Electrolytic partial fluorination of organic compound. Part: 53 Highly regioselective anodic mono- and difluorination of 4-arylthio-1,3-dioxolan-2-ones. A marked solvent effect on fluorinated product selectivity

Article abstract of DOI:10.1016/S0040-4020(01)00910-3

Anodic fluorination of 4-arylthio-1,3-dioxolan-2-ones was investigated using various supporting fluoride salts and solvents. Their fluoro-desulfurization took place predominantly in Et₄NF·5HF/CH₂Cl₂ while the use of Et₄NF·4HF/DME resulted in α-fluorination, without the desulfurization, selectively. Electrolytic solvents affected markedly the product selectivity as compared with supporting fluoride salts. This is the first example of a solvent effect on the fluorinated product selectivity in the anodic fluorination.

Full text of DOI:10.1016/S0040-4020(01)00910-3

TETRAHEDRON
Pergamon
Tetrahedron 57 <2001) 9067±9072
Electrolytic partial ¯uorination of organic compound. Part: 53q
Highly regioselective anodic mono- and di¯uorination
of 4-arylthio-1,3-dioxolan-2-ones. A marked solvent effect
on ¯uorinated product selectivity
Hideki Ishii, Norihisa Yamada and Toshio Fuchigamip
Department of Electronic Chemistry, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
Received 2 August 2001; accepted 5 September 2001
AbstractÐAnodic ¯uorination of 4-arylthio-1,3-dioxolan-2-ones was investigated using various supporting ¯uoride salts and solvents.
Their ¯uoro-desulfurization took place predominantly in Et4NF´5HF/CH2Cl2 while the use of Et4NF´4HF/DME resulted in a-¯uorination,
without the desulfurization, selectively. Electrolytic solvents affected markedly the product selectivity as compared with supporting ¯uoride
salts. This is the ®rst example of a solvent effect on the ¯uorinated product selectivity in the anodic ¯uorination. q 2001 Elsevier Science
Ltd. All rights reserved.
1. Introduction
ene carbonate is expected to increase its electrochemical
stability and decrease its melting point. With these facts in
mind, we have attempted the anodic ¯uorination of ethylene
carbonates having an arylthio group using various support-
ing ¯uoride salts and solvents.11
Fluoroorganic compounds have attracted much interest
because of their pronounced chemical, physical and poten-
tial pharmaceutical properties.2 The direct ¯uorination is the
simplest way, however it generally requires special equip-
ments and techniques since many ¯uorinating reagents are
usually explosive, toxic, unstable, or hygroscopic.3 On the
other hand, the electrochemical ¯uorination has recently
been shown to be an alternative method for selective direct
¯uorination; the ¯uorination can be carried out under mild
and safe conditions using relatively simple equipment.4±6
One of the important factors in the anodic ¯uorination is
supporting ¯uoride salts.7 Quite recently, we have found
that solvent 1,2-dimethoxyethane <DME) is much more
suitable than MeCN which has been conventionally used
for the anodic ¯uorination.8 This ®nding enabled us to
carry out successfully anodic ¯uorination of oxygen-
containing heterocyclic compounds,9 of which anodic
¯uorination has not been reported except for the case of
N-alkylmorpholines.10
2. Results and discussion
2.1. Preparation of 4-arylthio-1,3-dioxolan-2-ones
The starting 4-arylthio-1,3-dioxolan-2-ones were synthe-
sized in good yields by the reaction of vinylenecarbonate
with arenethiol in boiling THF in the presence of Et3N as
shown in Scheme 1.
Fluorinated ethylene carbonates seem to be promising
organic electrolytic solvents or additives for rechargeable
Li batteries since introduction of ¯uorine atom<s) into ethyl-
Scheme 1.
q See Ref. 1 for Part 52.
2.2. Oxidation potentials of 4-arylthio-1,3-dioxolan-2-
ones
Keywords: electrolytic partial ¯uorination; solvent effect; product selec-
tivity.
p
The oxidation potentials <anodic peak potentials) of 1a±e
were determined by cyclic voltammetry using a platinum
Corresponding author. Tel.: 181-45-924-5406; fax: 181-459245406;
e-mail: fuchi@echem.titech.ac.jp
0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020<01)00910-3

9068
H. Ishii et al. / Tetrahedron 57 *2001) 9067±9072
Table 1. Oxidation potentials <peak potentials, EPOX) of 4-arylthio-1,3,-
dioxolan-2-ones
the starting material was almost consumed. The results are
summarized in Table 2.
As shown in Table 2, anodic ¯uoro-desulfurization of 1a
leading to product 3 proceeded selectively in Et4NF´4HF/
CH3CN, Et4NF´4HF/CH2Cl2 and Et3N´5HF/CH2Cl2 in
moderate to good yields <runs 3, 7 and 8). In sharp contrast,
a-¯uorination of 1a to 2a took place preferentially in
Et4NF´3HF/DME and Et4NF´4HF/DME <runs 10 and 11).
In these cases, di¯uorinated products such as 5 <Scheme 3)
were not formed. This can be explained in terms of the
oxidation potential of 2a <Epox: 2.2 V vs SCE) being 0.3 V
higher than that of 1a <Epox: 1.9 V vs SCE).
1
X
EPOX <V) vs SCE
1a
1b
1c
1d
1e
H
Me
Cl
Br
OMe
1.92
1.76
1.94
1.95
1.57
Next, we extended this anodic ¯uorination to other
4-arylthio derivatives 1b±e as shown in Table 3. Their
¯uoro-desulfurization proceeded smoothly in Et3N´5HF/
CH2Cl2 regardless of the substituent X groups on the ben-
zene ring to give 3 in moderate to high yields <runs 4, 6, 8
and 10). In sharp contrast, anodic ¯uorination of 1b±d in
Et4NF´4HF/DME was strongly affected by substituents on
the benzene ring. In the cases of 1c and 1d, the correspond-
ing a-mono¯uorinated products 2c and 2d were obtained
selectively in high yields <runs 5 and 7). On the other
hand, 1b and 1e gave the ¯uorodesulfurization products 3
as the major products along with the corresponding sulf-
oxide in 14 and 12% yields, respectively <runs 3 and 9).
In the case of 1b, mono¯uorination also took place to
some extent at the methyl group of the p-tolyl group <run
3). Thus, electron-withdrawing chloro and bromo sub-
stituents on the benzene ring promote a-¯uorination,
whereas electron-donating methyl and methoxy groups
drastically disfavor it. Therefore, the presence of an
electron-withdrawing group is essential for the successful
a-¯uorination of 4-arylthio-1,3-dioxolane-2-ones <1). It is
noted that electrolytic conditions, particularly electrolytic
solvents greatly affected the ¯uorinated product selectivity
although there are some exceptions <1b and 1e). Such
marked product selectivity depending on electrolytic
Pt electrodes; 0.1 M Bu4NClO4/MeCN; sweep rate, 100 mV/s.
electrode in 0.1 M Bu4N´ClO4/MeCN and a SCE reference
electrode. All the compounds chosen in the present study
showed irreversible oxidation waves. The ®rst oxidation
peak potentials <EpOX) were observed in the range of
1.57±1.94 V as shown in Table 1. p-Tolylthio- and
p-anisylthio derivatives 1b,e, respectively were oxidized
at a less positive potential as compared with the other
three derivatives <1a,c,d), owing to the electron-donating
methyl and methoxy substituents on the benzene ring.
2.3. Anodic ¯uorination and ¯uoro-desulfurization of
4-arylthio-1,3-dioxolan-2-ones
Initially, anodic mono¯uorination was investigated in detail
using 4-phenylthio-1,3-dioxolan-2-one <1a) as a model
compound. The ¯uorination was carried out at platinum
electrodes using an undivided cell in anhydrous acetonitrile,
dichloromethane and dimethoxyethane <DME) containing
various ¯uoride salts as the supporting electrolyte and
¯uoride ion source. A constant current was applied until
Table 2. Effect of supporting ¯uoride salts and solvents on anodic ¯uorination of 4-phenylthio-1,3-dioxolane-2-one <1a)
Run
Solvent
CH3CN
CH2Cl2
DME
Supporting electrolyte
Charge passed <F/mol)
Yield <%)a
2a
28
3
1
2
3
4
5
6
7
8
Et3N´3HF
Et4NF´3HF
Et4NF´4HF
Et3N´5HF
Et3N´3HF
Et4NF´3HF
Et4NF´4HF
Et3N´5HF
Et3N´3HF
Et4NF´3HF
Et4NF´4HF
Et3N´5HF
5.1
3.2
4.3
2.6
4.2
3.1
5.2
5.5
18.0
7.2
3.4
4.0
Trace
14
50
10
6
29
53
67
Trace
5
28
11
Trace
Trace
28
16
Trace
Trace
5
40
55
9
10
11
12
6
40
a
Determined by 19F NMR spectroscopy.

H. Ishii et al. / Tetrahedron 57 *2001) 9067±9072
Table 3. Anodic ¯uorination of 4-arylthio-1,3-dioxolan-2-ones
9069
Run
Substrate
Supporting electrolyte
Solvent
Electricity <F mol21
)
Yield <%)a
No.
X
2
3
1
1a
1a
1b
1b
1c
1c
1d
1d
1e
1e
H
H
Et4NF´4HF
Et3N´5HF
Et4NF´4HF
Et3N´5HF
Et4NF´4HF
Et3N´5HF
Et4NF´4HF
Et3N´5HF
Et4NF´4HF
Et3N´5HF
DME
CH2Cl2
DME
CH2Cl2
DME
CH2Cl2
DME
CH2Cl2
DME
CH2Cl2
3.4
5.5
3.1
7.2
5.2
3.4
7.2
4.0
4.2
4.3
55 <44)b
Trace
28
67
23
40
20
2
3c
4
Me
Me
Cl
Cl
Br
Br
OMe
OMe
4
0
5
6
7
80 <70)b
0
96 <75)b
84 <66)b
4
54
41
62
8
0
9d
10
Trace
0
a
Determined by 19F NMR spectroscopy.
Isolated yield.
The corresponding sulfoxide <14%) and 4-<40-¯uoromethylphynylthio)-1,3-dioxo-2-one <4) <5%) were formed.
The corresponding sulfoxide <12%) was formed
b
c
d
solvents has never been reported in the anodic ¯uorination
so far.
Therefore, A seems to be unstable in CH2Cl2. Reasonably,
the desulfurization of A followed by ¯uorination mainly
takes place prior to a-¯uorination of A. On the other
hand, DME is known to coordinate cations strongly.12
Therefore, DME should stabilize the intermediate A and
also enhance the ¯uoride ion nucleophilicity.8 Then, the
deprotonation of A with ¯uoride ions takes place prior to
desulfurization followed by further oxidation to generate
cation B, and this cation reacts with a ¯uoride ion to provide
a-¯uorinated product. In addition to these solvent effects,
the deprotonation process should be also greatly affected
by the substituent groups on the benzene ring.13 In fact,
electron-withdrawing groups promoted this deprotonation
process signi®cantly, while the electron-donating groups
suppressed drastically.
In order to clarify the solvent effects, we investigated anodic
¯uorination of 1b in a mixed solvent of DME and dichloro-
methane containing Et4NF´4HF. As shown in Fig. 1, the
product ratio of 3 to 2c increased with an increase in the
ratio of CH2Cl2 to DME. Notably, addition of only 25%
CH2Cl2 into DME caused a dramatic change in the product
ratio and 3 was mainly formed in ca. 60% yield.
This interesting phenomenon can be explained as follows.
The ¯uorination can be rationalized by postulating a radical
cation intermediate A as shown in Scheme 2.
Dichloromethane has a poor ability to solvate carbocations.
Furthermore, we examined anodic ¯uoro-desulfurization of
2a. As shown in Scheme 3, electrolysis of 2a in Et4NF´4HF/
CH2Cl2 and Et3N´5HF/CH2Cl2 gave desired di¯uorinated
product 5 in reasonable yield. However, anodic ¯uorodesul-
furization of 2a did not take place at all in Et4NF´4HF/DME
and most of 2a was recovered. In this case, the oxidation of
solvent DME preferentially occurred to give ¯uorinated
DMEs.9a
It is well-known that methods for direct introduction of
¯uorine atom<s) into organic compounds often require
expensive or hazardous reagents. In recent years, N-¯uoro-
pyridinium tri¯ates have been shown to be effective ¯uori-
nating reagents with various ¯uorinating power.14
Therefore, ¯uorination of 1a as a model compound with
various N-¯uoropyridinium tri¯ates was attempted. As
shown in Table 4, less powerful N-¯uoropyridinium and
N-¯uoro-2,4,6-trimethylpyridinium tri¯ates gave only a
trace amount of 3, and 1a was recovered mostly <runs 1
Figure 1. Dependence of yield of 2c and 3 on the ratio of CH2Cl2 to DME.

9070
H. Ishii et al. / Tetrahedron 57 *2001) 9067±9072
Scheme 2.
3. Experimental
3.1. General
Et4NF´4HF and Et3N´5HF were obtained from Morita
Chemical Industries Co. Ltd <Japan). They are toxic and
cause serious burns if they are exposed to unprotected
skin. Et4NF´3HF and Et3N´3HF are much less aggressive.
However, proper safety precautions should be taken at all
times.15 It is therefore recommended to use hand protection.
Scheme 3.
and 2). On the other hand, a more powerful N-¯uoro-2,6-
dichloropyridinium tri¯ate provided 3 in low yield although
1a was completely consumed. Therefore, the electro-
chemical ¯uorination is more advantageous than the
conventional chemical methods for such heterocyclic
sul®des.
1H NMR, 19F NMR and 13C NMR spectra were recorded at
270, 254 and 68 MHz, respectively, with CDCl3 as a
solvent. The chemical shifts for 1H and 19F NMR are
given in d <ppm) from internal TMSand mono¯uoro-
benzene <236.5 ppm), respectively. High-resolution mass
spectra were obtained with a JEOL JMS-700 mass spectro-
meter. Cyclic voltammetry was performed with a Hokuto-
denko potentiostat/galvanostat HAB-151, and preparative
electrolysis experiments were carried out with a Metronnix
Corp. Tokyo constant current power supply.
In summary, the anodic ¯uorination of 4-arylthio-1,3-di-
oxolane-2-ones 1 provided a-¯uorinated and/or ¯uoro-
desulfurization products 2 and 3. The product selectivity
was greatly affected by electrolytic solvents, supporting
¯uoride salts, and substituents on the benzene ring. Thus,
we found the ®rst example of a unique marked solvent
effect on the ¯uorinated product selectivity. The ¯uoro-
desulfurization of 2 leading to di¯uorinated ethylene
carbonate 5 was also successfully carried out. Application
of ¯uorinated products 3 and 5 to electrolytic solvents or
additives for rechargeable Li batteries will be reported
somewhere.
3.2. Preparation of starting materials
A typical procedure for the synthesis of 4-arylthio-1,3-
dioxolan-2-ones 1 is as follows. To a solution of 1,3-dioxo-
len-2-one <15 mmol) and arenethiol <20 mmol) in 30 mL of
THF, was added Et3N <20 mmol). The reaction mixture was
Table 4. Chemical ¯uorination of 1a using N-¯uoropyridinium salts
Run
N-Fluoropyridinium salt <X, Y)
Condition
Reaction time <h)
Yield <%)
1
2
3
XˆYˆMe
XˆYˆH
Re¯ux
Re¯ux
08C
12
12
5
Trace
Trace
9
XˆCl, YˆH

H. Ishii et al. / Tetrahedron 57 *2001) 9067±9072
9071
heated under re¯ux for 4 h. The reaction mixture was
concentrated under reduced pressure and then puri®ed by
column chromatography on silica gel <hexane/EtOAcˆ5:1)
to provide the pure product 1.
further puri®ed by column chromatography on silica gel
using hexane/ethyl acetate <5:1) as an eluent.
3.3.1. 4-Fluoro-4-phenylthio-1,3-dioxolan-2-one .2a).
Colorless oil; H NMR d 7.66±7.62 <m, 2H), 7.50±7.39
1
3.2.1. 4-Phenylthio-1,3-dioxolan-2-one .1a). 73% Yield;
1
<m, 3H), 4.63 <dd, Jˆ17, 11 Hz, 1H), 4.47 <dd, Jˆ26,
11 Hz, 1H); 13C NMR d 150.64, 136.21, 130.89, 129.70,
125.03, 119.54 <d, Jˆ270 Hz), 73.88 <d, Jˆ31 Hz); 19F
NMR d 0.54 <dd, Jˆ27, 17 Hz); MS< m/z) 214 <M1), 123,
109; HRMS m/z Calcd for C9H7FO3S: 214.0100. Found:
214.0133.
colorless oil, H NMR d 7.55±7.53 <m, 2H), 7.50±7.38
<m, 3H), 5.91 <dd, Jˆ8.9, 6.4 Hz, 1H), 4.72 <dd, Jˆ9.2,
8.9 Hz, 1H), 4.22 <dd, Jˆ9.2, 6.4 Hz, 1H); 13C NMR d
153.48, 133.61, 129.34, 128.99, 83.16, 68.27; MS m/z 196
<M1), 152, 123, 109, 87; Anal. Calcd for C8H8O3S : C,
55.09; H, 4.11. Found: C, 55.40; H, 4.15.
3.3.2. 4-Fluoro-4-.p-tolylthio)-1,3-dioxolan-2-one .2b).
1
3.2.2. 4-.p-Tolylthio)-1,3-dioxolan-2-one .1b). 84% Yield;
Colorless oil; H NMR d 7.51 <d, Jˆ8.1 Hz, 2H), 7.23 <d,
1
colorless solid; mp 60.0±61.08C; H NMR d 7.43 <d, Jˆ
Jˆ8.1 Hz, 2H), 4.61 <dd, Jˆ17, 11 Hz, 1H), 4.45 <dd, Jˆ27,
11 Hz, 1H), 2.39 <s, 3H); 13C NMR d 150.61, 141.45,
136.19 <d, Jˆ1.1 Hz) 130.44, 121.46 <d, Jˆ3.4 Hz),
119.57 <d, Jˆ270 Hz), 73.80 <d, Jˆ31 Hz), 21.44; 19F
NMR d 20.24 <dd, Jˆ27, 17 Hz); MS< m/z) 228 <M1),
208 <M12HF), 135, 123; HRMS m/z Calcd for
C10H9FO3S: 228.0256. Found: 228.0254.
7.7 Hz, 2H), 7.19 <d, Jˆ7.7 Hz, 2H), 5.85 <dd, Jˆ8.2,
6.4 Hz, 1H), 4.70 <dd, Jˆ9.2, 8.2 Hz, 1H), 4.22 <dd, Jˆ
9.2, 6.4 Hz, 1H), 2.36 <s, 3H); 13C NMR d 153.55,
140.00, 134.30, 130.20, 124.94, 83.27, 68.25, 21.27; MS
m/z 210 <M1), 137, 124, 83. HRMS m/z Calcd for
C10H10O3S: 210.0351. Found: 210.0547.
3.2.3. 4-.p-Chlorophenylthio)-1,3-dioxolan-2-one .1c).
100%; Colorless solid; mp 74.0±75.08C; 1H NMR d
7.53±7.48 <m, 2H), 7.39±7.34 <m, 2H), 5.89 <dd, Jˆ8.4,
6.3 Hz, 1H), 4.75 <dd, Jˆ9.4, 8.4 Hz, 1H), 4.24 <dd, Jˆ
9.4, 6.3 Hz, 1H); 13C NMR d 153.30, 136.12. 135.09,
129.70, 127.50, 83.06, 68.30; MS m/z 232 <M112), 230
<M1), 188, 186, 157, 146, 144, 108, 87. HRMS: m/z Calcd
for C9H7ClO3S: 229.9804. Found: 229.9812.
3.3.3. 4-Fluoro-4-.p-chlorophenylthio)-1,3-dioxolan-2-
one .2c). Colorless needles; mp 60.0±61.08C; H NMR d
1
7.60±7.57 <m, 2H), 7.43±7.40 <m, 2H), 4.66 <dd, Jˆ17,
11 Hz, 1H), 4.47 <dd, Jˆ26, 11 Hz, 1H); 13C NMR d
150.40, 137.72, 137.43, 129.96, 123.34, 119.21 <d, Jˆ
270 Hz), 73.83 <d, Jˆ31 Hz); 19F NMR d 0.93 <dd, Jˆ27,
17 Hz); MS< m/z) 250 <M112), 248 <M1), 159, 157, 145,
143, 108; HRMS m/z Calcd for C9H6ClFO3S: 247.9710.
Found: 247.9720.
3.2.4. 4-.p-Bromophenylthio)-1,3-dioxolan-2-one .1d).
75%; Colorless solid; mp 84.5±85.08C; H NMR d 7.54±
1
3.3.4. 4-Fluoro-4-.p-bromophenylthio)-1,3-dioxolan-2-
one .2d). Colorless oil; H NMR d 7.58±7.48 <m, 4H),
1
7.41 <m, 4H), 5.93 <dd, Jˆ8.4, 6.3 Hz, 1H), 4.75 <dd, Jˆ9.6,
8.4 Hz, 1H), 4.24 <dd, Jˆ9.6, 6.3 Hz, 1H); 13C NMR d
153.29, 1135.11, 132.59, 128.23, 124.19, 82.96, 68.29;
MS m/z 276 <M112), 274 <M1), 203, 201, 190, 188, 122,
108, 69. HRMS: m/z Calcd for C9H7O3BrS: 273.9300.
Found: 273.9299.
4.66 <dd, Jˆ11, 17 Hz, 1H), 4.48 <dd, Jˆ17, 26 Hz, 1H);
13C NMR d 150.35, 137.52, 132.85, 125.91, 123.88, 119.08
<d, Jˆ270 Hz), 73.81 <d, Jˆ31 Hz); 19F NMR d 1.02 <dd,
Jˆ27, 17 Hz); MS< m/z) 294 <M112), 292 <M1), 203, 201,
189, 187, 108; HRMS m/z Calcd for C9H6BrFO3S:
291.9205. Found: 291.9213.
3.2.5. 4-.p-Methoxyphenylthio)-1,3-dioxolan-2-one .1e).
29% Yield; colorless solid; mp 61.0±61.58C; H NMR d
1
3.3.5. 4-Fluoro-1,3-dioxolan-2-one .3). Colorless cubes;
mp 19.0±20.08C; 1H NMR d 6.35 <ddd, Jˆ64, 3.6,
0.7 Hz, 1H), 4.66 <ddd, Jˆ34, 11, 3.6 Hz, 1H), 4.55 <ddd,
Jˆ21, 11, 0.7 Hz, 1H); 13C NMR d 152.69 <d, Jˆ1.7 Hz),
105.10 <d, Jˆ236 Hz), 70.71 <d, Jˆ28 Hz); 19F NMR d
244.75 <ddd, Jˆ64, 34, 21 Hz); MS< m/z) 106 <M1), 62;
Anal. Calcd for C3H3FO3: C, 33.98%; H, 2.85%; F, 17.91%.
Found: C, 33.73%; H, 2.91%; F, 17.72%.
7.51±7.47 <m, 2H), 6.93±6.88 <m, 2H), 5.80 <dd, Jˆ8.2,
6.3 Hz, 1H), 4.69 <dd, Jˆ9.4, 8.2 Hz, 1H), 4.23 <dd, Jˆ
9.4, 6.3 Hz, 1H), 3.82 <s, 3H); 13C NMR d 161.01,
153.57, 136.69, 118.49, 115.05, 83.34, 68.19, 55.42; MS
m/z 226 <M1), 182, 153, 140, 139. HRMS: m/z Calcd for
C10H10O4S: 226.0300. Found: 226.0269.
3.3. Anodic ¯uorination of 4-arylthio-1,3-dioxolan-2-ones
3.3.6. 4-.p-Fluoromethylphenylthio)-1,3-dioxolan-2-one
1
.4). Colorless oil; H NMR d 7.59 <d, Jˆ7.9 Hz, 2H),
A general procedure for the anodic ¯uorination of
4-arylthio-1,3-dioxolan-2-ones is as follows. Anodic oxi-
dation of 1 <1 mmol) was carried out with platinum-plate
electrodes <2£2 cm2) in 1.0 M Et4NF´4HF <40 equiv. of F2
to 1)/ DME, CH2Cl2 and/or MeCN <10 mL) in a cylindrical
undivided cell under nitrogen atmosphere at room tempera-
ture. Constant current <5 mA/cm2) was passed until the start-
ing material 1 was completely consumed <checked by silica
gel TLC). After electrolysis, the electrolytic solution was
passed through a short column ®lled with silica gel using
ethyl acetate to remove ¯uoride salts. The resulting solution
was evaporated under reduced pressure, and the residue was
7.39 <d, Jˆ7.9 Hz, 2H), 5.92 <dd, Jˆ8.4, 6.4 Hz, 1H),
5.40 <d, Jˆ47 Hz, 2H), 4.75 <dd, Jˆ9.6, 8.4 Hz, 1H), 4.25
<dd, Jˆ9.6, 6.4 Hz, 1H); 13C NMR d 153.40, 137.73 <d,
Jˆ17 Hz), 133.80, 129.59 <d, Jˆ2.8 Hz), 128.01 <d, Jˆ
6.1 Hz), 83.57 <d, Jˆ170 Hz), 83.09, 68.32; 19F NMR d
2134.13 <t, Jˆ47 Hz); MS< m/z) 228 <M1), 155, 142,
109; HRMS m/z Calcd for C10H9FO3S: 228.0256. Found:
228.0253.
3.3.7. 4,4-Di¯uoro-1,3-dioxolan-2-one .5). 1H NMR d 4.72
<t, Jˆ12 Hz, 2H); 19F NMR d 3.90 <t, Jˆ12 Hz); MS< m/z)

9072
H. Ishii et al. / Tetrahedron 57 *2001) 9067±9072
124 <M1), 109; HRMS m/z Calcd for C3H2F2O3: 123.9972.
Found: 123.9939.
4. <a) Fuchigami, T. In Organic Electrochemistry; Lund, H.,
Hammerich, O., Eds.; 4th ed., Marcel Dekker: New York,
2001 Chapter 25. <b) Fuchigami, T. Advances in Electron-
Transfer Chemistry; Mariano, P. S., Ed.; JAI: CT, 1999;
Vol. 6, p. 41. <c) Fuchigami, T.; Higashiya, S.; Hou, Y.;
Dawood, K. M. Rev. Heteroatom. Chem. 1999, 19, 67.
5. Andres, D. F.; Dietrich, U.; Laurent, E. G.; Marquet, B. S.
Tetrahedron 1997, 53, 647.
3.4. Chemical ¯uorination of 4-phenylthio-1,3-dioxolan-
2-one .1a)
To a solution of 1a <1.0 mmol) in CH2Cl2 <8 mL), was added
N-¯uoro-2,6-dichloropyridinium tri¯ate at 08C under N2.
The reaction mixture was stirred at 08C for 5 h. After the
starting material was completely consumed, the reaction
mixture was passed through a short column of silica gel
<CHCl3). The yield of 3 was determined by 19F NMR
spectrometry.
6. Hara, S.; Chen, S. Q.; Hoshio, T.; Fukuhara, T.; Yanoeda, N.
Tetrahedron Lett. 1996, 37, 8511.
7. <a) Momota, K.; Morita, M.; Matsuda, Y. Electrochim. Acta
1993, 38, 619. <b) Hou, Y.; Higashiya, S.; Fuchigami, T.
J. Org. Chem. 1997, 62, 8773. <c) Fuchigami, T.; Narizuka,
S.; Konno, A.; Momota, K. Electrochim. Acta 1998, 43, 1985.
<d) Higashiya, S.; Konno, A.; Maeda, T.; Momota, K.;
Fuchigami, T. J. Org. Chem. 1999, 64, 133. <e) Chen, S. Q.;
Hatakeyama, T.; Fukuhara, T.; Hara, S.; Yoneda, N. Electro-
chim. Acta 1997, 42, 1951.
Acknowledgements
We thank Kato Foundation and the Ministry of Education,
Science, Sports and Culture of Japan for ®nancial support
<Grant-in-Aid for Scienti®c Research, No. 12555252).
8. <a) Dawood, K. M.; Higashiya, S.; Hou, Y.; Fuchigami, T.
J. Fluorine Chem. 1999, 93, 159. <b) Dawood, K. M.;
Fuchigami, T. J. Org. Chem. 1999, 64, 138. <c) Dawood,
K. M.; Higashiya, S.; Hou, Y.; Fuchigami, T. J. Org. Chem.
1999, 64, 7935. <d) Hou, Y.; Fuchigami, T. J. Electrochem.
Soc. 2000, 147, 4567.
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