The investigation of fluorination reaction of p-substituted benzenesulfonimides with fluorine-nitrogen mixed gas to synthesize NFSI analogues

Article abstract of DOI:10.1016/j.jfluchem.2011.10.012

This paper studied the fluorination reaction of p-substituted benzenesulfonimides with diluted elemental fluorine to synthesize N-fluoro-benzenesulfonimide (NFSI) analogues. Several synthetic methods were compared and we found that, for many p-substituted

Full text of DOI:10.1016/j.jfluchem.2011.10.012

Journal of Fluorine Chemistry 133 (2012) 155–159
Contents lists available at SciVerse ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
The investigation of fluorination reaction of p-substituted benzenesulfonimides
with fluorine–nitrogen mixed gas to synthesize NFSI analogues
a
Guanlong Chen a, Fuli Chen a, Yan Zhang a, Xueyan Yang a, , Xiaoming Yuan ,
*
a,b,c,**
Fanhong Wu a,b, Xianjin Yang
a Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China
b Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
c Wengfu Group Co. Ltd., Guizhou 550000, China
A R T I C L E I N F O
A B S T R A C T
Article history:
This paper studied the fluorination reaction of p-substituted benzenesulfonimides with diluted
elemental fluorine to synthesize N-fluoro-benzenesulfonimide (NFSI) analogues. Several synthetic
methods were compared and we found that, for many p-substituted benzenesulfonimides, the
fluorination of their sodium salts with 10% F2–N2 mixed gas in acetonitrile at room temperature could
afford NFSI analogues in moderate to good yields.
Received 26 May 2011
Received in revised form 14 October 2011
Accepted 19 October 2011
Available online 2 November 2011
ß 2011 Elsevier B.V. All rights reserved.
Keywords:
Benzenesulfonimide
Fluorination
NFSI analogue
Dedicated to Professor Weiyuan Huang on
the occasion of his 90th birthday.
1. Introduction
reactivity for the fluorination reaction. Though several preparing
methods for NFSI [21–24] appeared in the literature, there was
Fluorine substituents have become widespread and important
drug and material components [1–6], their introduction was
facilitated by the development of safe and selective fluorinating
agents [7–8]. Today, an increasing number of such agents are
directly available to researchers from commercial suppliers [9–11].
Recently, NFSI, one of the commercial fluorinating reagents, has
engendered many attentions for its applications in high enantio-
no promising and effective approach for synthesizing NFSI
analogues. Herein, the fluorination of p-substituted benzene-
sulfonimides with fluorine–nitrogen mixed gas was investigated
in detail to develop an efficient method for the synthesis of NFSI
analogues.
2. Results and discussion
selective fluorination [12–17]. However, to become
a good
fluorinating reagent, there are still some drawbacks to overcome:
(i) in the enantioselective fluorination of carbanions, only a few
good examples appear in the literature, while for most compounds,
the results are not satisfactory [18–19], (ii) in the fluorination of
aromatic compounds, its reactivity is not high and usually the
fluorinated products are afforded in low yields [20].
Structure modification of NFSI by changing the substituent in
the benzene ring supplies one possible approach to improve its
fluorinating reactivity and selectivity. The substituent modifica-
tion to the benzene ring can change the molecular electronic
state and N–F bond strength, therefore is able to adjust its
According to Differding’s method [21], the reaction of p-
substituted benzenesulfonimides 1 with fluorine-nitrogen mixed
gas in CH3CN in the presence of sodium fluoride was firstly
investigated. The results are shown in Table 1.
We found that the reaction was sensitive to many factors such
the source of substrate, reaction temperature, reaction scale,
reaction time, pH value, etc., and as a result, reproducibility could
not be achieved at a satisfactory level. The source of substrates
influenced our reaction results apparently due to their different
solubility. For compound 1a purchased from Aldrich, it was
difficult to dissolve it in acetonitrile, thus compound 2a was
obtained in much low yield with the incomplete conversion of
compound 1a in this fluorination process (entries 1–5), while for
compound 1a prepared in our lab, which had a good solubility in
acetonitrile, the fluorination reaction afforded compound 2a in
82.2% yields (entry 6). Similarly, for compounds 1b and 1c
* Corresponding author.
** Corresponding author. Fax: +86 02164253074.
E-mail address: yxj@ecust.edu.cn (X. Yang).
0022-1139/$ – see front matter ß 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2011.10.012

156
G. Chen et al. / Journal of Fluorine Chemistry 133 (2012) 155–159
Table 1
The reaction of p-substitutent benzenesulfonimides with F2–N2 mixed gas.
O
S
O
O
10%F /N ,
O
S
O
S
2
2
O
O
O
S
CH CN, NaF,
3
N
H
N
F
o
-40 ~ -20 C
R
R
R
R
1
2
R = a:F; b:Cl; c: Br; d:CF ; e:OCF ; f:t-Bu; g:Me; h:OCH
3
3
3
Entry
Substrate 1 (R)
Quantity of 1 (g)a
Product/yield (%)b
1
2
1a (F)c
3.46
16.65
17.30
18.00
18.60
16.65
0.92
2a (10.7) (recovered 1a 1.14 g)
2a (34.7) (recovered 1a 8.40 g)
2a (38.4) (recovered 1a 12.00 g)
2a (25.8) (recovered 1a 12.50 g)
2a (19.4) (recovered 1a 12.00 g)
2a (82.2)
1a (F)c
3
1a (F)c
4
1a (F)c
5
1a (F)c
6
1a (F)d
7
1b (Cl)c
1b (Cl)c
1b (Cl)c
1b (Cl)d
1c (Br)c
1c (Br)c
1c (Br)c
1c (Br)c
1c (Br)d
1d (CF3)c
1e (OCF3)c
1f (t-Bu)c
1f (t-Bu)c
1h (OMe)c
2b (17.6)
8
10.80
23.30
22.00
1.10
2b (35.3) (recovered 1b 5.7 g)
2b (37.2) (recovered 1b 11.0 g)
9
e
10
11
12
13
14
15
16
17
18
19
20
2b (7.9)
2c (30.7)
28.00
38.00
43.75
14.45
4.30
2c (23.7) (recovered 1c 21.0 g)
2c (7.6) (recovered 1c 32.0 g)
2c (15.7) (recovered 1c 40.0 g)
f
2c (7.3)
2d (21.1)
2e (19.6)
2f (47.9)
2f (51.5)
2h (23.8)
20.60
5.00
40.00
5.00
a
The reaction was carried out in a glass bottle in acetonitrile at À40 to À20 8C with 3–5 equivalents of 10% F2–N2 mixed gas in the presence of 8 equivalents of NaF.
b
c
Separated yield.
Purchased from Aldrich.
Prepared in our lab.
d
eByproduct 3b was obtained except 2b.
fExcept 2c, compound 3c and 4c were obtained in 38.3% and 19.2%, respectively.
purchasedfromAldrich, theconversionofsubstratewasincomplete,
therefore2band 2cwereobtained inlow yields(entries7–9, 11–14).
While for 1b and 1c made in our lab, TLC monitoring indicated that
compound 1b and 1c actually gave 2b and 2c respectively at À40 8C,
but the solution color changed from colorless to red when solution
temperaturewasgraduallyraisedto0 8C, itturnedout that2band2c
were decomposed to give 3b, 4b and 3c, 4c respectively (entries 10
and 15, Scheme 1). Though the main reason forthe decomposition of
compounds 2b and 2c was unknown, we speculated it might result
from the weakening of their stability with the increase of solution
temperature at that pH circumstance. Different batches were tried,
but the yields were fluctuated (entries 1–5 for 1a, entries 7–9 for 1b,
entries 11–14 for 1c).
A patent [17] described the fluorination reaction of the sodium
salt of compound 1 in the acetonitrile–water cosolvent system. We
tried the reaction of compound 1a with 3–5 equivalents of 10% F2–
N2 in 1:1 acetonitrile/water at 0 8C in the presence of 1.05
equivalents of sodium hydroxide, but no 2a was obtained.
Similarly, as the reaction of 1 h with 3–5 equivalents of 10% F2–
N2 was tried in water at 25 8C in the presence of 1.05 equivalents
sodium hydroxide, only small amount of compound 2h
a
was obtained with a large amount of unconverted reactant 1 h
(Scheme 2). In this process water reacted with F2 accompanying
the fluorination reaction of sodium salts, therefore the acidity of
the solution was increased and the salt was changed back to
compound 1.
O
S
O
O
10%F2/N2
O
S
O
S
O
O
O
S
CH3CN, NaF,
N
H
N
F
2
-40 ~ -20 oC
R
R
R
R
1
R = b:Cl; c: Br
O
S
O
S
O
O
r.t
F
NH
F
+
R
R
3
4
Scheme 1. The decomposition of compounds 1b and 1c.

G. Chen et al. / Journal of Fluorine Chemistry 133 (2012) 155–159
157
NaOH
O
S
O
S
O O
O
O
O
O
S
S
CH3CN:H2O
10%F2/N2
N
H
N
F
R
R
R
R
R=OMe, F
low yields
Scheme 2. The reaction of p-substitutent benzenesulfonimides with 10% F2–N2 mixed gas in the presence of sodium hydroxide in the aqueous acetonitrile or water.
Table 2
The reaction of sodium salts of p-substituted benzenesulfonimides with 10% F2–N2 mixed gas in acetonitrile.
O
O
O
O
O
O
O
O
S
S
NaOH
S
S
N
N
H
water
Na
R
R
R
R
1
5
O
O
O
O
S
S
N
F
10%F2/N2
CH3CN
R
R
2
R = a:F; b:Cl; c: Br; d:CF3; e:OCF3; f:t-Bu; g:Me; h:OCH3
Entry
Substrate (R)
Conditions
Product
Yield (%)a
1
2
1b (Cl)
CH3CN, À30 to À20 8C
CH3CN, À30 to À20 8C
CH3CN, À30 to À20 8C
CH3CN, 5–15 8C
CH3CN, 5–15 8C
CH3CN, 5–15 8C
CH3CN/H2O = 200:1, 5–15 8C
CH3CN/H2O = 150:1, 5–15 8C
CH3CN, 5–15 8C
2b
2c
2f
65.3
69.6
77.6
87.5
88.6
30.0
68.5
89.4
20.9
28.0
1c (Br)
3
1f (t-Bu)
1d (CF3)
1e (OCF3)
1g (Me)
1g (Me)
1g (Me)
1h (OMe)
1h (OMe)
4
2d
2e
2g
2g
2g
2h
2h
5
6
7
8
9
10
CH3CN/H2O = 50:1, 5–15 8C
a
Separated yield.
Considering that water existing in this system resulted in a
decrease in the yield of fluorinated products, we investigated the
solubility of the sodium salts in acetonitrile and water. The sodium
salts 5 were prepared by the reaction of compound 1 with 2% NaOH
solution and subsequent precipitation, while for 1g and 1h, NaCl
was additionally added to deposit their sodium salts 5g and 5h
from the aqueous solution. Surprisingly, we found the solubility of
the salt 5b, 5c, 5d, 5e and 5f were poor in water but good in
acetonitrile, and only the salts 5g and 5h had a better solubility in
water than acetonitrile. On the basis of the above experiments, we
tried the fluorination reaction of sodium salts according to their
solubility. To our delight, the reaction of the sodium salts 5b, 5c
and 5f with elemental fluorine was finished quickly at À30 to
À20 8C and compounds 2 were given in moderate to good yields
(Scheme 2, entries 1–3). For the sodium salts 5d and 5e, the
fluorination reaction occurred at room temperature, similarly
compounds 2d and 2e were given in good yields (entries 4, 5). For
the sodium salt 5g, when some water was added to acetonitrile, its
solubility was enhanced greatly, and the reaction was carried out
completely with the generation of compound 2g in high yield
(entries 6–8). However, for the sodium salt 5h, the fluorination
reaction solution turned red and low yield was given both in
acetonitrile and in 50:1 acetonitrile/water cosolvent (entries 9 and
10), which might be contributed to the electron-donating effect of
methoxyl group on the N–F bond weakening (Table 2).
3. Conclusion
In conclusion, in this paper we investigated the fluorination
reaction of benzenesulfonimides with 10% F2–N2 mixed gas.
Different reaction methods were tried and we found that, for many
p-substituted benzenesulfonimides, the reaction of their sodium
salts with 10% F2–N2 mixed gas was finished quickly and gave
compounds 2 in moderate to good yields, which supplied one
efficient method for the synthesis of NFSI analogues.
4. Experimental
4.1. General
Melting points were measured on WRS-1B digital instrument.
1H, 13C and 19F NMR spectra were recorded on a Bruker 400 MHz
instrument with TMS and CFCl3 as external references, respective-
ly. Infrared spectra were measured on a Shimadzu IR-440. Mass
spectra were recorded on a Finnigan GC-MS-4021.
4.2. General experimental procedure for the fluorination reaction
of p-substituted benzenesulfonimides with 10% F2–N2 mixed gas
Method A:
A mixture of compound 1 (50 mmol), NaF
(400 mmol) and acetonitrile (380 ml) was stirred and cooled to

158
G. Chen et al. / Journal of Fluorine Chemistry 133 (2012) 155–159
À40 8C, a 13–18 L gaseous mixture of 10% F2 in nitrogen (volume
percent) was added at a rate of 150 ml/min to the solution. Then
the insoluble solid was removed by filtration. The filtrate was
evaporated under vacuum, residues were washed with water, and
a yellow solid was obtained. Recrystallization in ethanol afforded a
white crystal 2.
4.2.7. N-fluoro-p-trifluoromethylbenzenesulfonimide (2d)
White crystal, m.p. 127.9–128.6 8C. IR (cmÀ1, KBr):
n
3113,
3062, 2925, 1413, 1395, 1133, 851, 787; 1H NMR (CDCl3, 400 MHz)
d
: 8.18–8.16 (d, J = 8.4 Hz, 4H), 7.91–7.89 (d, J = 8.4 Hz, 4H); 19F
NMR (CDCl3, 376 MHz)
(CDCl3, 400 MHz)
d
: À35.99 (s, 1F), À63.50 (s, 6F); 13C NMR
d
: 137.96 (dd, J1 = 30.4 Hz, J2 = 63.9 Hz), 130.45,
Method B: The mixture of 1 (19.6 mmol) and 2% sodium
hydroxide aqueous solution (350 ml, 175 mmol) was stirred for
20 min, the precipitate was filtered and the solid (compound 5)
was air-dried. The mixture of compound 5 and acetonitrile
(150 ml) was stirred and cooled to À30 8C. A 5–8 L gaseous
mixture of 10% F2 in nitrogen (volume percent) was introduced at a
rate of 150 ml/min to the solution. The insoluble solid was
removed by filtration. The filtrate was evaporated under vacuum
and washed with water, a yellow solid was obtained. After
recrystallization in 8:1 ethanol/acetonitrile a white crystal 2 was
afforded.
126.78 (d, J = 3.7 Hz), 124.09, 121.37; HRMS (EI) calculated for
14H8F7NO4S2: 450.9783; found: 450.9790.
C
4.2.8. N-fluoro-p-trifluoromethoxylbenzenesulfonimide (2e)
White crystal, m.p. 81.5–82.4 8C. IR (cmÀ1, KBr):
3110, 3065,
1590, 1491, 1199, 857, 829; 1H NMR (CDCl3, 400 MHz)
: 8.10–8.08
n
d
(d, J = 8.8 Hz, 4H), 7.44–7.42 (d, J = 8.8 Hz, 4H); 19F NMR (CDCl3,
376 MHz)
400 MHz)
d
: À36.23 (s, 1F), À57.65 (s, 6F); 13C NMR (CDCl3,
d
: 154.71, 132.35, 121.41, 120.82, 118.82; HRMS (EI):
calculated for C14H8F7NO6S2: 482.9681; found: 482.9685.
4.2.9. N-fluoro-p-t-butylbenzenesulfonimide (2f)
4.2.1. N-fluoro-p-fluorobenzenesulfonimide (2a)
White crystal, m.p. 149.5–150.3 8C. IR (cmÀ1, KBr):
n
3102,
White crystal, m.p. 114.8–116.0 8C. IR (cmÀ1, KBr):
n
3112,
2967, 1591, 1374, 1185, 840, 800; 1H NMR (CDCl3, 400 MHz)
d:
3071, 1589, 1492, 1191, 839, 784; 1H NMR (CDCl3, 400 MHz)
8.08–8.05 (m, 4H), 7.33–7.29 (m, 4H); 19F NMR (CDCl3, 376 MHz)
d
d
:
:
7.96–7.94 (d, J = 8.8 Hz, 4H), 7.62–7.60 (d, J = 7.2, 4H), 1.36 (s, 18H);
19F NMR (CDCl3, 376 MHz)
100 MHz) d: 160.24, 131.74, 129.83, 126.51, 35.58, 30.97; HRMS
d
: À37.6 (s, 1F); 13C NMR (CDCl3,
À36.42 (s, 1F), À98.36 (s, 2F); 13C NMR (CDCl3, 100 MHz)
d
: 168.53
(d, J = 259 Hz), 133.12 (d, J = 10.3 Hz), 130.46, 117.24 (d,
J = 23.1 Hz); HRMS (EI): calculated for C12H8F3NO4S2: 350.9847;
found: 350.9850.
(EI): calculated for C20H26FNO4S2: 427.1287; found: 427.1283.
4.2.10. N-fluoro-p-methylsulfonimide (2g)
White crystal, m.p. 113.1–113.8 8C. IR (cmÀ1, KBr):
n
3096,
4.2.2. N-fluoro-p-fluorobenzenesulfonimide (2b)
3069, 2925, 1593, 1489, 1192, 814, 780; 1H NMR (CDCl3, 400 MHz)
White crystal, m.p. 142.8–143.9 8C. IR (cmÀ1, KBr):
n
3103,
d: 7.90–7.88 (d, J = 8.4 Hz, 4H), 7.40–7.38 (d, J = 8.4 Hz, 4H), 2.48 (s,
1574, 1474, 1200, 833, 761; 1H NMR (CDCl3, 400 MHz)
d
: 7.97–7.94
6H); 19F NMR (CDCl3, 376 MHz)
400 MHz) d: 147.44, 131.70, 130.08, 129.92, 21.93; HRMS (EI):
d
: À37.629 (s, 1F); 13C NMR (CDCl3,
(d, J = 8.8 Hz, 4H), 7.61–7.59 (d, J = 8.8 Hz, 4H); 19F NMR (CDCl3,
376 MHz)
d
: À36.43 (s, 1F); 13C NMR (CDCl3, 400 MHz)
d
: 143.25,
calculated for C14H14FNO4S2: 343.0348; found: 343.0349.
132.88, 131.24, 129.97; HRMS (EI): calculated for C12H8Cl2FNO4S2:
382.9256; found: 382.9260.
4.2.11. N-fluoro-p-methoxyphenylsulfonimide (2h)
White crystal, m.p. 138.2–138.8 8C. IR (cmÀ1, KBr):
n
3121,
4.2.3. p-Chlorobenzene-1-sulfonyl fluoride (3b)
2976, 2948, 1592, 1498, 1199, 809, 785; 1HNMR (CDCl3, 400 MHz)
White crystal, m.p. 38.4–39.8 8C, yield: 55.8%. IR (cmÀ1, KBr):
n
d: 7.94–7.92 (d, J = 9.2 Hz, 4H), 7.04–7.02 (d, J = 8.8 Hz, 4H), 3.91 (s,
3099, 1574, 1492, 1214, 832, 787; 1H NMR (CDCl3, 400 MHz)
d
:
6H); 19F NMR (CDCl3, 376 MHz)
400 MHz) d: 165.51, 132.42, 125.65, 114.67, 55.91; HRMS (EI):
d
: À37.59 (s, 1F); 13C NMR (CDCl3,
7.97–7.95 (d, J = 8.4 Hz, 2H), 7.63–7.61 (d, J = 8.4 Hz, 2H); 19F NMR
(CDCl3, 376 MHz)
d
: 66.45 (s, 1F); 13C NMR (CDCl3, 100 MHz)
d
:
calculated for C14H14FNO6S2: 375.0247; found: 375.0245.
142.68, 133.25, 130.12, 129.87; HRMS (EI): calculated for
C6H4ClFO2S: 193.9605; found: 193.9606.
Acknowledgements
4.2.4. N-fluoro-p-bromobenzenesulfonimide (2c)
We thank the financial support of Guizhou Wengfu Group
Company, Chinese Postdoctor Foundation, and New Teacher
Foundation of Education Minister.
White crystal, m.p. 181.8–182.9 8C. IR (cmÀ1, KBr):
n 3112,
3071, 1589, 1492, 1191, 839, 784; 1H NMR (CDCl3, 400 MHz)
d:
7.87ꢀ7.85 (d, J = 8.8 Hz, 4H), 7.78–7.75 (d, J = 8.8 Hz, 4H); 19F NMR
(CDCl3, 376 MHz)
133.40, 132.98, 132.03, 131.17; HRMS (EI): calculated for
d
: À36.46 (s, 1F); 13C NMR (CDCl3, 400 MHz)
d:
References
C
12H8Br2FNO4S2: 470.8246; found: 470.8252.
[1] T. Ishimaru, S. Ogawa, E. Tokunaga, J. Fluorine Chem. 130 (2009) 1049–1053.
[2] J.C. Biffinger, H.W. Kim, S.G. DiMagno, ChemBioChem 5 (2004) 622–627.
[3] K.D. James, N.N. Ekwunbe, Tetrahedron 58 (2002) 5905–5908.
[4] M.L.P. Price, W.L. Jorgensen, J. Am. Chem. Soc. 122 (2000) 9455–9466.
[5] I. Hussain, M.A. Yawer, H. Go¨rls, L. Peter, Eur. J. Org. Chem. 3 (2008) 503–518.
[6] M. Giovanni, U. Daniela, S. Raul, P. Massimo, S. Silvio, Antimicrob. Agents Che-
mother. 44 (2000) 1186–1194.
[7] K. Mu¨ller, C. Faeh, F. Diederich, Science 317 (2007) 1881–1886.
[8] W. Zhang, J. Hu, Adv. Synth. Catal. 352 (2010) 2799–2804.
[9] R.P. Singh, J.M. Shreeve, Acc. Chem. Res. 37 (2004) 31–44.
[10] P.T. Nyffeler, S.G. Duro´n, M.D. Burkart, S.P. Vincent, C.H. Wong, Angew. Chem. Int.
Ed. 44 (2005) 192–212.
4.2.5. 4-Bromobenzene-1-sulfonyl fluoride (3c)
White crystal, m.p. 58.1–59.8 8C. IR (cmÀ1, KBr):
n
3096, 1574,
: 7.89–7.87 (d,
J = 8.4 Hz, 2H), 7.80–7.78 (d, J = 8.4 Hz, 2H); 19F NMR (CDCl3,
376 MHz) : 133.37,
: 66.36 (s, 1F); 13C NMR (CDCl3, 100 MHz)
1492, 1212, 827, 783; 1H NMR (CDCl3, 400 MHz)
d
d
d
133.12, 131.31, 129.83; HRMS (EI): calculated for C6H4BrFO2S:
239.9079; found: 239.9079.
[11] A. Rostami, Synlett 18 (2007) 2924–2925.
[12] S. Lectard, Y. Hamashima, M. Sodeoka, Adv. Synth. Catal. 352 (2010) 2708–2732.
[13] P. Kwiatkowski, T.D. Beeson, J.C. Conrad, D.W.C. MacMillan, J. Am. Chem. Soc. 133
(2011) 1738–1741.
[14] D.S. Reddy, N. Shibata, T. Horikawa, S. Suzuki, S. Nakamura, T. Toru, M. Shiro,
Chem. Asian J. 4 (2009) 1411–1415.
[15] Y. Hamashima, T. Suzuki, H. Takano, Y. Shimura, M. Sodeoka, J. Am. Chem. Soc. 127
(2005) 10164–10165.
[16] T. Ishimaru, N. Shibata, T. Horikawa, M. Shiro, Angew. Chem. Int. Ed. 47 (2008)
4157–4161.
4.2.6. N-fluoro-p-bromo-benzenesulfonimide (4c)
White crystal, m.p. 88.6–89.7 8C. IR (cmÀ1, KBr):
n
3096, 1574,
1492, 1212, 827, 783; 1H NMR (CDCl3, 400 MHz)
d: 8.63–8.49 (d,
J = 52.8 Hz, 1H), 7.87–7.85 (d, J = 8.8 Hz, 2H), 7.78–7.76 (d,
J = 8.8 Hz, 2H); 19F NMR (CDCl3, 376 MHz)
NMR (CDCl3, 100 MHz)
d
: À89.69 (s, 1F); 13C
d
: 133.34, 132.98, 130.89, 130.51; HRMS
(EI): calculated for C6H5BrFNO2S: 254.9188; found: 254.9188.

G. Chen et al. / Journal of Fluorine Chemistry 133 (2012) 155–159
159
[17] Y. Hamashima, K. Yagi, H. Takano, M. Sodeoka, J. Am. Chem. Soc. 124 (2002)
14530–14531.
[18] D.H. Paull, M.T. Scerba, E.A. Danforth, L.R. Widger, T. Lectka, J. Am. Chem. Soc. 130
(2008) 17260–17261.
[20] R.V. Andreev, G.I. Borodkin, V.G. Shubin, Russ. J. Org. Chem. 45 (2009) 1468–1473.
[21] E. Differding, H. Ofner, Synlett 3 (1991) 187–189.
[22] H. Teare, E.G. Robins, E. Arstad, S.K. Luthra, V. Gouverneur, Chem. Commun. 23
(2007) 2330–2332.
[19] H. Yasui, T. Yamamoto, T. Ishimaru, T. Fukuzumi, E. Tokunaga, J. Fluorine Chem.
132 (2011) 222–225.
[23] US5254732.
[24] WO9408955.