Facile synthesis of (E)-β-(trifluoromethyl)styrenes from halothane (HCFC-123B1)

Article abstract of DOI:10.1016/j.jfluchem.2014.07.018

A practical and convenient synthesis of (E)-β-(trifluoromethyl)styrenes has been achieved by the reaction of commercially available halothane (HCFC-123B1) and hydrazones prepared in advance in situ, in the presence of 1,2-ethylenediamine and a catalytic amount of CuCl₂·2H₂O at room temperature. The products showed acceptable to high yields and high to excellent stereoselectivity. This handy synthetic method provided easy access to a variety of (E)-β-(trifluoromethyl)styrenes.

Full text of DOI:10.1016/j.jfluchem.2014.07.018

Journal of Fluorine Chemistry 171 (2015) 169–173
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Facile synthesis of (E)-b-(trifluoromethyl)styrenes from halothane
(HCFC-123B1)
*
Kensuke Hirotaki, Genyu Kawazoe, Takeshi Hanamoto
Department of Chemistry and Applied Chemistry, Saga University, Honjyo-machi 1, Saga 840-8502, Japan
A R T I C L E I N F O
A B S T R A C T
Article history:
A practical and convenient synthesis of (E)-b-(trifluoromethyl)styrenes has been achieved by the
Received 22 May 2014
reaction of commercially available halothane (HCFC-123B1) and hydrazones prepared in advance in situ,
in the presence of 1,2-ethylenediamine and a catalytic amount of CuCl2Á2H2O at room temperature. The
products showed acceptable to high yields and high to excellent stereoselectivity. This handy synthetic
Received in revised form 15 July 2014
Accepted 23 July 2014
Available online 1 August 2014
method provided easy access to a variety of (E)-
b
-(trifluoromethyl)styrenes.
ß 2014 Elsevier B.V. All rights reserved.
Keywords:
2-Bromo-2-chloro-1,1,1-trifluoroethane
(halothane, HCFC-123B1)
Hydrazone
Cupper(I) chloride
1,2-Ethylenediamine
(E)-b-(trifluoromethyl)styrene
1. Introduction
alkenes have incorporated this methodology. As much as this type
of reaction adequately addresses the issue of stereoselectivity, the
use of relatively expensive reagents remains a major drawback.
Besides the aforementioned methodologies, there also exists a
different catalytic olefination reaction developed mainly by
Nenajdenko et al. (type III) [29–32]. Specifically, his group has
Considering the richness of the trifluromethylaryl moiety in
biologically active molecules and functional materials, the selec-
tive introduction of trifluoromethyl (CF3) substituents at specific
positions of aromatic rings is an important synthetic transforma-
tion [1]. Thus, various methods for incorporating CF3 into aromatic
rings have recently been developed by many groups [2–6]. On the
other hand, the corresponding selective introduction of trifluor-
omethyl (CF3) substituents at specific positions in olefins has
received relatively less attention so far. However, the approach
toward such transformation also has gradually evolved over the
last several years.
One of the traditional methods for the preparation of trifluor-
omethylated alkenes employs the Wittig- and/or Julia–Kocienski
reaction involving carbonyl compounds (Scheme 1, Type I) [7–11].
However, this type of reaction has mainly two disadvantages: (i) low
stereoselectivity and (ii) narrow scope of substrates (aromatic
aldehydes are employed, in general). Another method involves the
transition-metal-mediated coupling reaction (Type II) [12–28].
Taking the incessant emergence of well-elaborated procedures into
account, it appears that the syntheses of trifluoromethylated
already reported the efficient synthesis of
b-halo-b-(trifluoro-
methyl)styrenes [29]. Their method involves the initial formation of
hydrazones of carbonyl compounds followed by the treatment with
polyhalogenalkanes in the presence of a base and catalytic amount
of copper salt. However, the development of the relevant
b-
(trifluoromethyl)styrenes remains unexplored. Therefore, we con-
sidered the use of halothane (HCFC-123B1) instead of the
polyhalogenalkanes, employed by Nenajdenko et al., to afford the
corresponding
b-(trifluoromethyl)styrenes under similar reaction
conditions [33]. We report herein the practical synthesis of
b-
(trifluoromethyl)styrenes using halothane as a trifluoroethylidene
(CF3CH55) source.
2. Results and discussion
4-Chloro-benzaldehyde (1a) was reacted with an excess
amount of hydrazine hydrate (3.0 equiv.). The reaction readily
proceeded to afford the corresponding hydrazone in quantitative
yield for 10 min at room temperature and monitored using TLC.
Then, 1,2-ethylenediamine (2.4 equiv.), halothane (2.0 equiv.), and
*
Corresponding author. Tel.: +81 952 28 8704; fax: +81 952 28 8548.
E-mail address: hanamoto@cc.saga-u.ac.jp (T. Hanamoto).
http://dx.doi.org/10.1016/j.jfluchem.2014.07.018
0022-1139/ß 2014 Elsevier B.V. All rights reserved.

170
K. Hirotaki et al. / Journal of Fluorine Chemistry 171 (2015) 169–173
Scheme 1. Previous synthesis of
b-(trifluoromethyl)styrenes.
a catalytic amount of CuCl (20 mol%) were successively added to
the reaction mixture. After the reaction mixture was stirred for 3 h
at room temperature, a small amount of the target olefin molecules
was observed along with the corresponding azine using GC–MS.
However, the conversion of the hydrazone was only 30% while the
unreacted hydrazone remained intact (entry 1). In order to
improve the percent conversion, we continued to explore different
reaction conditions. We observed that the input of a large amount
of hydrazine hydrate (5.0 equiv.) yielded a significant enhance-
ment in the conversion (entry 2). The use of a combination catalyst
system containing CuCl and a ligand (PPh3 or 1,10-phenanthroline)
led to either a similar or reduced conversion (entries 3 and 4).
Reducing the catalyst loading to 5 mol% did not essentially affect
the conversion (entries 5 to 7). However, increasing the amount of
1,2-ethylenediamine improved the conversion (entry 9). By
comparison, CuCl2Á2H2O was no less effective than CuCl (entry
10). Taking easy handling of the catalyst into account, we hereafter
adopted the use of CuCl2Á2H2O instead of CuCl. It is noteworthy
that the choice of solvent significantly influenced the conversion,
with ethylene glycol proving to be the optimal reaction solvent.
The use of ethylene glycol resulted in the complete conversion of
the hydrazone substrate and adequate reduction in the quantities
of byproducts. We opine that the hydrogen bonding between the
reaction in the cupper-chlorine intermediate [34]. Thus, we carried
out the reaction under the above reaction conditions to obtain the
desired product in 79% yield with a ratio of E/Z = 94/6 (entry 11).
Compared with the complete conversion, the isolated yield was not
as high as our expectation. We confirmed that the reaction itself
proceeded neatly. One of the reasons for the reduced isolated yield
was the difficulty in isolation owing to the volatility of the product
(Table 1).
With an optimized procedure in hand, we examined the
olefination of halothane using other aldehydes. For various
benzaldehydes, acceptable to high yields (45–95%) and high to
excellent (E)-stereoselectivity (93/7–98/2) were accomplished for
the synthesis of styrene derivatives, regardless of the electronic
nature of the substituents and substitution patterns on the
benzene ring. It is noteworthy that the free hydroxyl group on
the benzene ring did not necessarily retard the reaction albeit it led
to acceptable yields (entries 3, 7 and 8). In fact, in these cases the
reaction did not proceed as cleanly as other substrates. For both
a-
and -naphthaldehyde, high yields and excellent (E)-stereoselec-
b
tivity were also achieved (entries 11 and 12). On the other hand,
attempts to employ undecanal as an aliphatic aldehyde and
cinnamaldehyde as an
a,b-unsaturated aldehyde under the same
conditions yielded the complex reaction mixtures (entries 13 and
14). In addition, benzophenone as a ketone was also not suitable
solvent and chlorine presumably facilitated the
b
-elimination
Table 1
Optimization of reaction conditionsa.
Entry
CF3CHClBr (equiv.)
H2NNH2ÁH2O (equiv.)
EDAb (equiv.)
Cat. Cu (mol%)
Temp. (8C)
Time (h)
2-Conv.c (%)
1
2
2
2
2
2
6
6
6
6
6
6
6
3
5
5
5
5
5
5
5
5
5
5
2.4
2.4
2.4
2.4
2.4
2.4
2.4
2.4
4.4
4.4
4.4
CuCl (20)
r.t.
3
3
3
3
3
3
3
5
3
3
1
30
CuCl (20)
r.t.
60
3
CuCl (20), PPh3 (20)
CuCl (20), Phend (20)
CuCl (20)
r.t.
63
4
r.t.
40
5
0-r.t.
0-r.t.
0-r.t.
0
76
6
CuCl (10)
73
7
CuCl (5)
79
8
CuCl (5)
72
9
CuCl (5)
0-r.t.
0-r.t.
0-r.t.
87
10
11e
CuCl2Á2H2O (5)
CuCl2Á2H2O (5)
84
100 (79)f,g
a
1a (1.0 equiv.) and hydrazine-monohydride were used.
1,2-Ethylenediamine.
b
c
d
e
f
Determined using GC–MS.
1,10-Phenanthroline.
Ethylene glycol was used instead of ethanol as a solvent.
Isolated yield.
E/Z = 94/6 as a diastereomer ratio determined using 19F NMR.
g

K. Hirotaki et al. / Journal of Fluorine Chemistry 171 (2015) 169–173
171
Table 2
Scope of substrates for the reaction involving various aldehydesa.
Entry
Aldehyde
3
Yield (%)b
E/Zc
1
2
4-Cl
3a
3b
3c
3d
3e
3f
79
46
54
95
67
95
58
45
54
74
80
94/6
93/7
93/7
98/2
97/3
98/2
95/5
98/2
97/3
98/2
98/2
4-OMe
4-OH
3
4
4-NO2
4-CN
5
6
4-Ph
7
3-OH
3g
3h
3i
8
2-OH
9
3,4-OMe
3,5-Me
10
11
3j
3k
CHO
12
13
3l
72
99/1
–
CHO
Undecanal
3m
CMd
14
15
Cinnamaldehyde
Benzophenone
3n
3o
CMd
0e,f
–
–
a
Reaction was carried out using 1 (1.0 equiv.), H2NNH2ÁH2O (5.0 equiv.), CF3CHClBr (6.0 equiv.), EDA (1,2-ethylenediamine, 4.4 equiv.), and CuCl2Á2H2O (5 mol%) in
ethyleneglycol (EG).
b
Isolated yield.
Determined using 19F NMR or GC–MS.
c
d
Complex mixture.
e
Corresponding hydrazone (2o) was prepared at 100 8C.
No reaction.
f
for this reaction, thereby leading to the recovering of the
corresponding hydrazone in quantitative yield (entry 15). Al-
though the reaction mechanism of this reaction was not fully
elucidated, we presumed that it should be similar to that
prescribed by Nenajdenko et al., involving the corresponding
Cu–carbene intermediate [31] (Table 1).
4.1. (E)-1-(4-chlorophenyl)-3,3,3-trifluoropropene (3a) [14]
A 25 mL two-neck flask equipped with a magnetic stir bar, a
stopcock and a three-way stopcock, was charged with 3.0 mL of
ethylene glycol, H2NNH2ÁH2O (73.0
mL, 1.50 mmol, 5.0 equiv.), 4-
chlorobenzardehyde 1a (42.0 mg, 0.299 mmol, 1.0 equiv.) and
stirred at room temperature for 10 min until the complete
consumption of 1a (checked by TLC and GC–MS) and generation
of the corresponding hydrazone. To this mixture was added
3. Conclusion
CF3CHClBr (190.0
mL, 1.80 mmol, 6.0 equiv.), 1,2-ethylenediamine
We developed a convenient synthetic route for obtaining (E)-b-
(88.0 L, 1.32 mmol, 4.4 equiv.). The flask was then immersed in
m
(trifluoromethyl)styrene derivatives in acceptable to high yields
with high to excellent stereoselectivity. The substrates required for
this reaction were easily available and inexpensive; moreover, the
procedure involved was simple and convenient. Although several
an ice bath. To this mixture was added CuCl2Á2H2O (2.6 mg,
0.017 mmol, 0.05 equiv.) and the resulting mixture was stirred for
1 h at room temperature. To the mixture was added distilled water
(5 mL), and the resulting mixture was extracted with Et2O (5 mL)
three times. The combined solution was dried over sodium
sulphate, concentrated in vacuo then the residual oil was purified
by chromatography on silica gel column [hexane as an eluent] to
give 3a as colorless oil (48.9 mg).
attractive preparations of (E)-b-(trifluoromethyl)styrene deriva-
tives have already been reported so far, we believe that our method
will fulfill the need of the research community, and serve as a
convenient synthetic tool.
Colorless oil: Yield 79% (48.9 mg, E/Z = 94/6); 1H NMR (CDCl3,
400 MHz)
J = 16.0, 6.7 Hz, 1H); 13C NMR (CDCl3, 101 MHz)
J = 6.2 Hz), 136.0, 131.9, 129.1, 128.7, 123.5 (q, J = 268.6 Hz), 116.4
d
7.50–7.30 (m, 4H), 7.09 (d, J = 16.0 Hz, 1H), 6.17 (dq,
4. Experimental
d
136.4 (q,
Infrared (IR) spectra are reported in cmÀ1
spectra were measured in CDCl3 solutions. Chemical shifts were
given by
relative to that of an internal Me4Si (TMS) for 1H NMR and
13C NMR spectra and hexafluorobenzene (C6F6) for 19F NMR spectra.
.
1H, 19F and 13C NMR
(q, J = 34.3 Hz); 19F NMR (CDCl3, 376 MHz)
d
À64.6 (d, J = 6.7 Hz);
d
GC–MS (EI, m/z, 70 eV) 206 (100, M+[35Cl]), 208 (33, M+[37Cl]), 171
(25), 151 (48), 137 (12), 101 (16), 75 (16), 51 (8).

172
K. Hirotaki et al. / Journal of Fluorine Chemistry 171 (2015) 169–173
4.2. (E)-1-(4-methoxyphenyl)-3,3,3-trifluoropropene (3b) [14]
White solid; Yield 46% (38.1 mg, E/Z = 93/7); 1H NMR (CDCl3,
(t, J = 7.5 Hz, 1H), 6.78 (d, J = 7.5 Hz, 1H), 6.38 (q, J = 15.9, 6.3 Hz,
1H), 5.09 (bs, 1H); 13C NMR (CDCl3, 101 MHz) 154.1, 132.8 (q,
J = 6.9 Hz), 131.0, 129.0, 123.9 (q, J = 268.9 Hz), 121.2, 120.8, 116.8
400 MHz)
d
7.40 (d, J = 8.8 Hz, 2H), 7.09 (d, J = 16.2 Hz, 1H), 6.91 (d,
(q, J = 33.8 Hz), 116.2; 19F NMR (CDCl3, 376 MHz)
d
À64.6 (d,
J = 8.8 Hz, 2H), 6.06 (dq, J = 16.2, 6.6 Hz, 1H), 3.84 (s, 3H); 13C NMR
(CDCl3, 101 MHz) 161.0, 137.1 (q, J = 6.3 Hz), 129.0, 126.1, 123.9 (q,
J = 268.9 Hz), 114.3, 113.4 (q, J = 33.8 Hz), 55.3; 19F NMR (CDCl3,
J = 4.1 Hz); GC–MS (EI, m/z, 70 eV) 188 (71, M+), 167 (39), 149
(100), 118 (55), 91 (24), 63 (13), 51 (10).
376 MHz)
d
À64.1(d, J = 6.6 Hz);GC–MS(EI, m/z,70 eV)202 (100), 187
4.9. (E)-1-(3,4-dimethoxyphenyl)-3,3,3-trifluoropropene (3i) [16]
Colorless oil: yield 54% (37.7 mg, E/Z = 97/3); 1H NMR (CDCl3,
(17), 183 (10), 159 (5), 151 (7), 139 (13), 119 (8), 109 (34), 89 (5), 63 (6).
4.3. (E)-1-(4-hydroxyphenyl)-3,3,3-trifluoropropene (3c) [18]
Pale yellow oil: yield 54% (50.0 mg, E/Z = 93/7); 1H NMR (CDCl3,
400 MHz)
d 7.08 (d, J = 16.0 Hz, 1H), 7.02 (d, J = 7.8 Hz, 1H), 6.96 (s,
1H), 6.86 (d, J = 7.8 Hz, 1H), 6.07 (dq, J = 16.0, 6.5 Hz, 1H), 3.91 (s,
6H); 13C NMR (CDCl3, 101 MHz) 150.6, 149.0, 137.2 (q, J = 6.9 Hz),
126.0, 123.7 (q, J = 268.3 Hz), 121.4, 113.1 (q, J = 33.8 Hz), 110.8,
400 MHz)
d 7.34 (d, J = 8.3 Hz, 2H), 7.07 (d, J = 16.1 Hz, 1H), 6.84 (d,
J = 8.3 Hz, 2H), 6.05 (dq, J = 16.1, 6.4 Hz, 1H), 4.49 (bs, 1H); 13C NMR
(CDCl3, 101 MHz) 157.0, 137.0 (q, J = 7.0 Hz), 129.3, 126.4, 123.9 (q,
J = 268.9 Hz), 115.8, 113.6 (q, J = 34.3 Hz); 19F NMR (CDCl3,
109.1, 55.4; 19F NMR (CDCl3, 376 MHz)
d
À64.1 (d, J = 6.5 Hz); GC–
MS (EI, m/z, 70 eV) 232 (100, M+), 217 (24), 189 (11), 169 (6), 149
(12), 125 (14), 91 (7), 51 (4).
376 MHz)
d
À64.2 (d, J = 6.4 Hz); GC–MS (EI, m/z, 70 eV) 188
(100, M+), 169 (15), 138 (21), 119 (25), 91 (11), 63 (8).
4.4. (E)-1-(4-nitrophenyl)-3,3,3-trifluoropropene (3d) [13]
White solid: yield 95% (123.6 mg, E/Z = 98/2); 1H NMR (CDCl3,
4.10. (E)-1-(3,5-dimethyphenyl)-3,3,3-trifluoropropene (3j)
Colorless oil: yield 74% (55.2 mg, E/Z = 98/2); IR (ATR) 1666,
1603, 1331, 1269, 1257, 1108, 969, 822, 687 cmÀ1; 1H NMR (CDCl3,
400 MHz)
d 7.30–7.00 (m, 4H), 6.17 (dq, J = 16.0, 6.7 Hz, 1H), 2.33
400 MHz)
d
8.27 (d, J = 8.4 Hz, 2H), 7.64 (d, J = 8.4 Hz, 2H), 7.23 (d,
(s, 6H); 13C NMR (CDCl3, 101 MHz) 138.5, 137.9 (q, J = 6.2 Hz),
133.3, 131.7, 125.4, 123.7 (q, J = 268.6 Hz), 115.4 (q, J = 34.2 Hz),
J = 16.3 Hz, 1H), 6.37 (dq, J = 16.3, 6.5 Hz, 1H); 13C NMR (CDCl3,
101 MHz) 148.5, 139.5, 135.4 (q, J = 6.9 Hz), 128.3, 124.2, 122.8 (q,
J = 269.8 Hz), 120.1 (q, J = 34.4 Hz); 19F NMR (CDCl3, 376 MHz)
21.2; 19F NMR (CDCl3, 376 MHz)
d
À64.5 (d, J = 6.7 Hz); GC–MS (EI,
m/z, 70 eV) 200 (100, M+), 185 (55), 165 (21), 131 (23), 115 (19), 91
(9), 77 (5), 51 (4); anal. calcd. for C11H11F3: C, 65.99; H, 5.54. Found:
C, 66.13; H, 5.29%.
d
À65.3 (d, J = 6.5 Hz); GC–MS (EI, m/z, 70 eV) 217 (60, M+), 187
(22), 151 (100), 109 (22), 102 (16), 75 (10), 51 (8).
4.5. (E)-1-(4-cyanophenyl)-3,3,3-trifluoropropene (3e) [15]
White solid: yield 67% (40.7 mg, E/Z = 97/3); 1H NMR (CDCl3,
4.11. (E)-1-(1-naphthyl)-3,3,3-trifluoropropene (3k) [21]
Colorless oil: yield 80% (58.8 mg, E/Z = 98/2); 1H NMR (CDCl3,
400 MHz)
d
7.70 (d, J = 8.2 Hz, 2H), 7.56 (d, J = 8.2 Hz, 2H), 7.13 (dm,
400 MHz) d 7.90–7.82 (m, 4H), 7.60 (dm, J = 8.6 Hz, 1H), 7.56–7.48
J = 16.3 Hz, 1H), 6.32 (dq, J = 16.3, 6.5 Hz, 1H); 13C NMR (CDCl3,
101 MHz) 137.6, 135.9 (q, J = 6.3 Hz), 132.7, 128.0, 122.9 (q,
J = 268.9 Hz), 119.4 (q, J = 34.4 Hz), 118.2, 113.5; 19F NMR (CDCl3,
(m, 2H), 7.32 (dm, J = 16.0 Hz, 1H), 6.32 (dq, J = 16.0, 6.4 Hz, 1H);
13C NMR (CDCl3, 101 MHz) 135.2 (q, J = 6.9 Hz), 133.6, 131.1, 131.0,
130.2, 128.8, 126.9, 126.3, 125.4, 124.8, 123.4 (q, J = 269.5 Hz),
376 MHz)
d
À64.1 (d, J = 6.5 Hz); GC–MS (EI, m/z, 70 eV) 197 (100,
123.2, 118.8 (q, J = 33.8 Hz); 19F NMR (CDCl3, 376 MHz)
d
À64.5 (d,
M+), 176 (20), 147 (30), 128 (17), 101 (10), 75 (12), 51 (7).
J = 6.4 Hz); GC–MS (EI, m/z, 70 eV) 222 (50, M+), 201 (20), 183 (10),
153 (100), 126 (4), 101 (4), 76 (5).
4.6. (E)-1-(4-biphenyl)-3,3,3-trifluoropropene (3f) [14]
4.12. (E)-1-(2-naphthyl)-3,3,3-trifluoropropene (3l) [21]
Pale yellow solid: yield 95% (64.7 mg, E/Z = 98/2); 1H NMR
(CDCl3, 400 MHz)
d
7.62 (t, J = 7.9 Hz, 4H), 7.54 (d, J = 7.9 Hz, 2H),
White solid: yield 72%, 53.0 mg (E/Z = 99/1); 1H NMR (CDCl3,
7.46 (t, J = 7.9 Hz, 2H), 7.39 (d, J = 7.9 Hz, 1H), 7.19 (d, J = 16.0 Hz,
1H), 6.24 (dq, J = 16.0, 6.4 Hz, 1H); 13C NMR (CDCl3, 101 MHz)
142.8, 140.1, 137.2 (q, J = 6.9 Hz), 132.3, 128.9, 128.0, 127.8, 127.5,
127.0, 123.7 (q, J = 268.9 Hz), 115.7 (q, J = 33.8 Hz); 19F NMR
400 MHz)
d 7.85–7.72 (m, 4H), 7.56 (d, J = 8.6 Hz, 1H), 7.55–7.45
(m, 2H), 7.29 (d, J = 16.0 Hz, 1H), 6.30 (dq, J = 16.0, 6.4 Hz, 1H); 13
C
NMR (CDCl3, 101 MHz) 137.7 (q, J = 6.8 Hz), 134.0, 133.2, 130.8,
129.1, 128.8, 128.4, 127.8, 127.1, 126.8, 123.7 (q, J = 268.9 Hz),
(CDCl3, 376 MHz)
d
À64.5 (d, J = 6.4 Hz); GC–MS (EI, m/z, 70 eV)
123.1, 116.0 (q, J = 33.8 Hz); 19F NMR (CDCl3, 376 MHz)
d
À64.4 (d,
248 (100, M+), 227 (6), 178 (21), 152 (8), 99 (3), 76 (4), 51 (2).
4.7. (E)-1-(3-hydroxyphenyl)-3,3,3-trifluoropropene (3g) [18]
Pale yellow solid: yield 58% (44.7 mg, E/Z = 95/5); 1H NMR
J = 6.4 Hz); GC–MS (EI, m/z, 70 eV) 222 (100, M+), 201 (24), 172 (8),
152 (27), 127 (4), 76 (4).
(CDCl3, 400 MHz) d 7.40–7.35 (m, 1H), 7.09 (d, J = 16.2 Hz, 1H), 7.03
Appendix A. Supplementary data
(d, J = 7.7 Hz, 1H), 6.92 (s, 1H), 6.85 (d, J = 7.8 Hz, 1H), 6.17 (dq,
J = 16.2, 6.5 Hz, 1H), 4.88 (s, 1H); 13C NMR (CDCl3, 101 MHz) 155.6,
137.2 (q, J = 6.8 Hz), 135.1, 130.2, 123.5 (q, J = 268.9 Hz), 120.5,
Supplementary material related to this article can be found, in the
online version, at http://dx.doi.org/10.1016/j.jfluchem.2014.07.018.
117.1, 116.3 (q, J = 34.3 Hz), 114.0; 19F NMR (CDCl3, 376 MHz)
d
À64.7 (d, J = 6.5 Hz); GC–MS (EI, m/z, 70 eV) 188 (100, M+), 167
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