One-pot synthesis of arylfluoroalkylsulfoxides and study of their anomalous 19F NMR behavior

Article abstract of DOI:10.1016/j.jfluchem.2009.12.019

Arylfluoroalkylsulfoxides were successfully synthesized in one-pot when fluoroalkylsulfinate reacted with benzene and triflic anhydride in triflic acid and dichloromethane as the medium. The characteristics of their ¹⁹F NMR spectra were examine

Full text of DOI:10.1016/j.jfluchem.2009.12.019

Journal of Fluorine Chemistry 131 (2010) 433–438
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
One-pot synthesis of arylfluoroalkylsulfoxides and study of their
19
anomalous F NMR behavior
Cheng-Pan Zhang a, Zong-Ling Wang a,b, Qing-Yun Chen a, Chun-Tao Zhang b, Ji-Chang Xiao a,
*
a Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
b Hunan University of Chinese Medicine, Changsha, Hunan Province 410208, China
A R T I C L E I N F O
A B S T R A C T
Article history:
Arylfluoroalkylsulfoxides were successfully synthesized in one-pot when fluoroalkylsulfinate reacted
with benzene and triflic anhydride in triflic acid and dichloromethane as the medium. The characteristics
of their 19F NMR spectra were examined and analyzed for these structures. Electronic and steric effects of
Received 7 December 2009
Received in revised form 19 December 2009
Accepted 23 December 2009
Available online 4 January 2010
substituents at a- or b-position were revealed to be the main cause of the anomalous behavior of their
chemical shifts and coupling constants. Interactions between arylfluoroalkylsulfoxides and solvents
were also investigated and discussed.
Keywords:
ß 2009 Elsevier B.V. All rights reserved.
Arylfluoroalkylsulfoxides
Polyfluoroalkylsulfinylation
Chemical shifts
Coupling constants
Diastereotopic
1. Introduction
of the S55O group causes marked differences in chemical shift
between the two gem-fluorine atoms. We report herein an
Introducing fluorine-containing groups into organic com-
pounds and materials has attracted great interest in different
fields of chemistry such as material science, biochemistry,
pharmaceuticals and coordination chemistry. The fluorine-con-
taining substituents often conferred unusual physical properties
and enhanced chemical reactivities [1–4]. For example, the
introduction of trifluoromethanesulfinyl group into benzene
resulted in S-(trifluoromethyl)-diphenylsulfonium triflates with
significantly different properties and applications from its
precursor [5–9]. Little work on arylfluoroalkylsulfoxides has been
available in the literature, however. These fluorinated sulfoxides
were usually synthesized by the oxidation of corresponding
sulfides with peracids, a process that is hard to control because
a mixture of sulfoxide and sulfone compounds plus the initial
sulfide was often obtained. In 2001, Wakselman et al. reported that
aryltrifluoromethyl sulfoxides could directly be yielded from
substituted benzenes and triflinates in the triflic acid medium [10].
Nevertheless, the preparation of other kinds of arylfluoroalkyl
sulfoxides by this method is still undocumented. Aryl(iododi-
fluoromethyl)sulfoxides, the first optically active compounds with
polyfluoroalkyliodo groups, synthesized by Yagupolskii and
Matsnev exhibited characteristic 19F NMR spectra [11]. Chirality
improved procedure for the synthesis of arylfluoroalkylsulfoxides
and examine the 19F NMR spectra of the variously substituted
fluoroalkylsulfoxides.
2. Results and discussion
The introduction of a trifluoromethanesulfinyl group into
organic compounds using trifluoromethanesulfinyl chloride, or
sodium trifluoromethanesulfinate and phosphoryl chloride, suffers
from a low conversion efficiency problem due to the poor stability
and low reactivity of these reagents [12–14]. Wakselman et al.
consequently improved the method through the preparation of
aryltrifluoromethyl sulfoxides from substituted benzenes and
triflinates in the triflic acid medium [10]. Triflic anhydride and
triflic acid were employed as activated reagents instead of
commonly used acyl chloride or phosphoryl chloride. According
to the literature, this method was effective for trifluoromethane-
sulfinylation of substituted aromatic compounds [10]. Application
of this method to benzene itself, however, resulted in polymeric
reactions. It was found that when sodium 2-chloro-1,1,2,2-
tetrafluoroethanesulfinate reacted with benzene and triflic anhy-
dride in triflic acid at room temperature, the system became
ineffectual. 19F NMR analyses of the reaction mixture showed the
formation of undesired polyarylenesulfonium salts [15–17]. The
yield of 1-(2-chloro-1,1,2,2-tetrafluoroethylsulfinyl)benzene (1d)
was only 20% after 23 h, although the polyfluoroalkylsulfinate salt
* Corresponding author. Tel.: +86 21 54925340; fax: +86 21 64166128.
E-mail address: jchxiao@mail.sioc.ac.cn (J.-C. Xiao).
0022-1139/$ – see front matter ß 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2009.12.019

434
C.-P. Zhang et al. / Journal of Fluorine Chemistry 131 (2010) 433–438
Table 1
Table 2
Preparation of 1-(2-chloro-1,1,2,2-tetrafluoroethylsulfinyl)benzene (1d)
Polyfluoroalkylsulfination of aromatic compounds
Yielda (%)
Entry
R
RfSO2Na
Time (h) Yielda (%)
Entry
RfSO2Na:Tf2O:TfOH
Time (h)
Solvent
1
2
3
4
1:1.1:10
1:1.1:10
1:0:10
23
38
67
67
–
20
CH2Cl2
CH2Cl2
CH2Cl2
30
Trace
0
1:1.0:2.2
1
2
H
HCF2
1a
1b
1c
1d
19
19
36
38
41
41
25
10
30
23
44
28
37
30
60
35
41
21
34
–
a
Isolated yield.
H
BrCF2
3
H
CF3CF2
ClCF2CF2
4
H
b
5
H
C3H3N2CF2CF2 1e
PhOCF2CF2 1f
ClCF2CF2CF2CF2 1g
was completely consumed (entry 1, Table 1). To optimize the
reaction system, dichloromethane was added as part of the
medium. It was found that the polymerization reaction was
efficiently inhibited, giving 1d in 30% yield (entry 2, Table 1).
However, longer reaction time was needed under this reaction
condition. The polyfluoroalkylsulfinylation was also tremendously
influenced by the amount of Tf2O and TfOH. Only trace of 1d was
detected if no triflic anhydride was added at room temperature
(entry 3, Table 1). Sufficient TfOH was necessary for the formation
of 1d (entry 4, Table 1).
6
H
7
H
8
Ph
Ph
HCF2
1h
1i
–
9
10c
ClCF2CF2
4-PhC6H4 ClCF2CF2
a
Isolated yield.
b
c
Sodium 1,1,2,2-tetrafluoro-2-(1H-imidazol-1-yl)ethanesulfinate.
Determined by 19F NMR.
than those in 1a (Fig. 1). The bromine atom attached directly to CF2
makes the two gem-fluorine atoms so different that the JFF
2
In order to investigate the applicability of this method, we
extended the reaction to the synthesis of other arylfluoroalk-
ylsulfoxides. 1-(difluoromethylsulfinyl)benzene (1a) was prepared
in 44% yield after 19 h from sodium difluoromethanesulfinate and
benzene using triflic acid and dichloromethane as medium (entry
1, Table 2). Similar results were obtained in the case of sodium
bromodifluoromethanesulfinate and sodium perfluoroethylsulfi-
nate (entries 2 and 3, Table 2). With increased length of the
polyfluoroalkyl chain, polyfluoroalkylsulfinylation reactions be-
tween benzene and polyfluoroalkylsulfinate were also successful,
giving the desired sulfoxides 1e, 1f and 1g in moderate yield
(entries 5–7, Table 2). When diphenyl was employed as the
substrate, the reaction stopped at the monofluoroalkylsulfinyla-
tion stage, giving para-substituted 1h and 1i as the only product
(entries 8 and 9, Table 2). However, no sulfinylated product was
observed in the case of terphenyl (entry 10, Table 2), as confirmed
by 19F NMR.
coupling constant is raised to 145.3 Hz for 1b compared to
2JFF = 5.1 Hz for 1a. This is also the reason that the chemical shift of
one fluorine atom in 1b is À52.9 ppm and the other À54.9 ppm.
As shown in Fig. 2, when the fluorinated carbon was attached to
the
between the two diastereotopic fluorines at the
adjacent to the S55O group were observed in 1c–f. For example,
in 1c, the chemical shifts for the two -CF2 fluorine nuclei were
À115.6 and À126.1 ppm, respectively. Substitution with a weaker
electronegative species relative to fluorine atoms at the -position
has a mild deshielding impact on the -CF2 group. For example,
when the ClCF2 group instead of CF3 was employed to bond to
CF2, the chemical shift of
-CF2 moved to the lower field (À109.7
and À121.9 ppm). Similar results were also found in 1e and 1f. As
was the case in 1b, stronger electronegative substituents at the
position greatly deshielded the two -CF2 fluorine nuclei, leading
a
-CF2 group, large differences up to 11 ppm in chemical shift
a-position
a
b
a
a
-
a
b
-
b
The chemical shift and coupling constant of CF2 adjacent to the
S55O group were dramatically influenced by its substituents. For
example, the two fluorine nuclei of the CF2 group in 1a both
appeared upfield at À119.1 ppm and the ones in 1b shifted to
downfield at À52.9 and À54.9 ppm, respectively (Fig. 1), indicating
that the fluorine nuclei were sharply deshielded by the bromine
to lower field in chemical shift (1d–f in Fig. 2). Chlorine displayed
the largest deshielding effect compared to phenoxyl and imida-
zolyl function groups in these systems. But unnoticeable difference
was observed in chemical shift between the two fluorine nuclei at
the
b-position in 1d–f. This may be resulted from the longer
distance between the fluorine nuclei and the optically active S55O
atom at
a
-position in 1b [18]. Further investigations showed that
group. A sulfinyl group was difficult to create diastereotopic
geminal coupling constants between the two fluorine atoms in 1a
and 1b are markedly different. The chiral nature of the S55O group
makes a favorable diastereotopic environment for the two fluorine
atoms to differentiate, leading to that the two diastereotopic
fluorines in 1b possess larger observed geminal coupling constants
environments for the two fluorine nuclei at b-position (1d). The
steric effect which strengthens the diastereotopic environments of
the fluorine nuclei by phenoxyl group and imidazolyl function was
also substantially weakened by the increased spacious separation
between the fluorine nuclei and the S55O group. As a result, only
Fig. 1. 19F NMR spectra of the CF2 group in 1a and 1b in CDCl3 (282 MHz).

C.-P. Zhang et al. / Journal of Fluorine Chemistry 131 (2010) 433–438
435
Fig. 2. 19F NMR spectra of the
a-CF2 group and the b-CF2 or CF3 group in 1c–f in CDCl3 (282 MHz).
1 ppm difference of
determined in 1e and 1f. In addition, coupling constants of the
fluorine nuclei at both - and -positions were quite specific in 1c–
f. As shown in Fig. 2, geminal coupling constants between the two
diastereotopic fluorines at the -position for all these compounds
were between 230 and 245 Hz whereas the range of 2JFF coupling
constants between the two fluorine nuclei at the -position was
from 0 to 230 Hz. 3JFF coupling constants for diastereotopic fluorine
nucleus between - and - positions in these compounds were
also significantly distinguished. To the best of our knowledge,
vicinal F–F coupling constants were mainly dictated by torsional
angles between the coupled nuclei. A Karplus-type dependence of
F–F three-bond coupling constants on the dihedral angle between
the coupling nuclei was confirmed empirically by Williamson et al.
b
-fluorine atoms in chemical shift was
[19]. Functional and steric groups at the
b
-position in 1d–f were
assumed to determine the optimal conformation of these fluorine
atoms. Different values of the optimal dihedral angles between the
coupled fluorine nuclei were simultaneously ascertained. These
optimal conformations would further restrict the transformation
of dihedral angle and thus lead to the coupled fluorine nucleus
having the characteristic coupling constants in 19F NMR spectra
[18]. Similar analysis can be made about the chemical shift and
coupling constants for other fluoroalkylsulfoxides such as 1g–i and
the same conclusions can be drawn.
We have however observed variations in fluorine chemical
shifts and coupling constants for these typical compounds
especially for 1a and 1h, in different solvents such as CDCl3,
CD3OD and acetone-d6. Taking 1a as an example, we found that
a
b
a
b
a
b

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C.-P. Zhang et al. / Journal of Fluorine Chemistry 131 (2010) 433–438
Fig. 3. 19F NMR spectra of 1a in different solvents.
variations in fluorine chemical shifts for these three solvents were
solvent effect as well as the hydrogen bond of 1a with different
solvent molecules seriously differentiates the diastereotopic
environments of the two fluorine nuclei and intensifies the
difference in chemical shift and coupling constants between the
fluorine atoms.
In addition, the chemical shift and 2JFF coupling constant of 1a in
CDCl3 were also affected by the addition of triflic acid. As shown in
Fig. 4, the 19F NMR spectrum of 1a in CDCl3 with the addition of
CF3SO3H (0.10 equiv.) exhibited higher upfield signals than the one
enormous, as shown in Fig. 3. The chemical shift for 1a in CDCl3
2
was À119.1 ppm with the geminal JFF coupling constant 5.1 Hz.
But in CD3OD the same quantities were found to be À122.1 and
2
À125.6 ppm, respectively, with the JFF coupling constant of
259.6 Hz. The larger difference in chemical shift between the two
fluorine nuclei of the same compound was also observed in
CD3COCD3. One of the fluorine nuclei appeared at À121.7 ppm, in a
little lower field than that in CD3OD. These results indicate that the
Fig. 4. 19F NMR spectra of 1a in CDCl3 with CF3SO3H.

C.-P. Zhang et al. / Journal of Fluorine Chemistry 131 (2010) 433–438
437
without CF3SO3H in the same solvent. In this case, almost the same
2JFF coupling constants were obtained. When the amount of triflic
acid was increased to 0.50 equiv., a doublet of doublets at
À120.3 ppm with the geminal F–F coupling of 259.9 Hz as well as
two-bond H–F coupling of 55.7 Hz from one fluorine and a broad
doublet at À118.4 ppm with two-bond F–F coupling from the other
fluorine were seen. The diastereotopic environment for each of the
two fluorine nuclei could further be altered by increasing the
amount of CF3SO3H. About 5 ppm of difference between the two
fluorine nuclei in chemical shift was found when 1.80 equiv. of
CF3SO3H was added into CDCl3. The 2JFF and 2JHF coupling constants
for the fluorine nucleus moving downfield to À115.0 ppm were
observed, exhibiting a doublet of doublets in its 19 F NMR spectrum.
These results led us further to suggest that the solvent effect and the
hydrogen bond interaction could markedly differentiate the two
fluorine nuclei adjacent to the diastereotopic S55O group.
129.5, 126.7. MS (EI, m/z, %): 260 (M+, 1.99), 125 (100.00), 97
(26.93), 77 (33.29), 51(20.22). IR (KBr): 3067, 1584, 1477, 1448,
1257, 1178, 1122, 1064, 1017, 902, 803, 749, 688, 485 cmÀ1. Anal.
calcd. for C8H5ClF4OS: C, 36.87; H, 1.93; Found: C, 36.71; H, 2.00.
Difluoromethylsulfinylbenzene (1a): Colorless liquid. 1H NMR:
7.73 (m, 2H), 7.63 (m, 3H), 6.04 (t, J = 55.8 Hz, 1H). 19F NMR:
À119.1 (dd, J = 55.8 Hz, J = 5.1 Hz, 2F).
d
d
Bromodifluoromethylsulfinylbenzene (1b): Colorless liquid. 1H
NMR:
J = 145.3 Hz, 1F), À54.9 (d, J = 145.3 Hz, 1F).
Perfluoroethylsulfinylbenzene (1c): Light yellow liquid. 1H NMR:
d
7.81 (d, J = 7.8 Hz, 2H), 7.64 (m, 3H). 19F NMR:
d
À52.9 (d,
d
7.81 (d, J = 7.4 Hz, 2H), 7.65 (m, 3H). 19F NMR:
d
À79.1 (s, 3F),
À115.6 (d, J = 243.3 Hz, 1F), À126.1 (d, J = 243.3 Hz, 1F). 13C NMR:
d
134.7, 133.8, 129.5, 126.6. MS (EI, m/z, %): 244 (M+, 2.20), 125
(100.00), 97 (32.36), 77 (39.19), 51 (24.67). IR (KBr): 3066, 1584,
1478, 1448, 1333, 1223, 1169, 1127, 1104, 1065, 946, 749, 688,
522, 481 cmÀ1. Anal. calcd. for C8H5F5OS: C, 39.35; H, 2.06; Found:
C, 38.92; H, 1.93.
3. Conclusion
[1,1,2,2-Tetrafluoro-2-(1H-imidazol-1-yl)ethylsulfinyl]benzene
In conclusion, in the present work, we have developed an
improved method for the synthesis of arylpolyfluoroalkylsulf-
oxides. With fluoroalkylsulfinates reacting with benzene and triflic
anhydride in triflic acid and dichloromethane as the medium, this
method enables us to prepare various arylfluoroalkylsulfoxide
compounds in one-pot. Meanwhile, 19F NMR spectrum features of
these new compounds were carefully examined and analyzed.
(1e): Colorless liquid. 1H NMR:
d
7.83 (m, 1H), 7.77 (d, J = 7.8 Hz,
2H), 7.63 (m, 3H), 7.20 (s, 2H). 19F NMR:
d
À91.4 (dd, J = 227.9 Hz,
J = 7.2 Hz, 1F), À92.4 (dd, J = 227.9 Hz, J = 3.1 Hz, 1F), À112.2 (d,
J = 240.2 Hz, 1F), À124.9 (dd, J = 240.2 Hz, J = 7.2 Hz, 1F). 13C NMR:
d
134.7, 133.8, 130.7, 129.5, 126.6, 126.5, 116.2. MS (EI, m/z, %): 292
(M+, 4.24), 125 (100.00), 97 (17.17), 90 (12.58), 77 (22.18), 51
(12.92). IR (KBr): 3125, 3067, 1524, 1483, 1447, 1382, 1299, 1245,
Electronic and steric effects of substituents at
a- or
b
-position
1176, 1127, 1062, 966, 888, 819, 752, 689, 653, 515, 452 cmÀ1
.
were identified to be the main cause of the different behavior in
chemical shift and coupling constants. Interactions between
substrates and solvents were also found to play an important role
in their anomalous 19F NMR behavior. Further studies on the
nature of these effects from both experimental and computational
perspectives are in progress.
Anal. calcd. for C11H8F4N2OS: C, 45.21; H, 2.76; N, 9.59; Found: C,
45.48; H, 2.89; N, 9.92.
(1,1,2,2-Tetrafluoro-2-phenoxyethylsulfinyl)benzene (1f): Color-
less liquid. 1H NMR:
d
7.85 (d, J = 7.3 Hz, 2H), 7.64 (m, 3H), 7.41 (t,
J = 7.7 Hz, 2H), 7.28 (m, 3H). 19F NMR:
d
À80.2 (dd, J = 141.2 Hz,
J = 8.2 Hz, 1F), À81.2 (ddd, J = 141.2 Hz, J = 5.1 Hz, J = 4.1 Hz, 1F),
À114.5 (dd, J = 232.0 Hz, J = 8.3 Hz, 1F), À125.1 (ddd, J = 232.0 Hz,
4. Experimental
J = 5.1 Hz, J = 4.1 Hz, 1F). 13C NMR:
d 133.4, 129.7, 129.3, 126.9,
126.8, 126.8, 121.8. MS (EI, m/z, %): 318 (M+, 17.62), 125 (100.00),
97 (12.55), 77 (31.22), 65 (8.30), 51 (9.96). IR (KBr): 3066, 1591,
1492, 1447, 1326, 1208, 938, 747, 688, 482 cmÀ1. Anal. calcd. for
4.1. General
Unless otherwise stated, NMR spectra were recorded in
C
14H10F4O2S: C, 52.83; H, 3.17; Found: C, 53.15; H, 3.29.
(4-Chloro-1,1,2,2,3,3,4,4-octafluorobutylsulfinyl)benzene
deuterated chloroform at 300 MHz (1H NMR) and 282 MHz (19
F
(1g):
NMR). 13C NMR spectra were recorded at 75 or 100 MHz in CDCl3.
All chemical shifts were reported in ppm relative to TMS and CFCl3
(positive for downfield shifts) as external standards. All coupling
constants are reported in hertz. The solvent CH2Cl2 was distilled
from CaH2 before use. All starting fluoroalkylsulfinate salts were
prepared by using the known procedures [20–25].
Light yellow liquid. 1H NMR:
3H). 19F NMR:
d
7.81 (d, J = 7.8 Hz, 2H), 7.65 (m,
d
À68.0 (t, J = 13.4 Hz, 2F), À111.2 (d, J = 244.3 Hz,
1F), À118.3–121.1 (m, 4F), À122.5 (dm, J = 244.3 Hz, 1F). 13C NMR:
d
135.0, 133.7, 129.4, 126.7. MS (EI, m/z, %): 360 (M+, 0.94), 125
(100.00), 97 (26.29), 77 (30.36), 51 (28.46). IR (KBr): 3068, 1584,
1477, 1448, 1309, 1198, 1143, 1104, 1066, 1043, 949, 799, 774,
750, 703, 687, 667, 492, 482, 433 cmÀ1
.
Anal. calcd. for
10H5ClF8OS: C, 33.30; H, 1.40; Found: C, 33.57; H, 1.51.
1-(Difluoromethylsulfinyl)-4-phenylbenzene (1h): Colorless sol-
4.2. Typical procedure for the preparation of 1a–i
C
Sodium 2-chloro-1,1,2,2-tetrafluoroethanesulfinate (0.685 g,
3.08 mmol) was placed in a 25 mL round bottom flask equipped
id. 1H NMR:
J = 55.3 Hz, 1H). 19F NMR:
d 7.81 (m, 4H), 7.62 (m, 2H), 7.47 (m, 3H), 6.09 (t,
d
À119.1 (d, J = 55.3 Hz, 2F). 13C NMR:
d
with
a
magnetic stir bar and
a
nitrogen inlet. Anhydrous
146.0, 139.3, 135.2, 129.1, 128.5, 128.3, 127.3, 126.0, 121.0 (t,
J = 289.9 Hz, CF2H). MS (EI, m/z, %): 252 (M+, 4.98), 201 (100.00),
152 (24.72). IR (KBr): 3857, 3747, 3678, 3652, 1592, 1561, 1480,
1451, 1396, 1256, 1124, 1094, 1056, 1045, 1005, 846, 838, 781,
763, 691, 655, 525, 509, 488 cmÀ1. Anal. calcd. for C13H10F2OS: C,
61.89; H, 4.00; Found: C, 62.15; H, 4.12.
dichloromethane (5 mL) and triflic acid (2.70 mL, 30.7 mmol)
were added under nitrogen atmosphere. After stirring for 5 min,
benzene (0.60 mL, 6.69 mmol) and triflic anhydride (0.60 mL,
3.55 mmol) were introduced. The reaction system was kept
stirring at room temperature for 38 h. Then the reaction mixture
was poured into ice-water and neutralized by a NaHCO3 solution,
extracted with diethyl ether (50 mL), washed with water (3Â
20 mL) and dried over anhydrous Na2SO4. The crude product was
purified by flash column chromatography on silica gel using
petroleum ether/diethyl ether (10:1) as the eluent. At last, 0.243 g
of 1d (0.93 mmol) was obtained as a light yellow liquid (yield:
1-(2-Chloro-1,1,2,2-tetrafluoroethylsulfinyl)-4-phenylbenzene
(1i): Colorless solid. 1H NMR:
d 7.84 (m, 4H), 7.63 (m, 2H), 7.48 (m,
3H). 19F NMR:
d
À66.5 (dd, J = 5.1 Hz, 2F), À109.7 (dm, J = 233.1 Hz,
1F), À121.9 (dt, J = 233.1 Hz, J = 5.1 Hz, 1F). 13C NMR:
d 146.8,
139.2, 133.7, 129.1, 128.7, 128.1, 127.4, 127.2. MS (EI, m/z, %): 336
(M+, 0.75), 201 (100.00), 152 (22.69). IR (KBr): 3063, 3033, 1593,
1561, 1481, 1450, 1399, 1256, 1147, 1119, 1103, 1073, 1053, 1016,
902, 840, 800, 761, 719, 697, 657, 558, 511, 491, 462 cmÀ1. Anal.
calcd. for C14H9ClF4OS: C, 49.94; H, 2.69; Found: C, 50.44; H, 2.83.
30%). 1H NMR:
d d
7.81 (d, J = 7.8 Hz, 2H), 7.65 (m, 3H). 19F NMR:
À66.6 (dd, J = 5.1 Hz, J = 4.5 Hz, 2F), À109.8 (dm, J = 233.0 Hz, 1F),
À121.9 (dt, J = 233.0 Hz, J = 5.1 Hz, 1F). 13C NMR:
d 135.3, 133.7,

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C.-P. Zhang et al. / Journal of Fluorine Chemistry 131 (2010) 433–438
[9] Y. Mace´, B. Raymondeau, C. Pradet, J.-C. Blazejewski, E. Magnier, Eur. J. Org. Chem.
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We thank the Chinese Academy of Sciences (Hundreds of
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