% yield. 1H NMR (500 MHz, CDCl3) δ 3.70-3.63
(m, 2H), 3.50-3.44 (m, 2H), 3.33 (t, J = 7.8 Hz, 2H), 3.11 (q, J = 9.9 Hz, 2H), 2.75 (t, J
= 7.0 Hz, 2H), 2.48-2.32 (dm, J = 48.7 Hz, 4H), 1.95-1.76 (dm, J = 52.8 Hz, 4H). 19F
NMR (471 MHz, CDCl3) δ -66.4 (t, J = 9.8 Hz, 3F), -78.4 (s, 3F). 13C NMR (126 MHz,
CDCl3) δ 124.4 (q, J = 275.6 Hz), 122.0 (q, J = 320.4 Hz), 43.5 (s), 41.8 (s), 34.2 (q, J =
33.2 Hz), 32.1 (s), 28.6 (s), 27.2 (s), 24.0 (s). IR (KBr): 3052, 2942, 2860, 1645, 1417,
1259, 1225, 1159, 1116, 1030, 757, 638, 574, 518 cm-1. ESI-MS (m/z): 259.0 ([M]+).
Anal. Calcd for C11H18F6O3S3•H2O: C, 30.98; H, 4.73; Found: C, 30.97; H, 4.57.
4.2.27. 1-(2-Fluoroethyl)tetrahydro-1H-thiophen-1-ium trifluoromethanesulfonate
(5gc). Dark brown oil, 169.5 mg from 0.500 mmol of 4g and 1.00 mmol of 2c, > 99%
yield. 1H NMR (400 MHz, CD3COCD3) δ 4.95 (t, J = 5.2 Hz, 1H), 4.84 (t, J = 4.8 Hz,
1H), 3.68 (t, J = 5.2 Hz, 1H), 3.61 (t, J = 5.0 Hz,1H), 3.58-3.43 (dm, J = 21.8 Hz, 4H),
2.28-2.11 (m, 4H). 19F NMR (471 MHz, CD3COCD3) δ -77.8 (s, 3F), -218.2 (m, 1F).
13C NMR (126 MHz, CD3COCD3) δ 121.4 (q, J = 325.6Hz), 79.2 (d, J = 167.2 Hz),
44.2 (s), 42.9 (d, J = 19.0 Hz), 28.5 (s). IR (KBr): 3048, 2950, 1755, 1429, 1402, 1256,
1226, 1163, 1029, 952, 638, 516 cm-1. ESI-MS (m/z): 135.0 ([M]+). Anal. Calcd for
C7H12F4O3S2•3H2O: C, 24.85; H, 5.36; Found: C, 25.16; H, 4.95.
4.2.28. Triisopropylsulfonium trifluoromethanesulfonate (6h). Light brown oil, 95.7
mg from 5.00 mmol of 4h and 1.00 mmol of 2a, 0.31 mmol, 31% yield; 269.0 mg from
3.00 mmol of 4h and 1.00 mmol of 2b, 0.87 mmol, 87% yield. 1H NMR (500 MHz,
CD3COCD3) δ 4.16 (m, 3H), 1.68 (d, J = 5.7 Hz, 18H). 19F NMR (471 MHz,
CD3COCD3) δ -79.0 (s, 3F). 13C NMR (126 MHz, CDCl3) δ 120.7 (q, J = 319.4 Hz),
43.3 (s), 20.0 (s). IR (KBr): 2987, 2947, 2876, 1647, 1466, 1397, 1383, 1283, 1249,
1168, 1030, 941, 876, 761, 640, 575 cm-1. HRMS-ESI Calcd for [C9H21S+] (M+):
161.1358; Found: 161.1351.
4.2.29. (2,2-Difluoroethyl)diisopropylsulfonium trifluoromethanesulfonate (5hb).
White solid, 275.0 mg from 3.00 mmol of 4h and 1.00 mmol of 2b (at 60 oC for 8 h),
0.83 mmol, 83% yield; 98.9 mg from 3.00 mmol of 4h and 1.00 mmol of 2b (at r.t. for
13

24 h), 0.30 mmol, 30% yield. 1H NMR (500 MHz, CDCl3) δ 6.44 (t, J = 54.2 Hz, 1H),
4.05 (m, 2H), 3.99 (t, J = 17.9 Hz, 2H), 1.59 (s, 12H). 19F NMR (471 MHz, CDCl3) δ
-78.6 (s, 3F), -114.3 (dt, J = 54.2, 17.7 Hz, 2F). 13C NMR (126 MHz, CDCl3) δ 120.6
(q, J = 319.9 Hz), 111.1 (t, J = 242.9 Hz), 45.9 (s), 37.2 (t, J = 21.8 Hz), 18.8 (s), 17.6
(s). IR (KBr): 2997, 2950, 1635, 1466, 1400, 1382, 1259, 1160, 1030, 943, 874, 757,
639, 575 cm-1. HRMS-ESI Calcd for [C8H17F2S+] (M+): 183.1014; Found: 183.1005.
<ACK>Acknowledgements
We are grateful to Wuhan University of Technology, the Natural Science Foundation of
Hubei Province (China) (2015CFB176), the ‘‘Chutian Scholar’’ Program from the
Department of Education of Hubei Province (China), and the ``Hundred Talent'' Project
of Hubei Province for financial support.
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16

[13] CCDC 1497093, CCDC 1497096, and CCDC 1497098 contain the supplementary
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<Figure>Figure 1 ORTEP diagrams of 3aa (left), 3ab (middle), and 6d (right).
Ellipsoids are shown at the 50% probability level.
<Figure>Scheme 1 The SN2-type reactions between 4g and 2a or 2c
<Figure>Scheme 2 The solvent-free reactions of steric hindered 4h with 2a or 2b
<Table>Table 1 The solvent-free reactions between diaryl sulfides and 2a-d
Entry R1
R2
H
H
H
H
H
Molar ratio
Conditions
Yield (3, %)a
3aa, 61
CFnH2-nX
CF3
1
H
H
H
H
H
H
H
H
H
H
H
H
H
H
1a / 2a (5 : 1)
1a / 2b (3 : 1)
1a / 2b (1 : 3)
150 oC, 48 h
120 oC, 48 h
120 oC, 48 h
2
CF2H
3ab, 94
3ab, 84
3ac, 84
3
CF2H
4
CH2F
1a / 2c (1.5 : 1) 60 oC, 15 h
5
CF2CF3
1a / 2d (5 : 1)
1b / 2a (5 : 1)
1b / 2b (3 : 1)
1b / 2c (1 : 2)
1c / 2a (5 : 1)
1c / 2b (3 : 1)
1c / 2c (1 : 2)
1d / 2c (1 : 2)
1e / 2b (1 : 2)
1e / 2c (1 : 2)
150 oC, 72 h
150 oC, 48 h
120 oC, 48 h
60 oC, 15 h
150 oC, 48 h
120 oC, 48 h
80 oC, 15 h
80 oC, 15 h
120 oC, 48 h
100 oC, 15 h
3ad, 7
6
OCH3 CF3
OCH3 CF2H
OCH3 CH2F
3ba, 32
3bb, > 99
3bc, 98
7
8
9
Cl
Cl
Cl
NO2
H
CF3
complicated
10
11
12
13c
14c
CF2H
CH2F
CH2F
CF2H
CH2F
3cb, 66
3cc, 93b
3dc, 57
3eb, 15
H
3ec, 61
17

a Isolated yield. b The product was decolored by activated charcoal in CH2Cl2 refluxing
for 0.5 h. c Dibenzothiophene (1e) was used instead of diaryl sulfide.
<Table>Table 2. Selected bond lengths [Å] and angles [deg] for [Ph2SCH2CF3][OTf]
(3aa), [Ph2SCH2CF2H][OTf] (3ab), and [PhS(CH3)2][OTf] (6d).a
Atoms
Bond length (Å)
Atoms
Angles (deg)
[Ph2SCH2CF3][OTf] (3aa)
S1-C1
S1-C3
S1-C9
1.789(5)
C3-S1-C1
C9-S1-C1
C3-S1-C9
H(1A)-C1-H(1B)
F1-C2-F2
103.1(2)
104.8(2)
105.6(2)
107.9
1.779(4)
1.789(5)
C1-H(1A), C1-H(1B) 0.9700
F1-C2
F2-C2
F3-C2
1.310(6)
1.314(7)
1.320(7)
106.4(6)
107.8(5)
106.3(5)
F1-C2-F3
F2-C2-F3
[Ph2SCH2CF2H][OTf] (3ab)
S1-C1
S1-C3
S1-C9
1.805(3)
C9-S1-C1
104.01(13)
104.34(13)
103.71(13)
108.1
1.781(3)
1.772(3)
C3-S1-C1
C9-S1-C3
C1-H(1A), C1-H(1B) 0.9700
H(1A)-C1-H(1B)
F2-C2-H2
F1-C2-H2
F2-C2-F1
C2-H2
0.9800
109.9
F1-C2
1.341(3)
1.338(4)
109.9
F2-C2
105.8(3)
[PhS(CH3)2][OTf] (6d)
S1-C7
S1-C8
S1-C1
1.785(5)
1.775(5)
1.768(6)
C1-S1-C7
C1-S1-C8
C8-S1-C7
103.1(3)
104.4(3)
101.6(3)
C7-H(7B), C8-H(8B) 0.9600
a: Bond lengths are in angstroms. Angles are in degrees. Estimated standard deviations
are given in parentheses.
<Table>Table 3 The solvent-free reactions of dialkyl and alkylaryl sulfides with 2a-c
Entry R3
R4
Molar ratio
18
Conditions
Yield (5/6, %)a
CFnH3-n

1
C4H9 C4H9
C4H9 C4H9
C4H9 C4H9
C4H9 C4H9
C4H9 C4H9
CF3
4a / 2a (3 : 1) 100 oC, 24 h 6a, 55
4a / 2b (3 : 1) 100 oC, 24 h 6a, 97
2
CF2H
CF2H
CH2F
CH2F
CF3
3
4a / 2b (3 : 1) r.t., 24 h
4a / 2c (1 : 2) 60 oC, 15 h
4a / 2c (3 : 1) 60 oC, 15 h
5ab, 91
5ac, > 99
5ac, 98
4
5
6
allyl
allyl
allyl
allyl
allyl
allyl
allyl
allyl
4b / 2a (5 : 1) 100 oC, 24 h 6b, 43
7
CF2H
CH2F
CH2F
CF3
4b / 2b (3 : 1) 60 oC, 24 h
4b / 2c (3 : 1) 60 oC, 15 h
4b / 2c (1 : 2) r.t, 15 h
6b, 99
8
6b, 92
9
5bc, > 99
10
11b
12
13
14
15
16
17
18
19
20
21
C2H5 C2H5
C2H5 C2H5
C2H5 C2H5
C6H5 CH3
C6H5 CH3
C6H5 CH3
C6H5 C2H5
C6H5 C2H5
C6H5 C2H5
4c / 2a (5 : 1) 100 oC, 24 h 6c, 27
CF2H
CH2F
CF3
4c / 2b (3 : 1) 100 oC, 24 h 5cb, 34 / 6c, 65
4c / 2c (3 : 1) 60 oC, 15 h
4d / 2a (5 : 1) 100 oC, 24 h 6d, 21
5cc, 99
CF2H
CH2F
CF3
4d / 2b (3 : 1) 60 oC, 24 h
4d / 2c (1 : 2) 60 oC, 5 h
6d, 98
5dc, 97
4e / 2a (5 : 1) 120 oC, 24 h 6e, 7
4e / 2b (3 : 1) 100 oC, 24 h 6e, > 99
CF2H
CH2F
4e / 2c (1 : 2) 60 oC, 5 h
5ec, 97c
C6H5 n-C4H9 CF3
C6H5 n-C4H9 CF2H
C6H5 n-C4H9 CH2F
4f / 2a (5 : 1) 120 oC, 24 h 6f, 12
4f/ 2b (3 : 1)
4f / 2c (1 : 2) 60 oC, 5 h
100 oC, 8 h
6f, > 99
5fc, 99
a Isolated yield. b The molar ratio of 5cb and 6c was determined by NMR spectroscopy.
c The product was decolored by activated charcoal in CH2Cl2 refluxing for 0.5 h.
TDENDOFDOCTD
19