Addition of ArSSAr to carbon-carbon multiple bonds using electrochemistry

Article abstract of DOI:10.1016/j.tet.2010.02.049

ArS(ArSSAr)⁺ (arylbis(arylthio)sulfonium ions), which were generated and accumulated by the electrochemical oxidation of diaryl disulfides (ArSSAr) in CH₂Cl₂ at -78 °C, reacted with alkenes to give the corresponding diaryl

Full text of DOI:10.1016/j.tet.2010.02.049

Tetrahedron 66 (2010) 2823–2829
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Addition of ArSSAr to carbon–carbon multiple bonds using electrochemistry
y
*
Shunsuke Fujie, Kouichi Matsumoto, Seiji Suga , Toshiki Nokami, Jun-ichi Yoshida
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
a r t i c l e i n f o
a b s t r a c t
ArS(ArSSAr)þ (arylbis(arylthio)sulfonium ions), which were generated and accumulated by the electro-
chemical oxidation of diaryl disulfides (ArSSAr) in CH2Cl2 at ꢀ78 ꢁC, reacted with alkenes to give the
corresponding diarylthio-substituted compounds in a stereospecific manner in good yields, when the
reaction was quenched with a soft nucleophile, such as allylsilanes, ketene silyl acetals, and triethyl-
amine. A mechanism involving the initial formation of an episulfonium ion followed by ring-opening by
the attack of ArSSAr has been suggested. The reactions of ArS(ArSSAr)þ with alkynes also took place to
give 1,2-diorganothio-substitued alkenes stereoselectively under similar conditions.
Article history:
Received 13 January 2010
Received in revised form
10 February 2010
Accepted 10 February 2010
Available online 13 February 2010
Ó 2010 Published by Elsevier Ltd.
1. Introduction
Recently, we revealed that highly reactive arylbis(arylth-
io)sulfonium ions (ArS(ArSSAr)þ),7 which can be seen as ArSþ sta-
Organosulfur compounds have attracted a great deal of interest
in various research fields of chemistry, and a variety of methods for
their synthesis have been reported so far.1 Among them, the ad-
dition of diorgano disulfides to carbon–carbon multiple bonds
serves as a useful method. A stoichiometric or a catalytic amount of
acids, such as BF3–OEt2, GaCl3, AlCl3, and PhIO–OTf are effective to
drive this type of transformation.2
bilized by the interaction with ArSSAr, were generated and
accumulated by the electrochemical oxidation8 of ArSSAr in CH2Cl2
using Bu4NBF4 as supporting electrolyte at ꢀ78 ꢁC (Scheme 1 (a)),
and that these species served as electrophilic ‘ArSþ’ for reactions
with various nucleophiles.9
anodic oxidation
ArSþ are also effective as electrophilic reagents to introduce ArS
groups into carbon–carbon multiple bonds, although some doubts
have been advanced of their existence in this form in the solution
phase. The reactions of ‘ArSþ’ (ArSþ or their equivalents)3 with
carbon–carbon multiple bonds give rise to the formation of epis-
ulfonium ions or thiirenium ions intermediates,4 which undergo
ring-opening reaction by the action of quenching nucleophiles.
In addition to the chemical method, the electrochemical
method5 is also effective for generation of ‘ArSþ’.6 In fact, the
electrochemical oxidation of ArSSAr is the most straightforward
method for generating ‘ArSþ’. The radical cation of ArSSAr produced
by one electron oxidation of ArSSAr undergoes the cleavage of
sulfur–sulfur bond to give ArSþ and an ArSꢂ. ArSꢂ is further oxidized
to give ArSþ. Thus, the electrochemical generation, in principle,
does not produce any byproducts, and therefore is superior to the
chemical generation, which needs the use of toxic reagents and
produces byproducts derived from them.
(0.67 F/mol, -78 oC)
ArS SAr
SAr
(a)
(b)
ArSSAr
Bu4NBF4/CH2Cl2
quenching
ArS SAr
SAr
with a soft
R1
R2
R3
R4
R3
ArS
nucleophile
R1
R4
R2
SAr
quenching
with a soft
nucleophile
ArS SAr
SAr
ArS
R5
R6
(c) R5
R6
SAr
Scheme 1. Stereoselective addition of ArSSAr to carbon–carbon multiple bonds using
ArS(ArSSAr)þ
.
To the best of our knowledge, however, the addition of two ArS
groups by the action of ‘ArSþ’ to carbon–carbon multiple bonds has
not yet been reported so far. Herein, we report that the reactions of
electrochemically generated ArS(ArSSAr)þ with alkenes and al-
kynes led to stereoselective addition of ArSSAr to the carbon–car-
bon multiple bonds when a suitable nucleophile was used as
a quenching reagent (Scheme 1 (b) and (c)).
* Corresponding author. Tel.: þ81 75 383 2726; fax: þ81 75 383 2727.
E-mail address: yoshida@sbchem.kyoto-u.ac.jp (J. Yoshida).
Present address: Division of Chemistry and Biochemistry, Graduate School of
Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka,
Kita-ku, Okayama 700-8530, Japan
y
0040-4020/$ – see front matter Ó 2010 Published by Elsevier Ltd.
doi:10.1016/j.tet.2010.02.049

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S. Fujie et al. / Tetrahedron 66 (2010) 2823–2829
2. Results and discussion
silyl acetal 4, allylsilane 6, and triethylamine selectively attacks B to
cleave the S–S bond giving diarylthio-substituted compound D as
the final product (pathway II).
A solution of (ArS(ArSSAr)þ BF4ꢀ) (1) (Ar¼p-FC6H4) was gen-
erated by the anodic oxidation of ArSSAr (Ar¼p-FC6H4) in
Bu4NBF4/CH2Cl2 at ꢀ78 ꢁC (0.67 F/mol)10 according to the pro-
cedure reported previously (Scheme 1 (a)).9a First, we examined
reactions of 1 with 1-methylcyclohexene using various quench-
ing nucleophiles (Scheme 2). 1-Methylcyclohexene (1 equiv) was
added to the resulting solution of 1 at ꢀ78 ꢁC. Quenching of the
reaction with MeOH as a nucleophile afforded adduct 2 (Mar-
kovnikov product) in 68% yield. A MeO group was introduced on
the tertiary carbon, suggesting that MeOH attacked a partially
developed carbocationic center.11,12 It is also noteworthy that the
anti addition product was obtained exclusively. These observa-
tions are quite similar to those obtained for ‘ArSþ’ generated by
other methods in the absence of ArSSAr. The use of H2O as
a quenching nucleophile led to the formation of 3 in a similar
manner.
The existence of the equilibrium between A and B is supported
by the fact that the treatment of diarylthio-substituted product 5
with 1 followed by quenching with MeOH gave compound 2 ster-
eoselectively (Scheme 4). Presumably, the reaction of 5 with ArSþ
gave 14 (B). The ring-closing to episulfonium ion 15 (A) followed by
nucleophilic attack by MeOH gave 2.
The attack of a soft nucleophile on B is supported by the ex-
periment shown in Scheme 5. When (Z)-diphenylethene was
reacted with 1 and the resulting mixture was treated with a ketene
silyl acetal 4, ArS substituted ester 16 and ArSSAr addition product 9
were obtained in equal amounts.16
Table 1
Reactions of ArS(ArSSAr)þ (1) (Ar¼p-FC6H4) with Alkenesa
Alkene
Product
Yield (%)b
Quenching nucleophile
OMe
MeOH
4
6
Et3N
72c
ArS
SAr
SAr
2
68%
64
36
ArS SAr
SAr
(Ar = p-FC6H4)
OH
H2O
7
n-C6H13
SAr
79%
1
35
68
42
66c
84c
(1 equiv)
n-C6H13
3
OSiMe3
ArS
SAr
30 min, -78 oC
8
OMe
SAr
4
SAr
71d
5
54%
ArS
SAr
SAr
SiMe3
SAr
SAr
9
6
5
58%
54
53d
Trace
Scheme 2. The reactions of ArS(ArSSAr)þ (1) (Ar¼p-FC6H4) with 1-methylcyclohexene
ArS
followed by addition of a quenching nucleophile.
10
However, it was surprising that use of ketene silyl acetal 4 as
a quenching nucleophile led to anti addition of two ArS groups to
give compound 5.13 No appreciable carbon–carbon bond formation
took place. The formation of 5 indicated that ArSSAr attacked the
episulfonium ion as a nucleophile. Use of an allylsilane, such as 6 as
a quenching nucleophile also gave rise to the formation of 5. The
reactions of other alkenes using 4 or 6 as a quenching nucleophile
also gave the corresponding diarylthio-substituted compounds as
depicted in Table 1. Et3N was also found to be an effective quenching
nucleophile for formation of diarylthio-substituted compounds.
The reactions of (Z)- and (E)-diphenylethene were carried out to
examine the stereoselectivity of the present reaction (Table 1). The
stereochemistry of the products was determined by X-ray crystal-
lographic analysis (Fig. 1).14 The reaction with (Z)-diphenylethene
exclusively gave the DL product (9) and (E)-diphenylethene exclu-
sively gave meso product (10), indicating that the reactions are
stereospecific and anti-selective.
Although the reaction mechanism has not yet been fully clari-
fied, the following mechanistic arguments seem to be reasonable
(Scheme 3). In the first step, episulfonium ion intermediate4 A is
generated by the reaction of ArS(ArSSAr)þ with an alkene. Nucle-
ophilic attack of ArSSAr on A opens the three-membered ring to
give sulfonium intermediate B. There is an equilibrium between A
and B.15 A hard quenching nucleophile, such as MeOH or H2O se-
lectively attacks A to give the corresponding product C (pathway I).
On the other hand, a soft quenching nucleophile, such as ketene
SAr
56d
31d
41d
30d
51d
60d
0
ArS
11
73c,d
ArS
SAr
SAr
12
3c,d
ArS
13
a
Typical procedure: ArSSAr (Ar¼p-FC6H4; 0.40 mmol) was electrochemically
oxidized in 0.3 M Bu4NBF4/CH2Cl2 (8 mL) at ꢀ78 ꢁC using 0.67 F/mol of electricity.
The solution of 1 (ca. 0.27 mmol) thus obtained was allowed to react with an alkene
(0.27 mmol, 1 equiv) at ꢀ78 ꢁC for 30 min. A quenching nucleophile (3 equiv) was
added and the mixture was stirred for 30 min at the same temperature. Then, Et3N
(1 mL) was added to quench the reaction.
b
Yields of isolated products.
c
3 equiv of 1 was used.
d
Yields determined by NMR.

S. Fujie et al. / Tetrahedron 66 (2010) 2823–2829
2825
ArS SAr
SAr
1
OSiMe3
OMe
9 68 %
(1 equiv)
4
(3 eqiv)
30 min
ArS
ArS
SAr
30 min
-78 oC
-78 o
C
+
(Ar = p-FC6H4)
O
16 61 %
OMe
Scheme 5. Evidence of the attack of a soft nucleophile.
It was also found that the reactions of ArS(ArSSAr)þ (1) (Ar¼p-
FC6H4) with alkynes gave the corresponding diarylthio-substituted
compounds, when a soft nucleophile, such as allylsilane 6 and
triethylamine was used as a quenching nucleophile (Table 2). The
reactions were highly stereoselective (except for formation of 19),
and the stereochemistry of the products were identified as E-iso-
mers by comparison of the NMR spectra with those reported in the
literature.17
Table 2
Reactions of ArS(ArSSAr)þ (1) (Ar¼p-FC6H4) with Alkynes
Alkene
Product
Yield (%)a
Quenching nucleophile
6b
Et3Nc
SAr
Figure 1. X-ray structures of 9 and 10.
99
80
ArS
17
Ar
ArS SAr
SAr
ArS
R1
R3
R4
R1
R2
R3
R4
S
ArSSAr
soft
R1
R2
R3
nucleophile
R4
SAr
R2
SAr
S
77 (E/Z¼94:6)
95 (E/Z¼92:8)
Me
H
A
hard
B
ArS
ArS
Me
Ar
nucleophile
18
pathway I
ArS
pathway II
SAr
H
62d (E/Z¼59:41) 57 (E/Z¼85:15)
R3
R4
R3
ArS
R1
R2
R4
SAr
R1
19
R2
Nu
Me3Si
ArS
SAr
H
C
D
Me3Si
H
34
62
Scheme 3. Plausible reaction mechanism.
20
n-C6H13
SAr
49d
33d
n-C6H13
ArS
21
ArS SAr
SAr
(Ar = p-FC6H4)
a
Yields of isolated products.
b
c
1 equiv of ArS(ArSSAr)þ was used.
3 equiv of ArS(ArSSAr)þ was used.
Yields determined by NMR.
OMe
SAr
SAr
SAr
1
(3 equiv)
MeOH
d
30 min, -78 o
C
ArS(ArSSAr)þ having various substituent(s) on the aromatic ring
(Ar = p-FC6H4)
2 78%
5
could also be generated and accumulated by the electrochemical
oxidation of the corresponding ArSSAr in CH2Cl2 at ꢀ78 ꢁC. Their
reactions with diphenylethyne took place smoothly to give the
corresponding (E)-1,2-diarylthio-1,2-diphenylethenes (Table 3).
The reactions were highly stereoselective and only a single ste-
reoisomer was obtained. Therefore, the present method serves as
an efficient method for synthesizing diarylthio-substituted alkenes
bearing various substituents on the aromatic rings.
SAr
SAr
ArSSAr
ArSSAr
ArS
MeOH
S
Ar
SAr
14(B)
15 (A)
Scheme 4. Existence of the equilibrium.

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S. Fujie et al. / Tetrahedron 66 (2010) 2823–2829
3. Conclusions
We found that ArS(ArSSAr)þ generated and accumulated by the
Table 3
electrochemical oxidation of ArSSAr in CH2Cl2 at ꢀ78 ꢁC reacted
with alkenes and alkynes giving rise to stereoselective addition of
ArSSAr to a carbon–carbon multiple bond when a soft nucleophile,
such as allylsilanes, ketene silyl acetals, and triethylamine was used
as a quenching nucleophile. The present method serves as an effi-
cient and convenient method for highly stereoselective synthesis of
organosulfur compounds.
Reactions of ArS(ArSSAr)þ with diphenylethynea
-e
-78 oC
ArSSAr
ArS SAr
SAr
(1 equiv)
SAr
Et3N
30 min, -78 o
C
ArS
4. Experimental section
4.1. General remarks
ArSSAr
Product
Yield (%)b
Cl
1H and 13C NMR spectra were recorded in CDCl3 on a Varian
Gemini 2000 (1H 300 MHz, 13C 75 MHz), Varian MERCURY plus-400
(1H 400 MHz, 13C 100 MHz), or JEOL ECA-600P (1H 600 MHz, 13C
150 MHz) with Me4Si as an internal standard unless otherwise
noted. Mass spectra were obtained on a JEOL JMS-SX102A mass
spectrometer, JEOL JMS-HX110A mass spectrometer, JEOL MS-
BU250 mass spectrometer, or JEOL JMS-MS700 mass spectrome-
ter. Thin-layer chromatography (TLC) was carried out by using
Merck precoated silica gel F254 plates (thickness 0.25 mm). Flash
chromatography was carried out on a column of silica gel (Kanto
S
71c
S
Cl
S
S
Cl
Cl
22
Chem. Co., Silica Gel N, spherical, neutral, 40–100 mm). Gel per-
S
meation chromatography (GPC) was carried out on a Japan Ana-
lytical Industry LC-9201 equipped with JAIGEL-1H and 2H using
CHCl3 as eluent. X-ray single crystal structure analysis was per-
formed on RIGAKU R-AXIS RAPID. All reactions were carried out
under Ar atmosphere unless otherwise noted.
S
53
S
S
23
Me
4.2. Materials
Dichloromethane (CH2Cl2) was washed with water, distilled
from P2O5, redistilled from dried K2CO3 to remove a trace amount of
S
56
acid,
and
stored
over
molecular
sieves
4A.
Tri-
S
Me
S
S
Me
81d
fluoromethanesulfonic acid (TfOH) was purchased from Nacalai
and was used without further purification. ArSSAr (Ar¼p-FC6H4)
was prepared according to the procedures in the literatures,18 and
identified by the comparison of its spectral data with that of au-
thentic sample.19
Me
24
OMe
4.2.1. Bis(2,4-difluoropheny) disulfide. To a solution of 2,4-difluor-
obenzenethiol (4.49 g, 31 mmol) in CH2Cl2 (10 mL) was added
a solution of SO2Cl2 (2.28 g, 16.9 mmol) in 10 mL of CH2Cl2 at
0 ꢁC.20 Then, the mixture was heated to room temperature and
stirred for additional 7 h. The reaction was quenched with water
(15 mL) and the resulted mixture was extracted with Et2O
(2ꢃ20 mL). The combined extracts were washed with saturated
NaHCO3 (20 mL), and brine (25 mL) and dried over MgSO4. After
removal of the solvent, the residue was purified via flash chro-
matography (hexane/EtOAc 100:1) to obtain the title compound
(4.01 g, 90%): TLC Rf 0.33 (hexane/EtOAc 100:1); 1H NMR
S
32
S
MeO
S
S
OMe
50d
MeO
25
F
F
(400 MHz, CDCl3)
(100 MHz, CDCl3)
d
6.81–6.88 (m, 4H), 7.47–7.53 (m, 2H); 13C NMR
S
F
S
S
F
62
d
104.7 (t, J¼26.0 Hz), 112.1 (dd, J¼18.3, 4.0 Hz),
79d
F
F
S
119.2 (dd, J¼18.3, 4.0 Hz), 134.7 (dd, J¼9.5, 2.0 Hz), 161.7 (dd,
J¼249.1, 12.3 Hz), 163.6 (dd, J¼250.5, 11.3 Hz); LRMS (EI) m/z 290
(Mþ), 145 (MþꢀSC6H3F2); HRMS (EI) calcd for C12H6F4S2 289.9847,
found 289.9848.
F
F
26
a
1 equiv of ArS(ArSSAr)þ was used and Et3N was used as quenching nucleophile.
Yields of isolated products.
Compound 6 was used as quenching nucleophile.
The reaction was carried out for 90 min.
4.3. Electrochemical generation and accumulation of
b
c
ArS(ArSSAr)D (Ar[p-FC6H4) (1)
d
The anodic oxidation was carried out in an H-type divided cell
(4 G glass filter) equipped with a carbon felt anode (Nippon Carbon

S. Fujie et al. / Tetrahedron 66 (2010) 2823–2829
2827
JF-20-P7, ca. 320 mg, dried at 250 ꢁC/1 mmHg for 2 h before use)
(150 MHz, CDCl3)
d
22.2, 22.3, 30.1, 39.2, 53.5, 56.7, 115.6
and a platinum plate cathode (40 mmꢃ20 mm). In the anodic
chamber was placed a solution of ArSSAr (Ar¼p-FC6H4) (104.2 mg,
0.410 mmol) in 0.3 M Bu4NBF4/CH2Cl2 (8.0 mL). In the cathodic
chamber were placed 0.3 M Bu4NBF4/CH2Cl2 (8.0 mL) and tri-
fluoromethanesulfonic acid (44.6 mg, 0.297 mmol). The constant
current electrolysis (8 mA) was carried out at ꢀ78 ꢁC with magnetic
stirring until 0.67 F/mol of electricity10 was consumed. The solution
of 1 (0.038 M at ꢀ78 ꢁC) thus obtained was used for the subsequent
reaction.
(d, J¼20.5 Hz), 116.0 (d, J¼21.7 Hz), 126.5 (d, J¼3.6 Hz), 130.7
(d, J¼2.4 Hz), 134.5 (d, J¼7.2 Hz), 139.6 (d, J¼8.5 Hz), 162.1 (d,
J¼245.1 Hz), 163.5 (d, J¼248.8 Hz); LRMS (EI) m/z 350 (Mþ), 223
(MþꢀSC6H4pꢀF); HRMS (EI) calcd for C19H20F2S2 350.0974, found
350.0969.
4.4.4. (1RS,2RS)-1,2-Bis(4-fluorophenylthio)cyclohexane (7). TLC Rf
0.28 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d 1.31–1.38
(m, 2H), 1.51–1.59 (m, 2H), 1.59–1.67 (m, 2H), 2.11–2.19 (m, 2H),
3.02–3.07 (m, 2H), 6.89–6.98 (m, 4H), 7.28–7.36 (m, 4H); 13C NMR
4.4. Reaction of ArS(ArSSAr)D with alkenes
(100 MHz, CDCl3)
d
23.8, 30.5, 50.7, 115.8 (d, J¼21.4 Hz), 129.1 (d,
J¼3.1 Hz), 135.1 (d, J¼7.9 Hz), 162.1 (d, J¼245.5 Hz); LRMS (CI) m/z
336 (Mþ), 209 (MþꢀSC6H4pꢀF); HRMS (CI) calcd for C18H18F2S2
336.0818, found 336.0804.
4.4.1. (1RS,2RS)-1-(4-Fluorophenylthio)-2-methoxy-2-methyl-
cyclohexane (2) (a typical procedure for the reaction with alkenes
using a hard quenching nucleophile). To the solution of 1 (0.038 M at
ꢀ78 ꢁC, 8.0 mL, 0.304 mmol) was added 1-methylcyclohexene
(28.7 mg, 0.298 mmol) at ꢀ78 ꢁC and the reaction mixture was
stirred for 30 min. The reaction was quenched by addition of MeOH
(1 mL) and the mixture was stirred for 30 min at the same tem-
perature. Then, Et3N (1 mL) was added to complete the quenching
and the mixture was warmed to room temperature. The solvent
was removed under reduced pressure and the residue was quickly
filtered through a short column (5 cm) of silica gel to remove
Bu4NBF4. The silica gel was washed with ether (70 mL). The com-
bined filtrate was concentrated in vacuo and the crude product thus
obtained was purified via flash chromatography (hexane/EtOAc
30:1) and GPC to give the title compound (2) (52.3 mg, 68%): TLC Rf
4.4.5. 1,2-Bis(4-fluorophenylthio)octane (8). TLC Rf 0.30 (hexane/
EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
1.21–1.36 (m, 6H), 1.36–1.60 (m, 3H), 1.85–1.95 (m, 1H), 2.83 (dd,
J¼9.2, 13.2 Hz, 1H), 2.92–2.99 (m, 1H), 3.10 (dd, J¼4.0, 13.2 Hz, 1H),
6.88–6.98 (m, 4H), 7.14–7.20 (m, 2H), 7.25–7.32 (m, 2H); 13C NMR
d
0.88 (t, J¼6.8 Hz, 3H),
(100 MHz, CDCl3)
d 14.2, 22.7, 26.8, 29.1, 31.7, 32.6, 40.6, 49.3, 115.9
(d, J¼21.4 Hz), 128.9 (d, J¼3.2 Hz), 130.5 (d, J¼3.2 Hz), 132.5 (d,
J¼7.9 Hz), 135.2 (d, J¼8.0 Hz), 161.6 (d, J¼244.3 Hz), 162.2 (d,
J¼245.9 Hz); LRMS (CI) m/z 366 (Mþ), 239 (MþꢀSC6H4pꢀF); HRMS
(CI) calcd for C20H24F2S2 366.1287, found 366.1275.
4.4.6. (1RS,2RS)-1,2-Bis(4-fluorophenylthio)-1,2-bisphenylethane
0.32 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d
1.24–1.31
(9). TLC Rf 0.34 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
(m, 2H), 1.28 (s, 3H), 1.32–1.43 (m, 1H), 1.48–1.76 (m, 6H), 1.92–2.00
d
4.52 (s, 2H), 6.82–6.86 (m, 4H), 6.91–6.93 (m, 4H), 7.02–7.05 (m,
(m, 1H), 3.18 (dd, J¼8.8, 4.0 Hz, 1H), 3.22 (s, 3H), 6.94–7.00 (m, 2H),
6H), 7.17–7.21 (m, 4H); 13C NMR (100 MHz, CDCl3)
d
59.4, 115.7 (d,
7.41–7.46 (m, 2H); 13C NMR (100 MHz, CDCl3)
d
20.1, 22.2, 23.5,
J¼21.4 Hz), 127.1, 127.6, 128.8, 129.1 (d, J¼3.5 Hz), 135.7 (d,
J¼8.0 Hz), 138.6, 162.4 (d, J¼245.9 Hz); LRMS (CI) m/z 434 (Mþ), 307
(MþꢀSC6H4pꢀF); HRMS (CI) calcd for C26H20F2S2 434.0974, found
434.0966. X-ray data for 9: C26H20F2S2, M¼434.56, monoclinic,
space group C2/c (No. 15), a¼25.319(13) Å, b¼8.637(11) Å,
29.6, 34.2, 76.6, 115.7 (d, J¼21.4 Hz), 131.1 (d, J¼3.6 Hz), 134.5 (d,
J¼8.0 Hz), 161.9 (d, J¼245.2 Hz); LRMS (EI) m/z 254 (Mþ), 239
(MþꢀMe), 223 (MþꢀOMe); HRMS (EI) calcd for C14H19FOS 254.1141,
found 254.1139.
c¼10.397(8) Å,
b
¼101.10(3)ꢁ, V¼2231.1(21) Å3, Z¼4, Dc¼1.294 g/
4.4.2. (1RS,2RS)-1-(4-Fluorophenylthio)-2-methyl-2-cyclohexanol
cm3,
m
¼2.649 cmꢀ1. Intensity data were measured on a Rigaku
(3). TLC Rf 0.06 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
RAXIS imaging plate area detector with graphite-monochromated
d
1.18–1.28 (m, 2H), 1.28 (s, 3H), 1.33–1.60 (m, 3H), 1.64–1.76 (m,
Mo K
a
radiation. The data were collected at 23ꢄ1 ꢁC to maximum
2H), 1.82–1.88 (m, 1H), 2.03 (dddd, J¼13.7, 1.7, 1.7, 1.7 Hz, 1H), 2.60
2q
value of 55.0ꢁ. A total of 10,640 reflections were collected. The
(s, 1H), 2.97 (dd, J¼12.2, 4.2 Hz, 1H), 6.95–7.02 (m, 2H), 7.43–7.48
structure was solved by SHELX-9721 and expanded using Fourier
techniques. The non-hydrogen atoms were refined anisotropically.
Hydrogen atoms were refined by using the riding model. The final
cycle of full-matrix least-squares refinement on F2 was based on
(m, 2H); 13C NMR (150 MHz, CDCl3)
d 22.7, 23.2, 26.0, 32.1, 39.7,
62.7, 72.6, 116.0 (d, J¼21.7 Hz), 130.6 (d, J¼3.6 Hz), 134.6 (d,
J¼8.4 Hz),162.2 (d, J¼245.1 Hz); LRMS (EI) m/z 240 (Mþ); HRMS (EI)
calcd for C13H17FOS 240.0984, found 240.0985.
2561 observed reflections (I>2.00s(I)) and 136 variable parameters
and converged (largest parameter shift was 0.00 times its esd) with
unweighted and weighted agreement factors of R¼0.041
(Rw¼0.120). All calculations were performed using the Yadokari-XG
crystallographic software package.
4.4.3. (1RS,2RS)-1,2-Bis(4-fluorophenylthio)-1-methylcyclohexane
(5) (a typical procedure for the reaction with alkenes using a soft
quenching nucleophile). To the solution of 1 (0.038 M at ꢀ78 ꢁC,
8.0 mL, 0.304 mmol) was added 1-methylcyclohexene (29.3 mg,
0.305 mmol) at ꢀ78 ꢁC and the reaction mixture was stirred for
30 min. The reaction was quenched with 3-(trimethylsilyl)cyclo-
hexene (6) (140.0 mg, 0.907 mmol) and the mixture was stirred for
30 min at the same temperature. Then, Et3N (1 mL) was added to
complete the quenching and the mixture was warmed to room
temperature. The solvent was removed under reduced pressure and
the residue was quickly filtered through a short column (5 cm) of
silica gel to remove Bu4NBF4. The silica gel was washed with ether
(70 mL). The combined filtrate was concentrated in vacuo and the
crude product was obtained. The yield of title compound (5) was
determined by 1H NMR analysis using CH2Br2 as internal standard
(61.7 mg, 58%): TLC Rf 0.25 (hexane/EtOAc 20:1); 1H NMR
4.4.7. (1RS,2SR)-1,2-Bis(4-fluorophenylthio)-1,2-bisphenylethane
(10). TLC Rf 0.33 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d
4.48 (s, 2H), 6.73–6.78 (m, 4H), 6.96–7.01 (m, 4H), 7.13–7.16 (m,
4H), 7.20–7.23 (m, 6H); 13C NMR (100 MHz, CDCl3)
d
60.3, 115.5 (d,
J¼21.8 Hz), 127.5, 128.0, 128.5, 129.1 (d, J¼3.1 Hz), 135.8 (d,
J¼8.4 Hz), 139.3, 162.3 (d, J¼245.6 Hz); LRMS (FAB) m/z 434 (Mþ),
307 (MþꢀSC6H4pꢀF); HRMS (FAB) calcd for C26H20F2S2 434.0974,
found 434.0992. X-ray data for 10: C26H20F2S2, M¼434.56,
monoclinic, space group P21/c (No. 14), a¼12.8076(10) Å,
b¼5.6338(4) Å, c¼15.6116(13) Å, i¼108.543(8)ꢁ, V¼1067.98(14) Å3,
Z¼2, Dc¼1.351 g/cm3,
m
¼2.767 cmꢀ1. Intensity data were mea-
sured on a Rigaku RAXIS imaging plate area detector with
(400 MHz, CDCl3)
d
1.10–1.21 (m, 1H), 1.36 (s, 3H), 1.36–1.47 (m, 1H),
graphite-monochromated Mo K
a
q
radiation. The data were col-
1.56–1.69 (m, 4H), 1.93–2.01 (m, 1H), 3.04 (dd, J¼10.0, 4.0 Hz, 1H),
lected at 20ꢄ1 ꢁC to maximum 2
value of 50.6ꢁ. A total of 8,146
6.95–7.05 (m, 4H), 7.35–7.40 (m, 2H), 7.53–7.58 (m, 2H); 13C NMR
reflections were collected. The structure was solved by SHELX-

2828
S. Fujie et al. / Tetrahedron 66 (2010) 2823–2829
9721 and expanded using Fourier techniques. The non-hydrogen
atoms were refined anisotropically. Hydrogen atoms were re-
fined by using the riding model. The final cycle of full-matrix least-
squares refinement on F2 was based on 1945 observed reflections
(114.9 mg, 99%): TLC Rf 0.30 (hexane/EtOAc 20:1); 1H NMR
(400 MHz, CDCl3) 6.70–6.76 (m, 4H), 7.03–7.08 (m, 4H), 7.14–7.18
(m, 2H), 7.19–7.24 (m, 4H), 7.31–7.34 (m, 4H); 13C NMR (100 MHz,
CDCl3)
129.8, 134.3 (d, J¼7.9 Hz), 136.8, 138.3, 161.8 (d, J¼245.2 Hz); LRMS
(FAB) m/z 432 (Mþ), 305 (MþꢀSC6H4pꢀF); HRMS (FAB) calcd for
C26H18F2S2 432.0818, found 432.0812.
d
d
115.4 (d, J¼21.9 Hz), 127.60, 127.62, 129.0 (d, J¼3.6 Hz),
(I>2.00
s
(I)) and 137 variable parameters and converged (largest
parameter shift was 0.00 times its esd) with unweighted and
weighted agreement factors of R¼0.036 (Rw¼0.074). All calcula-
tions were performed using the Crystal Structure crystallographic
software package.
4.5.2. 1,2-Bis(4-fluorophenylthio)-1-phenylpropene (18). This com-
pound was characterized as the mixture of two geometrical iso-
mers (E/Z¼94:6) by 1H NMR analysis, in case of use of 6: TLC Rf 0.31
4.4.8. (1RS,2SR)-1,2-Bis(4-fluorophenylthio)-1,2-bis(4-methyl-
phenyl)ethane (11). TLC Rf 0.31 (hexane/EtOAc 20:1); 1H NMR
(hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3) E isomer;
d 2.23 (s,
(400 MHz, CDCl3)
d
2.31 (s, 6H), 4.44 (s, 2H), 6.73–6.79 (m, 4H),
21.2, 60.0, 115.5 (d,
3H), 6.77–6.84 (m, 2H), 6.95–7.01 (m, 2H), 7.10–7.23 (m, 7H), 7.26–
6.97–7.05 (m, 12H); 13C NMR (100 MHz, CDCl3)
d
7.32 (m, 2H); 13C NMR (100 MHz, CDCl3) E isomer;
d
22.2, 115.6 (d,
J¼21.5 Hz), 128.5, 128.8, 129.5 (d, J¼3.2 Hz), 135.8 (d, J¼8.4 Hz),
136.5, 137.3, 162.4 (d, J¼245.9 Hz); LRMS (FAB) m/z 461 (MþꢀH),
335 (MþꢀSC6H4pꢀF); HRMS (FAB) calcd for C28H24F2S2 462.1287,
found 462.1304.
J¼21.8 Hz), 116.0 (d, J¼21.4 Hz), 127.5, 127.7, 129.3 (d, J¼3.2 Hz),
129.4 (d, J¼3.1 Hz), 129.7, 133.6 (d, J¼8.3 Hz), 134.2, 134.3, 134.4 (d,
J¼8.3 Hz), 139.0, 162.0 (d, J¼245.5 Hz), 162.4 (d, J¼248.4 Hz); LRMS
(CI) m/z 370 (Mþ), 351 (MþꢀF), 243 (MþꢀSC6H4F); HRMS (CI) calcd
for C21H16F2S2 370.0661, found 370.0660.
4.4.9. (1RS,2RS)-1,2-Bis(4-fluorophenylthio)-1-phenylpropane
(12). TLC Rf 0.25 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
4.5.3. 1,2-Bis(4-fluorophenylthio)-1-phenylethene (19). This com-
pound was characterized as a mixture of two geometrical isomers
(E/Z¼85:15 by GC analysis, in case of use of Et3N): TLC Rf 0.28
d
1.23 (d, J¼6.8 Hz, 3H), 3.50 (dq, J¼6.9, 6.7 Hz, 1H), 4.14 (d,
J¼6.0 Hz, 1H), 6.83–6.88 (m, 2H), 6.94–7.00 (m, 2H), 7.16–7.27 (m,
7H), 7.30–7.35 (m, 2H); 13C NMR (100 MHz, CDCl3)
17.9, 48.3, 58.8,
d
(hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d 6.73 (s, 1H),
115.8 (d, J¼21.4 Hz), 116.0 (d, J¼21.8 Hz), 127.5, 127.87, 127.88, 129.1
(d, J¼3.2 Hz), 129.4 (d, J¼3.2 Hz), 134.8 (d, J¼8.0 Hz), 135.3 (d,
J¼8.3 Hz), 137.9, 162.2 (d, J¼245.6 Hz), 162.3 (d, J¼246.0 Hz); LRMS
(EI) m/z 366 (Mþ), 239 (MþꢀSC6H4pꢀF); HRMS (EI) calcd for
C21H18F2S2 372.0818, found 372.0816.
6.87–6.92 (m, 2H), 6.98–7.04 (m, 2H), 7.26–7.34 (m, 7H), 7.49–7.52
(m, 2H); 13C NMR (75 MHz, CDCl3) E isomer;
d
116.0 (d, J¼21.9 Hz),
116.2 (d, J¼21.8 Hz), 128.1, 128.3, 128.6, 128.9, 129.5 (d, J¼3.6 Hz),
130.6 (d, J¼3.5 Hz), 131.9 (d, J¼8.0 Hz), 132.7 (d, J¼7.9 Hz), 133.0,
136.6, 161.9 (d, J¼245.2 Hz), 162.1 (d, J¼245.6 Hz); LRMS (CI) m/z
357 (MHþ), 337 (MþꢀF), 229 (MþꢀSC6H4pꢀF); HRMS (CI) calcd for
C20H14F2S2 356.0505, found 356.0507.
4.4.10. (1RS,2SR)-1,2-Bis(4-fluorophenylthio)-1-phenylpropane
(13). TLC Rf 0.30 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d
1.41 (d, J¼6.8 Hz, 3H), 3.55 (quintet, J¼6.8 Hz, 1H), 4.16 (d,
4.5.4. (E)-1,2-Bis(4-fluorophenylthio)-1-(trimethylsilyl)ethene
J¼6.8 Hz, 1H), 6.80–6.86 (m, 2H), 6.92–6.97 (m, 2H), 7.11–7.16 (m,
(20). TLC Rf 0.30 (hexane); 1H NMR (400 MHz, CDCl3)
d
0.28 (s,
9H), 6.56 (s, 1H), 6.96–7.04 (m, 4H), 7.17–7.22 (m, 2H), 7.31–7.34
(m, 2H); 13C NMR (100 MHz, CDCl3)
2H), 7.16–7.25 (m, 5H), 7.30–7.35 (m, 2H); 13C NMR (100 MHz,
CDCl3)
d
19.3, 50.5, 60.7, 115.7 (d, J¼21.8 Hz), 115.9 (d, J¼21.4 Hz),
d
0.2, 116.1 (d, J¼21.8 Hz),
127.3, 128.0, 128.5, 129.48 (d, J¼2.4 Hz), 129.51 (d, J¼3.2 Hz), 134.8
(d, J¼8.4 Hz), 135.5 (d, J¼7.9 Hz), 139.7, 162.1 (d, J¼245.1 Hz), 162.3
(d, J¼245.6 Hz); LRMS (EI) m/z 372 (Mþ), 245 (MþꢀSC6H4pꢀF), 217
(Mþꢀ(SC6H4pꢀF)ꢀCHCH3); HRMS (EI) calcd for C21H18F2S2
372.0818, found 372.0823.
116.3 (d, J¼21.8 Hz), 129.9 (d, J¼3.2 Hz), 130.8 (d, J¼7.9 Hz), 131.2
(d, J¼3.2 Hz), 133.6 (d, J¼8.0 Hz), 135.8, 137.6, 161.8 (d,
J¼244.7 Hz), 162.1 (d, J¼245.6 Hz); LRMS (CI) m/z 352 (Mþ), 337
(MþꢀCH3); HRMS (CI) calcd for C17H18F2S2Si 352.0587, found
352.0576.
4.4.11. 2-(4-Fluorophenylthio)-2-methylpropionic acid methyl ester
(16). TLC Rf 0.26 (hexane/EtOAc, 20/1); 1H NMR (300 MHz, CDCl3)
4.5.5. (E)-1,2-Bis(4-fluorophenylthio)-1-octene (21). TLC Rf 0.36
(hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d
0.88 (t, J¼6.8 Hz,
d
1.48 (s, 6H), 3.67 (s, 3H), 6.97–7.07 (m, 2H), 7.39–7.47 (m, 2H); 13
C
3H), 1.24–1.34 (m, 6H), 1.51–1.58 (m, 2H), 2.34–2.38 (m, 2H), 6.13 (s,
NMR (75 MHz, CDCl3)
d
25.6, 51.1, 52.2,115.8 (d, J¼27.5 Hz),126.7 (d,
1H), 6.94–7.04 (m, 4H), 7.23–7.26 (m, 2H), 7.35–7.39 (m, 2H); 13C
J¼3.5 Hz),138.8 (d, J¼9.2 Hz),163.7 (d, J¼249.4 Hz),174.1; LRMS (CI)
m/z 228(Mþ), 209 (MþꢀF); HRMS (CI) calcd for C11H13FO2S (Mþ)
228.0620, found 228.0620.
NMR (100 MHz, CDCl3)
d 14.2, 22.7, 28.2, 28.9, 31.7, 32.7, 116.1 (d,
J¼21.9 Hz), 116.2 (d, J¼21.4 Hz), 123.0, 128.4 (d, J¼3.6 Hz), 130.8 (d,
J¼7.9 Hz), 130.9, 134.0 (d, J¼7.9 Hz), 138.7, 161.6 (d, J¼244.3 Hz),
162.3 (d, J¼245.6 Hz); LRMS (CI) m/z 365 (MHþ), 345 (MþꢀF), 237
(MþꢀSC6H4pꢀF); HRMS (CI) calcd for C20H22F2S2 364.1131, found
364.1129.
4.5. Reaction of ArS(ArSSAr)D with alkynes
4.5.1. (E)-1,2-Bis(4-fluorophenylthio)-1,2-bisphenylethene (17) (a typical
procedure for the reaction with alkynes using a soft quenching
nucleophile). To the solution of 1 (0.038 M at ꢀ78 ꢁC, 7.1 mL,
0.270 mmol) was added diphenylethyne (47.7 mg, 0.268 mmol) at
ꢀ78 ꢁC and the reaction mixture was stirred for 30 min. The
reaction was quenched with 3-(trimethylsilyl)cyclohexene (6)
(149.2 mg, 0.967 mmol) and the mixture was stirred for 30 min at
the same temperature. Then, Et3N (1 mL) was added to complete
the quenching and the mixture was warmed to room temperature.
The solvent was removed under reduced pressure and the residue
was quickly filtered through a short column (5 cm) of silica gel to
remove Bu4NBF4. The silica gel was washed with ether (70 mL). The
combined filtrate was concentrated in vacuo and the crude product
was purified with flash chromatography (hexane/EtOAc 20:1)
4.5.6. (E)-1,2-Bis(4-chlorophenylthio)-1,2-bisphenylethene (22). TLC
Rf 0.43 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d
7.01 (br s,
8H), 7.17–7.22 (m, 6H), 7.38–7.39 (m, 4H); 13C NMR (100 MHz,
CDCl3)
d 127.8, 128.0, 128.6, 129.9, 132.7, 132.9, 133.0, 137.2, 138.4;
LRMS (FAB) m/z 464 (Mþ), 321 (MþꢀSC6H4pꢀCl); HRMS (FAB) calcd
for C26H18Cl2S2 464.0227, found 464.0222.
4.5.7. (E)-1,2-Bis(phenylthio)-1,2-bisphenylethene (23). TLC Rf 0.31
(hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d
7.00–7.07 (m,
6H), 7.10–7.15 (m, 6H), 7.17–7.21 (m, 4H), 7.40–7.43 (m, 4H); 13C
NMR (100 MHz, CDCl3) d126.6,127.5,128.2,129.8,131.5,134.2,137.2,
138.7; LRMS (EI) m/z 396 (Mþ), 287 (MþꢀSC6H5), 210

S. Fujie et al. / Tetrahedron 66 (2010) 2823–2829
2829
(MþꢀSC6H5ꢀC6H5); HRMS (EI) calcd for C26H20S2 396.1006, found
(o) Heiba, E. I.; Dessau, R. M. J. Org. Chem. 1967, 32, 3837; (p) Benati, L.;
Montevecchi, P. C.; Spagnolo, P. J. Chem. Soc., Perkin Trans. 1 1991, 2103.
3. For example (a) Smit, W. A.; Krimer, M. Z.; Vorobieva, E. A. Tetrahedron Lett.
1975, 16, 2451; (b) Capozzi, G.; Lucchini, V.; Modena, G.; Rivetti, F. J. Chem. Soc.,
Perkin Trans. 2 1975, 361.
4. For example, (a) Smit, W. A.; Caple, R.; Smoliakova, L. P. Chem. Rev. 1994, 94,
2359; (b) Fox, D. J.; House, D.; Warren, S. Angew. Chem., Int. Ed. 2002, 41, 2462;
(c) Denmark, S. E.; Collins, W. R.; Cullen, M. D. J. Am. Chem. Soc. 2009, 131, 3490
and references therein.
5. (a) Moeller, K. D. Tetrahedron 2000, 56, 9527; (b) Sperry, J. B.; Wright, D. L.
Chem. Soc. Rev. 2006, 35, 605; (c) Yoshida, J.; Kataoka, K.; Horcajada, R.;Nagaki, A.
Chem. Rev. 2008, 108, 2265.
6. Do, Q. T.; Elothmani, D.; Simonet, J.; Guillanton, G. L. Electrochim. Acta 2005, 50,
4792 and references therein.
396.1009.
4.5.8. (E)-1,2-Bis(4-methylphenylthio)-1,2-bisphenylethene
(24). TLC Rf 0.34 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d
2.17 (s, 6H), 6.84 (d, J¼7.6 Hz, 4H), 6.97–7.00 (m, 4H), 7.10–7.14 (m,
2H), 7.16–7.21 (m, 4H), 7.38–7.41 (m, 4H); 13C NMR (100 MHz,
CDCl3)
d 21.1, 127.3, 127.4, 129.0, 129.8, 130.6, 131.8, 136.6, 137.2,
138.9; LRMS (FAB) m/z 424 (Mþ), 301 (MþꢀSC6H4pꢀCH3); HRMS
(FAB) calcd for C28H24S2 424.1319, found 424.1325.
7. (a) Gybin, A. S.; Smit, W. A.; Bogdanov, V. S.; Krimer, M. Z.; Kalyan, J. B. Tetra-
hedron Lett. 1980, 21, 383; (b) Bogdanov, V. S.; Gybin, A. S.; Cherepanova, E. G.;
Smith, W. A. Izv. Akad. Nauk, Ser. Khim. 1981, 2681.
4.5.9. (E)-1,2-Bis(4-methoxyphenylthio)-1,2-bisphenylethene
(25). TLC Rf 0.21 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
8. Recent reports using low-temperature electrochemical oxidation; (a)
Maruyama, T.; Mizuno, Y.; Shimizu, I.; Suga, S.; Yoshida, J. J. Am. Chem. Soc. 2007,
129, 1902; (b) Nokami, T.; Ohata, K.; Inoue, M.; Tsuyama, H.; Shibuya, A.; Soga,
K.; Okajima, M.; Suga, S.; Yoshida, J. J. Am. Chem. Soc. 2008, 130, 10864; (c) Suga,
S.; Shimizu, I.; Ashikari, Y.; Mizuno, Y.; Maruyama, T.; Yoshida, J. Chem. Lett.
2008, 37, 1008; (d) Okajima, M.; Soga, K.; Watanabe, T.; Terao, K.; Nokami, T.;
Suga, S.; Yoshida, J. Bull. Chem. Soc. Jpn. 2009, 82, 594.
d
3.67 (s, 6H), 6.54–6.59 (m, 4H), 6.98–7.02 (m, 4H), 7.11–7.16 (m,
2H), 7.18–7.22 (m, 4H), 7.31–7.33 (m, 4H); 13C NMR (100 MHz,
CDCl3)
d 52.2, 113.8, 124.5, 127.2, 127.5, 129.8, 134.4, 136.7, 138.8,
158.8; LRMS (EI) m/z 456 (Mþ), 317 (MþꢀSC6H4pꢀOCH3); HRMS
(EI) calcd for C28H24O2S2 456.1218, found 456.1217.
9. (a) Suga, S.; Matsumoto, K.; Ueoka, K.; Yoshida, J. J. Am. Chem. Soc. 2006, 128,
7710; (b) Matsumoto, K.; Ueoka, K.; Fujie, S.; Suga, S.; Yoshida, J. Heterocycles
2008, 76, 1103; (c) Matsumoto, K.; Ueoka, K.; Suzuki, S.; Suga, S.; Yoshida, J.
Tetrahedron 2009, 65, 10901; (d) Fujie, S.; Matsumoto, K.; Suga, S.; Yoshida, J.
Chem. Lett. 2009, 38, 1186 See also: (e) Matsumoto, K.;Fujie,S.;Ueoka,K.;Suga, S.;
Yoshida, J. An
Suga, S.; Nokami, T.; Yoshida, J. Chem. Commun. 2009, 5448.
10. The theoretical amount of electricity to convert ArSSAr to ArS(ArSSAr)þ.
11. Carbocation Chemistry; Olah, G. A., Prakash, G. K. S., Eds.; Wiley: New Jersey, NJ,
2004.
4.5.10. (E)-1,2-Bis(2,4-difluorophenylthio)-1,2-bisphenylethene
(26). TLC Rf 0.31 (hexane/EtOAc 20:1); 1H NMR (400 MHz, CDCl3)
d
6.53–6.60 (m, 4H), 7.04–7.10 (m, 2H), 7.12–7.17 (m, 2H), 7.19–7.23
(m, 4H), 7.35–7.38 (m, 4H); 13C NMR (75 MHz, CDCl3)
d
104.0 (t,
gew. Chem., Int. Ed. 2008, 47, 2506; (f) Matsumoto, K.; Fujie, S.;
J¼26.2 Hz), 111.3 (dd, J¼4.0, 21.0 Hz), 116.2 (dd, J¼3.9, 17.7 Hz),
127.87,127.91,129.6,135.0,136.4 (dd, J¼2.3, 9.1 Hz),138.0,162.2 (dd,
J¼12.0, 248.8 Hz), 162.9 (dd, J¼11.4, 249.4 Hz); LRMS (FAB) m/z 468
(Mþ), 323 (MþꢀSC6H3F2); HRMS (FAB) calcd for C26H16F4S2
468.0630, found 468.0648.
12. Reactivity of cations: (a) Mayr, H.; Ofial, A. R. Angew. Chem., Int. Ed. 2006, 45,
1844; (b) Hofmann, M.; Hampel, N.; Kanzian, T.; Mayr, H. Angew. Chem., Int. Ed.
2004, 43, 5402.
13. It is reported that the reaction of an episulfonium ion with a ketene silyl acetal
led to the carbon–carbon bond formation Patel, S. K.; Paterson, I. Tetrahedron
Lett. 1983, 24 1315.
Acknowledgements
14. CCDC 745683 (9) and CCDC 745684 (10) contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
15. Although we tried to observe the intermediate A or B in Scheme 3 using the
reaction of 1-octene and ArS(ArSSAr)þ (1) (Ar¼ p-FC6H4) by the low temper-
ature NMR measurement at ꢀ80 ꢁC extensively, we could not observe definite
signals of the intermediates. Only a complex signals including broad peaks
were observed, presumably because of the equilibrium between A and B. By
increasing the temperature, signals due to thiofluorinated compound (ArS–C–
C–F) appeared. See also Ref. 9d.
This work was financially supported in part by a Grant-in-Aid for
Scientific Research from the Japan Society for the Promotion of
Science. K.M. acknowledges JSPS for financial support.
References and notes
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