Mild and metal-free trifluoromethylation and pentafluoroethylation of gem-difluoroalkenes with TMSCF3 and TMSCF2CF3

Article abstract of DOI:10.1016/j.tet.2015.08.016

A direct and efficient approach for the trifluoromethylation and pentafluoroethylation of 1,1-diaryl-2,2-difluoroethenes with TMSCF₃ and TMSCF₂CF₃ in the presence of TBAF was developed. The reactions proceeded smoothly und

Full text of DOI:10.1016/j.tet.2015.08.016

Tetrahedron xxx (2015) 1e8
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Mild and metal-free trifluoromethylation and pentafluoroethylation
of gem-difluoroalkenes with TMSCF3 and TMSCF2CF3
*
Guanyi Jin, Xuxue Zhang, Dan Fu, Wenpeng Dai, Song Cao
Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology (ECUST), Shanghai 200237, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A direct and efficient approach for the trifluoromethylation and pentafluoroethylation of 1,1-diaryl-2,2-
difluoroethenes with TMSCF3 and TMSCF2CF3 in the presence of TBAF was developed. The reactions
proceeded smoothly under mild reaction conditions to give the corresponding monotrifluoromethylated,
bistrifluoromethylated, monopentafluoroethylated and bispentafluoroethylated products in fair to good
yields, respectively, without the addition of metal catalyst.
Received 19 June 2015
Received in revised form 22 July 2015
Accepted 7 August 2015
Available online xxx
Ó 2015 Elsevier Ltd. All rights reserved.
Keywords:
Trifluoromethylation
Pentafluoroethylation
gem-Difluoroalkenes
(Trifluoromethyl)trimethylsilane
(Pentafluoroethyl)trimethylsilane
1. Introduction
gem-Difluoroalkenes have unique reactivities toward nucleo-
philes, which render them more useful in organic synthesis.8 It is
Trifluoromethylated alkenes are useful structural motifs that
have been widely used in pharmaceuticals, agrochemicals as well as
material science.1 Therefore, a variety of methods for nucleophilic,
electrophilic, and radical trifluoromethylation of alkenes with var-
ious trifluoromethylating reagents have been developed over the
past few years.2 However, drawbacks of these methods are the use
of expensive Togni’s or Umemoto’s reagents, transition-metal cat-
alysts and the handling of gaseous CF3X.3
well-known that the trifluoromethyl anion could be generated in
situ from TMSCF3 in combination with KF.9 Although the ‘naked’
trifluoromethyl carbanion is unstable and easily decomposes at
room temperature,4a we expected that the nucleophilic tri-
fluoromethylation of the polarized gem-difluoroalkenes with the
active CF3 anion species might take place. A survey of the literature
reveals that trifluoromethylation of CeF bond of arenes and alkenes
with trifluoromethylating reagents has been scarcely reported.10 In
continuation of our interest in the cleavage and functionalization of
the CeF bond,11 in this paper, we report a straightforward method
for the trifluoromethylation (pentafluoroethylation) of 1,1-diaryl-
2,2-difluoroethenes with TMSCF3 (TMSCF2CF3) in the presence of
TBAF under mild reaction conditions (Scheme 1). In addition, we
(Trifluoromethyl)trimethylsilane (TMSCF3), known as Rup-
pertePrakash reagent, is a powerful and versatile reagent for facile
introduction of the trifluoromethyl moiety into organic molecules.4
€
In 2011, Brase reported an efficient method for the tri-
fluoromethylation of alkenyl iodides and bromides using a system
of TMSCF3/CuI/KF.5 Buchwald developed a palladium-catalyzed
trifluoromethylation of various cyclohexenyl triflates and non-
aflates with TMSCF3 and a variety of trifluoromethylated cyclo-
hexenes were obtained in good to high yields.6 Yu described
also report a novel Pd-catalyzed trifluoromethylation of N-(a-flu-
orovinyl)azoles with TMSCF3 (Scheme 6).
a copper-catalyzed trifluoromethylation of internal olefins, a-oxo-
ketene dithioacetals, using Cu(OH)2 as a catalyst and TMSCF3 as
a trifluoromethylating reagent to afford the corresponding multi-
functionalized tetrasubstituted CF3 olefins and trifluoromethylated
N-heterocycles.7
Ar
Ar
CF3
CF3
Ar
Ar
CF3
F
TMSCF3 (3.0 equiv)
TBAF (1.5 equiv)
THF, 30 oC, Ar
TMSCF3 (1.2 equiv)
TBAF (1.2 equiv)
THF, 60 oC, Ar
F
F
Ar
Ar
CF2CF3
F
Ar
Ar
CF2CF3
Ar
Ar
TMSCF2CF3 (5.0 equiv)
TMSCF2CF3 (2.5 equiv)
TBAF (1.2 equiv)
THF, 25 oC, Ar
TBAF (2.0 equiv)
THF, 25 oC, Ar
CF2CF3
* Corresponding author. Tel.: þ86 21 64253452; e-mail address: scao@ecust.edu.
Scheme 1. Trifluoromethylation and pentafluoroethylation of gem-difluoroalkenes.
cn (S. Cao).
http://dx.doi.org/10.1016/j.tet.2015.08.016
0040-4020/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Jin, G.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.08.016

2
G. Jin et al. / Tetrahedron xxx (2015) 1e8
2. Results and discussion
Our initial investigations focused on the reaction between 4,40-
(2,2-difluoroethene-1,1-diyl)bis(fluorobenzene) 1a and TMSCF3
using TBAF as fluoride source (Table 1). The results indicated that
the amounts of TMSCF3, TBAF and reaction temperature had sig-
nificant effects on the yields and ratios of two types of products,
monotrifluoromethylated product 2a and bistrifluoromethylated
product 3a. However, no matter what the reaction conditions were,
a mixture of 2a and 3a along with the recovered starting material
1a were obtained. Further decreasing the amount of TMSCF3 to
1.0 equiv or increasing the amount of TMSCF3 to 4.0 equiv, re-
spectively, could not provide the sole product (2a or 3a) (entries 2
and 6). Fortunately, the mixture of 2a and 3a could be separated by
column chromatography. Consequently, the optimal reaction con-
ditions for the synthesis of 2a are as follows: 1.2 equiv of TMSCF3,
1.2 equiv of TBAF, and THF as the solvent at 60 ꢀC (entry 3). The
optimal reaction conditions for the synthesis of 3a are as follows:
3.0 equiv of TMSCF3, 1.5 equiv of TBAF, and THF as the solvent at
30 ꢀC (entry 15).
a Reaction conditions: 1a–g (1.0 mmol), TMSCF3 (1.2 mmol), TBAF (1 M in
THF, 1.2 mmol), THF (5 mL), 60 °C, 0.5–1 h, Ar. Isolated yields (some
b
products are volatile and are lost during the chromatographic purification and
rotary evaporation). c 3.0 mmol TMSCF3 was used.
Scheme 2. Monotrifluoromethylation of 1,1-diaryl-2,2-difluoroethenes with
TMSCF3.a,b
Table 1
Optimization of the reaction conditions for the synthesis of 2a and 3aa
Entry TMSCF3 (equiv) TBAF (equiv) Temp (ꢀC) Yield 2ab (%) Yield 3ab (%)
1
2
3
4
5
6
7
8
0.5
1.0
1.2
2.0
3.0
4.0
1.2
1.2
1.2
3.0
3.0
3.0
3.0
3.0
3.0
3.0
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.0
1.5
1.2
1.2
1.2
1.2
1.2
1.5
2.0
60
60
60
60
60
60
30
60
60
10
20
30
40
50
30
30
14
63
85
80
72
69
65
81
76
65
63
59
53
69
34
41
0
17
15
20
28
31
27
17
20
2
31
43
38
31
56
52
a Reaction conditions: 1a–h (1.0 mmol), TMSCF3 (3.0 mmol), TBAF (1 M in
b
THF, 1.5 mmol), THF (5 mL), 30 °C, 0.5–1 h, Ar. Isolated yields (some
products are volatile and are lost during the chromatographic purification and
rotary evaporation). c 5.0 mmol TMSCF3 was used.
9
10
11
12
13
14
15
16
Scheme 3. Bistrifluoromethylation of 1,1-diaryl-2,2-difluoroethenes with TMSCF3.a,b
The CF3CF2-substituted moiety serves as a useful structural
element in many pharmaceuticals and agrochemicals. Much re-
cent attention has been devoted to the development of new
methods for the construction of CvinylꢁCF2CF3 bonds.12 Encour-
aged by the success in the mono- and bis-trifluoromethylation of
1,1-diaryl-2,2-difluoroethenes with TMSCF3, we next attempted to
pentafluoroethylate gem-difluoroalkenes with TMSCF2CF3. Thus,
the pentafluoroethylation of 1,1-diaryl-2,2-difluoroethenes 1a
with TMSCF2CF3 in the presence of TBAF was selected as a model
reaction to optimize the reaction conditions (Table 2). The be-
haviour of TMSCF2CF3 towards 1a is almost the same as that ob-
a
Reaction conditions: 1a (1.0 mmol), THF (5 mL), Ar, 1 h.
Yields determined by GC analysis and based on 1a.
b
With the optimized conditions in hand (Table 1, entries 3 and
15), we next examined the scope of the novel nucleophilic tri-
fluoromethylation of different 1,1-diaryl-2,2-difluoroethenes
with TMSCF3 (Schemes 2 and 3). Most substrates could afford
monotrifluoromethylated
fluoromethylated alkenes 3aeh in moderate to good yields, re-
spectively. However, the reaction efficiency of the
bistrifluoromethylation of gem-difluoroalkenes was lower than
that of the monotrifluoromethylation. Generally, gem-difluor-
oalkenes bearing electron-withdrawing group gave the desired
products in higher yields than substrates bearing electron-
donating or neutral groups with 1.2 equiv of TMSCF3 (e.g., the
isolated yields of 2e and 2f were very low, Scheme 2). To obtain
satisfactory yields, the amounts of TMSCF3 was increased to
3.0 equiv and 5.0 equiv, respectively (2e, 2f and 3e, 3f). The
reaction of 9-(difluoromethylene)-9H-fluorene 1h with TMSCF3
could provide bistrifluoromethylated alkene 3h as a sole product
with 80% yield.
alkenes
2aeg
or
bistri-
served previously with TMSCF3. Generally,
monopentafluoroethylated product 4a
a
and
mixture of
bispenta-
fluoroethylated product 5a was observed. After screening of
a number of reaction conditions, the optimal reaction conditions
for the synthesis of 4a (or 5a) are as follows: 2.5 (or 5.0) equiv of
TMSCF2CF3, 1.2 (or 2.0) equiv of TBAF, and THF as the solvent at
25 ꢀC (entries 3 and 12).
Next, the scope of this novel pentafluoroethylation reaction was
investigated
by
treatment
of
different
1,1-diaryl-2,2-
difluoroethenes with TMSCF2CF3 under the aforementioned opti-
mized reaction conditions (Table 2, entries 3 and 12).
Please cite this article in press as: Jin, G.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.08.016

G. Jin et al. / Tetrahedron xxx (2015) 1e8
3
Table 2
Optimization of the reaction conditions for the synthesis of 4a and 5aa
Entry
TMSCF2CF3 (equiv)
TBAF (equiv)
Temp (ꢀC)
Yield 4ab (%)
Yield 5ab (%)
1
2
3
4
5
6
7
8
1.0
2.0
2.5
2.5
2.5
2.5
2.5
2.5
3.0
4.0
5.0
5.0
5.0
1.2
1.2
1.2
1.2
1.2
1.2
1.0
1.5
1.2
1.2
1.2
2.0
2.0
25
25
25
0
10
40
25
25
25
25
25
25
40
48
75
83
38
41
82
69
77
53
49
46
42
44
0
8
7
0
0
8
5
12
47
51
54
58
55
9
10
11
12
13
a
Reaction conditions: 1a (1.0 mmol), THF (5 mL), Ar, 1 h.
Yields determined by GC analysis and based on 1a.
b
As shown in Schemes 4 and 5, both monopentafluoroethylation
and bispentafluoroethylation reaction proceeded smoothly and
afforded the corresponding products in 35e83% yields. Addition-
ally, the structure of 4h was confirmed by X-ray crystallographic
analysis (Fig. 1).
a
Reaction conditions: 1a–d, 1f, 1h (1.0 mmol), TMSCF2CF3 (5.0 mmol),
b
TBAF (1 M in THF, 2.0 mmol), THF (5 mL), 25 °C, 0.5–1 h, Ar. Isolated
yields (some products are volatile and are lost during the chromatographic
purification and rotary evaporation).
a
Reaction conditions: 1a–f, 1h (1.0 mmol), TMSCF2CF3 (2.5 mmol), TBAF
b
(1 M in THF, 1.2 mmol), THF (5 mL), 25 °C, 0.5–1 h, Ar. Isolated yields
Scheme
5. Bispentafluoroethylation
of
1,1-diaryl-2,2-difluoroethenes
with
TMSCF2CF3.a,b
(some products are volatile and are lost during the chromatographic
purification and rotary evaporation).
Scheme 4. Monopentafluoroethylation of 1,1-diaryl-2,2-difluoroethenes with
TMSCF2CF3.a,b
Inspired by the observed reactivity of TMSCF3 towards gem-
difluoroalkenes, we next extended the substrates to several N-(
a-
fluorovinyl)azoles. Unfortunately, the CeF bonds in N-( -fluo-
a
rovinyl)azoles are less reactive under the abovementioned opti-
mized reaction conditions and the nucleophilic vinylic substitution
reaction (SNV) could not take place. Therefore, we used 1-(1-fluoro-
2,2-diphenylvinyl)-1H-imidazole 1i as a model substrate to rein-
vestigate the reaction conditions (Table 3). The results indicated
that the reactivity of the CeF bond in 1i toward TMSCF3 was very
low. For example, no trifluoromethylated product 6i was observed
in absence of metal catalyst (entry 1). Both Ni and Pd salts could
catalyze the trifluoromethylation of 1i with TMSCF3, however, their
catalytic activity was not very high and the desired product 6i was
obtained in moderate yield along with small amounts of CeN bond
cleavage product 3f (bistrifluoromethylated product) (such as en-
tries 4, 7e12). Based on these experiments, the relatively optimal
reaction conditions were established as follows: 5.0 equiv of
Fig. 1. Crystal structure of compound 4h.
Please cite this article in press as: Jin, G.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.08.016

4
G. Jin et al. / Tetrahedron xxx (2015) 1e8
Table 3
addition of the metal catalyst. The reactions proceeded smoothly
Optimization of the reaction conditions for the synthesis of 6ia
and furnished the corresponding monotrifluoromethylated, bistri-
fluoromethylated, monopentafluoroethylated and bispenta-
fluoroethylated alkenes in fair to good yields, respectively, under
four different reaction conditions. In addition, we also developed
a novel Pd-catalyzed trifluoromethylation of N-(a-fluorovinyl)
azoles with TMSCF3. These protocols provide convenient and al-
ternative approaches for the direct construction of CvinyleCF3 and
Entry
Catalyst (mol %)
Temp (ꢀC)
Yield 6i (%)
Yield 3f (%)b
CvinyleCF2CF3 bonds from the fluoroalkenes.
1
2
3
4
5
6
7
8
None
60
60
60
60
30
30
30
30
30
30
30
30
0
3
0
56
10
16
15
63
11
12
7
NiCl2(dppe) (30)
NiCl2(PCy3)2 (30)
NiCl2(dppp) (30)
NiCl2(PCy3)2 (30)
NiCl2(dppe) (30)
NiCl2(dppp) (30)
NiBr2(PPh3)2 (30)
PdCl2(dppe) (30)
PdCl2(CH3CN)2 (30)
PdCl2(PCy3)2 (30)
PdCl2(PCy3)2 (20)
4. Experimental
31
50
37
37
49
51
48
49
60
50
4.1. General information
All reagents were of analytical grade, and obtained from com-
mercial suppliers and used without further purification. THF was
9
ꢀ
freshly dried and stored over activated 4 A molecular sieves under
10
11
12
11
20
15
argon. The products were purified by column chromatography over
silica gel (300e400 mesh size). Melting points were measured in an
a
€
open capillary using Buchi melting point B-540 apparatus and are
Reaction conditions: 1i (1.0 mmol), TMSCF3 (5.0 mmol), TBAF (1 M in THF,
2.0 mmol), THF (5 mL), Ar, 1 h.
Yields referred to the desired product 6i. Yields determined by GC analysis and
based on 1i.
uncorrected. 1H NMR and 13C NMR spectra were recorded on
a Bruker AM-400 spectrometer (400 MHz and 100 MHz, re-
spectively) using TMS as internal standard. The 19F NMR was ob-
tained using a Bruker AM-400 spectrometer (376 MHz) with CDCl3
as the NMR solvent. Gas chromatography-mass spectra (GCeMS)
were recorded on HP 5973 MSD with 6890 GC. High resolution
mass spectra (HRMS) were recorded under electron impact con-
ditions using a MicroMass GCT CA 055 instrument and recorded on
a MicroMass LCTTM spectrometer.
b
TMSCF3, 2.0 equiv of TBAF, 0.3 equiv of PdCl2(PCy3)2 and THF as the
solvent at 30 ꢀC (entry 11).
To determine the limitations of this method, we applied this Pd-
catalyzed trifluoromethylation reaction to several additional N-(a-
fluorovinyl)azoles. As shown in Scheme 6, substrates 1ien could
react with TMSCF3 in presence of 30 mol % PdCl2(PCy3)2 and
afforded slightly lower yields of trifluoromethylated N-vinylazoles
(6ien). The lack of reactivity and incomplete conversions displayed
by these substrates (1ien) might be ascribed to the fact that the
electron-donating inductive effect exerted by the azole nitrogen
atom makes CeF bond relatively unreactive.
4.2. Synthesis of compounds 1aeh and 1ien
Compounds 1aeh were prepared according to the literature
procedure.13 Compounds 1ien were prepared according to the
literature procedure.11a
4.3. General procedure for the synthesis of compounds 2aeg
Under an argon atmosphere, a 25 mL of dried round-bottom
flask was charged with gem-difluoroalkenes 1aeg (1.0 mmol),
TMSCF3 (170.6 mg, 1.2 mmol), and THF (5 mL). The mixture was
stirred at 25 ꢀC for 5 min, and then TBAF (1.2 mmol, 1.2 mL, 1.0 M in
dry THF) was added dropwise to the mixture. The mixture was
stirred at 60 ꢀC for 0.5e1 h (TLC). After the consumption of 1aeg,
the reaction mixture was quenched with H2O (5 mL), and sub-
sequently extracted with CH2Cl2 (3ꢂ20 mL). The combined organic
layer was washed with brine (2ꢂ10 mL), dried over MgSO4, and
concentrated under reduced pressure. The residue was then puri-
fied by chromatography on silica gel (n-hexane as eluent) to pro-
vide the corresponding products 2aeg.
4.3.1. 4,40-(Perfluoroprop-1-ene-1,1-diyl)bis(fluorobenzene)
(2a). Colourless liquid. Yield: 75%. 1H NMR (400 MHz, CDCl3):
d
7.27e7.17 (m, 4H), 7.09e7.01 (m, 4H) ppm; 13C NMR (100 MHz,
164.3, 164.1 (d, 1JCF¼247.5 Hz), 162.9 (dd, 1JCF¼248.8 Hz,
a Reaction conditions: 1i–n, (1.0 mmol), TMSCF3 (5.0 mmol), PdCl2(PCy3)2
(0.3 mmol), TBAF (1 M in THF, 2.0 mmol), THF (5 mL), 30 °C, 0.5–1 h, Ar.
b Isolated yields.
CDCl3):
d
6JCF¼1.2 Hz), 160.9, 142.3 (dq, JCF¼261.7 Hz, JCF¼37.3 Hz),
1
2
131.7e131.4 (m), 131.4e131.2 (m), 131.0, 130.2e127.7 (m),
126.9e126.8 (m), 119.4 (qd, 1JCF¼271.5 Hz, JCF¼41.4 Hz) ppm; 19F
2
Scheme 6. Trifluoromethylation of 1-(1-fluoro-2,2-diarylvinyl)-1H-azoles with
TMSCF3.a,b
NMR (376 MHz, CDCl3):
d
ꢁ64.3 (d, J¼9.8 Hz, 3F), ꢁ111.2 to ꢁ111.3
(m, 1F), ꢁ112.1 to ꢁ112.2 (m, 1F), ꢁ128.0 (q, J¼9.4 Hz, 1F) ppm.
HRMS (EI): calcd for C15H8F6 [M]þ 302.0530, found 302.0531.
3. Conclusions
4.3.2. 3,30-(Perfluoroprop-1-ene-1,1-diyl)bis(fluorobenzene)
(2b). Colourless liquid. Yield: 74%. 1H NMR (400 MHz, CDCl3):
In summary, we have developed an efficient method for the
trifluoromethylation and pentafluoroethylation of 1,1-diaryl-2,2-
difluoroethenes with TMSCF3 and TMSCF2CF3 without the
d
7.37e7.30 (m, 2H), 7.19e7.15 (m, 1H), 7.06e6.97 (m, 5H) ppm; 13
C
1
NMR (100 MHz, CDCl3):
d
161.5 (d, JCF¼244.8 Hz), 161.2 (d,
Please cite this article in press as: Jin, G.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.08.016

G. Jin et al. / Tetrahedron xxx (2015) 1e8
5
3
1JCF¼244.6 Hz), 155.7e149.9 (m), 141.6 (d, JCF¼6.9 Hz), 134.5 (d,
TMSCF3 (426.6 mg, 3.0 mmol), and THF (5 mL). The mixture was
stirred at 30 ꢀC for 5 min, and then TBAF (1.5 mmol, 1.5 mL, 1.0 M in
dry THF) was added dropwise to the mixture. The mixture was
stirred at 30 ꢀC for 0.5e1 h (TLC). After the consumption of 1aeh,
the reaction mixture was quenched with H2O (5 mL), and sub-
sequently extracted with CH2Cl2 (3ꢂ20 mL). The combined organic
layer was washed with brine (2ꢂ10 mL), dried over MgSO4, and
concentrated under reduced pressure. The residue was then puri-
fied by chromatography on silica gel (n-hexane as eluent) to pro-
vide the corresponding products 3aeh.
3JCF¼8.1 Hz), 128.8 (d, JCF¼8.2 Hz), 128.3 (d, JCF¼8.0 Hz),
3
3
124.2e124.1 (m), 122.5, 115.4 (dq, 2JCF¼29.4 Hz, 3JCF¼3.5 Hz), 114.5,
4
2
114.3, 114.0 (d, JCF¼1.5 Hz), 113.6 (d, JCF¼40.9 Hz), 97.6e94.1 (m)
ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ64.6 (d, J¼9.4 Hz, 3F),
ꢁ112.1eꢁ112.2 (m, 2F), ꢁ126.0 (q, J¼9.4 Hz, 1F) ppm. HRMS (EI):
calcd for C15H8F6 [M]þ 302.0530, found 302.0532.
4.3.3. 4,40-(Perfluoroprop-1-ene-1,1-diyl)bis(chlorobenzene)
(2c). Colourless liquid. Yield: 60%. 1H NMR (400 MHz, CDCl3):
d 7.41
(d, J¼8.4 Hz, 2H), 7.36 (d, J¼8.4 Hz, 2H), 7.23 (d, J¼8.4 Hz, 2H), 7.18
(d, J¼8.4 Hz, 2H) ppm; 13C NMR (100 MHz, CDCl3):
d
142.5 (dq,
4.4.1. 4,40-(3,3,3-Trifluoro-2-(trifluoromethyl)prop-1-ene-1,1-diyl)
bis(fluorobenzene) (3a). Colourless liquid. Yield: 45%. 1H NMR
2
1JCF¼262.8 Hz, JCF¼37.2 Hz), 135.4, 135.3, 133.1, 132.4e132.3 (m),
130.9, 130.8, 128.8, 128.7, 126.9e126.7 (m), 119.2 (qd, 1JCF¼272.1 Hz,
(400 MHz, CDCl3):
d C
7.19e7.15 (m, 4H), 7.11e7.07 (m, 4H) ppm; 13
2JCF¼41.4 Hz) ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ64.3 (d, J¼9.8 Hz,
NMR (100 MHz, CDCl3):
d
162.2 (d, 1JCF¼249.9 Hz), 158.1e158.0 (m),
3F), ꢁ126.6 (q, J¼9.8 Hz, 1F) ppm. HRMS (EI): calcd for C15H8Cl2F4
135.1e135.0 (m), 130.9e130.8 (m), 121.5 (q, 1JCF¼274.2 Hz), 118.2 (q,
[M]þ 333.9910, found 333.9915.
2JCF¼22.0 Hz), 115.6 (d, JCF¼21.9 Hz) ppm; 19F NMR (376 MHz,
2
CDCl3):
d
ꢁ55.3 (s, 6F), ꢁ110.0eꢁ110.1 (m, 2F) ppm. HRMS (EI):
4.3.4. 4,40-(Perfluoroprop-1-ene-1,1-diyl)bis(bromobenzene)
(2d). Colourless liquid. Yield: 65%. 1H NMR (400 MHz, CDCl3):
calcd for C16H8F8 [M]þ 352.0498, found 352.0499.
d
7.50 (d, J¼8.4 Hz, 2H), 7.45 (d, J¼8.4 Hz, 2H), 7.11 (d, J¼8.4 Hz,
4.4.2. 3,30-(3,3,3-Trifluoro-2-(trifluoromethyl)prop-1-ene-1,1-diyl)
bis(fluorobenzene) (3b). Colourless liquid. Yield: 46%. 1H NMR
2H), 7.06 (d, J¼8.4 Hz, 2H) ppm; 13C NMR (100 MHz, CDCl3):
d
142.5 (dq, 1JCF¼262.9 Hz, 2JCF¼37.4 Hz), 133.5, 132.8, 131.8, 131.7,
(400 MHz, CDCl3): d 7.36e7.24 (m, 2H), 7.13e7.00 (m, 2H),
131.4, 131.3, 131.2e131.1 (m), 126.7 (dq, 2JCF¼10.6 Hz,
7.00e6.83 (m, 4H) ppm; 13C NMR (100 MHz, CDCl3):
d 162.4 (d,
3JCF¼2.5 Hz), 119.2 (qd, JCF¼272.0 Hz, JCF¼41.3 Hz) ppm; 19F
1JCF¼246.9 Hz), 140.3 (d, JCF¼7.7 Hz), 130.2 (d, JCF¼8.2 Hz), 124.5
1
2
3
3
4
1
2
NMR (376 MHz, CDCl3):
d
ꢁ64.3 (d, J¼9.8 Hz, 3F), e126.3 (q,
(d, JCF¼2.8 Hz), 121.2 (q, JCF¼272.9 Hz), 117.0 (d, JCF¼21.0 Hz),
2
J¼9.8 Hz, 1F) ppm. HRMS (EI): calcd for
C
15H8Br2F4 [M]þ
116.5e116.2 (m), 115.8 (d, JCF¼21.1 Hz), 115.6e115.4 (m) ppm; 19F
425.8888, found 425.8882.
NMR (376 MHz, CDCl3):
d
ꢁ55.6 (s, 6F), ꢁ111.7eꢁ111.8 (m, 2F) ppm;
HRMS (EI): calcd for C16H8F8 [M]þ 352.0499, found 352.0500.
4.3.5. 4,40-(Perfluoroprop-1-ene-1,1-diyl)bis(methylbenzene)
(2e). 426.6 mg (3.0 mmol) TMSCF3 was used. Colourless liquid.
4.4.3. 4,40-(3,3,3-Trifluoro-2-(trifluoromethyl)prop-1-ene-1,1-diyl)
bis(chlorobenzene) (3c). Colourless liquid. Yield: 41%. 1H NMR
Yield: 85%. 1H NMR (400 MHz, CDCl3):
d 7.17e7.12 (m, 6H),
7.10e7.08 (m, 2H), 2.36 (s, 3H), 2.33 (s, 3H) ppm; 13C NMR
(400 MHz, CDCl3):
d
7.38 (d, J¼8.4 Hz, 4H), 7.11 (d, J¼8.4 Hz, 4H)
2
(100 MHz, CDCl3):
138.6, 137.3e136.8 (m), 132.6e132.5 (m), 131.7e131.6 (m), 131.5,
d
141.6 (dq, 1JCF¼258.5 Hz, JCF¼37.3 Hz), 139.1,
ppm; 13C NMR (100 MHz, CDCl3):
d
157.6, 137.1, 136.5, 130.0, 128.8,
1
2
121.4 (q, JCF¼276.8 Hz), 119.1 (q, JCF¼30.7 Hz) ppm; 19F NMR
1
2
129.6, 129.5, 129.0, 119.6 (qd, JCF¼271.5 Hz, JCF¼41.9 Hz), 21.3,
(376 MHz, CDCl3):
d
ꢁ55.3 (s, 6F) ppm. HRMS (EI): calcd for
21.2 ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ64.1 (d, J¼10.2 Hz, 3F),
C
16H8Cl2F6 [M]þ 383.9907, found 383.9903.
ꢁ129.6 (q, J¼10.0 Hz, 1F) ppm. HRMS (EI): calcd for C17H14F4 [M]þ
294.1032, found 294.1033.
4.4.4. 4,40-(3,3,3-Trifluoro-2-(trifluoromethyl)prop-1-ene-1,1-diyl)
bis(bromobenzene) (3d). Colourless liquid. Yield: 72%. 1H NMR
4.3.6. (Perfluoroprop-1-ene-1,1-diyl)dibenzene
(3.0 mmol) TMSCF3 was used. Colourless liquid. Yield: 50%. 1H NMR
(400 MHz, CDCl3): 7.45e7.43 (m, 3H), 7.41e7.39 (m, 3H),
7.37e7.35 (m, 2H), 7.31e7.29 (m, 2H) ppm; 13C NMR (100 MHz,
(2f). 426.6
mg
(400 MHz, CDCl3):
d
7.51 (d, J¼8.5 Hz, 4H), 7.01 (d, J¼8.5 Hz, 4H)
ppm; 13C NMR (100 MHz, CDCl3):
d 137.5, 131.8, 130.6, 130.1, 124.8,
1
2
d
121.4 (q, JCF¼276.9 Hz), 118.8 (q, JCF¼31.5 Hz) ppm; 19F NMR
(376 MHz, CDCl3):
d
ꢁ55.3 (s, 6F) ppm. HRMS (EI): calcd for
1
2
CDCl3):
d
142.1 (dq, JCF¼260.0, JCF¼37.2 Hz), 135.2, 135.1, 134.5,
C16H8Br2F6 [M]þ 473.8876, found 473.8877.
1
134.4, 129.6, 129.5, 129.0, 128.7, 128.4, 119.5 (qd, JCF¼273.5 Hz,
2JCF¼37.3 Hz) ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ64.4 (d,
4.4.5. 4,40-(3,3,3-Trifluoro-2-(trifluoromethyl)prop-1-ene-1,1-diyl)
bis(methylbenzene) (3e). 710.8 mg (5.0 mmol) TMSCF3 was used.
J¼10.2 Hz, 3F), ꢁ128.8 (q, J¼9.8 Hz, 1F) ppm. HRMS (EI): calcd for
C
15H10F4 [M]þ 266.0719, found 266.0720.
Colourless liquid. Yield: 32%. 1H NMR (400 MHz, CDCl3):
d
7.16e7.14
(m, 4H), 7.04e7.02 (m, 4H), 2.36 (s, 6H) ppm; 13C NMR (100 MHz,
4.3.7. 3,30-(Perfluoroprop-1-ene-1,1-diyl)bis((trifluoromethyl)ben-
zene) (2g). Colourless liquid. Yield: 56%. 1H NMR (400 MHz, CDCl3):
CDCl3): d 140.1, 136.8, 129.5, 129.0, 128.9, 128.8, 121.9 (q,
1JCF¼274.3 Hz), 117.1e116.8 (m) ppm; 19F NMR (376 MHz, CDCl3):
d
7.71e7.63 (m, 3H), 7.58e7.49 (m, 3H), 7.46e7.36 (m, 2H) ppm; 13
C
d
ꢁ55.0 (s, 6F) ppm. HRMS (EI): calcd for C18H14F6 [M]þ 344.1000,
2
NMR (100 MHz, CDCl3):
140.9, 135.1e135.0 (m), 134.3e134.2 (m), 132.9, 132.7e132.6 (m),
132.3, 131.8e130.7 (m), 129.3, 129.2, 129.1, 126.2e126.1 (m), 125.6
d
143.6 (dq, 1JCF¼264.4 Hz, JCF¼37.5 Hz),
found 344.1001.
4.4.6. (3,3,3-Trifluoro-2-(trifluoromethyl)prop-1-ene-1,1-diyl)di-
benzene (3f). 710.8 mg (5.0 mmol) TMSCF3 was used. Colourless
3
3
1
(q, JCF¼5.8 Hz), 123.4 (q, JCF¼3.7 Hz), 123.7 (q, JCF¼270.8 Hz),
1
1
2
123.6 (q, JCF¼270.8 Hz), 118.9 (qd, JCF¼272.2 Hz, JCF¼41.1 Hz)
liquid. Yield: 31%. 1H NMR (400 MHz, CDCl3):
d
7.44e7.34 (m, 6H),
ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ62.9 (s, 6F), ꢁ64.6 (d, J¼9.4 Hz,
7.20e7.18 (m, 4H) ppm; 13C NMR (100 MHz, CDCl3):
d 160.3e160.2
3F), ꢁ125.1 (q, J¼10.0 Hz, 1F) ppm. HRMS (EI): calcd for C17H8F10
(m), 139.3, 129.7, 128.5, 128.2, 125.7, 121.8 (q, 1JCF¼274.8 Hz) ppm;
[M]þ 402.0466, found 402.0468.
19F NMR (376 MHz, CDCl3):
d
ꢁ55.2 (s, 6F) ppm. HRMS (EI): calcd for
C
16H10F6 [M]þ 316.0687, found 316.0685.
4.4. General procedure for the synthesis of compounds 3aeh
4.4.7. 3,30-(3,3,3-Trifluoro-2-(trifluoromethyl)prop-1-ene-1,1-diyl)
bis((trifluoromethyl)benz-ene) (3g). Colourless liquid. Yield: 35%. 1H
Under an argon atmosphere, a 25 mL of dried round-bottom
flask was charged with gem-difluoroalkenes 1aeh (1.0 mmol),
NMR (400 MHz, CDCl3): d 7.76e7.61 (m, 3H), 7.57e7.50 (m, 3H),
Please cite this article in press as: Jin, G.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.08.016

6
G. Jin et al. / Tetrahedron xxx (2015) 1e8
3
7.44e7.35 (m, 2H) ppm; 13C NMR (100 MHz, CDCl3):
d
143.8 (q,
2JCF¼36.7 Hz, JCF¼3.5 Hz), 112.3e106.4 (m) ppm; 19F NMR
2JCF¼37.4 Hz), 141.2 (q, JCF¼37.4 Hz), 131.8, 131.7, 131.2 (q,
3JCF¼4.7 Hz), 131.1e131.0 (m), 125.0e123.7 (m), 123.5, 119.4 (q,
1JCF¼272.0 Hz), 119.0 (q, 1JCF¼272.0 Hz) ppm; 19F NMR (376 MHz,
(376 MHz, CDCl3):
d
ꢁ82.9eꢁ83.0 (m, 3F), ꢁ113.3eꢁ113.4 (m, 2F),
2
ꢁ124.4eꢁ124.5 (m, 1F) ppm. HRMS (EI): calcd for C16H8Cl2F6 [M]þ
383.9907, found 383.9908.
CDCl3):
d
ꢁ55.5 (s, 6F), e62.9 (s, 6F) ppm. HRMS (EI): calcd for
C
18H8F12 [M]þ 452.0434, found 452.0435.
4.5.4. 4,40-(Perfluorobut-1-ene-1,1-diyl)bis(bromobenzene)
(4d). White solid. Mp: 33.1e33.6 ꢀC. Yield: 69%. 1H NMR (400 MHz,
4.4.8. 9-(Perfluoropropan-2-ylidene)-9H-fluorene (3h). Yellow liq-
uid. Yield: 80%. 1H NMR (400 MHz, CDCl3):
7.88 (d, J¼8.0 Hz, 2H),
7.56 (d, J¼7.2 Hz, 2H), 7.43 (t, J¼7.6 Hz, 2H), 7.28 (d, J¼8.0 Hz, 2H)
CDCl3):
d
7.52 (d, J¼8.4 Hz, 2H), 7.49 (d, J¼8.8 Hz, 2H), 7.13 (d,
d
J¼7.6 Hz, 2H), 7.07 (d, J¼8.4 Hz, 2H) ppm; 13C NMR (100 MHz,
1
2
CDCl3):
d
142.2 (dt, JCF¼260.3 Hz, JCF¼26.9 Hz), 133.7 (d,
ppm; 13C NMR (100 MHz, CDCl3):
d
152.5, 142.7, 135.0, 132.4,
4JCF¼1.3 Hz),133.0 (d, 3JCF¼4.6 Hz),131.8,131.7,131.0,130.9,129.6 (d,
2JCF¼11.0 Hz),123.8 (d, 4JCF¼1.2 Hz), 123.3, 118.3 (qtd, 1JCF¼285.9 Hz,
128.6e128.4 (m), 128.2, 122.1 (q, 1JCF¼269.3 Hz), 119.8, 114.9e113.5
(m) ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ56.0 (s, 6F) ppm. HRMS
2JCF¼36.5 Hz, JCF¼3.4 Hz), 112.3e106.4 (m) ppm; 19F NMR
3
(EI): calcd for C16H8F6 [M]þ 314.0530, found 314.0531.
(376 MHz, CDCl3):
d
ꢁ82.9eꢁ83.0 (m, 3F), ꢁ113.3eꢁ113.4 (m, 2F),
ꢁ124.1eꢁ124.3 (m, 1F) ppm. HRMS (EI): calcd for C16H8Br2F6 [M]þ
475.8856, found 475.8864.
4.5. General procedure for the synthesis of compounds 4aef,
4h
4.5.5. 4,40-(Perfluorobut-1-ene-1,1-diyl)bis(methylbenzene)
(4e). Colourless liquid. Yield: 82%. 1H NMR (400 MHz, CDCl3):
Under an argon atmosphere, a 25 mL of dried round-bottom
flask was charged with gem-difluoroalkenes 1aef, 1h (1.0 mmol),
TMSCF2CF3 (480.5 mg, 2.5 mmol), and THF (5 mL). The mixture was
stirred at 25 ꢀC for 5 min, then TBAF (1.2 mmol, 1.2 mL, 1.0 M in dry
THF) was added dropwise to the mixture. The mixture was stirred
at 25 ꢀC for 0.5e1 h (TLC). After the consumption of 1aeg, 1h, the
reaction mixture was quenched with H2O (5 mL), and subsequently
extracted with CH2Cl2 (3ꢂ20 mL). The combined organic layer was
washed with brine (2ꢂ10 mL), dried over MgSO4, and concentrated
under reduced pressure. The residue was then purified by chro-
matography on silica gel (n-hexane as eluent) to provide the cor-
responding products 4aef, 4h.
d
7.18e7.14 (m, 6H), 7.11e7.07 (m, 2H), 2.35 (s, 3H), 2.32 (s, 3H) ppm;
13C NMR (100 MHz, CDCl3):
d
139.1, 138.4, 137.3, 132.8e132.7 (m),
131.6, 131.5, 129.5e129.4 (m), 129.1, 129.0, 128.9, 120.4e119.7 (m),
112.6e106.7 (m), 21.3, 21.2 ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ82.9eꢁ83.0 (m, 3F), ꢁ113.0eꢁ113.1 (m, 2F), ꢁ127.3eꢁ127.5 (m,
1F) ppm. HRMS (EI): calcd for C18H14F6 [M]þ 344.1000, found
344.1001.
4.5.6. (Perfluorobut-1-ene-1,1-diyl)dibenzene (4f). White solid. Mp:
42.7e43.2 ꢀC. Yield: 83%. 1H NMR (400 MHz, CDCl3):
d
7.18e7.14 (m,
141.3 (dt,
6H), 7.11e7.07 (m, 4H) ppm; 13C NMR (100 MHz, CDCl3):
d
1JCF¼256.0 Hz, JCF¼26.7 Hz), 139.1, 138.4, 137.3, 132.8, 131.6e131.4
2
(m), 129.5e129.4 (m), 129.1, 129.0, 128.9, 120.4e116.8 (m),
4.5.1. 4,40-(Perfluorobut-1-ene-1,1-diyl)bis(fluorobenzene)
(4a). White solid. Mp: 42.7e43.2 ꢀC. Yield: 66%. 1H NMR (400 MHz,
112.6e106.7 (m) ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ82.9eꢁ83.0
(m, 3F), ꢁ113.0eꢁ113.1 (m, 2F), ꢁ127.3eꢁ127.4 (m, 1F) ppm. HRMS
7.28e7.17 (m, 4H), 7.08e7.00 (m, 4H) ppm; 13C NMR
(EI): calcd for C16H10F6 [M]þ 316.0687, found 316.0689.
CDCl3):
d
1
(100 MHz, CDCl3):
d
163.0 (d, JCF¼247.4 Hz), 162.9 (d,
1JCF¼249.2 Hz), 142.0 (dt, JCF¼258.2 Hz, JCF¼27.1 Hz), 131.5 (d,
1
2
4.5.7. 9-(Perfluoropropylidene)-9H-fluorene (4h). White solid. Mp:
3JCF¼5.6 Hz), 131.4 (d, JCF¼5.7 Hz), 131.3 (d, JCF¼2.7 Hz), 131.2 (d,
3
4
52.0e52.8 ꢀC. Yield: 82%. 1H NMR (400 MHz, CDCl3):
d 7.98 (d,
4JCF¼2.7 Hz), 129.9e128.3 (m), 118.4 (qtd, JCF¼285.8 Hz,
1
J¼8.0 Hz, 1H), 7.83 (d, J¼8.0 Hz, 1H), 7.67 (d, J¼7.2 Hz, 2H),
2JCF¼36.6 Hz, JCF¼3.5 Hz), 115.5 (d, JCF¼21.6 Hz), 115.4 (d,
3
2
7.44e7.38 (m, 2H), 7.34e7.25 (m, 2H) ppm; 13C NMR (100 MHz,
2JCF¼21.7 Hz), 112.4e106.9 (m) ppm; 19F NMR (376 MHz, CDCl3):
CDCl3):
d
146.0, 143.4 (d, 2JCF¼32.1 Hz), 141.7 (d, 3JCF¼4.1 Hz), 140.0,
d
ꢁ83.1eꢁ83.2 (m, 3F), ꢁ111.1eꢁ111.2 (m, 1F), ꢁ112.4eꢁ112.5 (m,
135.4, 132.0e131.9 (m), 130.4, 130.3, 130.2, 130.1, 128.3, 127.8, 127.6,
127.4, 127.2e127.0 (m), 126.1e125.9 (m) ppm; 19F NMR (376 MHz,
1F), ꢁ113.3eꢁ113.4 (m, 2F), ꢁ125.7eꢁ125.8 (m, 1F) ppm. HRMS
(EI): calcd for C16H8F8 [M]þ 352.0498, found 352.0497.
CDCl3):
d
ꢁ83.1eꢁ83.2 (m, 3F), ꢁ114.6eꢁ114.7 (m, 2F),
ꢁ117.8eꢁ117.9 (m, 1F) ppm. HRMS (EI): calcd for C16H8F6 [M]þ
4.5.2. 3,30-(Perfluorobut-1-ene-1,1-diyl)bis(fluorobenzene)
(4b). Colourless liquid. Yield: 40%. 1H NMR (400 MHz, CDCl3):
314.0530, found 314.0534.
d
7.37e7.28 (m, 2H), 7.11e6.93 (m, 6H) ppm; 13C NMR (100 MHz,
1
1
CDCl3):
d
162.6 (d, JCF¼245.4 Hz), 162.5 (d, JCF¼246.4 Hz), 142.7
4.6. General procedure for the synthesis of compounds 5aed,
5f, 5h
1
2
3
(dt, JCF¼261.0 Hz, JCF¼27.2 Hz), 136.6 (d, JCF¼7.9 Hz), 135.5 (d,
4JCF¼4.5 Hz), 135.4 (d, 4JCF¼4.6 Hz), 130.0 (d, 3JCF¼8.2 Hz), 129.9 (d,
2JCF¼8.4 Hz), 129.3 (d, 2JCF¼10.8 Hz), 125.3e125.2 (m), 125.1e125.0
Under an argon atmosphere, a 25 mL of dried round-bottom
flask was charged with gem-difluoroalkenes 1aed, 1f, 1h
(1.0 mmol), TMSCF2CF3 (961.0 mg, 5.0 mmol), and THF (5 mL).
The mixture was stirred at 25 ꢀC for 5 min, and then TBAF
(2.0 mmol, 2.0 mL, 1.0 M in dry THF) was added dropwise to the
mixture. The mixture was stirred at 25 ꢀC for 0.5e1 h (TLC). After
the consumption of 1aed, 1f, 1h, the reaction mixture was
quenched with H2O (5 mL), and subsequently extracted with
CH2Cl2 (3ꢂ20 mL). The combined organic layer was washed with
brine (2ꢂ10 mL), dried over MgSO4, and concentrated under
reduced pressure. The residue was then purified by chromatog-
raphy on silica gel (n-hexane as eluent) to provide the corre-
sponding products 5aed, 5f, 5h.
1
2
3
(m), 118.3 (qtd, JCF¼285.9 Hz, JCF¼36.3 Hz, JCF¼3.5 Hz),
2
2
116.7e116.3 (m), 116.3 (d, JCF¼21.1 Hz), 115.9 (d, JCF¼20.8 Hz),
111.9e106.7 (m) ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ83.1eꢁ83.2
(m, 3F), ꢁ112.1eꢁ112.2 (m, 1F), ꢁ112.3eꢁ112.4 (m, 1F),
ꢁ113.8eꢁ113.9 (m, 2F), ꢁ123.9eꢁ124.0 (m, 1F) ppm. HRMS (EI):
calcd for C16H8F8 [M]þ 352.0498, found 352.0502.
4.5.3. 4,40-(Perfluorobut-1-ene-1,1-diyl)bis(chlorobenzene)
(4c). Colourless liquid. Yield: 64%. 1H NMR (400 MHz, CDCl3):
d
7.37e7.31 (m, 4H), 7.21e7.13 (m, 4H) ppm; 13C NMR (100 MHz,
CDCl3):
d
142.2 (dt, 1JCF¼260.0 Hz, 2JCF¼26.8 Hz), 135.4, 135.1, 133.3,
1
132.1, 132.0, 130.8, 130.7, 128.8, 128.7, 118.3 (qtd, JCF¼285.7 Hz,
Please cite this article in press as: Jin, G.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.08.016

G. Jin et al. / Tetrahedron xxx (2015) 1e8
7
4.6.1. 4,40-(3,3,4,4,4-Pentafluoro-2-(perfluoroethyl)but-1-ene-1,1-
diyl)bis(fluorobenzene) (5a). Colourless liquid. Yield: 45%. 1H NMR
residue was then purified by chromatography on silica gel (hexane/
dichloromethane/Et3N¼10/1/0.1) to provide the corresponding
products 6ien.
(400 MHz, CDCl3):
d
7.09e7.05 (m, 4H), 7.01e6.96 (m, 4H) ppm; 13
C
1
NMR (100 MHz, CDCl3):
d
162.6 (d, JCF¼248.1 Hz), 128.9 (d,
3JCF¼8.4 Hz), 120.5e112.0 (m), 116.2 (d, JCF¼21.8 Hz), 116.2e116.0
4.7.1. 1-(3,3,3-Trifluoro-1,1-diphenylprop-1-en-2-yl)-1H-imidazole
(6i). White solid. Mp: 67.6e68.5 ꢀC. Yield: 51%. 1H NMR (400 MHz,
2
(m), 115.7e114.9 (m), 115.1 (d, 2JCF¼21.9 Hz), 109.3e102.9 (m) ppm;
19F NMR (376 MHz, CDCl3):
d
ꢁ81.6eꢁ81.7 (m, 6F), ꢁ101.4 (s, 4F),
CDCl3):
d 7.43e7.41 (m, 4H), 7.32e7.30 (m, 2H), 7.21e7.15 (m, 3H),
ꢁ112.2eꢁ112.3 (m, 2F) ppm. HRMS (EI): calcd for C18H8F12 [M]þ
7.03 (s, 2H), 6.91e6.89 (m, 2H) ppm; 13C NMR (100 MHz, CDCl3):
452.0434, found 452.0435.
d 150.8, 150.7, 137.6, 137.1, 129.2, 129.1, 128.7, 128.6, 128.5, 128.3,
128.1, 121.3 (q, 1JCF¼273.6 Hz), 121.7, 121.5e121.1 (m) ppm; 19F NMR
4.6.2. 3,30-(3,3,4,4,4-Pentafluoro-2-(perfluoroethyl)but-1-ene-1,1-
diyl)bis(fluorobenzene) (5b). Colourless liquid. Yield: 65%. 1H NMR
(376 MHz, CDCl3):
C
d
ꢁ60.0 (s, 3F) ppm. HRMS (EI): calcd for
18H13F3N2 [M]þ 314.1031, found 314.1029.
(400 MHz, CDCl3):
d
7.19e7.16 (m, 2H), 6.96e6.89 (m, 6H) ppm; 13
C
1
NMR (100 MHz, CDCl3):
d
162.1 (d, JCF¼246.4 Hz), 141.2 (d,
4.7.2. 1-(3,3,3-Trifluoro-1,1-diphenylprop-1-en-2-yl)-1H-benzo[d]
imidazole (6j). White solid. Mp: 85.4e86.1 ꢀC. Yield: 46%. 1H NMR
3JCF¼7.6 Hz), 129.7 (d, JCF¼8.2 Hz), 125.2e124.5 (m), 123.0e118.8
3
2
2
(m), 122.3, 115.5 (d, JCF¼20.9 Hz), 113.9 (d, JCF¼23.6 Hz),
(400 MHz, CDCl3):
d
7.87 (s, 1H), 7.74e7.72 (m, 1H), 7.48e7.39 (m,
112.3e108.9 (m) ppm; 19F NMR (376 MHz, CDCl3):
ꢁ102.4 (s, 4F), ꢁ112.4eꢁ112.5 (m, 2F) ppm. HRMS (EI): calcd for
18H8F12 [M]þ 452.0434, found 452.0435.
d
ꢁ81.8 (s, 6F),
6H), 7.33e7.24 (m, 2H), 7.10e6.99 (m, 3H), 6.87e6.85 (m, 2H) ppm;
3
13C NMR (100 MHz, CDCl3):
d
153.6 (q, JCF¼2.4 Hz), 143.8, 142.7,
C
137.4, 137.0, 129.4, 129.3, 128.8, 128.7, 128.4, 128.3, 127.7, 124.0,
1
2
122.9, 121.7 (q, JCF¼274.3 Hz), 120.0 (q, JCF¼33.9 Hz), 120.4,
4.6.3. 4,40-(3,3,4,4,4-Pentafluoro-2-(perfluoroethyl)but-1-ene-1,1-
diyl)bis(chlorobenzene) (5c). Colourless liquid. Yield: 64%. 1H NMR
110.6 ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ59.3 (s, 3F) ppm. HRMS
(EI): calcd for C22H15F3N2 [M]þ 364.1187, found 364.1186.
(400 MHz, CDCl3):
ppm; 13C NMR (100 MHz, CDCl3):
130.2e128.2 (m), 128.3, 128.0, 120.0e117.0 (m), 114.5e111.8 (m)
d
7.28 (d, J¼8.4 Hz, 4H), 7.04 (d, J¼8.0 Hz, 4H)
d
163.7e163.6 (m), 138.0, 134.9,
4.7.3. 5,6-Dimethyl-1-(3,3,3-trifluoro-1,1-diphenylprop-1-en-2-yl)-
1H-benzo[d]imidazole (6k). White solid. Mp: 92.2e93.1 ꢀC. Yield:
ppm; 19F NMR (376 MHz, CDCl3):
d
ꢁ81.7 (s, 6F), ꢁ101.9 (s, 4F) ppm.
47%. 1H NMR (400 MHz, CDCl3):
d
7.67 (s, 1H), 7.47e7.37 (m, 6H),
7.18 (s, 1H), 7.06e6.98 (m, 3H), 6.85e6.83 (m, 2H), 2.37 (s, 3H), 2.33
(s, 3H); 13C NMR (100 MHz, CDCl3):
153.2, 143.1, 141.4, 137.5, 137.1,
HRMS (EI): calcd for C18H8Cl2F10 [M]þ 483.9843, found 483.9839.
d
4.6.4. 4,40-(3,3,4,4,4-Pentafluoro-2-(perfluoroethyl)but-1-ene-1,1-
diyl)bis(bromobenzene) (5d). White solid. Mp: 60.3e60.9 ꢀC. Yield:
133.6, 133.3, 131.8, 129.3, 128.8, 128.4, 128.3, 127.8, 121.9 (q,
1JCF¼272.6 Hz), 120.4, 110.8, 20.7, 20.2; 19F NMR (376 MHz, CDCl3):
82%. 1H NMR (400 MHz, CDCl3):
d
7.43 (d, J¼8.4 Hz, 4H), 6.97 (d,
d
ꢁ59.1 (s, 3F). HRMS (EI): calcd for C24H19F3N2 [M]þ 392.1500,
J¼8.4 Hz, 4H) ppm; 13C NMR (100 MHz, CDCl3):
d
163.6e163.5 (m),
found 392.1501.
138.3, 131.8e131.7 (m), 131.3, 128.2, 123.0, 123.5e119.3 (m),
114.0e108.7 (m) ppm; 19F NMR (376 MHz, CDCl3):
(m, 6F), ꢁ101.8eꢁ101.9 (m, 4F) ppm. HRMS (EI): calcd for
18H8Br2F10 [M]þ 573.8813, found 573.8813.
d
ꢁ81.5eꢁ81.6
4.7.4. 2-Methyl-1-(3,3,3-trifluoro-1,1-diphenylprop-1-en-2-yl)-1H-
benzo[d]imidazole (6l). White solid. Mp: 79.8e80.9 ꢀC. Yield: 38%.
C
1H NMR (400 MHz, CDCl3):
d
7.65e7.63 (m, 1H), 7.47e7.45 (m, 3H),
7.40e7.26 (m, 5H), 7.13e7.10 (m, 1H), 7.03e6.99 (m, 2H), 6.83e6.81
(m, 2H), 2.43 (s, 3H); 13C NMR (100 MHz, CDCl3):
154.9e154.8 (m),
4.6.5. (3,3,4,4,4-Pentafluoro-2-(perfluoroethyl)but-1-ene-1,1-diyl)di-
benzene (5f). Colourless liquid. Yield: 40%. 1H NMR (400 MHz,
d
151.6, 142.4, 142.3, 137.4, 137.3, 137.1, 129.6, 129.3, 128.7, 128.4, 127.6,
CDCl3):
d
7.26e7.24 (m, 6H), 7.12 (d, J¼7.2 Hz, 4H) ppm; 13C NMR
123.3, 122.7, 121.6 (q, 1JCF¼273.2 Hz), 120.0 (q, 2JCF¼34.8 Hz), 119.3,
3
(100 MHz, CDCl3):
d
166.1 (t, JCF¼3.4 Hz), 140.1, 129.4e128.2 (m),
110.6, 45.8; 19F NMR (376 MHz, CDCl3):
d
ꢁ58.4 (s, 3F). HRMS (EI):
128.1, 127.8, 126.6, 120.6e114.8 (m), 112.5e109.0 (m) ppm; 19F NMR
calcd for C23H17F3N2 [M]þ 378.1344, found 378.1343.
(376 MHz, CDCl3):
d
ꢁ81.4eꢁ81.6 (m, 6F), ꢁ101.7eꢁ101.8 (m, 4F)
ppm. HRMS (EI): calcd for C18H10F10 [M]þ 416.0623, found 416.0622.
4.7.5. 1-(1-Fluoro-2,2-diphenylvinyl)-1H-indole (6m). Yellow oil.
Yield: 39%. 1H NMR (400 MHz, CDCl3):
d 7.64e7.43 (m, 6H),
4.6.6. 9-(Perfluoropentan-3-ylidene)-9H-fluorene (5h). White solid.
7.28e6.98 (m, 9H), 6.69e6.60 (m, 1H) ppm; 13C NMR (100 MHz,
3
Mp: 72.8e73.5 ꢀC. Yield: 35%. 1H NMR (400 MHz, CDCl3):
d
7.64 (d,
J¼8.0 Hz, 2H), 7.56 (d, J¼7.2 Hz, 2H), 7.42e7.38 (m, 2H), 7.26e7.20
(m, 2H) ppm; 13C NMR (100 MHz, CDCl3):
142.7, 135.5, 132.2,
CDCl3):
d
153.6 (q, JCF¼2.4 Hz), 143.9, 142.9, 137.5, 137.0, 134.8,
129.4, 129.3, 128.8, 128.7, 128.4, 128.3, 127.7, 124.0, 122.9, 121.7 (q,
d
1JCF¼274.3 Hz), 120.4, 120.0 (q, JCF¼33.9 Hz), 110.6 ppm; 19F NMR
2
130.7e130.4 (m), 128.7e128.5 (m), 128.3e128.2 (m), 128.0,
(376 MHz, CDCl3):
d
ꢁ59.3 (s, 3F) ppm. HRMS (EI): calcd for
120.7e120.5 (m), 119.6, 117.6e116.8 (m) ppm; 19F NMR (376 MHz,
C
23H16F3N [M]þ 363.1235, found 363.1236.
CDCl3):
d
ꢁ74.8eꢁ74.9 (m, 6F), ꢁ96.9 (s, 4F) ppm. HRMS (EI): calcd
for C18H8F10 [M]þ 414.0466, found 414.0462.
4.7.6. 1-(3,3,3-Trifluoro-1,1-diphenylprop-1-en-2-yl)-1H-1,2,4-tri-
azole (6n). White solid. Mp: 99.2e100.1 ꢀC. Yield: 26%. 1H NMR
4.7. General procedure for the synthesis of compounds 6ien
(400 MHz, CDCl3): d 7.63e7.62 (m, 1H), 7.42e7.36 (m, 5H), 7.18e7.14
(m, 3H), 7.00e6.97 (m, 2H), 6.21e6.20 (m, 1H) ppm; 13C NMR
Under an argon atmosphere, a 25 mL of dried round-bottom
flask was charged with fluoroalkenes 1ien (1.0 mmol), TMSCF3
(710.2 mg, 5.0 mmol), PdCl2(PCy3)2 (221.5 mg, 0.3 mmol), and THF
(5 mL). The mixture was stirred at 30 ꢀC for 5 min, then TBAF
(2.0 mmol, 2.0 mL, 1.0 M in dry THF) was added dropwise to the
mixture. The mixture was stirred at 30 ꢀC for 0.5e1 h (TLC). After
the consumption of 1ien, the reaction mixture was quenched with
H2O (5 mL), and subsequently extracted with CH2Cl2 (3ꢂ20 mL).
The combined organic layer was washed with brine (2ꢂ10 mL),
dried over MgSO4, and concentrated under reduced pressure. The
(100 MHz, CDCl3):
d
151.4 (q, 3JCF¼6.3 Hz), 141.2, 138.0, 137.2, 133.1,
4
129.0, 128.9, 128.7 (q, JCF¼1.8 Hz), 128.4, 128.3, 128.1, 125.2 (q,
2JCF¼33.6 Hz), 121.6 (q, JCF¼274.1 Hz) ppm; 19F NMR (376 MHz,
1
CDCl3):
315.0983, found 315.0984.
d
ꢁ59.1 (s, 3F) ppm. HRMS (EI): calcd for C17H12F3N3 [M]þ
Acknowledgements
We are grateful for financial supports from the National Natural
Science Foundation of China (grant nos. 21472043, 21272070).
Please cite this article in press as: Jin, G.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.08.016

8
G. Jin et al. / Tetrahedron xxx (2015) 1e8
2014, 161, 134e141; (c) Prakash, G. K. S.; Yudin, A. K. Chem. Rev. 1997, 97,
Supplementary data
757e786; (d) Boechat, N.; Bastos, M. M. Curr. Org. Synth. 2010, 7, 403e413; (e)
Liu, Q.; Wu, Y.; Chen, P.; Liu, G. Org. Lett. 2013, 15, 6210e6213; (f) Krishnamurti,
R.; Bellew, D. R.; Prakash, G. K. S. J. Org. Chem. 1991, 56, 984e989; (g) Prakash,
G. K. S.; Panja, C.; Vaghoo, H.; Surampudi, V.; Kultyshev, R.; Mandal, M.; Rasul,
G.; Mathew, T.; Olah, G. A. J. Org. Chem. 2006, 71, 6806e6813.
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2015.08.016.
€
5. Hafnera, A.; Brase, S. Adv. Synth. Catal. 2011, 353, 3044e3048.
References and notes
6. Cho, E. J.; Buchwald, S. L. Org. Lett. 2011, 13, 6552e6555.
7. Mao, Z.; Huang, F.; Yu, H.; Chen, J.; Yu, Z.; Xu, Z. Chem.dEur. J. 2014, 20,
3439e3445.
8. (a) Fuchibe, K.; Takahashi, M.; Ichikawa, J. Angew. Chem., Int. Ed. 2012, 51,
12059e12062; (b) Fujita, T.; Sakoda, K.; Ikeda, M.; Hattori, M.; Ichikawa, J.
Synlett 2013, 57e60; (c) Ichikawa, J.; Wada, Y.; Fujiwara, M.; Sakoda, K. Synthesis
2002, 13, 1917e1936.
1. (a) Liu, X.; Shimizu, M.; Hiyama, T. Angew. Chem., Int. Ed. 2004, 43, 879e882; (b)
Innocenti, P.; Cheung, K.-M. J.; Solanki, S.; Mas-Droux, C.; Rowan, F.; Yeoh, S.;
Boxall, K.; Westlake, M.; Pickard, L.; Hardy, T.; Baxter, J. E.; Aherne, G. W.;
Bayliss, R.; Fry, A. M.; Hoelder, S. J. Med. Chem. 2012, 55, 3228e3241; (c) Shi-
mizu, M.; Takeda, Y.; Higashi, M.; Hiyama, T. Angew. Chem., Int. Ed. 2009, 48,
3653e3656; (d) Hong, J.; Lai, H.; Liu, Y.; Yuan, C.; Li, Y.; Liu, P.; Fang, Q. RSC Adv.
2013, 3, 1069e1072; (e) Rivkin, A.; Chou, T.-C.; Danishefsky, S. J. Angew. Chem.,
Int. Ed. 2005, 44, 2838e2850; (f) Numata, Y.; Ashraful, I.; Shirai, Y.; Han, L. Chem.
Commun. 2011, 47, 6159e6161; (g) Shi, Z.; Davies, J.; Jang, S.-H.; Kaminsky, W.;
Jen, A. K.-Y. Chem. Commun. 2012, 7880e7882.
2. (a) Alonso, C.; de Marigorta, E. M.; Rubiales, G.; Palacios, F. Chem. Rev. 2015, 115,
1847e1935; (b) Iqbal, N.; Choi, S.; Kim, E.; Cho, E. J. J. Org. Chem. 2012, 77,
11383e11387; (c) Li, Y.; Wu, L.; Neumann, H.; Beller, M. Chem. Commun. 2013,
2628e2630; (d) Chu, L.; Qing, F.-L. Org. Lett. 2010, 12, 5060e5063; (e) Li, Z.; Cui,
Z.; Liu, Z.-Q. Org. Lett. 2013, 15, 406e409; (f) Hang, Z.; Li, Z.; Liu, Z.-Q. Org. Lett.
2014, 16, 3648e3651; (g) Qing, F.-L.; Zhang, X.; Peng, Y. J. Fluorine Chem. 2001,
111, 185e187.
9. (a) Wiedemann, J.; Heiner, T.; Mloston, G.; Prakash, G. K. S.; Olah, G. A. Angew.
Chem., Int. Ed. 1998, 37, 820e821; (b) Prakash, G. K. S.; Krishnamurti, R.; Olah,
G. A. J. Am. Chem. Soc. 1989, 111, 393e395.
€
10. (a) Hubinger, R.; Pawelke, G. J. Fluorine Chem. 2002, 115, 115e118; (b) Kitazume,
T.; Nakajima, S. J. Fluorine Chem. 2004, 125, 1447e1449; (c) German, L. S.;
ꢁ
Mysov, E. I.; Ter-Gabrielyan, E. G. Russ. Chem. B 1990, 2, 491e492; (d) Burton, D.
J.; Hansen, S. W. ARKIVOC 2010, 8, 41e54.
11. (a) Xiong, Y.; Zhang, X.; Huang, T.; Cao, S. J. Org. Chem. 2014, 79, 6395e6402; (b)
Dai, W.; Xiao, J.; Jin, G.; Wu, J.; Cao, S. J. Org. Chem. 2014, 79, 10537e10546; (c)
Jin, G.; Zhang, J.; Wu, W.; Cao, S. J. Fluorine Chem. 2014, 168, 240e246; (d) Wang,
M.; Liang, F.; Xiong, Y.; Cao, S. RSC Adv. 2015, 5, 11996e11999; (e) Zhang, X.; Dai,
W.; Wu, W.; Cao, S. Org. Lett. 2015, 17, 2708e2711.
3. (a) Lin, Q.-Y.; Xu, X.-H.; Qing, F.-L. J. Org. Chem. 2014, 79, 10434e10446; (b) Iqbal,
N.; Jung, J.; Park, S.; Cho, E. J. Angew. Chem., Int. Ed. 2014, 53, 539e542; (c)
Kathiravan, S.; Nicholls, I. A. Org. Lett. 2015, 17, 1874e1877; (d) Tomita, R.; Yasu,
Y.; Koike, T.; Akita, M. Beilstein J. Org. Chem. 2014, 10, 1099e1106; (e) Yasu, Y.;
Koike, T.; Akita, M. Chem. Commun. 2013, 2037e2039; (f) Besset, T.; Cahard, D.;
Pannecoucke, X. J. Org. Chem. 2014, 79, 413e418; (g) Liu, T.; Shen, Q. Org. Lett.
2011, 13, 2342e2345; (h) He, Z.; Luo, T.; Hu, M.; Cao, Y.; Hu, J. Angew. Chem., Int.
Ed. 2012, 51, 3944e3947; (i) Fang, Z.; Ning, Y.; Mi, P.; Liao, P.; Bi, X. Org. Lett.
2014, 16, 1522e1525.
12. (a) Lu, H.; Silverman, R. B. J. Med. Chem. 2006, 49, 7404e7412; (b) Pierce, M. E.;
Carini, D. J.; Huhn, G. F.; Wells, G. J.; Arnett, J. F. J. Org. Chem. 1993, 58,
4642e4645; (c) Lishchynskyi, A.; Mazloomi, Z.; Grushin, V. V. Synlett 2015,
45e50; (d) Gassman, P. G.; O’Reilly, N. J. J. Org. Chem. 1987, 52, 2481e2490; (e)
Hafner, A.; Bihlmeier, A.; Nieger, M.; Klopper, W.; Brase, S. J. Org. Chem. 2013, 78,
7938e7948.
13. Hu, M.; He, Z.; Gao, B.; Li, L.; Ni, C.; Hu, J. J. Am. Chem. Soc. 2013, 135,
17302e17305.
€
4. (a) Liu, X.; Xu, C.; Wang, M.; Liu, Q. Chem. Rev. 2015, 115, 683e730; (b) Barata-
~
Vallejo, S.; Torviso, M. R.; Lantanno, B.; Bonesi, S. M.; Postigo, A. J. Fluorine Chem.
Please cite this article in press as: Jin, G.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.08.016