Syntheses of mono-, di-, and trifluorinated styrenic monomers

Article abstract of DOI:10.1055/s-0029-1218785

Concise syntheses of gram quantities of three fluorinated -methylstyrenic monomers suitable for polymerisation studies are disclosed, all based on the use of reasonably priced commercially available starting materials and reagents. Georg Thieme Verlag Stuttgart New York.

Full text of DOI:10.1055/s-0029-1218785

SPECIAL TOPIC
1883
Syntheses of Mono-, Di-, and Trifluorinated Styrenic Monomers
S
ynthese
s
u
of Mono-,
D
s
i-, and
T
r
t
ifluorin
y
ated Styrenic
n
Monomer
s
a Walkowiak,a Teresa Martinez del Campo,a Bruno Ameduri,b Véronique Gouverneur*a
a
Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
b
Institut Charles Gerhardt, Ingénierie et Architectures Macromoléculaires, UMR CNS 5253,
Ecole Nationale Supérieure de Chimie de Montpellier, 8 rue de l’Ecole Normale, 34296 Montpellier, France
Fax +44(1865)275644; E-mail: veronique.gouverneur@chem.ox.ac.uk
Received 29 April 2010
to electrophilic fluorination. A palladium-catalysed cross-
coupling reaction of allyltrimethylsilane with the corre-
sponding triflates 1a or 1b delivered the desired allylsi-
lanes 2a,b in good yields. Subsequent fluorodesilylation
(SE2¢) of these allylsilanes was conducted at room temper-
ature with Selectfluor in acetonitrile and led within two
hours to 3a and 3b in 93% and 76% isolated yield, respec-
tively (Scheme 1, Table 1).6 Studies aimed at probing the
efficiency of this synthetic route for the preparation of
larger quantities of material (up to 40 and 30 mmol scale)
indicated that the overall yields for this sequence de-
creased significantly, with both the synthesis of allylsilane
and the fluorodesilylation becoming more problematic
(Table 1). Attempts to improve the synthesis of the al-
lylphenylsilane derivatives 2a,b using ionic-liquid-pro-
moted palladium-catalysed coupling of halobenzenes
with allyltrimethylsilane were not fruitful.7 This limita-
tion combined with the high cost of the aryl triflates 1a,b
and of the reagents necessary to prepare the corresponding
allylsilanes prompted us to examine alternative routes.
Abstract: Concise syntheses of gram quantities of three fluorinated
a-methylstyrenic monomers suitable for polymerisation studies are
disclosed, all based on the use of reasonably priced commercially
available starting materials and reagents.
Key words: fluorination, nucleophilic fluoroalkylation, palladium
catalysis, monomer synthesis, functional fluoropolymers
Fluoropolymers are performance materials with unique
properties.1 Key characteristics are their advantageously
high thermostability and chemical inertness combined
with low refractive index, friction coefficient, dielectric
constant, dissipation factor, as well as low water absorp-
tivity. These high value products have, therefore, found
applications in various fields of advanced technology
(e.g., chemical and automobile industries, fuel cell mem-
branes, engineering, microelectronics, optics,2,3 textile fin-
ishing,3 and aeronautics4). Fluorinated aromatic polymers
belong to a highly desirable subcategory of fluorinated
polymers, but only few examples of the copolymerisation
of fluorine-functionalised aromatic monomers with fluo-
roolefins have been reported to date.5
F
F
F
F
F
F
With the objective to prepare new functional fluoropoly-
mers for fuel cell membranes, we have developed conve-
nient and cost-effective routes to access various
noncommercially available fluorinated styrenic mono-
mers of increasing fluorine content. The a-(monofluo-
romethyl)styrene I (FMST), a-(difluoromethyl)styrene II
(DFMST) and a-(trifluoromethyl)styrene III (TFMST),
either unsubstituted at the aryl group or possessing a bro-
mo substituent at the para position, were identified as
prime candidates for further studies (Figure 1). (Co)poly-
merisation of these monomers could deliver material suit-
able for post-modification (e.g., sulfonylation or
phosphonylation). Alternatively, if this strategy suffers
from lack of control over the degree and location of func-
tionalisation, these monomers can be manipulated prior to
polymerisation.
X
X
X
X = H, Br, P(O)(OEt)2
I
II
III
Figure 1 Three classes of fluorinated monomers: a-(monofluoro-
methyl)styrenes I (FMST), a-(difluoromethyl)styrenes II (DFMST),
a-(trifluoromethyl)styrenes III (TFMST).
OSO2CF3
Si
F
i
ii
X
X
X
1a (X = H)
40 mmol scale
1b (X = Br)
2a (X = H, 60%)
2b (X = Br, 57%)
3a (X = H, 65%)
3b (X = Br, 63%)
The monofluorinated monomers FMST 3a and 4-
BrFMST 3b were prepared following a two-step process
(Scheme 1). In preliminary work, we studied the reactivi-
ty of allylsilanes 2a,b (3–5 mmol scale), which are prone
30 mmol scale
Scheme 1 Synthesis of a-(monofluoromethyl)styrenes 3 by electro-
philic fluorodesilylation of allylsilanes 2 with Selectfluor. Reagents
and conditions: (i) for 1a: Pd(OAc)2 (0.03 equiv) dppf (0.13 equiv),
allylTMS (5 equiv), Et3N (2 equiv), MeCN, 60 °C, 20 h; for 1b
Pd(OAc)2 (0.03 equiv), dppf (0.13 equiv), allylTMS (5 equiv), K2CO3
(2 equiv), MeCN, 65 °C, 20 h; (ii) (b) Selectfluor (1.1 equiv), MeCN,
r.t., 2 h.
SYNTHESIS 2010, No. 11, pp 1883–1890
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Advanced online publication: 12.05.2010
DOI: 10.1055/s-0029-1218785; Art ID: C02810SS
© Georg Thieme Verlag Stuttgart · New York

1884
J. Walkowiak et al.
SPECIAL TOPIC
Table 1 Electrophilic Fluorination of 2a,b
ylenation was performed by reacting these aldehydes with
the Eschenmoser’s salt [dimethyl(methylene)ammonium
iodide] in the presence of a large excess of triethylamine.
Without isolation, the resulting products were reduced,
leading uneventfully to the desired allylic alcohols 8a and
8b in moderate to good yields over two steps. These alco-
hols were converted into the corresponding fluorides 3a
and 3b by direct nucleophilic fluorination. In comparative
studies, both DAST and FLUOLEAD, a more stable re-
agent used in combination with triethylamine trihydrofluo-
ride, were employed.11 The yields for the fluorination
were consistent and comparable, independent of the re-
agent or the scale of the reaction, averaging 67% and 61%
for 3a and 3b, respectively.
Entry Triflate
(mmol)
X
Silanea
(yield)
Allylic fluoride Overall
(yield)
yieldb (%)
1
2
3
4
5
6
7
1a (3)
H
2a (84%)
2a (83%)
2a (72%)
2a (60%)
2b (78%)
2b (67%)
2b (57%)
3a (93%)
3a (74%)
3a (72%)
3a (65%)
3b (76%)
3b (65%)
3b (63%)
78
61
52
39
59
43
36
1a (6)
H
1a (20)
1a (40)
1b (5)
H
H
Br
Br
Br
1b (15)
1b (30)
a Isolated yield.
b Isolated overall yield over 2 steps.
This three-step synthetic route to a-(monofluorometh-
yl)styrenes using direct nucleophilic fluorination was
found to be easy to implement, selective, cost-effective,
and easily scalable (up to 100 mmol) giving the desired al-
lylic fluorides 3a (X = H) and 3b (X = Br) in 47% and
38% overall yield, respectively (Scheme 3, Table 2).
Recently, Luo and Loh reported a one-step direct electro-
philic fluorination of a-methylstyrene (4) with Select-
fluor.8 For this less reactive alkene, the fluorination
required higher temperatures and extended reaction times
to reach completion. Carried out on a 2 mmol scale, this
reaction was found reproducible and delivered (3-fluoro-
prop-1-en-2-yl)benzene (3a) in 75% isolated yield. When
using up to 38 mmol of a-methylstyrene (4), the fluorina-
tion led to the formation of significant amounts of byprod-
ucts identified as the isomerised fluoroalkenes (E)-5 and
(Z)-5. The subsequent purification proved difficult and
this was directly reflected in the low isolated yield of the
pure desired product 3a (35%). This route was therefore
abandoned (Scheme 2).
OH
iii
F
O
O
i
ii
X
X
X
X
6a (X = H)
100 mmol scale 7b (X = Br)
6b (X = Br)
70 mmol scale
7a (X = H)
8a (X = H, 73%)
over 2 steps
8b (X = Br, 66%)
over 2 steps
3a (X = H, 65%)
3b (X = Br, 58%)
Scheme 3 Synthesis of a-(monofluoromethyl)styrenes 3 by direct
nucleophilic deoxyfluorination of the allylic alcohols 8 with DAST or
FLUOLEAD. Reagents and conditions: (i) Me2N+=CH2 I– (2 equiv),
Et3N (10 equiv), CH2Cl2, r.t., 30 min; (ii) NaBH4 (1 equiv), CeCl3·7
H2O (1 equiv), r.t., 1 h; (iii) DAST (1.5 equiv), CH2Cl2, r.t., 6 h or
FLUOLEAD (1.25 equiv), Et3N·3 HF (1.25 equiv), CH2Cl2, r.t., 6 h.
F
F
i
+
3a (35%)
(E/Z)-5 (9%)
4
The monofluorinated styrenic monomer 3b was further
manipulated taking advantage of the presence of the bro-
mo substituent. The introduction of a phosphonate group
was elected as a suitable post-modification since it is well
documented that polymers substituted with phosphonic
acid groups display advantageous characteristics for fuel
cell membrane applications.12 To form the necessary aryl–
P bond, different approaches were considered inclusive of
the classical Michaelis–Arbuzov or Michaelis–Becker
Scheme 2 Direct electrophilic fluorination of a-methylstyrene.8
Reagents and conditions: (i) Selectfluor (1.1 equiv), DMF, 75 °C, 18
h.
At this stage, the availability of both diethylaminosulfur
trifluoride (DAST) and 4-tert-butyl-2,6-dimethylphenyl-
sulfur trifluoride (FLUOLEAD), two reagents suitable for
nucleophilic fluorination, encouraged further work. The
synthesis of allylic alcohols 8a,b to be used as starting
materials was first examined using metal-mediated cou-
pling chemistry. Both ionic-liquid-promoted palladium-
catalysed Heck coupling of various halobenzenes with al-
lylic alcohols9 and nickel-catalysed cross-coupling of 2-
chloroallylic alcohol with Grignard reagents10 were at-
tempted, but these transformations were either poorly re-
gioselective or low yielding.
14
15
reactions13 as well as NiCl2 or Pd(PPh3)4 mediated
cross-coupling processes. However, metal–halogen ex-
change followed by P–C bond formation proved to be the
most efficient protocol. Accordingly, the reaction of the in
situ generated aryllithium intermediate derived from 3b
with diethyl chlorophosphate produced the desired
arylphosphonate 9 (4-PFMST) in 54% isolated yield. This
reaction was performed on
a 25.7 mmol scale
(Scheme 4).16
The most convenient large-scale synthesis (up to 100
mmol) of 8a,b began with the aldehydes 6a and 6b. a-Meth-
Synthesis 2010, No. 11, 1883–1890 © Thieme Stuttgart · New York

SPECIAL TOPIC
Syntheses of Mono-, Di-, and Trifluorinated Styrenic Monomers
1885
Table 2 Nucleophilic Fluorination of 8a,b
Entry
1
Aldehyde (mmol)
X
H
Allylic alcohola (yield) Allylic fluoride (yield)
Overall yieldb (%)
6a (5)
8a (75%)
8a (73%)
8a (75%)
8a (73%)
8b (67%)
8b (59%)
8b (63%)
8b (66%)
3a (68%)c
3a (65%)d
51c
49d
2
3
4
5
6
7
8
6a (10)
6a (50)
6a (100)
6b (5)
H
3a (69%)c
3a (70%)d
50c
51d
H
3a (67%)c
3a (66%)d
50c
49d
H
3a (65%)c
3a (67%)d
47c
49d
Br
Br
Br
Br
3b (65%)c
3b (65%)d
43c
43d
6b (10)
6b (50)
6b (70)
3b (61%)c
3b (63%)d
36c
37d
3b (59%)c
3b (57%)d
37c
36d
3b (58%)c
3b (59%)d
38c
39d
a Isolated yield over 2 steps.
b Isolated overall yield over 3 steps.
c Fluorination with DAST.
d Fluorination with FLUOLEAD.
gave the desired sulfone 12 in 82% yield (Lit. 83%).19a
This bromodifluoromethyl phenyl sulfone (12) was con-
verted into the corresponding difluoromethylating reagent
13 by treatment with chlorotrimethylsilane in the presence
of n-butyllithium at –78 °C.20 This three-step synthetic
route to difluoromethyl phenyl sulfone (13) was found to
be effective and easily scalable giving the desired product
in 44% overall yield.
F
F
i
54%
O
P
OEt
Br
OEt
9
3b
Scheme 4 Synthesis of diethyl 4-(3-fluoroprop-1-en-2-yl)phenyl-
phosphonate (9). Reagents and conditions: (i) n-BuLi (1.1 equiv),
(EtO)2P(O)Cl (1.1 equiv), THF, –78 °C, 4 h.
F
F
F
F
F
F
S–Na+
O
O
S
Br
S
Br
S
H
ii
i
iii
O
O
69%
82%
78%
Our long-term objective is to examine the influence of the
fluorine content of styrenic monomers on both reactivity
and copolymer composition. Since the difluoromethyl
group has been used extensively to modulate the physico-
chemical properties of organic molecules, we considered
accessing the a-(difluoromethyl)styrene 17 for subse-
quent polymerisations.17 Attempts to access this monomer
by direct fluorination of the corresponding 1,3-dithiolane
using DAST in the presence of either 1,3-dibromo-5,5-
dimethylhydantoin or N-bromosuccinimide were not suc-
cessful.18 We, therefore, examined an alternative strategy
based on a nucleophilic difluoromethylation process us-
ing the well-documented reagent difluoromethyl phenyl
sulfone (13) (Scheme 5). This reagent was prepared by
using a three-step literature protocol.19 The reaction of
sodium thiophenolate (10, 40 mmol scale) with dibromo-
difluoromethane in the presence of catalytic amount of
dibenzo-18-crown-6 ether resulted in the formation of
bromodifluoromethyl sulfide 11 in a good yield (69%).
Oxidation of 11 with excess m-chloroperoxybenzoic acid
10 (40 mmol)
11 (27.6 mmol)
12 (22.6 mmol)
13 (17.7 mmol)
Scheme 5 Three-step synthesis of difluoromethyl phenyl sulfone
(13). Reagents and conditions: (i) CF2Br2 (3 equiv), dibenzo-18-
crown-6 (0.02 equiv), Et2O, –40 °C, 8 h; (ii) MCPBA (3 equiv),
CH2Cl2, 0–20 °C, 2 h; (iii) n-BuLi (1.8 equiv), TMSCl (1.5 equiv),
THF, –78 °C, 1 h, silica gel purification.
The base-induced coupling of 13 with acetophenone 14
was performed in tetrahydrofuran at –78 °C.21 The result-
ing carbinol 15 was isolated in 74% yield (Scheme 6). De-
hydration of 15 was high yielding (90%) using
phosphorus pentoxide in toluene at reflux. Reductive de-
sulfonylation of the resulting difluorinated sulfone 16 af-
forded the desired a-(difluoromethyl)styrene 17, albeit in
low yield.22 Despite the low yield of the last step, this syn-
thetic route was found easy to implement and was applied
Synthesis 2010, No. 11, 1883–1890 © Thieme Stuttgart · New York

1886
J. Walkowiak et al.
SPECIAL TOPIC
CF2SO2Ph
mono-, a-di-, and a-trifluoromethyl-substituted styrene
analogues were made available in gram quantities allow-
ing for subsequent polymerisation studies. If superior
polymers emerge, further improvement will be necessary
to carry out the synthesis of these monomers on a much
larger scale. The results of (co)polymerisation of these
monomers with styrene or fluorinated olefins will be re-
ported in due course.
O
CF2SO2Ph
iii
30%
CF2H
OH
ii
i
90%
74%
14
15
16
17
Scheme 6 Synthesis of a-(difluoromethyl)styrene 17 by nucleophi-
lic difluoromethylation of acetophenone 14 with difluoromethyl phe-
nyl sulfone (13). Reagents and conditions: (i) acetophenone (14, 2
equiv), PhSO2CF2H (13, 1 equiv), LiHMDS (2 equiv), HMPA–THF,
–78 °C, 2 h; (ii) P2O5 (3 equiv), toluene, reflux, 2 h; (iii) Mg (15
equiv), AcOH–NaOAc buffer, DMF, r.t., 2 h.
1H NMR spectra were recorded in deuterated solvents using Bruker
DPX200, AV400 spectrometers, calibrated using residual undeuter-
ated solvent as an internal reference. 13C NMR spectra were record-
ed in deuterated solvents using Bruker DPX200, AV400
spectrometers. 19F and 31P spectra were recorded on a AV400 spec-
trometer. Mass spectral data were recorded on Micromass GCT (CI)
or Bruker FT-ICR-MS Apex III (EI) instruments. All reactions re-
quiring anhydrous conditions were conducted in dried apparatus un-
der an inert atmosphere of N2. Solvents were dried and purified
before use according to standard procedures. Room temperature =
20 °C. All reactions were monitored by TLC using Merck Kiesegel
60 F254 plates. Visualisation of the reaction components was
achieved using UV fluorescence (254 nm) and KMnO4 stain. Col-
umn chromatography was carried out over Merck silica gel C60
(40–60 mm). Purification of large-scale reactions was performed on
Biotage SP-4 System, using Biotage KP-SIL SNAP Flash Car-
tridges (10 g, 25 g, 50 g, 100 g, 340 g). Petroleum ethers PE 30-40
and PE 40-60 used refer to the fraction boiling in the ranges 30–40
°C and 40–60 °C, respectively.
for the synthesis of gram quantities of 17 (20 mmol scale)
allowing for polymerisation studies.
Preliminary efforts to access the trifluorinated monomers
20a,b (TFMST) focused on palladium-catalysed cross-
coupling reactions of both organoboron compounds with
3,3,3-trifluoroprop-1-en-2-yl tosylate,23 and of haloben-
zenes with a 1:1 complex of 3,3,3-trifluoropropen-2-yl-
zinc bromide and N,N,N¢,N¢-tetramethylethylenediamine.24
These reactions failed to deliver 20a leading instead to
complex mixture of products. Pleasingly, the Suzuki cou-
pling of organoboron 18a with 2-bromo-3,3,3-trifluoro-
propene (19) was successful affording the a-
(trifluoromethyl)styrene derivatives 20a in good chemical
yield. The coupling was also successful with the para-
brominated phenylboronic acid 18b leading to 20b in 54%
yield. This chemistry was routinely performed on a 30
mmol scale (Scheme 7, Table 3).25
Trimethyl(2-phenylallyl)silanes 2; General Procedure (GP1)
A mixture of triflate 1 (1 equiv), Pd(OAc)2 (0.03 equiv), dppf (0.13
equiv), allyltrimethylsilane (5 equiv), base (2 equiv), and anhyd
MeCN (4 mL) was placed in a pressure tube. The tube was sealed
and the mixture was heated for 20 h with vigorous stirring. The re-
sulting dark soln was allowed to cool to r.t. and the mixture was
quenched with H2O (8 mL) and extracted with Et2O (3 × 8.5 mL).
The combined organic layers were dried (Na2SO4) and concentrated
at reduced pressure. The residue was purified by column chroma-
tography (silica gel, PE 40-60) or by Biotage SP-4 System (PE 40-
60).
In conclusion, we have developed efficient routes to novel
functional aromatic fluorinated monomers. Various a-
CF3
B(OH)2
CF3
i
+
Br
Trimethyl(2-phenylallyl)silane (2a)
X
X
Following GP1 using triflate 1 (9.05 g, 6.48 mL, 40.0 mmol),
Pd(OAc)2 (0.27 g, 1.20 mmol), dppf (2.96 g, 5.33 mmol), allyltri-
methylsilane (22.8 g, 31.8 mL, 200 mmol), Et3N (8.09 g, 11.2 mL,
80.0 mmol), and anhyd MeCN (160 mL), heated at 60 °C, with
quenching with H2O (320 mL) and extraction with Et2O (3 × 350
mL) gave 2a; yield: 4.57 g (24.0 mmol, 60%); Rf = 0.68 (hexane).
1H NMR (400 MHz, CDCl3): d = –0.11 [s, 9 H, Si(CH3)3], 2.02 [m,
2 H, CH2Si(CH3)3], 4.86 (m, 1 H, C=CH2), 5.12 (m, 1 H, C=CH2),
7.26–7.34 (m, 3 H, HAr), 7.38–7.43 (m, 2 H, HAr).
18a (X = H)
30 mmol scale
18b (X = Br)
20 mmol scale
19
20a (X = H, 84%)
20b (X = Br, 54%)
Scheme 7 Synthesis of a-(trifluoromethyl)styrenes 20a,b by Suzuki
coupling of the phenylboronic acids 18a,b with 2-bromo-3,3,3-
trifluoropropene (19). Reagents and conditions: (i) PdCl2(PPh3)2
(0.03 equiv), AsPh3 (0.15 equiv), DME–THF (1:1), 2 M KOH, 74 °C,
16 h.
13C NMR (100 MHz, CDCl3): d = –1.4 [Si(CH3)3], 26.2
[CH2Si(CH3)3], 110.1 (C=CH2), 126.3 (CAr), 127.2 (CAr), 128.1
(CAr), 142.8 (CAr), 146.6 (C=CH2).
Table 3 Palladium-Catalysed Cross-Coupling of 18a,b with 19
HRMS (CI): m/z [M]+ calcd for C12H18Si: 190.1178; found:
190.1177.
Entry Phenylboronic acid X
(mmol)
a-(Trifluoromethyl)
styrene
Yielda
(%)
1
2
3
4
18a (10)
18a (30)
18b (3)
H
20a
20a
20b
20b
73
84
54
54
[2-(4-Bromophenyl)allyl]trimethylsilane (2b)
Following GP1 using triflate 1a (9.15 g, 30.0 mmol), Pd(OAc)2
(0.20 g, 0.90 mmol), dppf (2.16 g, 3.99 mmol), allyltrimethylsilane
(17.1 g, 23.8 mL, 150 mmol), K2CO3 (8.29 g, 60.0 mmol), and an-
hyd MeCN (120 mL), heated at 65 °C, with quenching with H2O
(240 mL) and extraction with Et2O (3 × 250 mL); yield: 4.61 g (17.1
mmol, 57%); Rf = 0.68 (hexane).
H
Br
Br
18b (20)
a Isolated yield.
Synthesis 2010, No. 11, 1883–1890 © Thieme Stuttgart · New York

SPECIAL TOPIC
Syntheses of Mono-, Di-, and Trifluorinated Styrenic Monomers
1887
1H NMR (400 MHz, CDCl3): d = –0.09 [s, 9 H, Si(CH3)3], 1.99 [d,
J = 0.9 Hz, 2 H, CH2Si(CH3)3], 4.88 (m, 1 H, C=CH2), 5.12 (d,
J = 1.5 Hz, 1 H, C=CH2), 7.28 (d, J = 8.7 Hz, 2 H, HAr), 7.43 (d,
J = 8.7 Hz, 2 H, HAr).
13C NMR (100 MHz, CDCl3): d = –1.4 [Si(CH3)3], 26.0
[CH2Si(CH3)3], 110.6 (C=CH2), 121.1 (CAr), 127.9 (CAr), 131.1
(CAr), 141.6 (CAr), 145.5 (C=CH2).
13C NMR (100 MHz, CDCl3): d = 64.8 (CH2OH), 113.3 (C=CH2),
121.9 (CAr), 127.7 (CAr), 131.6 (CAr), 137.3 (CAr), 146.1 (C=CH2).
HRMS (EI): m/z [M]+ calcd for C9H9OBr: 211.9837; found:
211.9842.
2-Phenylallylic Fluorides 3 by Fluorodesilylation; General Pro-
cedure (GP3)
A soln of the allylsilane 2 (1 equiv) in anhyd MeCN (8 mL) was
treated with Selectfluor (1.1 equiv). The mixture was stirred at r.t.
for 2 h. When the reaction was complete, the mixture was poured
into a separating funnel charged with sat. aq NaHCO3 and extracted
with Et2O (3 × 20 mL). The combined organic layers were washed
with brine, dried (MgSO4), and concentrated under reduced pres-
sure. The residue was purified by column chromatography (silica
gel, PE 30-40) or by Biotage SP-4 System (PE 30-40), or by short-
path distillation under reduced pressure.
HRMS (EI): m/z [M]+ calcd for C12H17BrSi: 268.0283; found:
268.0281.
2-Arylacrylaldehydes 7 and 2-Arylallylic Alcohols 8; General
Procedure (GP2)
To a soln of aldehyde 6 (50 mmol, 1 equiv) and Et3N in anhyd
CH2Cl2 (500 mL), was added portion wise Me2N+=CH2 I– (100
mmol, 2 equiv). The mixture was stirred at r.t. until the starting ma-
terial had been consumed (TLC monitoring). The mixture was then
washed with sat. aq NaHCO3 and brine, dried (MgSO4), and con-
centrated under reduced pressure (note that the temperature of rota-
ry evaporator bath should not exceed 20 °C). The crude residue of
allylic aldehyde 7 was then submitted to the next step of synthesis
without purification. To a soln of crude aldehyde 7 and CeCl3·7 H2O
(50 mmol, 1 equiv) in abs EtOH (500 mL) was added portionwise
NaBH4 (50 mmol, 1 equiv). The mixture was stirred at r.t. for 1 h.
H2O was slowly added and the mixture was extracted with CH2Cl2
(3 × 500 mL). The combined organic layers were dried (MgSO4)
and concentrated under reduced pressure. Crude alcohol 8 was pu-
rified by column chromatography (silica gel, gradient PE 30-40–
Et2O) or by Biotage SP-4 System (gradient PE 30-40–Et2O).
(3-Fluoroprop-1-en-2-yl)benzene (3a)
According to GP3 using 2a (4.57 g, 24.0 mmol) in anhyd MeCN
(190 mL) and Selectfluor (9.35 g, 26.4 mmol) with extraction with
Et2O (3 × 480 mL); yield: 2.12 g (15.6 mmol, 65%); bp 80–81 °C/
17 mbar; Rf = 0.4 (pentane).
1H NMR (400 MHz, CDCl3): d = 5.26 (d, J = 47.1 Hz, 2 H, CH2F),
5.44 (s, 1 H, C=CH2), 5.63 (m, 1 H, C=CH2), 7.32–7.41 (m, 3 H,
HAr), 7.46–7.48 (m, 2 H, HAr).
13C NMR (100 MHz, CDCl3): d = 84.3 (d, J = 169.4 Hz, CH2F),
115.3 (d, J = 11.2 Hz, H2C=CCH2F), 125.9 (CAr), 128.2 (CAr), 128.5
(CAr), 137.2 (CAr), 143.0 (d, J = 15.2 Hz, H2C=CCH2F).
19F NMR (376 MHz, CDCl3): d = –212.7 (t, J = 47.0 Hz, 1 F,
2-Phenylacrylaldehyde (7a)
Crude product; Rf = 0.65 (hexane–Et2O, 4:1).
CH2F).
HRMS (CI): m/z [M]+ calcd for C9H9F: 136.0688; found: 136.0685.
1H NMR (400 MHz, CDCl3): d = 6.19 (m, 1 H, C=CH2), 6.64 (m, 1
H, C=CH2), 7.37–7.44 (m, 3 H, HAr), 7.45–7.50 (m, 2 H, HAr), 9.82
(s, 1 H, CHO).
13C NMR (100 MHz, CDCl3): d = 128.0 (CAr), 128.3 (CAr), 128.7
(CAr), 133.6 (C=CH2), 135.6 (CAr), 148.3 (C=CH2), 192.9 (CHO).
1-Bromo-4-(3-fluoroprop-1-en-2-yl)benzene (3b)
According to GP3 using 2b (4.61 g, 17.1 mmol) in anhyd MeCN
(140 mL) and Selectfluor (6.66 g, 18.8 mmol) with extraction with
Et2O (3 × 350 mL); yield: 2.32 g (10.8 mmol, 63%); Rf = 0.4 (pen-
tane).
1H NMR (400 MHz, CDCl3): d = 5.21 (d, J = 47.1 Hz, 2 H, CH2F),
5.45 (d, J = 3.1 Hz, 1 H, C=CH2), 5.62 (m, 1 H, C=CH2), 7.33 (d,
J = 8.5 Hz, 2 H, HAr), 7.50 (d, J = 8.5 Hz, 2 H, HAr).
13C NMR (100 MHz, CDCl3): d = 84.1 (d, J = 169.1 Hz, CH2F),
116.2 (d, J = 10.3 Hz, H2C=CCH2F), 122.2 (CAr), 127.5 (CAr), 131.6
(CAr), 136.1 (d, J = 2.3 Hz, CAr), 142.0 (d, J = 14.9 Hz,
H2C=CCH2F).
2-(4-Bromophenyl)acrylaldehyde (7b)
Crude product; Rf = 0.65 (hexane–Et2O, 4:1).
1H NMR (400 MHz, CDCl3): d = 6.21 (s, 1 H, C=CH2), 6.65 (s, 1
H, C=CH2), 7.35 (d, J = 8.4 Hz, 2 H, HAr), 7.52 (d, J = 8.5 Hz, 2 H,
HAr), 9.78 (s, 1 H, CHO).
13C NMR (100 MHz, CDCl3): d = 125.6 (CAr), 129.7 (CAr), 131.5
(CAr), 131.8 (C=CH2), 136.3 (CAr), 147.3 (C=CH2), 192.6 (CHO).
19F NMR (376 MHz, CDCl3): d = –212.3 (dt, J = 47.1 Hz, J = 3.1
2-Phenylprop-2-en-1-ol (8a)
Yield: 5.03 g (37.5 mmol, 75%, over 2 steps); Rf = 0.37 (hexane–
Et2O, 3:1).
Hz, 1 F, CH2F).
HRMS (EI): m/z [M]+ calcd for C9H8BrF: 213.9793; found:
1H NMR (400 MHz, CDCl3): d = 1.89 (br s, 1 H, OH), 4.54 (s, 2 H,
CH2OH), 5.36 (m, 1 H, C=CH2), 5.48 (m, 1 H, C=CH2), 7.31–7.39
(m, 3 H, HAr), 7.45–7.47 (m, 2 H, HAr).
13C NMR (100 MHz, CDCl3): d = 64.9 (CH2OH), 112.5 (C=CH2),
126.0 (CAr), 127.9 (CAr), 128.5 (CAr), 138.4 (CAr), 147.2 (C=CH2).
HRMS (EI): m/z [M]+ calcd for C9H10O: 134.0732; found:
134.0735.
213.9789.
(3-Fluoroprop-1-en-2-yl)benzene (3a) by Direct Electrophilic
Fluorination
To a soln of a-methylstyrene 4 (4.55 g, 5.00 mL, 38.0 mmol) in
DMF (200 mL) was added portionwise Selectfluor (14.9 g, 41.8
mmol). The mixture was stirred at 75 °C for 18 h and then allowed
to cool to r.t. and poured into a separating funnel charged with sat.
aq NaHCO3 (400 mL) and extracted with Et2O (3 × 250 mL). The
combined organic layers were washed with H2O, brine, dried
(MgSO4), and concentrated under reduced pressure. The residue
was purified by column chromatography (silica gel, PE 30-40) or by
Biotage SP-4 System (PE 30-40); yield: 1.81 g (13.3 mmol, 35%).
2-(4-Bromophenyl)prop-2-en-1-ol (8b)
Yield: 6.71 g (31.5 mmol, 63%, over 2 steps); Rf = 0.37 (hexane–
Et2O, 3:1).
1H NMR (400 MHz, CDCl3): d = 1.96 (br s, 1 H, OH), 4.50 (m, 2 H,
CH2OH), 5.36 (m, 1 H, C=CH2), 5.47 (m, 1 H, C=CH2), 7.32 (d,
J = 8.6 Hz, 2 H, HAr), 7.47 (d, J = 8.6 Hz, 2 H, HAr).
Synthesis 2010, No. 11, 1883–1890 © Thieme Stuttgart · New York

1888
J. Walkowiak et al.
SPECIAL TOPIC
a-(Monofluoromethyl)styrenes 3 by Nucleophilic Fluorination;
General Procedure (GP4)
J = 8.0 Hz, J = 3.8 Hz, 2 H, HAr), 7.80 (dd, J = 13.0 Hz, J = 8.0 Hz,
2 H, HAr).
Fluorination Procedure Using DAST: To a soln of allylic alcohol 8
(1 equiv) in anhyd CH2Cl2 (4 mL) at 0 °C was added dropwise
DAST (1.5 equiv). The mixture was then warmed to r.t. and stirred
for 6 h (TLC monitoring). Sat. aq NaHCO3 was then slowly added
and the mixture was extracted with CH2Cl2. The combined organic
layers were dried (MgSO4) and concentrated under reduced pres-
sure. The residue was purified by column chromatography (silica
gel, PE 30-40) or by Biotage SP-4 System (PE 30-40), or by short-
path distillation under reduced pressure.
13C NMR (100 MHz, CDCl3): d = 16.3 (d, J = 6.6 Hz, OCH2CH3),
62.1 (d, J = 5.3 Hz, OCH2CH3), 84.0 (d, J = 169.2 Hz, CH2F), 117.7
(d, J = 10.1 Hz, H2C=CCH2F), 125.9 (d, J = 15.4 Hz, CAr), 128.0 (d,
J = 189.4 Hz, CAr), 132.1 (d, J = 10.1 Hz, CAr), 141.2 (CAr), 142.2
(d, J = 15.4 Hz, H2C=CCH2F).
19F NMR (376 MHz, CDCl3): d = –212.5 (dt, J = 47.1 Hz, J = 3.1
Hz, 1 F, CH2F).
31P NMR (376 MHz, CDCl3): d = 18.5 [m, 1 P, (O)P(OCH2CH3)2].
HRMS (EI): m/z [M]+ calcd for C13H18FO3P: 272.0978; found:
272.0980.
Fluorination Procedure Using FLUOLEAD: To a soln of FLU-
OLEAD (1.25 equiv) and Et3N·3 HF (1.25 equiv) in anhyd CH2Cl2
(2 mL) at 0 °C was added dropwise a soln of allylic alcohol 8 (1
equiv) in anhyd CH2Cl2 (2 mL). The mixture was then warmed to
r.t. and stirred for 6 h (TLC monitoring). Sat. aq K2CO3 (5 mL) was
then slowly added, the mixture was additionally stirred for 1 h, and
then extracted with CH2Cl2 (3 × 3 mL). The combined organic lay-
ers were dried (MgSO4) and concentrated under reduced pressure.
The residue was purified by column chromatography (silica gel, PE
30-40) or by Biotage SP-4 System (PE 30-40), or by short-path dis-
tillation under reduced pressure.
1,1-Difluoro-2-phenyl-1-(phenylsulfonyl)propan-2-ol (15)
To a soln of PhSO2CF2H (13, 3.84 g, 20.0 mmol) and acetophenone
(14, 4.81 g, 4.67 mL, 40.0 mmol) in THF–HMPA (110 mL; 10:1 v/v)
cooled to –78 °C was added dropwise 1 M LiHMDS (40 mL, 40
mmol). The mixture was stirred at –78 °C for 2 h. Sat. aq NaCl (200
mL) was then added at –78 °C and the residue was brought to r.t.
and extracted with Et2O (3 × 400 mL). The combined organic layers
were dried (MgSO4) and evaporated under reduced pressure. The
crude product was purified by column chromatography (silica gel,
PE 40-60–CH2Cl2) or by Biotage SP-4 System (PE 40-60–CH2Cl2);
yield: 4.62 g (14.8 mmol, 74%); Rf = 0.21 (hexane–CH2Cl2, 4:1).
(3-Fluoroprop-1-en-2-yl)benzene (3a)
According to GP4-DAST using 8a (5.03 g, 37.5 mmol) in anhyd
CH2Cl2 (150 mL) and DAST (6.54 g, 5.40 mL, 56.3 mmol) then sat.
aq NaHCO3 (200 mL) and extraction with CH2Cl2 (3 × 200 mL);
yield: 3.42 g (25.1 mmol, 67%).
1H NMR (400 MHz, CDCl3): d = 1.99 (m, 3 H, CH3), 3.91 (br s, 1
H, OH), 7.37 (m, 3 H, HAr), 7.56 (m, 4 H, HAr), 7.71 (t, J = 7.6 Hz,
1 H, HAr), 7.89 (d, J = 8.0 Hz, 2 H, HAr).
13C NMR (100 MHz, CDCl3): d = 24.8, 76.8 [t, J = 19 Hz,
(OH)CCF2], 120.8 (t, J = 299 Hz, CF2), 126.6 (CAr), 128.2 (CAr),
128.6 (CAr), 129.3 (CAr), 130.4 (CAr), 133.8 (CAr), 135.3 (CAr), 138.9
(CAr).
1-Bromo-4-(3-fluoroprop-1-en-2-yl)benzene (3b)
According to GP4-DAST using 8b (6.71 g, 31.5 mmol) in anhyd
CH2Cl2 (120 mL) and DAST (7.62 g, 6.25 mL, 47.3 mmol) then sat.
aq NaHCO3 (150 mL) and extraction with CH2Cl2 (3 × 200 mL);
yield: 4.00 g (18.6 mmol, 59%).
19F NMR (376 MHz, CDCl3): d = –105.3 (s, 2 F, CF2).
HRMS (EI): m/z [M]+ calcd for C15H14F2O3S: 312.0632; found:
312.0633.
(3-Fluoroprop-1-en-2-yl)benzene (3a)
According to GP4-FLUOLEAD using 8a (5.03 g, 37.5 mmol) in an-
hyd CH2Cl2 (75 mL) and FLUOLEAD (11.7 g, 46.9 mmol) and
Et3N·3 HF (7.56 g, 7.68 mL, 46.9 mmol) in anhyd CH2Cl2 (75 mL)
and then sat. aq K2CO3 (190 mL) and extraction with CH2Cl2 (3 ×
120 mL); yield: 3.37 g (24.8 mmol, 66%).
3,3-Difluoro-2-phenyl-3-(phenylsulfonyl)prop-1-ene (16)
To a soln of 15 (4.62 g, 14.8 mmol) in toluene (120 mL) was added
P2O5 (6.30 g, 44.4 mmol) and the mixture was stirred at reflux for 2
h. The mixture was then allowed to cool to r.t. and poured into a sep-
arating funnel charged with H2O (200 mL) and extracted with Et2O
(3 × 300 mL). The combined organic layers were dried (Na2SO4)
and concentrated under reduced pressure. The residue was purified
by column chromatography (silica gel, PE 40-60–CH2Cl2) or by
Biotage SP-4 System (PE 40-60–CH2Cl2); yield: 3.92 g (13.3
mmol, 90%); Rf = 0.33 (hexane–CH2Cl2, 4:1).
1-Bromo-4-(3-fluoroprop-1-en-2-yl)benzene (3b)
According to GP4-FLUOLEAD using 8b (6.71 g, 31.5 mmol) in an-
hyd CH2Cl2 (65 mL) and FLUOLEAD (9.86 g, 39.4 mmol) and
Et3N·3 HF (6.35 g, 6.40 mL, 39.4 mmol) in anhyd CH2Cl2 (65 mL)
and then sat. aq K2CO3 (160 mL) and extraction with CH2Cl2 (3 ×
100 mL); yield: 3.86 g (18.0 mmol, 57%).
1H NMR (400 MHz, CDCl3): d = 5.98 (s, 1 H, C=CH2), 6.13 (s, 1
H, C=CH2), 7.31 (m, 2 H, HAr), 7.51 (m, 3 H, HAr), 7.60 (t, J = 7.7
Hz, 2 H, HAr), 7.75 (t, J = 7.2 Hz, 1 H, HAr) 8.02 (d, J = 7.7 Hz, 2 H,
HAr).
13C NMR (100 MHz, CDCl3): d = 121.2 (t, J = 288 Hz, CF2), 125.3
(CAr), 127.9 (CAr), 128.2 (CAr), 128.7 (t, J = 9 Hz, H2C=CCF2),
128.9 (CAr), 129.0 (CAr), 129.2 (CAr), 130.6 (CAr), 135.2 (CAr), 137.7
(t, J = 21 Hz, H2C=CCF2).
Diethyl 4-(3-Fluoroprop-1-en-2-yl)phenylphosphonate (9)
To a soln of 1-bromo-4-(3-fluoroprop-1-en-2-yl)benzene (3b, 5.53
g, 25.7 mmol, 1 equiv) in anhyd THF (180 mL) cooled to –78 °C
was added dropwise 2.5 M n-BuLi (12.0 mL, 28.3 mmol, 1.1
equiv). The residue was stirred at –78 °C for 1 h and (EtO)2P(O)Cl
(4.88 g, 4.10 mL, 28.3 mmol, 1.1 equiv) was then added. The mix-
ture was stirred at –78 °C for an additional 1 h until the starting ma-
terial had been consumed (TLC monitoring), then allowed to warm
up to r.t. and Et2O and sat. aq NaHCO3 were added. The mixture
was extracted with Et2O (3 × 200 mL) and the combined organic
layers were dried (MgSO4) and concentrated under reduced pres-
sure. The residue was purified by column chromatography (silica
gel, CH2Cl2–EtOAc) or by Biotage SP-4 System (CH2Cl2–EtOAc);
yield: 3.78 g (13.9 mmol, 54%); Rf = 0.27 (CH2Cl2–EtOAc, 4:1).
19F NMR (376 MHz, CDCl3): d = –97.7 (s, 2 F, CF2).
HRMS (EI): m/z [M]+ calcd for C15H12F2O2S: 294.0526; found:
294.0528.
(3,3-Difluoroprop-1-en-2-yl)benzene (17)
To a soln of sulfone 16 (3.92 g, 13.3 mmol) in DMF (130 mL) at r.t.
was added AcOH–NaOAc (1:1) buffer soln (70 mL, 8 mol/L). Mg
turnings (4.85 g, 199 mmol) were added in portions. The mixture
was stirred at r.t. for 3 h followed by addition of H2O (400 mL). The
mixture was extracted with Et2O (3 × 300 mL) and the combined or-
1H NMR (400 MHz, CDCl3): d = 1.32 (t, J = 7.1 Hz, 6 H,
OCH2CH3), 4.11 (m, 4 H, OCH2CH3), 5.23 (d, J = 47.1 Hz, 2 H,
CH2F), 5.52 (m, 1 H, C=CH2), 5.70 (m, 1 H, C=CH2), 7.54 (dd,
Synthesis 2010, No. 11, 1883–1890 © Thieme Stuttgart · New York

SPECIAL TOPIC
Syntheses of Mono-, Di-, and Trifluorinated Styrenic Monomers
1889
ganic phases were washed with sat. NaHCO3 soln and brine and
dried (MgSO4). Et2O was removed and the crude product was puri-
fied by column chromatography (silica gel, PE 30-40) or by Biotage
SP-4 System (PE 30-40); yield: 0.62 g (4.0 mmol, 30%); Rf = 0.53
(pentane).
HRMS (EI): m/z [M]+ calcd for C9H6BrF3: 249.9605; found:
249.9608.
Acknowledgment
1H NMR (400 MHz, CDCl3): d = 5.69 (s, 1 H, C=CH2), 5.75 (s, 1
H, C=CH2), 6.42 (t, J = 55.4 Hz, 1 H, CF2H), 7.40 (m, 3 H, HAr),
7.51 (m, 2 H, HAr).
13C NMR (100 MHz, CDCl3): d = 115.4 (t, J = 239.7 Hz, CF2H),
118.9 (t, J = 9.7 Hz, H2C=CCF2H), 126.9 (CAr), 128.5 (CAr), 128.6
(CAr), 134.7 (CAr), 141.9 (t, J = 20.0 Hz, H2C=CCF2H).
19F NMR (376 MHz, CDCl3): d = –113.2 (d, J = 56.0 Hz, 2 F,
CF2H).
HRMS (CI): m/z [M]+ calcd for C9H8F2: 154.0594; found:
154.0593.
We gratefully thank the European Community for funding through
a Marie Curie Fellowship (PIEF-GA-2008-220323 for JW and
PIEF-GA-2009-235510 for TM). FLUOLEAD was kindly provi-
ded to us by Dr. Teruo Umemoto (IM&T Research, Inc.).
References
(1) (a) Wall, L. A. Fluoropolymers; Wiley: New York, 1972.
(b) Feiring, A. E. In Organofluorine Chemistry: Principles
and Commercial Applications; Banks, R. E.; Smart, B. E.;
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15, 339–372. (c) Scheirs, J. Modern Fluoropolymers;
Wiley: New York, 1997. (d) Hougham, G.; Davidson, T.;
Cassidy, P.; Johns, K. Fluoropolymers; Kluvert: New York,
1999. (e) Ameduri, B.; Boutevin, B. Well Architectured
Fluoropolymers: Synthesis, Properties and Applications;
Elsevier: Amsterdam, 2004.
(2) (a) Kobayashi, S.; Munekuta, S.; Unoki, M.; Iwamoto, T.
Patent EP 0239935, 1987. (b) Yamamoto, T.; Matsumoto,
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(d) Yamamoto, S.; Matsumoto, M. Patent JP 63430104,
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(3) Boutevin, B.; Pietrasanta, Y. Les Acrylates et poly Acrylates
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(4) Banks, B. A. The Use of Fluoropolymers in Space
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(5) (a) Souzy, R.; Ameduri, B.; Boutevin, B. J. Polym. Sci., Part
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Chem. 2009, 130, 537.
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Burton, D. J. J. Fluorine Chem. 1997, 82, 13. (b) Stone, C.;
Daynard, T. S.; Hu, L.-Q.; Mah, C.; Steck, A. E. J. New
Mater. Electrochem. Syst. 2000, 3, 43. (c) Lafitte, B.;
Jannasch, P. On the Prospects for Phosphonated Polymers
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Trans. 1 1979, 2023. (b) Obrycki, R.; Griffin, C. E. J. Org.
Chem. 1968, 33, 632. (c) Plumb, J. B.; Obrycki, R.; Griffin,
C. E. J. Org. Chem. 1966, 31, 2455.
a-(Trifluoromethyl)styrenes 20; General Procedure (GP5)
To a soln of 19 (1.5 equiv) in DME–THF (1:1, 3 mL) and aq 2 M
KOH (2 mL) was added phenylboronic acid 18 (1 equiv),
PdCl2(PPh3)2 (0.03 equiv), and AsPh3 (0.15 equiv) under an inert at-
mosphere in a pressure tube. The mixture was sealed and stirred at
74 °C for 12 h.25 The mixture was cooled to r.t., H2O (10 mL) was
added, and the mixture was extracted with Et2O (2 × 10 mL). The
combined organic layers were washed with brine (3 × 10 mL) and
dried (MgSO4). The solvent was removed and the residue was puri-
fied by short-path distillation under reduced pressure or by column
chromatography (silica gel, PE 30-40) or by Biotage SP-4 System
(PE 30-40).
(3,3,3-Trifluoroprop-1-en-2-yl)benzene (20a)
According to GP5 using 19 (7.87 g, 45.0 mmol) in DME–THF (1:1,
90 mL) and aq 2 M KOH (60 mL) and phenylboronic acid (18a,
3.66 g, 30.0 mmol), PdCl2(PPh3)2 (0.63 g, 0.90 mmol), and AsPh3
(1.38 g, 4.50 mmol); workup used H2O (300 mL), extraction with
Et2O (2 × 300 mL), and washing with brine (3 × 300 mL); yield:
4.34 g (25.2 mmol, 84%); bp 55–57 °C/17 mbar; Rf = 0.6 (pentane).
1H NMR (400 MHz, CDCl3): d = 5.79 (m, 1 H, C=CH2), 5.98 (m, 1
H, C=CH2), 7.41 (s, 3 H, HAr), 7.48 (s, 2 H, HAr).
13C NMR (100 MHz, CDCl3): d = 120.4 (q, J = 5.7 Hz,
H2C=CCF3), 123.4 (q, J = 274.1 Hz, H2C=CCF3), 127.4 (CAr),
128.6 (CAr), 129.0 (CAr), 133.7 (CAr), 139.0 (q, J = 29.1 Hz,
H2C=CCF3).
19F NMR (376 MHz, CDCl3): d = –64.8 (s, 3 F, CF3).
HRMS (CI): m/z [M]+ calcd for C9H7F3: 172.0500; found:
172.0504.
1-Bromo-4-(3,3,3-trifluoroprop-1-en-2-yl)benzene (20b)
According to GP5 using 19 (5.25 g, 30.0 mmol) in DME–THF (1:1,
60 mL) and aq 2 M KOH (40 mL), and 4-bromophenylboronic acid
(18b, 4.02 g, 20.0 mmol), PdCl2(PPh3)2 (0.42 g, 0.60 mmol), and
AsPh3 (0.92 g, 3.00 mmol); workup used H2O (300 mL), extraction
with Et2O (2 × 200 mL), and washing with brine (3 × 200 mL);
yield: 2.71 g (10.8 mmol, 54%); bp 86–88 °C/17 mbar; Rf = 0.58
(pentane).
1H NMR (400 MHz, CDCl3): d = 5.78 (m, 1 H, C=CH2), 5.98 (m, 1
H, C=CH2), 7.33 (d, J = 8.5 Hz, 2 H, HAr), 7.52 (d, J = 8.5 Hz, 2 H,
HAr).
13C NMR (100 MHz, CDCl3): d = 120.9 (q, J = 5.8 Hz,
H2C=CCF3), 123.0 (q, J = 273.8 Hz, H2C=CCF3), 123.3 (CAr),
127.0 (CAr), 131.8 (CAr), 132.5 (CAr), 138.0 (q, J = 30.7 Hz,
H2C=CCF3).
(14) (a) Balthazor, T. M.; Grabiak, R. C. J. Org. Chem. 1980, 45,
5425. (b) Tavs, P. Chem. Ber./Recl 1970, 103, 2428.
19F NMR (376 MHz, CDCl3): d = –64.9 (s, 3 F, CF3).
Synthesis 2010, No. 11, 1883–1890 © Thieme Stuttgart · New York

1890
J. Walkowiak et al.
SPECIAL TOPIC
(15) (a) Schwan, A. L. Chem. Soc. Rev. 2004, 33, 218.
(b) Hirao, T.; Masunaga, T.; Yamada, N.; Ohshiro, Y.;
Agawa, T. Bull. Chem. Soc. Jpn. 1982, 55, 909.
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Applications; Hiyama, T., Ed.; Springer: New York, 2000.
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