Ligand-free palladium-catalyzed Mizoroki-Heck reaction to synthesize valuable α-trifluoromethylacrylates

Article abstract of DOI:10.1016/j.jfluchem.2020.109483

α-Trifluoromethylacrylates were synthesized using efficient ligand-free palladium catalyzed Mizoroki-Heck reaction. With the alkyl trifluoromethylacrylates used as substrates, different catalytic systems were explored including Pd/C as a catalyst. Good to excellent yields were obtained with good chemical tolerance.

Full text of DOI:10.1016/j.jfluchem.2020.109483

Journal Pre-proof
Ligand-Free Palladium-Catalyzed Mizoroki-Heck Reaction to Synthesize
Valuable ␣-Trifluoromethylacrylates
Pan Xiao, Claire Schlinquer, Xavier Pannecoucke, Samuel
Couve-Bonnaire, Jean-Philippe Bouillon
PII:
S0022-1139(20)30034-8
DOI:
https://doi.org/10.1016/j.jfluchem.2020.109483
FLUOR 109483
Reference:
To appear in:
Journal of Fluorine Chemistry
Received Date:
Revised Date:
Accepted Date:
13 December 2019
3 February 2020
3 February 2020
Please cite this article as: Xiao P, Schlinquer C, Pannecoucke X, Couve-Bonnaire S, Bouillon
J-Philippe, Ligand-Free Palladium-Catalyzed Mizoroki-Heck Reaction to Synthesize Valuable
␣-Trifluoromethylacrylates, Journal of Fluorine Chemistry (2020),
doi: https://doi.org/10.1016/j.jfluchem.2020.109483
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© 2019 Published by Elsevier.

Ligand-Free Palladium-Catalyzed Mizoroki-Heck Reaction to
Synthesize Valuable α-Trifluoromethylacrylates
Pan Xiao, Claire Schlinquer, Xavier Pannecoucke, Samuel Couve-Bonnaire,* and Jean-Philippe
Bouillon*
Normandie Univ, INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000 Rouen, France.
E-mail: samuel.couve-bonnaire@insa-rouen.fr; jean-philippe.bouillon@univ-rouen.fr; http://www.lab-cobra.fr/
Table of contents:
Highlights




α-Trifluoromethylacrylates synthesis
Efficient ligand-free palladium catalyzed Mizoroki-Heck reaction
Improvement to diastereomeric E:Z ratio
Use of two different catalytic systems
Abstract: α-Trifluoromethylacrylates were synthesized using efficient ligand-free palladium catalyzed Mizoroki-Heck reaction. With the alkyl
trifluoromethylacrylates used as substrates, different catalytic systems were explored including Pd/C as a catalyst. Good to excellent yields
were obtained with good chemical tolerance

Keywords: fluoroalkenes; fluoroacrylates; olefination; Mizoroki-Heck; palladium
1. Introduction
Fluorinated organic compounds have become unavoidable in many fields such as medicine, pharmacy, agrochemistry and materials
[1]. Among all the fluorinated building blocks, trifluoromethylacrylates proved to be very useful, as well as starting materials for the
synthesis of relevant polymers [2], as intermediates towards fine chemicals [3]. To obtain these α-trifluoromethylacrylate scaffolds,
some strategies have been described (Scheme 1) including double bond formation [4], trifluoromethylation of acrylates [5], radical
addition to alkynes [6] and decarboxylation-olefination reaction [7].
Concerning the double bond formation reaction (Scheme 1, part a)): in 1991, Allmendinger and Lang reported the first general
method for the preparation of α-trifluoromethylacrylates by using methyl 2,2-dichloro-3,3,3-trifluoropropanoate to react with
aldehydes in the presence of zinc dust and copper(I) salt, affording the corresponding acrylates in low to good yields (20-88%) and
low selectivities (E/Z from 47/53 to 34/66) [4a]. Then, in 2000, Schlosser and Volle utilized Wittig reaction to synthesize only one
specific α-trifluoromethylacrylate with methyl 3,3,3-trifluoropyruvate as fluorinated reagent, and moderate yield (51%) with low
selectivity (E/Z : 60/40) was obtained [4b]. Two years later, Paleta et al. used the same method to get four other α-
trifluoromethylacrylates in good yields (69-78%) with selectivities depending on different substrates (E/Z from 43/57 to 92/8) [4c].
Inspired by the reaction involving ylide intermediate, Zhu and coworkers developed a copper (II)-catalyzed method for the
construction of α-trifluoromethylacrylates with relatively unstable fluorinated diazo compound, providing the desired products in low
to good yields (36-85%) and moderate selectivities (E/Z from 24/76 to 84/16) [4d].
The trifluoromethylation reaction of acrylates consists of two parts (Scheme 1, part b)): 1) coupling reaction between in situ
generated CuCF3 species and vinyl halides, 2) radical trifluoromethylation of acrylates. In early 2000s, Qing and coworkers reported
the preparation of α-trifluoromethylacrylates through the coupling reaction between vinyl halides and CuCF3 which was generated
in situ from CuI and FSO2CF2CO2Me. With vinyl bromides (Z major) as substrates, fair to good yields (42-93%) and selectivities
(E/Z from 39/61 to 11/89) were obtained, but the yields (81-96%) and selectivities (E/Z from 18/82 to 5/95) were improved when
vinyl iodides (Z major) were used as substrates [5a-b]. In this reaction, the E/Z mixtures of vinyl halides determined the E/Z
selectivities of the products to some extent; therefore, the opposite selectivities (E/Z from 92/8 to 100/0) were observed when E
major vinyl bromides were involved instead of the Z major ones [5c]. In addition to FSO2CF2CO2Me, some other fluorinated reagents,
such as (CF3)2Hg [5d], TMSCF3 [5e], HCF3 [5f], were also used as the precursors of CuCF3 species, but just few examples for the
access to α-trifluoromethylacrylates were shown as a part of substrate scope [5d-f]. Recently, the methods for radical
trifluoromethylation of alkenes through a radical addition-elimination process were developed. There are several sources of CF3
radical such as Langlois reagent [5g], trifluoromethyl iodide [5h], and Togni’s reagent [5i], which could release CF3 radical in the
presence of oxidant or reductant. But in these cases, α-trifluoromethylacrylates were not major target molecules.
More recently (Scheme 1, part c)), a method for stereoselective photoredox-catalyzed transformation of alkynes into α-
trifluoromethylalkenes was developed by Akita [6a] and Han [6b], respectively. In both reaction systems, only one example was
dedicated to tetrasubstituted α-trifluoromethylacrylate and good selectivity was obtained, albeit in moderate yield (57%, and 44%,
respectively).
In 2018, our group has developed a method for palladium-catalyzed decarboxylative olefination reaction with methyl 2-
(trifluoromethyl)acrylate (Scheme 1, part d)). Trisubstituted α-trifluoromethylacrylates were synthesized in low to excellent yields
(24-99%) with various selectivities (E/Z from 60/40 to 12/88); however, the substrate scope was only limited to ortho-substituted
benzoic acids and low yields were obtained when electron-deficient groups were involved in the substrates [7].
For the above-mentioned methods, most of them showed limited substrate scope. Some reactions proceeded with good
stereoselectivity but not good yields. Some methods used expensive fluorinated reagents, unstable starting materials, or required
multistep synthesis of substrates and/or reagents.
We recently proposed a general access to these products using a ligand-free Mizoroki-Heck reaction [8]. The reaction proved to be
compatible with numerous active chemical moiety (cyano, amine, acid, alcohol, boronate…) and furnished good to excellent yields
of desired α-trifluoromethylacrylate products. The major drawback of this reaction is the diastereomeric E:Z ratio ranging around
70:30 in most of the cases. Herein, we proposed a structural modification to increase the E:Z ratio of the reaction as well as a new
relevant catalytic system to perform efficiently the reaction.
2. Results and Discussion
2.1 Synthesis of t-butyl -trifluoromethylacrylates.
To begin the study about the stereoselectivity, we chose the p-methoxy-iodobenzene as model substrate. As coupling partner, we
decided to increase the bulkiness of the ester group using t-butyl trifluoromethylacrylate 2a instead of the methyl one 2b.
Unfortunately, using our previous optimal reaction conditions with 2b [8], no product 3a was obtained with 2a (Table 1, entry 1).

Changing the silver triflate for the more basic silver acetate increased the yield to 76% (Table 1, entry 2). The use of silver carbonate
allowed the formation of the desired product 3a in good 19F NMR and isolated yields (Table 1, entries 3-5), excepted for the case
of reduced amount of catalyst loading (Table 1, entry 4). Using the potassium carbonate, a common base used in cross-coupling
reaction, led to a poor 20% yield of 3a (Table 1, entry 6). This last result pointed out the crucial role of silver cation serving as halide
abstracter as already reported for this kind of reaction [8,9]. The use of other catalyst proved to be less efficient than the electrophilic
Pd(TFA)2 (Table 1, entries 7 and 8). We then used these reaction conditions to synthesize various t-butyl 2-(trifluoromethyl)acrylates
3 (Scheme 2).
Para-substituted t-butyl acrylates 3a and 3b were obtained in high yield and good diastereoselectivity (E:Z ratio of 85:15). The
selectivity was lower for product 3c bearing a para-cyano group whereas only fair yield with almost no selectivity was obtained for
product 3d bearing a para-nitro group. Meta- and poly-substituted products were obtained with high yields and selectivities. Probably
due to the steric hindrance, the E/Z selectivity for the ortho-substituted products was decreased. These latter were synthesized in
fair to quantitative yields (Scheme 2).
In a mechanistic point of view, this reaction is very interesting. Indeed, based on various experimental results, we recently proposed
a Pd(II)/Pd(IV) catalytic cycle for the production of methyl trifluoromethylacrylates via the formation of a cationic palladium species
[8], thanks to silver triflate acting as a halide abstracter [10], remaining a highly acidic media (pH ≈ 1) at the end of the reaction. In
the case of t-butyl acrylate 2a as reagent, the presence of silver was essential for the reaction to proceed but also the presence of
base. In this case, we speculated that a “neutral” catalytic cycle proceeded with a classical role of silver carbonate, capturing the
hydrogen iodide released at the end of the catalytic cycle by reductive elimination. The control pH at the end of the reaction was
around 6 which is consistent with a neutral process. Nevertheless, for the moment, we have no explanation why the modification of
the ester moiety from methyl to t-butyl group had such a huge influence on the mechanism of the reaction. Some calculation will be
undertaken soon to better understand these mechanistic issues.
In the course of our optimization, we were wondering if the use of simple Pd/C catalyst, cheaper than common Pd(II) catalysts used
in cross-coupling reaction, could be used in this reaction.
2.2 Use of Pd/C to synthesize the -trifluoromethylacrylates.
The t-butyl trifluoromethylacrylate 2a proved to be unreactive in the presence of Pd/C (Table 2, entries 1 and 2) or Pd(OH)2/C (Table
2, entry 3). Delighfully, the less hindered methyl trifluoromethylacrylate 2b reacted using Pd/C catalyst furnishing a good isolated
yield of 80% of 4a using silver triflate as additive (Table 2, entry 4). The reaction was still efficient with a lower amount of catalyst
albeit the yield was a little bit lower (Table 2, entries 5 and 6). The yield decreased using Pd(OH)2/C as catalyst (Table 2, entry 7)
or carrying out the reaction for 2 h instead of 4 h (Table 2, entry 8). Using DMF as solvent dropped the yield of reaction (Table 2,
entry 9). The use of silver carbonate was inefficient (Table 2, entry 10) as well as the use of sodium acetate in DMA, classical
experimental conditions with Pd/C (Table 2, entry 11) [11]. The replacement of silver triflate by copper triflate failed (Table 2, entry
12). The reaction carried out without additive did not proceed (Table 2, entry 13).
With these new catalytic conditions in hand, we wondered if we could apply them to various substrates (Scheme 3). The reaction
was efficient with various substrates and tolerated numerous chemical functional groups. We began the scope of the reaction with
substituents in para-position. Electron-donating groups on aryl moiety gave fair to high yields of desired acrylates. Hydroxyl group
could be used without protection to furnish compound 4b in 67% isolated yield. 24 h of reaction was required to get 4c bearing a
methyl group in high 88% yield. Bromine atom proved to be unreactive in the reaction conditions furnishing the para-brominated
product 4e in 78% yield. It should be noted that with deactivated aromatic ring, i.e. bearing an electron-withdrawing group or a
substituent with negative inductive effect, such as bromine, the reaction was necessary to be performed at 110°C to be efficient.
This higher temperature allowed us to synthesize interesting products bearing a post-functionalizable function such as products 4f
(cyano), 4g (ester), 4h (nitro) and 4i (ketone) in good yields from 62 to 88%. Increasing the reaction time with electron-withdrawing
substituent was non effective to increase the yield of the reaction.
The reaction could be then applied to meta-substituted substrates, albeit the yield was slightly lower (42% to 71%). Ortho-substituted
products bearing a methyl (4m), a cyano (4n) or a nitro moiety (4o) were obtained in excellent yields (83% to 98%). Poly-substituted
products 4p and 4q were produced in good yields, 79% and 68%, respectively. An interesting functionnalized furan could also be
obtained in these conditions but only in low 29% yield. Finally, starting from the ortho-iodophenol, the relevant 3-
trifluoromethylcoumarin 5 could be obtained in fair 50% yield along with a small quantity of Z acrylate 4s.
The E:Z ratio was, in most of the case, independent of the nature of the substrate ranging from 76:24 to 70:30, except for para-nitro
4h (55:45) and ortho-substituted compounds 4m, 4n and 4o (66:34 to 60:40).
Concerning the mechanism of the reaction, the usual question regarding the use of Pd/C is, does the reaction occur through a
heterogeneous or homogeneous catalytic pathway? Does the reaction take place on the solid Pd surface (heterogeneous reaction)
or does the active catalytic species come from a dissolution of Pd (homogeneous reaction), leaching from Pd/C? In the latter case,
the Pd/C would act as a Pd reservoir [11]. Indeed, many research groups studied the mechanism of various cross-coupling reaction
using Pd/C catalyst and it appears that no general conclusion can be drawn as the catalytic pathway depends on various

experimental parameters [11,12]. We carried out some control experiments to get insight in the mechanism with Pd/C. First, the
reaction with Pd/C as catalyst was completely inhibited in the presence of mercury metal or CS2, poisons for heterogeneous catalyst
(Table 3, entries 2-4) [13]. Nevertheless, the reaction using homogeneous catalytic system based on Pd(TFA)2 was also impacted
by the presence of Hg or CS2 leading to, on one hand, only half yield (Table 3, entries 6 and 7) or traces (Table 3, entry 8) of desired
methyl acrylate product 4a or, on the other hand, complete inhibition of the reaction producing t-butyl acrylate 3a (Table 3, entries
10-12). ICP-AES measurements are inconclusive because they revealed a quantity of 58 ppm after 5 min of reaction and 11 ppm
after completion of reaction. Even if these quantities are rather low, they cannot allow to exclude a homogeneous process [11].
Finally, we undertook a recycle study. Only the first round of recycle proved to be efficient whereas the yield dramatically dropped
from the second recycle (reaction with 4a: 80% isolated yield, recycle 1: 75% isolated yield; recycle 2: less than 20% 19F NMR
yield). These “recycle“ results were in accordance with the report in the literature explaining that the structural change of Pd surface
at the end of the reaction (by dissolution-reprecipitation) as well as co-precipitation of salt and base involving the fouling of the
catalyst are responsible for rapid inactivation of recycled catalyst [11]. All these experiments cannot ruled out heterogeneous or
homogeneous process.
From the acrylates, the obtention of relevant α-trifluoromethylacrylic acids, attractive compounds with numerous applications in
medicinal chemistry or materials science [14], by simple hydrolysis could be envisioned. Taking into account that very few methods
have been described to get these valuable scaffolds [15], this simple method could constitute an easy synthetic alternative. In this
context, the t-butyl acrylates 3 proved to be suitable substrates to undergo hydrolysis compared to the methyl acrylates 4. Indeed,
whatever the basic or acidic conditions tested to hydrolyse the methyl acrylates 4, the reaction proved to be unfruitful while the
hydrolysis of the t-butyl α-trifluoromethylacrylates 3a,i in acidic conditions, generating a stable tert-butyl carbocation, allowed the
formation of the corresponding acids 6a,i in good yields (Scheme 4).
3. Conclusions
To conclude, we described here an updated method to synthesize α-trifluoromethylacrylates by ligand-free Mirozoki-Heck reaction.
The use of t-butyl trifluoromethylacrylate instead of methyl trifluoromethylacrylate allowed to improve the E:Z ratio of the reaction,
albeit a complete stereoselectivity was not obtained. Worthy of note that the t-butyl acrylates were good substrates to reach relevant
trifluoroacrylic acids by acid hydrolysis. Then we reported that the cheaper and useful Pd/C could be efficiently used to synthesize
the methyl trifluoromethylacrylates, being a good alternative towards these relevant compounds.
4. Experimental Section
4.1. General information.
Commercially available reagents and anhydrous solvents were purchased from standard chemical suppliers (Fisher, Sigma-Aldrich, Fluorochem,
Alfa Aesar) and used as received without further purification. Pd/C (Palladium, 10% on carbon, type 487, dry) was purchased from Alfa Aesar. Dry
CH2Cl2 was distillated from calcium hydride. Thin layer chromatography (TLC) analyses were done using aluminium sheets coated with silica gel 60
F254; flash column chromatography was carried out using Silicaflash P60 silica gel (40-60 m). NMR spectra were recorded using a Bruker Avance-
1
300 spectrometer operating at 300 MHz (1H), 282 MHz (19F), and 75 MHz (13C). H and 13C NMR chemical shifts () were calibrated on residual
proton and carbon resonances of CDCl3 (1H,  = 7.26 ppm and 13C,  = 77.16 ppm); 19F NMR chemical shifts () were determined relative to CFCl3
as an internal standard (19F,  = 0.0 ppm). The multiplicity signals were indicated with the common abbreviations: s (singlet), d (doublet), t (triplet), q
(quartet), m (multiplet), br (broad) and the combinations thereof. IR spectra were recorded on Perkin Elmer Spectrum 100 FT IR spectrometer. High
Resolution Mass Spectra (HRMS) were recorded on a JEOL AccuTOF 4G spectrometer coupled to a GC HP Agilent 7890.
4.2. General procedures for Heck reaction.
Pd(TFA)2, Ag2CO3 catalytic system. To a vial (2 mL) were added iodoarene 1 (0.2 mmol, 1.0 equiv), Ag2CO3 (0.4 mmol, 2.0 equiv), Pd(TFA)2 (0.02
mmol, 10 mol%), t-butyl 2-(trifluoromethyl)acrylate 2a (0.3 mmol, 1.5 equiv), and 1,4-dioxane (1.0 mL, 5 mL/mmol of iodoarene). The vial was then
o
sealed. The reaction mixture was stirred at 90 C for 2 hours and was then cooled to room temperature. The reaction mixture was transferred to a
50 mL flask (with the vial washed with 20 mL CH2Cl2) and was mixed with celite. After evaporation of solvents, the crude was purified by silica gel
column chromatography (eluent: petroleum ether/EtOAc).
Pd/C, AgOTf catalytic system. To a vial (2 mL) were added iodoarene 1 (0.2 mmol, 1.0 equiv), AgOTf (0.3 mmol, 1.5 equiv), Pd/C (Palladium, 10%
on carbon, type 487, dry) (0.02 mmol, 10 mol%), methyl 2-(trifluoro-methyl)acrylate 2b (0.3 mmol, 1.5 equiv), and 1,4-dioxane (1.0 mL, 5 mL/mmol
of iodoarene). The vial was then sealed. The reaction mixture was stirred at 90 or 110 oC for 4 hours and was then cooled to room temperature. The
reaction mixture was transferred to a 50 mL flask (with the vial washed with 20 mL CH2Cl2) and was mixed with celite. After evaporation of solvents,
the crude was purified by silica gel column chromatography (eluent: petroleum ether/EtOAc).
4.2.1.
Tert-butyl
(E)-3-(4-methoxyphenyl)-2-(trifluoromethyl)acrylate
(E-3a)
and
tert-butyl
(Z)-3-(4-methoxyphenyl)-2-
(trifluoromethyl)acrylate (Z-3a): 4-iodoanisole (0.2 mmol, 46.8 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl
2-(trifluoromethyl)acrylate (0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was
purified by silica gel column chromatography (petroleum ether/EtOAc, from 60/1 to 50/1, v/v), affording compound 3a in 84% yield [mixture of E/Z
isomers (85/15), 50.6 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 7.87 (s, 1H, Z), 7.50 – 7.37 (m, 2H, Z + 2H, E), 7.20 (s, 1H, E), 6.98 – 6.85

(m, 2H, Z + 2H, E), 3.83 (s, 3H, Z + 3H, E), 1.56 (s, 9H, Z), 1.50 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -58.5 (s, Z), -64.0 (d, J = 1.7 Hz, E). 13C{1H}
NMR (75 MHz, CDCl3): δ 163.1 (q, J = 2.1 Hz), 163.0 – 162.9 (m), 161.4 – 161.3 (m), 146.8 (q, J = 2.9 Hz), 138.3 (q, J = 5.8 Hz), 132.1 (q, J = 2.7
Hz), 131.5, 125.0, 124.9, 122.8 (q, J = 271.1 Hz), 122.6 (q, J = 30.5 Hz), 122.5 (q, J = 272.0 Hz), 121.7 (q, J = 31.5 Hz), 114.0, 113.9, 83.4, 82.8,
55.4, 28.1, 27.9. IR (Neat): 2981, 2938, 2843, 1721, 1606, 1514, 1370, 1280, 1260, 1242, 1150, 1122, 1030, 1007, 828 cm-1. HRMS (CI-TOF): Calcd
for C15H18F3O3 (m/z): 303.1208 [M+H]+, found: 303.1213.
4.2.2. Tert-butyl (E)-3-(4-bromophenyl)-2-(trifluoromethyl)acrylate (E-3b) and tert-butyl (Z)-3-(4-bromophenyl)-2-(trifluoromethyl)acrylate (Z-
3b): 1-bromo-4-iodobenzene (0.2 mmol, 56.4 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl 2-(trifluoro-
methyl)acrylate (0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was purified by
silica gel column chromatography (petroleum ether/EtOAc, from 60/1 to 50/1, v/v), affording compound 3b in 90% yield [mixture of E/Z isomers
(85/15), 63.3 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 7.79 (s, 1H, Z), 7.43 (d, J = 8.4 Hz, 2H, Z + 2H, E), 7.20 (d, J = 8.4 Hz, 2H, Z + 2H,
E), 7.15 (s, 1H, E), 1.48 (s, 9H, Z), 1.37 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -58.5 (s, Z), -64.6 (d, J = 1.4 Hz, E). 13C{1H} NMR (75 MHz, CDCl3):
δ 162.3, 162.1, 145.7 – 145.5 (m), 137.5 (q, J = 5.7 Hz), 131.8, 131.6, 130.9 – 130.6 (m), 126.1 (q, J = 30.9 Hz), 125.1 (q, J = 30.9 Hz), 124.53,
124.46, 122.2 (q, J = 271.7 Hz), 122.0 (q, J = 272.3 Hz), 83.9, 83.4, 28.1, 27.8. IR (Neat): 2982, 2933, 1723, 1650, 1489, 1370, 1289, 1274, 1244,
1152, 1130, 1073, 1010, 915, 868, 839, 815 cm-1. HRMS (CI-TOF): Calcd for C14H15BrF3O2 (m/z): 351.0208 [M+H]+, found: 351.0192.
4.2.3. Tert-butyl (E)-3-(4-cyanophenyl)-2-(trifluoromethyl)acrylate (E-3c) and tert-butyl (Z)-3-(4-cyanophenyl)-2-(trifluoromethyl)acrylate (Z-
3c): 4-iodobenzonitrile (0.2 mmol, 45.8 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was purified by silica gel column
chromatography (petroleum ether/EtOAc, from 60/1 to 15/1, v/v), affording compound 3c in 79% yield [mixture of E/Z isomers (75/25), 46.7 mg] as
a yellow oil. 1H NMR (300 MHz, CDCl3): δ 7.94 (s, 1H, Z), 7.68 (d, J = 8.4 Hz, 2H, Z + 2H, E), 7.49 (d, J = 8.1 Hz, 2H, E), 7.43 (d, J = 8.1 Hz, 2H, Z),
7.34 (s, 1H, E), 1.55 (s, 9H, Z), 1.40 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -58.4 (s, Z), -64.9 (d, J = 1.4 Hz, E). 13C{1H} NMR (75 MHz, CDCl3): δ
161.6 (q, J = l.7 Hz), 161.4 – 161.2 (m), 144.5 (q, J = 3.1 Hz), 137.6, 137.4, 137.1 (q, J = 5.8 Hz), 132.2, 132.0, 129.5, 129.3 (q, J = 2.3 Hz), 128.2
(q, J = 31.0 Hz), 127.0 (q, J = 31.4 Hz), 121.8 (q, J = 272.0 Hz), 121.6 (q, J = 272.8 Hz), 118.3, 118.2, 113.4, 113.2, 84.3, 83.8, 28.0, 27.7. IR (Neat):
2983, 2928, 2231, 1724, 1371, 1318, 1292, 1276, 1247, 1133, 1010, 915, 838 cm-1. HRMS (CI-TOF): Calcd for C15H15F3NO2 (m/z): 298.1055 [M+H]+,
found: 298.1054.
4.2.4. Tert-butyl (E)-3-(4-nitrophenyl)-2-(trifluoromethyl)acrylate (E-3d) and tert-butyl (Z)-3-(4-nitrophenyl)-2-(trifluoromethyl)acrylate (Z-3d):
1-iodo-4-nitrobenzene (0.2 mmol, 49.8 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was purified by silica gel column
chromatography (petroleum ether/EtOAc, from 60/1 to 15/1, v/v), affording compound 3d in 54% yield [mixture of E/Z isomers (52/48), 34.0 mg] as
a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.25 (d, J = 8.7 Hz, 2H, Z + 2H, E), 7.98 (s, 1H, Z), 7.56 (d, J = 8.7 Hz, 2H, E), 7.50 (d, J = 8.7 Hz, 2H, Z),
7.39 (s, 1H, E), 1.57 (s, 9H, Z), 1.42 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -58.4 (s, Z), -65.0 (d, J = 1.4 Hz, E). 13C{1H} NMR (75 MHz, CDCl3): δ
161.5 (q, J = l.7 Hz), 161.3, 148.4, 148.3, 144.1 (q, J = 2.9 Hz), 139.6, 139.3, 136.7 (q, J = 5.8 Hz), 129.8, 129.6 (q, J = 2.2 Hz), 128.7 (q, J = 31.1
Hz), 127.5 (q, J = 31.3 Hz), 123.7, 123.6, 121.8 (q, J = 272.1 Hz), 121.6 (q, J = 272.9 Hz), 84.5, 84.0, 28.1, 27.8. IR (Neat): 2983, 2934, 1724, 1602,
1523, 1371, 1347, 1278, 1248, 1134, 1013, 850, 692 cm-1. HRMS (CI-TOF): Calcd for C14H15F3NO4 (m/z): 318.0953 [M+H]+, found: 318.0940.
4.2.5. Tert-butyl (E)-3-(3-methoxyphenyl)-2-(trifluoromethyl)acrylate (E-3e) and tert-butyl (Z)-3-(3-methoxyphenyl)-2-(trifluoromethyl)-
acrylate (Z-3e): 3-iodoanisole (0.2 mmol, 46.8 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl 2-
(trifluoromethyl)acrylate (0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was
purified by silica gel column chromatography (petroleum ether/EtOAc, from 120/1 to 90/1, v/v), affording compound 3e in 87% yield [mixture of E/Z
isomers (87/13), 52.6 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 7.85 (s, 1H, Z), 7.25 – 7.16 (m, 2H, Z + 2H, E), 6.93 – 6.80 (m, 2H, Z + 3H,
E), 3.76 – 3.68 (m, 3H, Z + 3H, E), 1.48 (s, 9H, Z), 1.36 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -58.4 (s, Z), -64.5 (d, J = 1.4 Hz, E). 13C{1H} NMR
(75 MHz, CDCl3): δ 162.6 – 162.5 (m), 162.5 – 162.3 (m), 159.6, 159.3, 146.9 (q, J = 3.0 Hz), 138.4 (q, J = 5.8 Hz), 134.2, 134.0, 129.6, 129.4, 125.7
(q, J = 30.7 Hz), 124.7 (q, J = 31.4 Hz), 122.4 (q, J = 271.5 Hz), 122.0 (q, J = 272.5 Hz), 121.8 – 121.4 (m), 115.8, 115.7, 114.3, 83.6, 83.2, 55.40,
55.37, 28.1, 27.8. IR (Neat): 2982, 1724, 1600, 1581, 1489, 1458, 1370, 1300, 1241, 1149, 1127, 1043, 1011, 843, 689 cm-1. HRMS (CI-TOF): Calcd
for C15H18F3O3 (m/z): 303.1208 [M+H]+, found: 303.1206.
4.2.6. Tert-butyl (E)-3-(3-nitrophenyl)-2-(trifluoromethyl)acrylate (E-3f) and tert-butyl (Z)-3-(3-nitrophenyl)-2-(trifluoromethyl)acrylate (Z-3f):
1-iodo-3-nitrobenzene (0.2 mmol, 49.8 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was purified by silica gel column
chromatography (petroleum ether/EtOAc, from 60/1 to 50/1, v/v), affording compound 3f in 89% yield [mixture of E/Z isomers (83/17), 56.4 mg] as a
yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.32 – 8.19 (m, 2H, Z + 2H, E), 7.97 (s, 1H, Z), 7.74 – 7.64 (m, 1H, Z + 1H, E), 7.59 (t, J = 8.0 Hz, 1H, Z +
1H, E), 7.36 (s, 1H, E), 1.56 (s, 9H, Z), 1.45 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -58.4 (s, Z), -64.9 (d, J = 1.7 Hz, E). 13C{1H} NMR (75 MHz,
CDCl3): δ 161.6 (q, J = l.8 Hz), 161.5 – 161.4 (m), 148.3, 148.1, 143.9 (q, J = 3.0 Hz), 136.4 (q, J = 5.9 Hz), 135.0, 134.7 – 134.5 (m), 134.4, 129.7,
129.5, 128.1 (q, J = 31.1 Hz), 127.2 (q, J = 31.4 Hz), 124.5, 124.3, 123.7, 121.9 (q, J = 272.0 Hz), 121.7 (q, J = 272.8 Hz), 84.6, 83.9, 28.0, 27.8. IR
(neat): 2983, 2934, 1723, 1532, 1352, 1300, 1274, 1247, 1133, 1014, 922, 840, 735, 675 cm-1. HRMS (CI-TOF): Calcd for C14H15F3NO4 (m/z):
318.0953 [M+H]+, found: 318.0940.
4.2.7. Tert-butyl (E)-3-(2-methoxyphenyl)-2-(trifluoromethyl)acrylate (E-3g) and tert-butyl (Z)-3-(2-methoxyphenyl)-2-(trifluoromethyl)-
acrylate (Z-3g): 2-iodoanisole (0.2 mmol, 46.8 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl 2-
(trifluoromethyl)acrylate (0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was
purified by silica gel column chromatography (petroleum ether/EtOAc, from 100/1 to 60/1, v/v), affording compound 3g in 53% yield [mixture of E/Z
isomers (69/31), 31.8 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.12 (s, 1H, Z), 7.59 (s, 1H, E), 7.43 – 7.27 (m, 2H, Z + 2H, E), 6.99 – 6.86
(m, 2H, Z + 2H, E), 3.86 (s, 3H, Z), 3.85 (s, 3H, E), 1.57 (s, 9H, Z), 1.40 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -59.2 (s, Z), -64.4 (d, J = 1.4 Hz,
E). 13C{1H} NMR (75 MHz, CDCl3): δ 162.7 (q, J = l.8 Hz), 162.6 – 162.5 (m), 157.5, 143.7 (q, J = 3.0 Hz), 136.0 (q, J = 6.0 Hz), 131.7, 131.6, 130.5
(q, J = 3.5 Hz), 130.0, 125.0 (q, J = 30.3 Hz), 124.0 (q, J = 31.0 Hz), 122.6 (q, J = 271.4 Hz), 122.4 (q, J = 272.4 Hz), 122.2, 120.2, 110.7, 110.4,
83.0, 82.8, 55.6, 28.2, 27.8. IR (Neat): 2981, 1722, 1646, 1601, 1490, 1466, 1439, 1370, 1284, 1239, 1154, 1127, 1114, 1009, 843, 751 cm-1. HRMS
(CI-TOF): Calcd for C15H18F3O3 (m/z): 303.1208 [M+H]+, found: 303.1206.

4.2.8. Tert-butyl (E)-3-(2-methylphenyl)-2-(trifluoromethyl)acrylate (E-3h) and tert-butyl (Z)-3-(2-methylphenyl)-2-(trifluoromethyl)acrylate
(Z-3h): 2-iodotoluene (0.2 mmol, 43.6 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was purified by silica gel column
chromatography (petroleum ether/EtOAc, from 100/1 to 60/1, v/v), affording compound 3h in 77% yield [mixture of E/Z isomers (77/23), 44.3 mg] as
a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.01 (s, 1H, Z), 7.46 (s, 1H, E), 7.23 – 7.16 (m, 1H, Z + 1H, E), 7.16 – 7.04 (m, 3H, Z + 3H, E), 2.22 (s,
3H, Z + 3H, E), 1.49 (s, 9H, Z), 1.21 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -58.8 (s, Z), -64.8 (d, J = 1.7 Hz, E). 13C{1H} NMR (75 MHz, CDCl3): δ
162.3 (q, J = l.6 Hz), 162.0 – 161.9 (m), 147.0 (q, J = 3.1 Hz), 139.9 (q, J = 5.7 Hz), 136.2, 136.0, 133.1, 132.9, 130.1, 129.9, 129.53, 129.50, 128.3
(q, J = 3.2 Hz), 128.2 – 128.1 (m), 126.8 (q, J = 30.3 Hz), 125.8, 125.7, 125.3 (q, J = 30.7 Hz), 122.2 (q, J = 271.5 Hz), 122.1 (q, J = 272.8 Hz),
83.14, 83.11, 28.1, 27.6, 20.1, 19.8. IR (Neat): 2981, 1725, 1649, 1370, 1296, 1278, 1247, 1155, 1132, 1011, 843, 749 cm-1. HRMS (CI-TOF): Calcd
for C15H18F3O2 (m/z): 287.1259 [M+H]+, found: 287.1257.
4.2.9. (E)-methyl 2-(2-(tert-butoxycarbonyl)-3,3,3-trifluoroprop-1-en-1-yl)benzoate (E-3i) and (Z)-methyl 2-(2-(tert-butoxycarbonyl)-3,3,3-
trifluoroprop-1-en-1-yl)benzoate (Z-3i): methyl 2-iodobenzoate (0.2 mmol, 52.4 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg),
and tert-butyl 2-(trifluoromethyl)acrylate (0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure.
The crude was purified by silica gel column chromatography (petroleum ether/EtOAc, from 90/1 to 50/1, v/v), affording compound 3i in 99% yield
[mixture of E/Z isomers (67/33), 65.5 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.36 (s, 1H, Z), 8.05 – 7.97 (m, 1H, Z + 1H, E), 7.96 (s, 1H,
E), 7.51 – 7.42 (m, 1H, Z + 1H, E), 7.42 – 7.34 (m, 1H, Z + 1H, E), 7.21 – 7.13 (m, 1H, Z + 1H, E), 3.82 (s, 3H, Z + 3H, E), 1.50 (s, 9H, Z), 1.13 (s,
9H, E). 19F NMR (282 MHz, CDCl3): δ -58.0 (s, Z), -64.7 (d, J = 1.4 Hz, E). 13C{1H} NMR (75 MHz, CDCl3): δ 166.5, 166.4, 162.1 (q, J = l.6 Hz),
161.5, 148.7 (q, J = 3.2 Hz), 143.3 (q, J = 6.1 Hz), 136.4, 135.9, 132.3, 130.7, 130.6, 129.4 – 129.1 (m), 129.1, 129.0, 128.2, 127.8, 124.7 (q, J =
30.0 Hz), 123.2 (q, J = 30.3 Hz), 122.3 (q, J = 271.4 Hz), 122.2 (q, J = 272.6 Hz), 82.9, 82.8, 52.4, 52.3, 28.1, 27.5. IR (Neat): 2982, 1718, 1650,
1370, 1292, 1281, 1264, 1156, 1130, 1082, 1013, 843, 753 cm-1. HRMS (AP-TOF): Calcd for C16H17F3O4 (m/z): 330.1079 [M]-, found: 330.1077.
4.2.10. Tert-butyl (E)-3-(naphthalen-2-yl)-2-(trifluoromethyl)acrylate (E-3j) and tert-butyl (Z)-3-(naphthalen-2-yl)-2-(trifluoromethyl)acrylate
(Z-3j): 2-iodonaphthalene (0.2 mmol, 50.8 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was purified by silica gel column
chromatography (petroleum ether/EtOAc, from 100/1 to 60/1, v/v), affording compound 3j in less than 78% yield [mixture of E/Z isomers (86/14), 50.6
mg, not pure] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.14 (s, 1H, Z), 7.94 – 7.78 (m, 4H, Z + 4H, E), 7.58 – 7.45 (m, 3H, Z + 4H, E), 1.62 (s,
9H, Z), 1.47 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -58.3 (s, Z), -64.4 (d, J = 1.1 Hz, E). IR (Neat): 3059, 2983, 2937, 1722, 1651, 1370, 1281,
1270, 1247, 1152, 1121, 1009, 842, 825, 750 cm-1. HRMS (CI-TOF): Calcd for C18H18F3O2 (m/z): 323.1259 [M+H]+, found: 323.1269.
4.2.11. Tert-butyl (E)-3-(3,5-dichlorophenyl)-2-(trifluoromethyl)acrylate (E-3k) and tert-butyl (Z)-3-(3,5-dichlorophenyl)-2-(trifluoromethyl)-
acrylate (Z-3k): 3,5-dichloro-1-iodo-benzene (0.2 mmol, 54.6 mg), Ag2CO3 (0.4 mmol, 110.3 mg), Pd(TFA)2 (0.02 mmol, 6.4 mg), and tert-butyl 2-
(trifluoromethyl)acrylate (0.3 mmol, 58.9 mg) in 1,4-dioxane (1.0 mL) were reacted for 2 hours according to the general procedure. The crude was
purified by silica gel column chromatography (petroleum ether/EtOAc, from 100/1 to 60/1, v/v), affording compound 3k in 81% yield [mixture of E/Z
isomers (87/13), 55.5 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 7.74 (s, 1H, Z), 7.33 – 7.28 (m, 1H, Z + 1H, E), 7.24 – 7.17 (m, 1H, Z + 2H,
E), 7.15 – 7.09 (m, 1H, Z + 1H, E), 1.48 (s, 9H, Z), 1.38 (s, 9H, E). 19F NMR (282 MHz, CDCl3): δ -58.5 (s, Z), -65.0 (d, J = 1.7 Hz, E). 13C{1H} NMR
(75 MHz, CDCl3): δ 161.6 (q, J = l.7 Hz), 161.6 – 161.4 (m), 143.7 (q, J = 3.1 Hz), 135.9, 135.6, 135.5 (q, J = 5.7 Hz), 135.3, 135.1, 129.7, 129.6,
128.1 (q, J = 31.1 Hz), 127.2, 126.9 (q, J = 2.3 Hz), 121.8 (q, J = 271.9 Hz), 121.6 (q, J = 272.4 Hz), 84.5, 83.8, 28.1, 27.8. IR (Neat): 2983, 1726,
1563, 1370, 1285, 1240, 1218, 1135, 1014, 841, 803 cm-1. HRMS (CI-TOF): Calcd for C14H14Cl2F3O2 (m/z): 341.0323 [M+H]+, found: 341.0313.
4.2.12. Methyl (E)-3-(4-methoxyphenyl)-2-(trifluoromethyl)acrylate (E-4a) and methyl (Z)-3-(4-methoxyphenyl)-2-(trifluoromethyl)acrylate (Z-
4a) [8]: 4-iodoanisole (0.2 mmol, 46.8 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 90 oC for 4 hours according to the general procedure. The crude was purified by silica
gel column chromatography (petroleum ether/EtOAc, from 30/1 to 15/1, v/v), affording compound 4a in 80% yield [mixture of E/Z isomers (76/24),
41.6 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.01 (s, 1H, Z), 7.51 – 7.29 (m, 2H, Z + 3H, E), 6.99 – 6.84 (m, 2H, Z + 2H, E), 3.88 (s, 3H,
Z), 3.86 – 3.83 (m, 3H, Z + 3H, E), 3.82 (s, 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.5 (s, Z), -63.8 (d, J = 1.7 Hz, E).
4.2.13. Methyl (E)-3-(4-hydroxyphenyl)-2-(trifluoromethyl)acrylate (E-4b) and methyl (Z)-3-(4-hydroxyphenyl)-2-(trifluoromethyl)acrylate (Z-
4b) [8]: 4-Iodophenol (0.2 mmol, 44.0 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 90 oC for 4 hours according to the general procedure. The crude was purified by silica
gel column chromatography (petroleum ether/EtOAc, from 10/1 to 5/1, v/v), and was subsequently washed with n-pentane (0.3 mL × 3), affording
compound 4b in 67% yield [mixture of E/Z isomers (73/27), 33.0 mg] as a white solid. 1H NMR (300 MHz, CDCl3): δ 8.00 (s, 1H, Z), 7.42 – 7.27 (m,
2H, Z + 3H, E), 6.91 – 6.73 (m, 2H, Z + 2H, E), 5.77 (s, 1H, E), 5.70 (s, 1H, Z), 3.89 (s, 3H, Z), 3.84 (s, 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.5
(s, Z), -63.8 (s, E).
4.2.14 Methyl (E)-3-(p-tolyl)-2-(trifluoromethyl)acrylate (E-4c) and methyl (Z)-3-(p-tolyl)-2-(trifluoromethyl)acrylate (Z-4c): 1-iodo-4-
methylbenzene (0.2 mmol, 43.6 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate (0.3
mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 90 oC for 24 hours according to the general procedure. When the reaction mixture was
cooled to rt, 19F NMR spectrum of the crude was tested with PhCOCF3 (1.0 equiv) as an internal standard. 19F NMR yield: 88% [according to the
linear relationship, see SI], E/Z = 74/26. 19F NMR (282 MHz, CDCl3) for crude: δ -58.4 (s, Z), -64.1 (d, J = 1.7 Hz, E). We failed to obtain the pure
isolated product.
4.2.15. Methyl (E)-3-phenyl-2-(trifluoromethyl)acrylate (E-4d) and methyl (Z)-3-phenyl-2-(trifluoromethyl)acrylate (Z-4d) [8]: iodobenzene (0.2
mmol, 40.8 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate (0.3 mmol, 46.2 mg) in
1,4-dioxane (1.0 mL) were reacted at 90 oC for 4 hours according to the general procedure. The crude was purified by silica gel column
chromatography (petroleum ether/EtOAc, from 60/1 to 30/1, v/v), affording compound 4d in 63% yield [mixture of E/Z isomers (72/28), 29.0 mg] as
a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.12 (s, 1H, Z), 7.53 – 7.34 (m, 5H, Z + 6H, E), 3.90 (s, 3H, Z), 3.79 (s, 3H, E). 19F NMR (282 MHz, CDCl3):
δ -58.5 (s, Z), -64.4 (d, J = 1.4 Hz, E).

4.2.16. Methyl (E)-3-(4-bromophenyl)-2-(trifluoromethyl)acrylate (E-4e) and methyl (Z)-3-(4-bromophenyl)-2-(trifluoromethyl)acrylate (Z-4e)
[8]: 1-bromo-4-iodobenzene (0.2 mmol, 56.6 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoro-
methyl)acrylate (0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. The crude was
purified by silica gel column chromatography (petroleum ether/EtOAc, from 60/1 to 50/1, v/v), affording compound 4e in 78% yield [mixture of E/Z
isomers (73/27), 48.2 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 7.92 (s, 1H, Z), 7.50 – 7.40 (m, 2H, Z + 2H, E), 7.27 (s, 1H, E), 7.17 (d, J =
8.4 Hz, 2H, Z + 2H, E), 3.81 (s, 3H, Z), 3.71 (s, 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.5 (s, Z), -64.5 (d, J = 1.7 Hz, E).
4.2.17. Methyl (E)-3-(4-cyanophenyl)-2-(trifluoromethyl)acrylate (E-4f) and methyl (Z)-3-(4-cyanophenyl)-2-(trifluoromethyl)acrylate (Z-4f)
[8]: 4-iodobenzonitrile (0.2 mmol, 45.8 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. The crude was purified by silica
gel column chromatography (petroleum ether/EtOAc, from 20/1 to 5/1, v/v), affording compound 4f in 85% yield [mixture of E/Z isomers (67/33), 43.4
mg]. E/Z isomers were completely separated by column: compound E-4f 29.2 mg, white solid; impure Z-isomer was subsequently washed with n-
pentane (0.2 mL × 3) to obtain pure compound Z-4f 14.2 mg, white solid. [E-isomer (major)] 1H NMR (300 MHz, CDCl3): δ 7.69 (d, J = 8.1 Hz, 2H),
7.52 – 7.42 (m, 3H), 3.78 (s, 3H). 19F NMR (282 MHz, CDCl3): δ -64.7 (d, J = 1.4 Hz). [Z-isomer (minor)] 1H NMR (300 MHz, CDCl3): δ 8.09 (s, 1H),
7.70 (d, J = 8.4 Hz, 2H), 7.46 (d, J = 8.1 Hz, 2H), 3.92 (s, 3H). 19F NMR (282 MHz, CDCl3): δ -58.5 (s).
4.2.18. Methyl (E)-4-(3,3,3-trifluoro-2-(methoxycarbonyl)prop-1-en-1-yl)benz-oate (E-4g) and methyl (Z)-4-(3,3,3-trifluoro-2-(methoxy-
carbonyl)-prop-1-en-1-yl)benzoate (Z-4g) [8]: methyl 4-iodobenzoate (0.2 mmol, 52.4 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02
mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate (0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to
the general procedure. The crude was purified by silica gel column chromatography (petroleum ether/EtOAc, from 20/1 to 10/1, v/v), affording
compound 4g in 75% yield [mixture of E/Z isomers (74/26), 43.2 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.11 (s, 1H, Z), 8.09 – 7.99 (m,
2H, Z + 2H, E), 7.46 (s, 1H, E), 7.41 (d, J = 8.1 Hz, 2H, Z + 2H, E), 3.92 (s, 3H, Z + 3H, E), 3.90 (s, 3H, Z), 3.75 (s, 3H, Z). 19F NMR (282 MHz,
CDCl3): δ -58.5 (s, Z), -64.6 (d, J = 1.4 Hz, E).
4.2.19. Methyl (E)-3-(4-nitrophenyl)-2-(trifluoromethyl)acrylate (E-4h) and methyl (Z)-3-(4-nitrophenyl)-2-(trifluoromethyl)acrylate (Z-4h) [8]:
1-iodo-4-nitrobenzene (0.2 mmol, 49.8 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoro-
methyl)acrylate (0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. The crude was
purified by silica gel column chromatography (petroleum ether/EtOAc, from 15/1 to 7/1, v/v), affording compound 4h in 88% yield [mixture of E/Z
isomers (55/45), 48.4 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.25 (m, 2H, Z + 2H, E), 8.12 (s, 1H, Z), 7.63 – 7.43 (m, 2H, Z + 3H, E), 3.92
(s, 3H, Z), 3.78 (s, 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.5 (s, Z), -64.8 (d, J = 1.1 Hz, E).
4.2.20. Methyl (E)-3-(4-acetylphenyl)-2-(trifluoromethyl)acrylate (E-4i) and methyl (Z)-3-(4-acetylphenyl)-2-(trifluoromethyl)acrylate (Z-4i) [8]:
1-(4-iodophenyl)ethan-1-one (0.2 mmol, 49.2 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoro-
methyl)acrylate (0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. The crude was
purified by silica gel column chromatography (petroleum ether/EtOAc, from 15/1 to 8/1, v/v), affording compound 4i in 62% yield [mixture of E/Z
isomers (72/28), 33.8 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.10 (s, 1H, Z), 8.01 – 7.91 (m, 2H, Z + 2H, E), 7.57 – 7.38 (m, 2H, Z + 3H,
E), 3.89 (s, 3H, Z), 3.76 (s, 3H, E), 2.60 (s, 3H, Z + 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.5 (s, Z), -64.6 (d, J = 1.7 Hz, E).
4.2.21. Methyl (E)-3-(m-tolyl)-2-(trifluoromethyl)acrylate (E-4j) and methyl (Z)-3-(m-tolyl)-2-(trifluoromethyl)acrylate (Z-4j) [8]: 3-iodotoluene
(0.2 mmol, 43.6 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate (0.3 mmol, 46.2 mg)
in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. The crude was purified by silica gel column
chromatography (petroleum ether/EtOAc, from 50/1 to 40/1, v/v), affording compound 4j in 42% yield [mixture of E/Z isomers (72/28), 20.5 mg] as a
yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.00 (s, 1H, Z), 7.30 (s, 1H, E), 7.25 – 7.05 (m, 4H, Z + 4H, E), 3.81 (s, 3H, Z), 3.70 (s, 3H, E), 2.39 – 2.21
(s, 3H, Z + 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.5 (s, Z), -64.3 (d, J = 1.4 Hz, E).
4.2.22. Methyl (E)-3-(3-cyanophenyl)-2-(trifluoromethyl)acrylate (E-4k) and methyl (Z)-3-(3-cyanophenyl)-2-(trifluoromethyl)acrylate (Z-4k)
[8]: 3-iodobenzonitrile (0.2 mmol, 45.8 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. The crude was purified by silica
gel column chromatography (petroleum ether/EtOAc, from 20/1 to 7/1, v/v), affording compound 4k in 52% yield [mixture of E/Z isomers (70/30), 26.6
mg]. E/Z isomers were completely separated by column: compound E-4k 18.5 mg, colorless oil; impure Z-isomer was subsequently washed with
petroleum ether (0.1 mL × 3) to obtain pure compound Z-4k 11.3 mg, white solid. [E-isomer (major)] 1H NMR (300 MHz, CDCl3): δ 7.69 (d, J = 8.1
Hz, 2H), 7.64 – 7.48 (m, 2H), 7.44 (s, 1H), 3.79 (s, 3H). 19F NMR (282 MHz, CDCl3): δ -64.7 (d, J = 1.7 Hz). [Z-isomer (minor)] 1H NMR (300 MHz,
CDCl3): δ 8.05 (s, 1H), 7.70 (d, J = 7.5 Hz, 1H), 7.64 (s, 1H), 7.62 – 7.48 (m, 2H), 3.92 (s, 3H). 19F NMR (282 MHz, CDCl3): δ -58.5 (s).
4.2.23. Methyl (E)-3-(3-nitrophenyl)-2-(trifluoromethyl)acrylate (E-4l) and methyl (Z)-3-(3-nitrophenyl)-2-(trifluoromethyl)acrylate (Z-4l) [8]: 1-
iodo-3-nitrobenzene (0.2 mmol, 49.8 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoro-methyl)acrylate
(0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. The crude was purified by silica
gel column chromatography (petroleum ether/EtOAc, from 15/1 to 8/1, v/v), affording compound 4l in 71% yield [mixture of E/Z isomers (70/30), 38.9
mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.33 – 8.21 (m, 2H, Z + 2H, E), 8.12 (s, 1H, Z), 7.45 – 7.66 (m, 1H, Z + 1H, E), 7.65 – 7.55 (m, 1H,
Z + 1H, E), 7.51 (s, 1H, E), 3.93 (s, 3H, Z), 3.81 (s, 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.5 (s, Z), -64.7 (d, J = 1.4 Hz, E).
4.2.24. Methyl (E)-3-(o-tolyl)-2-(trifluoromethyl)acrylate (E-4m) and methyl (Z)-3-(o-tolyl)-2-(trifluoromethyl)acrylate (Z-4m): 1-iodo-2-
methylbenz-ene (0.2 mmol, 43.6 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate (0.3
mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. When the reaction mixture was
cooled to rt, 19F NMR spectrum of the crude was tested with PhCOCF3 (1.0 equiv) as an internal standard. 19F NMR yield: 83% [according to the
linear relationship, see SI], E/Z = 66/34. 19F NMR (282 MHz, CDCl3) for crude: δ -58.8 (s, Z), -64.4 (d, J = 1.7 Hz, E). We failed to obtain the pure
isolated product.

4.2.25. Methyl (E)-3-(2-cyanophenyl)-2-(trifluoromethyl)acrylate (E-4n) and methyl (Z)-3-(2-cyanophenyl)-2-(trifluoromethyl)acrylate (Z-4n):
2-iodobenzonitrile (0.2 mmol, 45.8 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. When the reaction mixture was
cooled to rt, 19F NMR spectrum of the crude was tested with PhCOCF3 (1.0 equiv) as an internal standard. 19F NMR yield: 98% [according to the
linear relationship, see SI], E/Z = 60/40. 19F NMR (282 MHz, CDCl3) for crude: δ -59.0 (s, Z), -64.8 (d, J = 1.7 Hz, E). We failed to obtain the pure
isolated product.
4.2.26. Methyl (E)-3-(2-nitrophenyl)-2-(trifluoromethyl)acrylate (E-4o) and methyl (Z)-3-(2-nitrophenyl)-2-(trifluoromethyl)acrylate (Z-4o) [8]:
1-iodo-2-nitrobenzene (0.2 mmol, 49.8 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)-
acrylate (0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. The crude was purified
by silica gel column chromatography (petroleum ether/EtOAc, from 15/1 to 8/1, v/v), affording compound 4o in 88% yield [mixture of E/Z isomers
(64/36), 48.4 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 8.46 (s, 1H, Z), 8.32 – 8.22 (m, 1H, Z + 1H, E), 8.04 (s, 1H, E), 7.75 – 7.55 (m, 2H, Z
+ 2H, E), 7.33 (t, J = 7.8 Hz, 1H, Z + 1H, E), 3.92 (s, 3H, Z), 3.61 (s, 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.6 (s, Z), -64.8 (d, J = 1.7 Hz, E).
4.2.27. Methyl (E)-3-(naphthalen-2-yl)-2-(trifluoromethyl)acrylate (E-4p) and methyl (Z)-3-(naphthalen-2-yl)-2-(trifluoromethyl)acrylate (Z-4p)
[8]: 2-iodonaphthalene (0.2 mmol, 50.8 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-(trifluoromethyl)acrylate
(0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. The crude was purified by silica
gel column chromatography (petroleum ether/EtOAc, from 60/1 to 50/1, v/v), affording compound 4p in 79% yield [mixture of E/Z isomers (74/26),
44.3 mg] as a yellow solid. 1H NMR (300 MHz, CDCl3): δ 8.27 (s, 1H, Z), 7.93 – 7.79 (m, 4H, Z + 4H, E), 7.62 – 7.41 (m, 3H, Z + 4H, E), 3.94 (s, 3H,
Z), 3.81 (s, 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.3 (s, Z), -64.2 (d, J = 1.4 Hz, E).
4.2.28. Methyl (E)-3-(3,5-dichlorophenyl)-2-(trifluoromethyl)acrylate (E-4q) and methyl (Z)-3-(3,5-dichlorophenyl)-2-(trifluoromethyl)acrylate
(Z-4q) [8]: 3,5-dichloroiodobenzene (0.2 mmol, 54.6 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-
o
(trifluoromethyl)acrylate (0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 C for 4 hours according to the general procedure. The
crude was purified by silica gel column chromatography (petroleum ether/EtOAc, from 60/1 to 50/1, v/v), affording compound 4q in 68% yield [mixture
of E/Z isomers (74/26), 40.7 mg] as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 7.88 (s, 1H, Z), 7.35 – 7.29 (m, 1H, Z + 1H, E), 7.25 (s, 1H, E), 7.21
– 7.12 (m, 2H, Z + 2H, E), 3.83 (s, 3H, Z), 3.73 (s, 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.6 (s, Z), -64.7 (d, J = 1.7 Hz, E).
4.2.29. Methyl (E)-3-(5-formylfuran-2-yl)-2-(trifluoromethyl)acrylate (E-4r) and methyl (Z)-3-(5-formylfuran-2-yl)-2-(trifluoromethyl)acrylate
(Z-4r): 5-iodofuran-2-carbaldehyde (0.2 mmol, 44.4 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol, 21.3 mg), and methyl 2-
(trifluoromethyl)acrylate (0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 oC for 4 hours according to the general procedure. When
the reaction mixture was cooled to rt, 19F NMR spectrum of the crude was tested with PhCOCF3 (1.0 equiv) as an internal standard. 19F NMR yield:
29% [according to the linear relationship, see SI], E/Z = 83/17. 19F NMR (282 MHz, CDCl3) for crude: δ -60.2 (s, Z), -64.2 (s, E). We failed to obtain
the pure isolated product.
4.2.30. 3-(Trifluoromethyl)-2H-chromen-2-one (5) [8]: 2-iodophenol (0.2 mmol, 44.0 mg), AgOTf (0.3 mmol, 77.1 mg), Pd/C (10%, dry) (0.02 mmol,
o
21.3 mg), and methyl 2-(trifluoromethyl)acrylate (0.3 mmol, 46.2 mg) in 1,4-dioxane (1.0 mL) were reacted at 110 C for 4 hours according to the
general procedure. The crude was purified by silica gel column chromatography (petroleum ether/EtOAc, from 20/1 to 10/1, v/v), affording compound
5 in 50% yield (21.3 mg) as a white solid. 1H NMR (300 MHz, CDCl3): δ 8.16 (s, 1H), 7.75 – 7.57 (m, 2H), 7.49 – 7.31 (m, 2H). 19F NMR (282 MHz,
CDCl3): δ -66.7 (s). The Z isomer 4s was obtained in less than 13% yield (5.5 mg). Methyl (Z)-3-(2-hydroxyphenyl)-2-(trifluoromethyl)-acrylate
(4s). 1H NMR (300 MHz, CDCl3): δ 8.27 (s, 1H), 7.36 – 7.20 (m, 2H), 6.96 (t, J = 7.7 Hz, 1H), 6.83 (d, J = 8.1 Hz, 1H), 5.41 (s, 1H), 3.91 (s, 3H). 19
NMR (282 MHz, CDCl3): δ -59.3 (s). We failed to obtain the pure isolated product.
F
4.3. General procedure for hydrolysis of t-butyl α-trifluoromethylacrylates.
To an oven-dried 10 mL reaction tube was added tert-butyl α-trifluoromethylacrylate 3 (0.2 mmol, 1.0 equiv), and the tube was then evacuated and
filled with argon three times. Anhydrous CH2Cl2 (1.0 mL) was added, and the mixture was cooled to 0 oC. CF3COOH (10.0 equiv) was added
dropwisely at 0 oC and the reaction mixture was then allowed to stir at rt for 4 hours. Water (0.2 mL) was added and the two phase reaction mixture
was further stirred at rt overnight. Water (5 mL) was added and the product was extracted with CH2Cl2 (3 × 10 mL), and the combined organic phase
was dried over anhydrous Na2SO4. After evaporation of solvents, the crude was purified by silica gel column chromatography (eluent: CH2Cl2/MeOH
(AcOH %)).
4.3.1. (E)-3-(4-methoxyphenyl)-2-(trifluoromethyl)acrylic acid (E-6a) and (Z)-3-(4-methoxyphenyl)-2-(trifluoromethyl)acrylic acid (Z-6a) [15d]:
the crude was purified by silica gel column chromatography (CH2Cl2/MeOH (AcOH), from 100/1 (0.5%) to 60/1 (0.5%), v/v), affording compound 6a
in 77% yield (mixture of E/Z isomers, 37.8 mg, E/Z = 84/16) as a pale yellow solid. 1H NMR (300 MHz, CDCl3): δ 11.30 (s, 1H, Z + 1H, E), 8.17 (s,
1H, Z), 7.58 – 7.43 (m, 2H, Z + 3H, E), 7.00 – 6.83 (m, 2H, Z + 2H, E), 3.87 (s, 3H, Z), 3.85 (s, 3H, E). 19F NMR (282 MHz, CDCl3): δ -58.6 (s, Z), -
63.7 (d, J = 1.4 Hz, E). 13C{1H} NMR (75 MHz, CDCl3): δ 169.4, 169.0, 162.2, 162.0, 150.8 (q, J = 2.4 Hz), 144.0 (q, J = 5.6 Hz), 133.1 (q, J = 2.7
Hz), 132.5, 124.4, 124.2, 122.6 (q, J = 271.3 Hz), 122.2 (q, J = 272.3 Hz), 119.0 (q, J = 31.1 Hz), 118.2 (q, J = 32.2 Hz), 114.2, 114.1, 55.6, 55.5.
IR: 2850, 1698, 1599, 1514, 1424, 1268, 1154, 1134, 1019, 838, 527 cm-1. HRMS (ES-TOF): Calcd for C11H8F3O3 (m/z): 245.0426 [M-H] found:
245.0429.
4.3.2. (E)-3-(2-(methoxycarbonyl)phenyl)-2-(trifluoromethyl)acrylic acid (E-6i) and (Z)-3-(2-(methoxycarbonyl)phenyl)-2-(trifluoromethyl)-
acrylic acid (Z-6i) [15d]: the crude was purified by silica gel column chromatography (CH2Cl2/MeOH (AcOH), 60/1 (0.5%), v/v), affording compound
6i in 71% yield (mixture of E/Z isomers, 39.0 mg, E/Z = 67/33) as a white solid. 1H NMR (300 MHz, CD3OD): δ 8.56 (s, 1H, Z), 8.18 – 7.99 (m, 1H, Z
+ 2H, E), 7.68 – 7.42 (m, 2H, Z + 2H, E), 7.32 (d, J = 7.5 Hz, 1H, E), 7.28 (d, J = 7.8 Hz, 1H, Z), 3.89 (s, 3H, Z), 3.88 (s, 3H, E). 19F NMR (282 MHz,
CD3OD): δ -59.3 (s, Z), -65.7 (d, J = 2.0 Hz, E). 13C{1H} NMR (75 MHz, CD3OD): δ 167.9, 167.7, 165.5 – 165.3 (m), 165.2, 151.3 (q, J = 3.2 Hz),
145.6 (q, J = 6.2 Hz), 137.3, 137.1, 133.53, 133.51, 131.5, 131.4, 130.4 – 130.0 (m), 129.9 (q, J = 2.8 Hz), 129.5, 128.9, 124.4 (q, J = 30.2 Hz),

123.8 (q, J = 270.3 Hz), 123.7 (q, J = 271.9 Hz), 122.9 (q, J = 29.8 Hz), 52.8, 52.7. IR: 2954, 1699, 1635, 1438, 1270, 1135, 1088, 755, 695 cm-1.
HRMS (ES-TOF): Calcd for C12H8F3O4 (m/z): 273.0375 [M-H] found: 273.0376.
Declaration of Competing Interest
The authors declare no conflict of interest.
Acknowledgements
This work was partially supported by INSA Rouen, Rouen University, CNRS, EFRD, Labex SynOrg (ANR-11-LABX- 0029), and
Rꢀgion Haute-Normandie (Crunch Network). P.X. thanks the CSC (China Scholarship Council) for a doctoral fellowship. The
authors thank Dr. D. Harakat for HRMS analyses, and Dr. B. Améduri for compound 2a gift.
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Scheme 1. Reported access to α-trifluoromethylacrylates.
Scheme 2. Scope of the alkenylation reaction with t-butyl 2-(trifluoromethyl)acrylate 2a.
a Yields based on isolated product after flash chromatography. b Not pure.

Scheme 3. Scope of the alkenylation reaction with methyl 2-(trifluoromethyl)acrylate 2b using Pd/C catalyst.
a Yields based on isolated product after flash chromatography. b 19F NMR yields were obtained by using PhCOCF3 as an internal
standard. c 110 °C. d 24 h. e Two E/Z isomers were separated.
Scheme 4. Hydrolysis of -trifluoromethylacrylates.

Table
Table 1
Optimization of the alkenylation reaction with t-butyl 2-(trifluoromethyl)acrylate.
[Pd]
Pd(TFA)2
(x mol%)
Additive
(y equiv)
Yield of 3a
(%)a
Entry
E/Z ratio
1
2
Pd(TFA)2
Pd(TFA)2
Pd(TFA)2
Pd(TFA)2
Pd(TFA)2
Pd(TFA)2
Pd(OAc)2
PdBr2
10
10
10
5
AgOTf (1.5)
AgOAc (2.0)
Ag2CO3 (2.0)
Ag2CO3 (2.0)
Ag2CO3 (2.0)
K2CO3 (2.0)
Ag2CO3 (2.0)
Ag2CO3 (2.0)
0
76
-
83/17
84/16
84/16
85/15
71/29
76/24
-
3
88
4
56
5b
6
10
10
10
10
90 (84)c
20
7
14
8
traces
a 19F NMR yields were obtained by using PhCOCF3 as an internal standard.
b 2 h.
c Isolated yield.
Table 2
Optimization of the alkenylation reaction with methyl or t-butyl 2-(trifluoromethyl)acrylate using Pd/C catalyst.
[Pd]
Additive
(y equiv)
Yield of
3a,4a (%)a
E/Z
ratio
Entry
2
Solvent
1
2
2a
2a
2a
2b
2b
2b
2b
2b
2b
2b
2b
2b
Pd
Pd
AgOTf (1.5)
Ag2CO3 (2.0)
Ag2CO3 (2.0)
AgOTf (1.5)
AgOTf (1.5)
AgOTf (1.5)
AgOTf (1.5)
AgOTf (1.5)
AgOTf (1.5)
Ag2CO3 (2.0)
NaOAc (1.5)
Cu(OTf)2 (1.5)
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
DMF
traces
-
traces
-
b
3
Pd(OH)2
Pd
-
-
4
87 (80)c
76/24
73/27
76/24
76/24
76/24
68/32
-
5d
6e
7
Pd
83 (76)c
Pd
80
76
b
Pd(OH)2
Pd
8f
9
78
Pd
18
10
11
12
Pd
1,4-dioxane
DMA
-
Pd
-
-
Pd
1,4-dioxane
traces
-

13
2b
Pd
-
1,4-dioxane
-
-
a
19F NMR yields were obtained by using PhCOCF3 as an internal standard.
b Pd(OH)2 (20%, dry)
c Isolated yield.
d 5 mol% of Pd
e 1 mol% of Pd
f 2 h.
Table 3
Control experiments to get insight in the mechanism with Pd/C
Catalytic system
t (h)
4
Yield of
Entry
1
2
Poisoning additive
-
E/Z ratio
3a,4a (%)a
Pd/C (10 % dry) 10 mol%
AgOTf (1.5 equiv)
2b
2b
2b
2b
2b
2b
2b
2b
2a
2a
2a
2a
87
76/24
Pd/C (10 % dry) 10 mol%
AgOTf (1.5 equiv)
4
2
Hg (one drop)
-
-
Pd/C (10 % dry) 10 mol%
AgOTf (1.5 equiv)
4
3
CS2 (0.5 equiv per metal atom)
CS2 (2 equiv per metal atom)
-
traces
-
Pd/C (10 % dry) 10 mol%
AgOTf (1.5 equiv)
4
4
-
92
41
38
-
-
Pd(TFA)2 10 mol%
AgOTf (1.5 equiv)
2
5
76/24
74/26
78/22
-
Pd(TFA)2 10 mol%
AgOTf (1.5 equiv)
2
6
Hg (one drop)
Pd(TFA)2 10 mol%
AgOTf (1.5 equiv)
2
7
CS2 (0.5 equiv per metal atom)
CS2 (2 equiv per metal atom)
-
Pd(TFA)2 10 mol%
AgOTf (1.5 equiv)
2
8
Pd(TFA)2 10 mol%
Ag2CO3 (2 equiv)
2
9
90
-
85/15
-
Pd(TFA)2 10 mol%
Ag2CO3 (2 equiv)
2
10
11
12
Hg (one drop)
Pd(TFA)2 10 mol%
Ag2CO3 (2 equiv)
2
CS2 (0.5 equiv per metal atom)
CS2 (2 equiv per metal atom)
5
83/17
-
Pd(TFA)2 10 mol%
Ag2CO3 (2 equiv)
2
-
a
19F NMR yields were obtained by using PhCOCF3 as an internal standard.
To conclude, we described here an updated method to synthesize α-trifluoromethylacrylates by ligand-free Mirozoki-Heck reaction.
The use of t-butyl trifluoromethylacrylate instead of methyl trifluoromethylacrylate allowed to improve the E:Z ratio of the reaction,
albeit a complete stereoselectivity was not obtained. Worthy of note that the t-butyl acrylates were good substrates to reach relevant
trifluoroacrylic acids by acid hydrolysis. Then we reported that the cheaper and useful Pd/C could be efficiently used to synthesize
the methyl trifluoromethylacrylates, being a good alternative towards these relevant compounds.