Base-mediated reactions of diethyl malonates derivatives with perfluorinated olefins: Novel synthetic routes to multifunctional ionomer precursors

Article abstract of DOI:10.1016/j.jfluchem.2021.109864

A novel synthetic method for the preparation of per- and polyfluorinated unsaturated 2-substituted malonates is presented involving the deprotonation of the starting diethyl malonate by a strong base, followed by in situ addition of the C-nucleophile to the terminal double bond of the perfluorinated olefin. Subsequent elimination of the corresponding leaving groups and restoring of the double bond leads to the target bifunctional perfluorinated olefins. In the case of unsubstituted diethyl malonate, the elimination is accompanied by a prototropic rearrangement with a double bond migration and the addition of a second equivalent of the C-nucleophile forming the tetrafunctional internal olefins. The reaction conditions, factors affecting the reactivity and regioselectivity of the process, the choice of reagent as well as the course of competitive reactions are also discussed.

Full text of DOI:10.1016/j.jfluchem.2021.109864

Journal of Fluorine Chemistry 250 (2021) 109864
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Base-mediated reactions of diethyl malonates derivatives with
perfluorinated olefins: Novel synthetic routes to multifunctional
ionomer precursors
,
,
Sergey N. Tverdomeda *, Markus E. Hirschbergb *, Romana Pajkerta,
a
¨
Gerd-Volker Roschenthaler
a Life Sciences & Chemistry, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
b 3M Advanced Materials Division, Dyneon GmbH, Industrieparkstr. 1, 84508 Burgkirchen, Germany
A R T I C L E I N F O
A B S T R A C T
Keywords:
A novel synthetic method for the preparation of per- and polyfluorinated unsaturated 2-substituted malonates is
presented involving the deprotonation of the starting diethyl malonate by a strong base, followed by in situ
addition of the C-nucleophile to the terminal double bond of the perfluorinated olefin. Subsequent elimination of
the corresponding leaving groups and restoring of the double bond leads to the target bifunctional perfluorinated
olefins. In the case of unsubstituted diethyl malonate, the elimination is accompanied by a prototropic rear-
rangement with a double bond migration and the addition of a second equivalent of the C-nucleophile forming
the tetrafunctional internal olefins. The reaction conditions, factors affecting the reactivity and regioselectivity of
the process, the choice of reagent as well as the course of competitive reactions are also discussed.
Perfluorinated carboxylic acid ionomer
precursors
Perfluoroalkenes
Addition/elimination reactions
Diethyl malonates
Prototropic rearrangement
1. Introduction
perfluorinated sulfonic acid monomers containing two SO3H groups are
known in the literature [6,6a].
Perfluorinated ionomer precursors are important monomers for the
synthesis of thermoplastic fluoropolymers ([1]), obtained e.g. by the
copolymerization of a nonpolar with a polar monomer via radical
polymerization process [2]. Therefore, ionomer precursors have been of
great interest in the polymer production for years [3]. Compared to
conventional thermoplastics, ionomers have the advantage that both
secondary valence forces and ionic bonds become effective. These ion
bonds are particularly firm and give the fabric its characteristic prop-
erties, but also enable the proton transport in fuel cells and electrolysis
devices. Therefore, ionic plastics can serve as solid polymer electrolytes
(SPE) [4a–c] or polymer electrolyte membranes (PEMs) [4d–f] for fuel
cells, unlike most other plastics. Currently, the biggest practical appli-
cation involves the possesses the perfluorinated sulfonic acid ionomer,
having sulfonic acid group in a structure (Fig. 1, A and B) [5a–c]. If the
ionomer is ion-conducting through a sulfonic acid group (-SO3H), then
the polymer is extruded in its sulfonyl fluoride form (-SO2F) [4d,5d].
Furthermore, ionomer dispersions in SO3H form are commercially
available (e.g. 3M™ Ionomers, Solvay Aquivion®, Chemours Nafion®).
Only a few examples of the synthesis of corresponding bifunctional
Moreover, the procedures for their preparation include multistage
synthesis using exotic and / or highly toxic reagents and proceed with
low yield [6b–d]. On the other hand, a carboxylate-form of per-
fluorinated ionomers, such as those made by DuPont (Nafion CR), with
the structure depicted in Fig. 1(C), have shown interesting properties
compared to their sulfonate analogues [7a–c]. These properties arise
from the weaker acidity of the carboxylic acid pendant group and the
smaller size of the carboxylate anion. Perfluorinated ionomers with
carboxylic groups are usually obtained by the modification of the cor-
responding polymer containing -SO2F groups (e.g. Rf-O-CF2CF2SO2F), its
reduction to sulfinic acids (Rf-O-CF2CF2SO2H) and subsequent oxidation
with oxygen in an aqueous medium at elevated temperatures to furnish
the target product (Rf-O-CF2CO2H) [7a,d]. However, this significantly
reduces the preparative availability of these materials, due to the limited
choice of ionomer precursors. It is known that the reaction of active
methylene compounds with EWG (Electron-withdrawing)-vinyl halides
in the presence of bases is a convenient route for the olefin functional-
ization [7e–i]. The reaction of malonic acid esters in the form of C-salts
with some vinyl halides proceeds by Pd/Cu-catalyzed coupling [7f–g] or
* Corresponding authors.
E-mail addresses: s.tverdomed@jacobs-university.de (S.N. Tverdomed), mhirschberg@mmm.com (M.E. Hirschberg).
https://doi.org/10.1016/j.jfluchem.2021.109864
Received 1 June 2021; Received in revised form 6 August 2021; Accepted 7 August 2021
Available online 11 August 2021
0022-1139/© 2021 Elsevier B.V. All rights reserved.

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
prolonged time [9c]; in the case of the chloro‑ and bromo‑derivatives,
the temperature and reaction time were reduced as much as possible
[9a]. This is caused by the possibility of their decomposition eliminating
alkali metal chloride and generating the corresponding carbenes and
their reaction with some olefins, which was proved by observing
substituted cyclopropanes in the reaction products [9d]. To the best of
our knowledge, the reaction of malonic acid derivatives, as well as other
active methylene compounds with perfluorinated olefins, has not been
previously studied and no examples could be found in literature.
Recently, we demonstrated the reactivity of diethyl 2-fluoromalonates
with perfluorinated alkenes, including hexafluoropropene (HFP) and
perfluoroallyl fluorosulfate (FAFS), in the presence of NaH as a base and
obtained the corresponding terminal and internal perfluoroalkene
malonates in good yields (66–70%) [9e]. Moreover, a systematic study
reacting 2-substituted malonates with perfluorinated alkenes, vinyl and
allyl ethers enables to develop a new methodology for the preparation of
monomers for promising perfluorinated sulfonic acid ionomers. In this
work, we demonstrated modification of some perfluoroalkenes used in
the fluoropolymer industry, e.g. HFP (Hexafluoropropene), FAFS (Per-
fluoroallyl fluorosulfate), PMVE (Perfluorovinyl trifluoromethyl ether),
MV-31 (Perfluoro(3-methoxypropyl vinyl ether)), PPVE-1 (Per-
fluoropropyl perfluorovinyl ether), MA-31 (Perfluoro(3-methoxypropyl
allyl ether)), DVE-3 (1,1,2,2,3,3-Hexafluoro-1,3-bis[(trifluoroethenyl)
oxy]propane) by the (Michael type) nucleophilic addition / elimination
of unsubstituted 2-halo substituted diethyl malonates as the C-salt.
Fig. 1. Some examples of perfluorinated ionomers.
Michael addition of the C-nucleophile and the elimination of the alkali
halide salt to form the corresponding 2-vinyl malonates (Fig. 2) [7h–i].
However, the use of diethyl 2-halogen malonates in such reactions has
not been known in the literature, yet. On the other hand, commercially
available diethyl malonate like 2-halogen-substituted-malonate are
common CH-acids forming corresponding salts with bases, which show
high reactivity towards both bromo‑ [8a] or iodo alkanes [8b] as well as
carbonyl compounds [8c]. In addition, diethyl malonates as in sit-
u-generated alkali salts can react with different olefins to produce the
corresponding 2-alkyl substituted malonates [8d]. To deprotonate
diethyl malonate derivatives, many organic and inorganic bases can be
used, including NaH [8b], EtONa [8d], DBU (1,8-Dia-
zabicycloundec-7-ene) [8e], K2CO3 [8a] or t-BuOK [8f]. Due to the
-I-effect of halogen, and especially fluorine, in the case of 2-halo
substituted malonates the acidity of these substrates slightly increases
[8 g] and the basicity of sodium acetate turned out to be sufficient for a
classical Michael addition [8 h].
2. Results and discussion
2.1. Reaction of diethyl malonates 1a-d as a C-salt 2a-d with
hexafluoropropene 3
Initially, we investigated the reaction of diethyl 2-fluoromalonate 1a
as its alkali metal salt with gaseous HFP in various aprotic solvents. Due
to the -I-effect of the fluorine atom and thus increased acidity of the CH
proton, 1a was easily deprotonated using NaH or n-BuLi in dry mono-
glyme (MG) to give the corresponding salt 2a (Scheme 1). The best re-
sults were obtained by utilizing 4–10% excess of NaH in anhydrous N,N-
dimethylformamide (DMF) for 1.5 h at 4–6 ◦C. In this case, 100% con-
version of 1a was achieved. The progress of the reaction was monitored
by 19F NMR spectroscopy which showed the disappearance of the
doublet from the fluorine nucleus at the 2-position (δ ꢀ 195.4 with 2JFH
= 48 Hz) [9f] and the appearance of a singlet atFδF ꢀ 127.1, corre-
sponding to 2a. In situ generated 2a reacts then with 20% excess of HFP
3 in dry DMF at -15 ◦C for 2.5 h with high regio- and stereoselectivity
Because of the lability of the halogen atom in 2‑chloro- or 2-bromo-
malonates and possible nucleophilic substitution, NaOEt and t-BuOK are
rarely used for their deprotonation. In turn, the most common bases for
the deprotonation of the above-mentioned malonates are sodium hy-
dride for 2‑chloro- [9a], and potassium carbonate for 2-bromomalonate
[9b], respectively. Solvents usually are THF, MeCN, DMF, toluene or
EtOH [8]. However, the application of protic solvents such as ethanol for
2‑chloro (bromo) malonates was not possible due to the aforementioned
reason. The temperature of the salt formation was determined by a trade
off between the solubility of the base in a particular solvent and the
thermal stability of the C-salts. Thus, H- and F-malonates were converted
into their salts, usually at temperatures close to room temperature for a
Fig. 2. Previous and current works.
2

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
Scheme 1. Reaction of 2-halomalonates 1a-b,d with HFP 3.
Table 1
Base-mediated reaction of malonic acid derivatives 1a-c with HFP 3.
Equiv.NaHa
1
Solventb,c
Equiv. of 3,
Method
Time, h
T, ◦
C
Product
Yield,%d
Other products,%e
◦
N
1
2
3
4
5
6
7
8
9
1.1
1a
1a
1a
1a
1b
1b
1b
1b
1b
1b
1d
1d
DMF
1.2
1.1
1.0
1.2
1.5
2.1
6.4
1.15
1.15
2.0
1.2
1.2
Ag
A
A
A
A
A
Bh
B
2.5
1.5
16
ꢀ 15
ꢀ 15
5
4a
4a
4a
4a
5
62
66
69
33f
22f
17f
26f
14
27
22
20
14
13
17
14
1a (1.5)
1.1
DMF
1a (3)
1.1
DMF
1a (5)
1.1
MeCN
2.0
3.0
2.0
3.0
3.5
3.0
2.0
2.0
2.5
ꢀ 35
ꢀ 25
ꢀ 15
ꢀ 50
ꢀ 35
ꢀ 30
ꢀ 15
ꢀ 25
ꢀ 40
1a (28)
1.04
1.02
1.04
1.03
1.03
1.03
1.04
1.03
DMF
4b (10)f
MeCN
5
4b (15)f
DMF/THF
DMF/Et2O
MeCN/ MeCN
MeCN/THF
DMF
4b
6
4c (24), 6 (26)
4c (11)f
B
6
–
10
11
12
B
6
–
A
A
4d‘
4c
7
4c (13), 7 (20), 1d (1)
4d‘ (22), 1d (1.5)
THF
13
14
1.03
1.05
1d
1c
DMF/Et2O
DMF
1.2
1.2
B
3.0
2.0
ꢀ 20
ꢀ 30
7
4c (14), 4d‘ (15), 1d (2)
4c‘ (28)
A
4cbis
a
As 60% suspension in mineral oil.
Anhydrous.
b
c
d
e
f
Solvent for generation of C-salt 2a-c/ solvent for dissolving HFP 3.
Isolated yield.
According to 19F NMR analysis of the crude product.
NMR-yield according to 19F NMR analysis of the crude product.
g
h
Method A: HFP 3 was condensed to dissolve salt 2a-c in solvent (“one pot “).
Method B: The solution of salt 2a-c in a solvent was added dropwise to the solution of HFP 3 in a solvent at [T].
3

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
giving rise only to the trans-isomer of the addition-elimination product
4a (62% yield; 98% purity; Table 1, entry 1). The configuration of 4a
was established by the characteristic trans-coupling constant values of
the fluorine nuclei attached to the double bond (3JFF ≈ 137 Hz) [9g].
The reaction was conducted by condensing HFP 3 into a solution of 2a,
frozen by liquid nitrogen, and subsequent rapid warming of the reaction
mixture up to -15 ◦C (Method A). After termination of the reaction
(8–12 h) and slow warming to ambient temperature, the mixture was
neutralized with sulfuric acid (2% solution), and the target product 4a
was purified by distillation under reduced pressure. In contrast, the
lithium salt 2a’
(2:1 mol ratio: 22% and 10% yield; 1:1 mol ratio: 17% and 15% yield;
Table 1, entries 5 and 6). In this case, a lower polarity of the reaction
medium led to the stabilization of 2b and increased the yield of 4b
(Table 1, entry 6). The order of addition of reagents also strongly
affected the selectivity of the reaction. In the synthesis of 4b, better
results were achieved using the reverse addition of reagents (Method B),
e.g. when the solution of sodium salt 2b in DMF was added to a solution
of HFP 3 (6.4 equiv.) in THF at ꢀ 50 ◦C. After a twofold distillation, the
product 4b was obtained in 26% yield and 80% purity as a pure trans-
isomer (transJFF ≈ 136 Hz; Table 1, entry 7). The crude product also
contained 4c (24%) and 6 (26%) as by-products as determined through
the composition of the equilibrium mixture 2b and 2c. Replacement of
the reaction medium by a DMF/ether mixture (Method B) and reducing
the excess of 3 up to 1.15 equiv. led to the formation of product 4b in
traces. As main products, 6 (14% yield, 90% purity) and 4c (11% yield,
70% purity) (Table 1, entry 8) were isolated. The formation of the salt
from 1b using NaH in MeCN at 5–6 ◦C and subsequent reaction (Method
B) of the equilibrium mixture of C-nucleophiles 2b and 2c with 3 in a
MeCN solution at -30 ◦C or in THF solution at -15 ◦C gave generally 6 as
a main product (22–27% yield, purity 96–98% (Table 1, entries 9–10).
Moreover, the addition-elimination products 4b and 4c were only
detected in traces (1–3%). Also, a large amount of oligomerization
products was formed in these cases (Table 1, entries 9–10). The steric
factor of the substituent in the 2-position of malonate, and lability of the
C–Br bond in perfluorinated compounds [10a] significantly influence
the reactivity in the reaction of diethyl 2-bromomalonate 1d with NaH
and the subsequent reaction of the resulting intermediates with HFP 3
(Scheme 1). 2-Bromomalonate 1d reacted with NaH similarly to 1b at
3–6 ◦C and formed an «equilibrium» mixture of 2d, 2c, and 2,2-dibro-
momalonate 7. Additionally, at low temperatures 2d is so stable that
no formation of cyclopropane 5 was observed. Consequently, also no
formation of the corresponding dimeric impurities was detected. By
carrying out the reaction in DMF, the equilibrium is slightly shifted to-
wards 2d In this case, the reactivity of 2d in comparison to 2b was
somewhat lower, probably due to the steric effect of the bromine atom.
Interestingly, the target product 4d turned out to be unstable and
immediately rearranges into a thermodynamically stable 4d’, which
was isolated as a main product (20% yield, 90% purity; Table 1, entry
11).
(δ ꢀ 128.7), generated in situ from 1a with 2.5 M n-BuLi in dry MG at
F
-50 ◦C, showed significantly lower reactivity towards HFP 3 at -50 ◦C.
After acidic hydrolysis, product 4a contained 24% of 1a, whereas the
yield of 4a was only 25%. This is probably due to the stronger bonding of
the small Li+ cation (in comparison to Na+) with the anionic centre of
2a’ and the delocalization of the negative charge onto the oxygen atom
of the carbonyl group, which, together with the strong solvation effect of
MG, noticeably reduced the 2-Cꢀ nucleophilicity of malonate 2a’. In this
case, we also detected the formation of a significant amount of oligo-
meric by-products in the reaction mixture, that included fragments of
HFP 3 as well as diethyl malonate 4a. Noteworthy, the products 1a and
4a cannot be separated by fractional distillation due to the similar
boiling points (82 - 83 ◦C/1.0 Torr for 1a [9 h] and 62 - 63 ◦C/0.5 Torr
for 4a). The target product 4a was always contaminated with traces of
1a (Table 1, entries 1–4). By decreasing the excess of HFP 3 to 1.1 equiv.
and the reaction time up to 1.5 h, a slight increase in yield of 4a (up to
66%) was observed. However, its purity decreased to 95% (Table 1,
entry 2). To determine the synthetic potential of this process and its
optimization for preparative application, the reaction of the generated
◦
salt 2a with a stoichiometric amount of HFP 3 at 5 C was conducted
within 16 h using DMF as solvent. Furthermore, the reaction was scaled
from 6.2 gs of 1a up to 35.5 g of 1a leading to the target product 4a in
69% yield (Table 1, entry 3). The purity of 4a decreased at the same time
to 92% containing 5% of the starting reagent 1a. By lowering the po-
larity of the solvent and using MeCN instead of DMF in the reaction of
salt 2a generated at 5 ◦C with 1.2 equiv. of HFP 3 (Method A) at -35 ◦C, a
significant decrease in the reactivity of 2a and in yield of 4a (up to 33%)
was determined (Table 1, entry 4). Hence, it was interesting to evaluate
the electronic and steric factors of the substituent X in the 2-position of
malonate. Therefore, the sodium salt 2b (X = Cl) of diethyl malonate 1b
was reacted with HFP 3 (Scheme 1).
Plausibly, the isomerization proceeded through the addition-
elimination of the bromide from 4d with simultaneous migration of
the double bond [10b], caused by the fact that the expected 4d was not
observed in the reaction products even in traces (Scheme 1). Moreover,
the content of by-products 4c and 7 in the reaction mixture was 13% and
20%, respectively. A topologically similar rearrangement was previ-
Salt 2b formation was achieved through the reaction of 1b with 4%
excess of NaH in dry DMF at 5 -
◦
7 C for 2.5 - 3.5 h until the total conversion of 1b was achieved.
Compound 2b is quite stable at temperatures <10 ◦C and can be stored
in a solution without noticeable changes for at least 10 h. However, at
room temperature already after 2 h its partial decomposition was
observed, apparently what is associated with the formation of NaCl and
metastable carbene I. Its further dimerization and interaction with the
solvent gave a noticeable amount of unidentified oligomeric impurities.
We also found that 2b reacted with the starting reagent 1b even at 0 ◦C
under nucleophilic substitution and gave diethyl malonate sodium salt
2c and 2,2-dichloromalonate 6. The by-product 2c substituted Cl in 6 to
give the corresponding 1b and 2b. As a result, an equilibrium was
established in the reaction mixture, which shifted to 2c and 6 when the
temperature increased. This «equilibrium» has not been previously
described in the literature and is reported by us for the first time. Thus,
due to the side transformations during salt formation 1b, 2-chloromalo-
nate 2b reacted with HFP 3 non-regioselectively to furnish also 5, 4c and
6, except for the target 4b, which due to close physical properties, could
not be separated using fractional distillation in vacuum (Scheme 1). Also
the solvent had a strong influence on the selectivity of the process. For
example, when DMF or MeCN was used for the generation of salt 2b and
subsequent reaction with 3 at ꢀ 25–-15 ◦C for 3 h, an inseparable
mixture of perfluorinated cyclopropanes 5 and target 4b was obtained
ously observed for α-bromine-containing perfluoroalkenes under basic
catalysis [10a-b]. In its turn, the use of THF to generate 2d, led to
preferential formation of 4c in trans-configuration (transJFF ≈ 134 Hz)
and 7, which were isolated (13–14% yield, 85–90% purity) after reac-
tion with 1.2 equiv. of 3 at -40 ◦C (Method A) for 2.5 h. On the contrary,
the bromomalonate 4d’, as a product of addition of 2d into 3, was
detected as an admixture in 22% content and it was not possible to
isolate it in a pure form (Table 1, entry 12). These results indicated that
in THF the equilibrium between 2d ⇌ 2с is slightly shifted towards 2с in
contrast to DMF. Interestingly, when the salt solution 2d ⇌ 2с prepared
in DMF was added to a solution of 3 in diethyl ether at ꢀ 20 ◦C, the re-
action products showed an equimolar ratio of 4d’ and 4c (15% to 14%).
However, the main product dibromide 7 was isolated in 17% yield and
92% purity (Table 1, entry 13). Plausibly, under these conditions in a
DMF–ether system an equilibrium was established in a ratio of 1:1:1
(2d:2c:7). This could be also confirmed by the composition of the re-
action products 4d’, 4c, and 7. To eliminate side reactions during the
salt formation and to develop a method for the selective synthesis of 4c,
diethyl malonate 1c was deprotonated with 60% suspension of NaH in
mineral oil under classical conditions, namely in dry DMF at 6 - 15 ◦C for
14 h [10c]. As expected, the Na-salt 2c was stable in solution and could
4

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
be stored at room temperature for few days, without any changes. We
found, that C-salt 2c reacted with HFP 3 in a DMF solution (Method A) at
-30 ◦C for 2 h with the formation of only isomeric olefin 4c’ (δF ꢀ 75.9,
Regardless of the reaction conditions and excess of 8, 100% conversion
of 2a could not be achieved. After acidic hydrolysis of the reaction
mixture, the target product 9a always contained some amount of 1a,
which could not be separated from 9a by distillation (82 ◦C/1.0 Torr for
1a [9 h] and 59 ◦C/0.5 Torr for 9a). Therefore, high conversion of 2a
into 9a and high purity of 9a was a great challenge. The salt 2a was
obtained by reacting 1a with 5 - 15% excess of NaH in a polar solvent. As
solvents, DMF, Me2SO, MeCN, THF were tested, both for the generation
of salt and reaction with FAFS 8. The reaction of 2a with 8 was carried
out from -60 ◦C up to 15 ◦C and by reverse order of addition of reagents
(Method A or B). The best results were obtained using an aprotic solvent
of medium polarity, such as MeCN at -15 ◦C with the reverse reagents
addition sequence (Method B) and 5% excess of NaH for the generation
of 2a. In this case, the target 9a was isolated in 72% yield and in 97%
purity (Table 2, entry 5). The presence of NaH in the reaction mixture
and the concentration of reagents strongly affected the efficiency of the
process. Thus, the utilization of 15% excess of NaH to produce 2a
reduced the yield of 9a (16%), and its purity (65%; Table 2, entry 1). In
this case, the process was accompanied by anionic oligomerization of 8,
which affected the conversion of 2a and yield of 9a. By reducing the
excess of NaH down to 10% and by the application of DMF as solvent for
the reaction of 2a with 8 at -15 ◦C, the yield of 9a (26%) and its purity
could be improved (85%; Table 2, entry 6).
ꢀ 103.3, ꢀ 209.3) and bis-adduct 4cbis (δ ꢀ 75.4, ꢀ 200.2) in a molar
F
ratio of 1:1.5, and the expected 4c (δF ꢀ 68.1, ꢀ 142.7, ꢀ 167.5) was not
observed even in traces (Table 1, entry 14) (Scheme 2).
Conceivably, this phenomenon could be explained by the prototropic
rearrangement of the initial intermediate 4cI into the more stable and
delocalized carbanion 4cII. After elimination of Fꢀ , 4cII gave the
isomeric product 4c’, which was found to be an active electrophile in the
reaction with an excess of Na-salt 2c allowing to isolate the bis-adduct
4cbis (14% yield, 92% purity; Table 1, entry 14). Due to the formation
of a significant amounts of by-products, 4c’ could not be isolated with
satisfactory purity.
2.2. Base-mediated reaction of diethyl malonates 1a-d with perfluoroallyl
derivatives 8 and 12
It is well-known that fluorosulfate group is a good leaving group and
can be easily substituted by a variety of nucleophilic reagents [10d].
This process is usually conducted via Michael-type addition of a nucle-
ophile to the double bond of FAFS 8, prior to the elimination of the
fluorosulfate anion (Scheme 3).
The use of a mixture of solvents, such as DMF/MeCN and particularly
We found, that in situ generated C-salt 2a, which was used as a
representative reagent, reacted regioselectively with perfluoroallyl flu-
orosulfate 8 in aprotic, polar solvents over a wide temperature range
similarly to other nucleophiles, such as various alcohols, phenols, per-
fluoroalcoholates, azides, halides and cyanides [10d–f], accompanied
with the formation of the desired adduct 9a in good yield (Scheme 3).
Due to the fact that FAFS 8 is a liquid under the chosen reaction con-
ditions, it was convenient to control the reaction progress and the con-
version of 8 and 2a by 19F-NMR spectroscopy. Immediately after
addition of 8 to a solution of 2a (Method A) or 2a to a solution of 8
(Method B), the disappearance of signals of SO2F 8 (δF +50) [10d] and
2-fluoro malonic salt 2a (δ ꢀ 127) and the presence of new signals at δ
◦
DMF/THF even with 5–10% excess of NaH at ꢀ 20–ꢀ 60 C led to the
oligomerization of 8 and to a yield of 9a of 14–34% (Table 2, entries
3–4). The application of Me2SO did not lead to 2a and reacted with 8. In
the presence of anionic initiators, oligomerization of 8 took place and 9a
was obtained only in 29% yield (60% purity; Table 2, entry 2). In
contrast, 2-chloromalonate sodium salt 2b reacted readily with per-
fluoroallyl fluorosulfate 8 under conditions optimized for 2a at -30 ◦C to
the target product 9b in 64% yield (97% purity; Scheme 3). Further-
more, the process was highly selective and the crude product, except for
9b, contained only 1b (3%) and traces of unidentified by-products. In
this case, 2,2-dichloride 6 as a proton containing by-product of addition
of 2c to HFP 3 was not detected even in traces (Table 2, entry 7). A
F
F
+38 and ꢀ 186, corresponding to –OSO2F [10 g] and 9a were detected.
Scheme 2. Reaction of diethyl malonate 1c with hexafluoropropene (HFP) 3.
5

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
Scheme 3. Reaction of 2-halomalonates 1a-d with perfluoroallyl fluorosulfate (FAFS) 8.
Table 2
Base-mediated reaction of malonic acid derivatives 1a-b, d with FAFS 8 and MA-31 12.
Equiv.NaHa
1
Solventb,c
Sub.
Equiv.
Method
Time, h
T, ◦
C
Product
Yield,%d
Purity,%e
◦
N
1
2
3
4
5
6
7
8
9
1.15
1.1
1a
1a
1a
1a
1a
1a
1b
1d
1d
1d
1a
DMF
8
8
8
8
8
8
8
8
8
8
12
1.2
Ag
A
Bh
B
2.5
2.0
4.0
2.0
3.5
1.5
2.0
3.5
2.0
2.0
1.5
ꢀ 20
+15
ꢀ 20
ꢀ 60
ꢀ 15
ꢀ 15
ꢀ 30
ꢀ 25
ꢀ 35
ꢀ 30
ꢀ 30
9a
9a
9a
9a
9a
9a
9b
7
16f
29f
34f
14f
72
26f
64
18
25
14
19
9
65
60
79
50
97
85
97
93
95
94
94
76
92
Me2SO
1.1
1.05
1.1
DMF/MeCN
DMF/THF
MeCN/MeCN
DMF
1.1
1.15
1.15
1.15
1.15
1.15
1.15
1.15
1.15
1.05
1.1
B
A
B
1.03
1.03
1.04
1.03
1.03
MeCN
MeCN/MeCN
MeCN/DMF
MeCN/Et2O
DMF/MeCN
B
B
7
10
11
B
7
B
9a
13
9b
12
a
b
c
d
e
f
1.03
1b
MeCN/MeCN
12
1.15
B
2.5
ꢀ 25
27
60% suspension in mineral oil.
Anhydrous.
For Method B: Solvent for generation of C-salt 2a-b, d / solvent for dissolving FAFS 8.
Isolated yield.
According to 19F NMR analysis of the crude product.
NMR yield according to 19F NMR analysis of the crude product.
Method A: FAFS 8 was added to dissolve salt 2a-b, d in solvent (“one pot “).
g
h
Method B: The solution of salt 2a-b, d in solvent was added dropwise to the solution of FAFS 8 in solvent at [T].
strong and non-nucleophilic base such as 1,8-diazabicyclo[5.4.0]
undec‑7-ene (DBU) [11a] was found to be too weak to deprotonate 1b.
After the reaction of 1b with 8 in the presence of 2% excess of DBU only
10% conversion of 1b was observed. Except for 90% of the starting
material 1b (δH 4.82) [11b], the crude product contained traces of the
target 9b (δF ꢀ 91.4, ꢀ 103.3, ꢀ 104.4, ꢀ 182.0) and 5% substitution
product of the sulfur containing compound 10 (δ ꢀ 73.5, ꢀ 94.5,
ꢀ 107.0, ꢀ 188.7). On the other hand, sodium salt 2d, gFenerated from 1d
with NaH in dry MeCN, was not sufficiently active in the reaction with 8,
probably due to the steric factor, and the desired adduct was not spec-
trally detected. After the reaction of 2d (Method B) with a small excess
of FAFS 8 in MeCN (Table 2, entry 9), DMF (Table 2, entry 9) or diethyl
ether (Table 2, entry 10) at ꢀ 35–ꢀ 25 ◦C and subsequent work-up of the
reaction mixture, the NMR analysis of the crude material showed the
presence of 2,2-dibromide 7 and diethyl malonate 1c in a 1:1 mol ratio,
as well as 2,3,3-trifluoroacrylic acid 11 (δ ꢀ 83.3, ꢀ 93.9, ꢀ 182.3)
F
[10d], 8, besides traces of 1d (5–7%). Removal of the acidic by-products
1c and 11 by washing with a saturated solution of NaHCO3 allowed to
6

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
isolate 7 in 14–25% yield (93–95% purity; Table 2, entries 8–10). In the
reaction of a proton-containing sodium salt 2c with FAFS 8, a constant
excess of reagents (Method A) or substrates (Method B) turned out to be
the key factor, which well illustrated the reactivity of this reagent with
some perfluorinated olefins, such as 3 or 8. As in the case of HFP 3
(Scheme 2), we were able to detect the presence of only 2–3% of 8 and
the starting reagent 1c (40%) as a result of the reaction of 2c with FAFS
8 with an excess of 2c in the reaction mixture (Method A) and using DMF
as a solvent (Scheme 3). The target product 9c, as well as alternative
addition products of 2c to 8, was not found even in traces (Table 3, entry
1). However, an unidentified mixture of perfluorinated polymers /
oligomers was the main reaction product in this case. Oligomerization of
the target 9с in the presence of an excess of 2c can be explained by the
high acidity of the proton in 9с caused by the additional I– effect of the
perfluorinated substituent. The salt 2c, deprotonated 9c as a base,
leading (after reaction with FAFS 8 and elimination of F–) to the for-
mation of a stable diene 9cI, which in the presence of F– was probably
prone to spontaneous oligomerization (Scheme 3). We also tested other
solvents (THF and MeCN), conducting the process to obtain 2c by the
reaction of NaH and subsequent reaction with 8 (Method A). However,
due to practical insolubility of 2c in these solvents, the conduction of the
process even at 12–21 ◦C gave no result and only pure 8 and 2c were
recovered (Table 3, entries 2–3).
purity achieved 91% (Table 3, entry 8). The change of diethylether to
◦
THF and carrying out the reaction at -20 C, allowed to increase the
purity (up to 95%) and yield (36%) of 9c (Table 2, entry 8). The
application of 2.8 equiv. of 8 in a THF solution at -10 ◦C for the reaction
with 2c increased the yield of 9c up to 50%. Its purity, however, was of a
technical quality (80%; Table 2, entry 9). The use of MeCN for the re-
action of 2c with 8 promoted the oligomerization of 9cI and reduced the
yield (14–24%) and purity (80–90%) of 9c (Table 3, entries 11–12).
Furthermore, it was also of interest to compare the reactivity of per-
fluoroallyl fluorosulfate 8, a typical perfluoroallyl ester, with the reac-
tivity
of
1,1,2,3,3-pentafluoro-3-[1,1,2,2,3,3-hexafluoro-3-
(trifluoromethoxy)propoxy]‑prop-1-ene (MA-31) 12, a perfluoroallyl
ether, in their reactions with the most active sodium salts 2a-b. It was
–
–
found that CF3O-(CF2)2 CF2O is an effective leaving group and as a
result of reaction of 2a-b with MA-31 12 fluoroallyl derivatives 9a-b
were obtained as main products (19 - 27% yield), which allows to use 12
as an alternative to 8 (Scheme 4).
Sodium salts 2a-b were obtained in situ upon treatment of 1a-b with
3% excess of NaH in DMF (2a) or MeCN (2b) and were added to the
◦
solution of 12 (1.15 equiv) in dry MeCN at ꢀ 25–ꢀ 30 C, respectively
(Table 2, entries 11–12). At the end of the reaction, the conversion of 2a-
b was approximately the same (93 - 94%). However, the polarity of the
reaction medium in the case of 2a due to the application of a mixture of
DMF/MeCN was slightly higher and the elimination of F– made a sig-
nificant contribution to the stabilization of the intermediate 13I. As a
result, the adduct 13 was isolated in 9% yield and in 76% purity as a
pure trans-isomer (transJFF = 137 Hz; Scheme 4). Probably, in MeCN a
kinetic control of the reaction determined the elimination of CF3O-
By changing the reagents addition sequence, it was possible to
dramatically change the regioselectivity of the process and to obtain 9с
as a main product in (up to 50% yield; Table 3, entries 4–12). The
additional formation of 9cI and its subsequent oligomerization was also
observed in all cases as a concomitant reaction, which strongly disturbed
the purification of 9c (Table 3, entries 4–12). To optimize the reaction
conditions, the solution of 2c in DMF was added to a solution of 8 in
various aprotic solvents (Method B), as THF, Et2O, 1,4-dioxane, MeCN
or dichloromethane (DCM), varying excess of 8 (1.5–2.9 equiv.) and
temperature of the reaction (15–ꢀ 20 ◦C). The best results were obtained
upon addition of 2c to the solution of 2.5 equiv. of FAFS 8 in Et2O at
ꢀ 20 ◦C. So 9c was isolated in 50% yield (92% purity; Table 3, entry 4).
By lowering the excess of 8 up to 2.0 equiv. and raising the temperature
up to -10 ◦C, a decrease in yield of 8 (to 35%), аnd in purity (to 90%)
were observed (Table 3, entry 5). Further increase of the temperature of
the process up to ꢀ 5–15 ◦C and lowering of the excess of 8 to 1.5 equiv.
led to the formation of oligomerization products and to a reduced yield
of 9c (to 10%, 75% purity; Table 3, entries 6–7). If 2c was added to a
large excess of 8 (2.7 equiv.) at ꢀ 20 ◦C, the yield of 9c was 30%, аnd its
–
I
–
(CF2)2 CF2O as the only possible pathway to stabilize 13 and the by-
product, similarly to 13, was not detected even in traces. It is well-
known that perfluorinated alcoholates are unstable compounds and
exist in solutions in equilibrium with the corresponding carbonyl fluo-
rides [10d,11c]. Moreover, when sodium is used as a cation, the equi-
librium is strongly shifted towards carbonyl fluoride [10d]. On the other
hand, we did not find the addition-elimination product of 2a or 2b to
–
CF3O-(CF2)2 C(O)F even in traces, and the leaving group itself, after
acid hydrolysis, was registered as a carboxylic acid 14 (δ ꢀ 55.1, ꢀ 86.2,
F
ꢀ 119.1) [11d]. Moreover, the examples of effective fluorine "substitu-
tion" in carbonyl fluorides by the action of 1c in the presence of bases are
reported in the literature [11e]. This indicates a high regiospecificity of
2-halogen substituted malonates as C-nucleophiles.
Table 3
Screening of the reaction conditions of sodium diethyl malonate 2c with FAFS 8.
Equiv.NaHa
Solventb
Equiv. of 8,
Method
Time, h
T, ◦
C
Product
Yield,%c
Purity,%d
◦
N
f
ꢀ
ꢀ
ꢀ
1
2
3
4
5
6
7
8
9
1.1
DMF
1.2
1.2
1.15
2.5
2.0
1.5
1.5
2.7
2.0
2.8
2.1
2.9
Ae
A
A
Bh
B
2.0
3.0
12
7
-
–
g
1.05
1.1
THF
12
r.t.
-
–
g
MeCN
Et2O
-
–
1.03
1.04
1.05
1.05
1.07
1.03
1.05
1.03
1.02
2.0
1.5
2.0
4.0
1.5
2.0
2.0
1.5
2.5
ꢀ 20
ꢀ 10
ꢀ 5
9c
9c
9c
9c
9c
9c
9c
9c
9c
50
35
92
90
75
75
91
95
80
80
90
Et2O
DCM
B
10i
12i
30
1,4-Dioxane
DCM
B
15
B
ꢀ 20
ꢀ 20
ꢀ 10
ꢀ 8
THF
B
36
10
11
12
THF
B
50i
14i
24
MeCN
MeCN
B
B
ꢀ 20
a
As 60% suspension in mineral oil.
Anhydrous.
b
c
d
e
f
Isolated yield.
According to 19F NMR analysis of the crude product.
Method A: FAFS 8 was added to dissolve salt 2c in solvent (“one pot “).
Not identifiable mixture of perfluorinated polymers.
Only starting compounds 1c and 8.
g
h
i
Method B: The solution of salt 2c in DMF was added dropwise to the solution of FAFS 8 in solvent at [T].
NMR yield according to 19F NMR analysis of the crude product.
7

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
Scheme 4. Reaction of 2-halomalonates 1a-b with perfluoroallyl derivative MA-31 12.
Scheme 5. Reaction of diethyl malonates 1a, c with perfluorovinyl ethers (PVE) 15–18.
8

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
2.3. Base-mediated reaction of diethyl malonates 1a-c with
perfluorovinyl ethers 15–18
noted that the spectral analysis of the reaction mixtures is particularly
complex, which is connected to the structure of RF and its presence in
oligomeric by-products. Perfluorodivinyl ether DVE-3 18, having two
reaction centers, reacted non-regioselectively with 2c in a MeCN solu-
tion at ꢀ 25 ◦C under formation of the expected complex product
mixture. Repeated distillation allowed to isolate the bis-adduct 18cbis
(9% yield), but contaminated with by-products, and also mono-adduct
18c (2% yield; 40% content in the crude product; Table 4, entry 6).
Low regioselectivity of the process in the case of perfluorovinyl
ethers can be explained by the variety of pathways stabilizing carbanion
I, arising after nucleophilic addition of 2a–c to the double bond of PVEs
15–18 (Scheme 5). Depending on the substituents X, RF, or reaction
conditions and according to the kinetic or thermodynamic control, the
following reaction pathways are proposed, based on the identified target
products. In case of X = H, it could be assumed that due to the high
acidity of the proton in I its intramolecular migration occured with the
formation of II, which stabilizes into a highly reactive III after elimi-
nation of F– (Scheme 5). Intermediate III could react a) with 2c as a
nucleophile, and in this case bis-adducts 15cbis-18cbis are formed (up to
20% yield) or b) with a base. In that case the formation of the stable
allene IV can be assumed, which in presence of F– could release auto-
condensation of 15–18 as previously described for perfluoroalkenes
[11 h]. Obviously, a competitive stabilization route of I was an elimi-
nation of F–, and as a result mono adducts 15c-18c were detected up to
5% yield. A more complex pathway was observed for 2-halogen malo-
nates 2a-b, when I was probably stabilized by the elimination of RFO– ↔
RF‘C(O)F, with subsequent decomposition and the formation of resin of
the reaction products as a result of side reactions. This was previously
described in literature [11i]. Only in the case of 2a, I was partially
stabilized due to elimination of F– and 16a, as well as 16abis, could be
isolated in technical quality (5 - 7% yield; Scheme 5).
F
Perfluorovinyl ethers (CF CF-OR ) due to the +M-effect of the
–
–
2
ether group are less active in the reactions with C-nucleophiles than
perfluorinated alkenes or allyl derivatives. Only a few examples of such
reactions are known when either strong nucleophiles, including PhLi
[11c] or n-BuLi [11f], are involved, or in specific condensations with
perfluoroalkenes in the presence of F– [11 g]. We realized that sodium C-
salts of 2-halomalonates 1a-b reacted with perfluorovinyl ethers (PVE),
such as PMVE (RF= CF3) 15, PPVE-1 (RF= n-C3F7) 16, MV-31 (RF=
(CF2)3 O-CF3) 17, DVE-3 (RF= (CF2)3 O-CF=CF2) 18 non-
regioselectively and with predominant formation of decomposition
and oligomerization products (Scheme 5).
–
–
Only in the reaction of 2a with PPVE-1 16 in MeCN at ꢀ 20 ◦C
(Method B) it was possible to isolate and partially characterize some of
the reaction products. Except for the main product 16a (5% yield; 29%
content in the product), the bis-adduct 16abis (7% yield, 62% content)
was also isolated from the reaction mixture with traces of the starting
compound 1a. The sodium salt 2c reacted more selectively with PVEs
15–18 at ꢀ 15–-25 ◦C furnishing the bis-adducts 15cbis–18cbis (9–20%
yield; Table 4). In all cases, the target mono-adducts 15c–18c were
detected. However, only 16c could be isolated (4% yield; 91% purity;
Table 4, entry 2). The reaction proceeded with high stereoselectivity and
only trans-15c–18c (transJFF ≈ 120 Hz) were found. Regardless of the
conditions, the reaction of 2c with 15–18 was always accompanied by
the formation of a vast amount of unidentified oligomerization products,
which were often formed as main products. At the same time, the con-
version of 2c reached 95–99% and the substrate 1c was observed in the
reaction products after hydrolysis of the reaction mixture only in traces.
The best results were accomplished upon addition of a solution of 2c in
DMF into a solution of PPVE-1 16 in Et2O at -25 ◦C. Compound 16cbis
was obtained in 20% yield and in 91% purity (Table 4, entry 1). The
reaction mixture contained small amounts of the target product 16c,
which could be isolated (2% yield, 25% purity). Increased solvent po-
larity in the reaction of 2c with 16 reduced the yield of 16cbis as well as
of 16c (Table 4, entry 3). Under similar conditions, the addition of
gaseous PMVE 15 to the solution of 2c (Method A) and carrying out the
reaction in DMF resulted in the bis-adduct 15cbis (16% yield, 92% pu-
rity; Table 4, entry 4). The mono-derivative 15c existed in the reaction
mixture in only traces (5%) and was obtained in 2% yield. MV-31 17
reacted with 2c, generated in DMF upon treatment of diethyl malonate
1c with NaH in MeCN solution, to bis- 17cbis (16% yield) and mono-
adduct 17c (3% yield; 60% purity; Table 4, entry 5). It should be
3. Conclusions
For the first time, a simple and convenient method for the synthesis
of fluorinated olefins that could serve as potential perfluorinated car-
boxylic acid ionomer precursors is reported. This access was realized by
the addition reaction of the pre-generated С-salt of 2-substituted diethyl
malonates 1a-d to the double bond of some perfluorinated alkenes (HFP
3), allyl derivatives (FAFS 8, MA-31 12), and perfluorovinyl ethers
(PMVE 15, PPVE-1 16, MV-31 17, DVE-3 18), followed by elimination of
the corresponding leaving group (e.g. Fꢀ , FSO3ꢀ , perfluoroalkyl alco-
holate anion). The С-salts 2a-d were easily and quantitatively generated
upon treatment of the corresponding diethyl malonates 1a-d with NaH
Table 4
Base-mediated reaction of diethyl malonate 1c with perfluorovinyl ethers (PVEs) 15–18.
Equiv, Naa
Solventb
PVE
Equiv. PVE
Time, h
T, ◦
C
Product
Yield,%c
Purity,%d
◦
N
1f
2f
3f
4g
5f
6f
1.03
Et2O
16
2.0
2.5
ꢀ 25
ꢀ 15
ꢀ 20
ꢀ 20
ꢀ 25
ꢀ 25
16cbis
20
2e
91
25
91
85
73
80
92
30
90
60
75
40
16c
1.03
1.03
1.04
1.03
1.03
MeCN
DMF
16
16
15
17
18
1.5
1.5
1.9
1.9
1.0
1.5
1.5
2.0
2.0
2.0
16c
4
16cbis
16cbis
16c
14e
12e
3e
DMF
15cbis
15c
16
2e
MeCN
MeCN
17cbis
17c
16
3e
18cbis
18c
9e
2e
a
b
c
As 60% suspension in mineral oil.
Anhydrous.
Isolated yield.
d
e
f
According to 19F NMR analysis of the crude product.
NMR yield according to 19F NMR analysis of the crude product.
Method B: The solution of salt 2c in DMF was added dropwise to the solution of PVEs 15–18 in solvent at [T].
Method A: PVEs 15–18 were added to the dissolved salt 2c in solvent (“one pot“).
g
9

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
in polar solvents, such as DMF or MeCN at 5–7 ◦C. During the salt for-
mation of 2b and 2d, side processes led to the formation of 2c and to the
2,2-dihalides 6 and 7. In presence of HFP 3, С-salts 2a-b reacted by the
elimination of F– and the formation of the target internal alkenes 4a-b in
26–69% yields. In the case of 2-bromomalonate, 2d was isolated as the
main product; unexpectedly, also the isomeric compound 4d’ (20%
yield) and 4c (14% yield). Due to the high acidity of the proton in 2-po-
sition, 2c formed the bis-adduct 4cbis as a main product (14% yield)
upon reaction with HFP 3. In the reaction with perfluoroallyl fluo-
rosulfate 8, sodium salts 2a-c eliminated the fluorosulfate anion,
short Vigreux column under high vacuum. The desired olefin 4a was
obtained as a clear colorless liquid with b. p. 62–63 ◦C / 0.5 mmHg. The
yield of olefin 4a was 62% (6.7 g; purity 98%).
4.2.1. Diethyl (E)ꢀ 2-fluoro-2-(perfluoroprop-1-ene-1-yl)malonate (4a)
1H NMR (401 MHz, CDCl3): δ 4.37 (qd, 3JHH = 7 Hz, 5JHF = 2 Hz,
OCH2, 4H), 1.32 (t, 3JHH = 7 Hz, CH3, 6H).
13C NMR (101 MHz, CDCl3): δ 161.1 (dd, 2JCF = 26 Hz, 3JCF = 2 Hz, C
(O), 2C), 148.2 (dddq, 1JCF = 268 Hz, 2JCF = 40 Hz, 2JCF = 23 Hz, 3JCF
=
2 Hz, CF=CF, 1C), 141.2 (dqd, 1JCF = 258 Hz, 2JCF = 42 Hz, 3JCF = 5 Hz,
CF=CF, 1C), 117.8 (qdd, 1JCF = 274 Hz, 2JCF = 35 Hz, 3JCF = 2 Hz, CF3,
1C), 89.1 (ddd, 1JCF = 204 Hz, 2JCF = 27 Hz, 3JCF = 3 Hz, CF, 1C), 64.3
(bs, CH2, 2C), 13.7 (bs, CH3, 2C).
resulting in the expected terminal α-substituted allyl derivatives 9a-c
(50–72% yield). Furthermore, 2d did not undergo any addition to FAFS
8, but formed 2,2-dibromide 7 as the main product. By the example of
MA-31 12, the possibility of the addition of C-nucleophiles to per-
fluorallyl ethers and elimination of perfluoroalkyl alcoholate as a leav-
ing group was demonstrated. In the case of 2-fluoromalonate 2a, the
competition between perfluoroalkyl alcoholate and fluorine anion was
established. The corresponding terminal alkene 9a and internal alkene
13 could be isolated (19% and 9% yield). Using perfluorovinyl ethers
(PVEs) 15–18, diethyl malonates 2a-d reacted non-regioselectively and
predominantly to unidentified oligomeric products. Regarding 2c, the
bis-adducts 15cbis-18cbis were obtained as main products (9 - 20%
yield), while targets 15c-18c only as by-products (2 - 4% yield). The
main reaction pathways and factors affecting the reactivity and regio-
selectivity of the process as well as the formation of by-products were
discussed. The structures of all new compounds were characterized and
confirmed by NMR spectroscopy.
19F NMR (376 MHz, CDCl3): ꢀ 68.5 (ddd, 3JFF = 22 Hz, 4JFF = 10 Hz,
5JFF = 3 Hz, CF3, 3F), ꢀ 149.3 (dquid, transJFF = 137 , 3JFF = 25 Hz, 4JFF
= 3 Hz, =CF, 1F), ꢀ 160.6 (ddq, 3JFF = 25 Hz, 4JFF = 12 Hz, 5JFF = 23 Hz,
trans
4
5
CF, 1F), ꢀ 161.3 (dquid,
=CF, 1F).
J
= 137 Hz, JFF = 10 Hz, JFF = 1 Hz,
FF
4.2.2. Diethyl 2-fluoromalonate (1a) (1.5 mol% content in reaction
mixture)
1H NMR (401 MHz, CDCl3): δ 5.24 (d, 3JHF = 48 Hz, CFH, 1H), 4.29
(qd, 3JHH = 7 Hz, 5JHF = 3 Hz, OCH2, 4H), 1.29 (t, 3JHH = 7 Hz, CH3, 6H).
[9f]
19F NMR (376 MHz, CDCl3): ꢀ 195.2 (d, 2JFH = 48 Hz, CHF, 1F). [9f]
4.3. Reaction of diethyl 2-chloromalonates 1b with hexafluoropropene
(HFP) 3
4. Experimental
4.3.1. Method a
4.1. General
Analogously to the example 4.2., the salt 2b was generated in a glass
ampoule (100 mL) with a PTFE stopper from a NaH suspension (60%;
1.53 g, 38.3 mmol, 1.04 equiv.) in mineral oil and 1b (7.21 g, 37.0
mmol, approx. 6.0 mL) in dry DMF (34 mL) for 1.5 h at 6–14 ◦C. The
reaction of HFP 3 (8.57 g (57.1 mmol, 1.52 equiv.) was conducted at -25
◦C for 3 h (Method A). The reaction mixture was worked-up in the
manner as described above (4.2.) and the crude product (12.5 g) was
distilled under high vacuum. The second fraction (8.3 g) with a b. p. of
62–66 ◦C / 0.5 mmHg contained the cyclic adduct 5 in 22% yield (30
mol% content).
All reactions were carried out in glass reaction vials under an at-
mosphere of dry argon. Diethyl ether (Et2O), tetrahydrofuran (THF),
monoglyme (MG) and 1,4-dioxane were distilled from sodium /
benzophenone and used immediately. Before use, MeCN, DMF, Me2SO,
and DCM were freshly distilled from CaH2. Unless stated otherwise, all
reagents and starting materials were purchased from commercial sour-
ces and used without further purification. FAFS 8 was synthesized
following a common procedure [10d] with the purity of 93% (GC–MS).
All boiling points are uncorrected. 13C NMR spectra were recorded at
100 MHz, 19F NMR spectra were recorded at 376 MHz on JEOL ECX 400
MHz spectrometer. 13C and 19F NMR chemical shifts (δ) are reported in
ppm from tetramethylsilane and CFCl3, using the residual solvent
4.3.1.1. Diethyl 2,2,3-trifluoro-3-(trifluoromethyl)cyclopropane-1,1-dicar-
boxylate (5) (30 mol% content). 1H NMR (401 MHz, CDCl3): δ 4.35 (q,
3JHF = 7 Hz, C(O)OCH2, 4H), 1.32 (t, 3JHH = 7 Hz, CH3, 6H).
resonance (CD3CN: δ 118.1 and 1.2) as an internal reference. Coupling
C
19F NMR (376 MHz, CDCl3): ꢀ 75.3 (ddd, 3JFF = 15 Hz, 4JFF = 10 Hz,
4JFF = 7 Hz, CF3, 3F), ꢀ 103.7 (ddt, 3JFF = 22 Hz, 3JFF = 16 Hz, 3JFF = 15
constants (J) are given in Hz.
4.2. Reaction of diethyl 2-fluoromalonates 1a with hexafluoropropene
(HFP) 3
Hz, CF, 1F), ꢀ 151.6 (ddq, gemJFF = 140 Hz, 3JFF = 22 Hz, 4JFF = 7 Hz,
gem
CFF, 1F), ꢀ 158.7 (ddq,
J
= 140 Hz, 3JFF = 16 Hz, 4JFF = 7 Hz, CFF,
FF
1F).
A three-necked flask (250 mL), equipped with a condenser (ꢀ 50 to
-60 ◦C) and connected to a vacuum line, was charged with diethyl 2-flu-
oromalonate 1a (6.23 g, 35.0 mmol) and dry DMF (90 mL). The obtained
solution was cooled to 2–3 ◦C with an ice bath. Afterwards, a suspension
of NaH in mineral oil (60%; 1.53 g, 38.5 mmol, 1.1 equiv.) was added at
once, so that the reaction temperature did not exceed 10 ◦C. Then, the
reaction mixture was stirred for 1.5 h at 4–6 ◦C. Next, it was cooled to
-160 ◦C using liquid nitrogen and HFP 3 (6.3 g, 42.0 mmol) was
condensed using a vacuum line (Method A). The reaction mixture was
slowly warmed up to -15 ◦C and stirred below this temperature for 2.5 h.
Afterwards, it was stirred at r.t. for more than 10 h with slow heating.
The r. m. was poured into ice-cold sulfuric acid (2%; 1000 mL) and the
lower layer was separated. The water phase was extracted with meth-
yl‑tert‑butyl ether (MTBE) (3 × 200 mL), the organic phases were
combined and dried over anhydrous Na2SO4. The solvent was evapo-
rated in vacuo and the residue (8.1 g) was collected and distilled via a
4.3.2. Method b
To a three-necked flask (100 mL), a suspension of NaH in mineral oil
(60%; 1.52 g, 38.0 mmol, 1.04 equiv.) and dry DMF (50 mL) were added.
The suspension was stirred for 20 min at r. t., then cooled to 5–6 ◦C and
diethyl 2-chlorotonate 1b (7.1 g, 36.5 mmol, approx. 6.0 mL) was added
dropwise at this temperature, so that the reaction temperature did not
exceed 7 ◦C. Then the r. m. was stirred at this temperature for 3.5 h until
the reaction mixture got transparent. Dry THF (125 mL) of were added
to a flask (250 mL) equipped with a thermometer and a condenser (-60
◦C). The reaction solution was cooled to ꢀ 180 ◦C with liquid nitrogen
and HFP 3 (35.5 g, 236.6 mmol, 6.4 equiv.) was condensed into the flask
using a vacuum line. The reaction mixture was warmed to ꢀ 55 ◦C using
EtOH/N2 and the cold salt solution of 2b was added dropwise at this
temperature with a syringe (Method B). During the addition of 2b, a
slight external heat was observed, and the reaction temperature
10

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
increased to -50 ◦C. The reaction mixture was stirred at -50 ◦C for 3 h,
then slowly heated to ambient temperature for 14 h. The reaction
mixture was evaporated in vacuo and poured into ice-cold sulfuric acid
(3%; 1500 mL) and the bottom layer was separated. The water phase
was extracted with MTBE (3 × 400 mL), the organic phases were com-
bined, washed with ice-cold water (3 × 500 mL) and then dried over
anhydrous Na2SO4. The solvent was evaporated under vacuum. The
remaining residue (6.86 g) was collected and distilled twice via a short
Vigreux column under high vacuum. The desired olefin 4b was obtained
as a yellowish liquid with b.p. 56–57 ◦C / 0.5 mmHg. The yield of olefin
4b was 26% (3.0 g; purity 80%). Product 4b contained 20% by-product
4c.
mmHg contained the olefin 4c with 14% yield and 85 mol% content. The
◦
third fraction (1.53 g) with a boiling point of 66–70 C / 0.5 mmHg
contained 2,2-dibromomalonate 7, which was isolated in 13% yield
(90% purity).
4.5.1. Diethyl (E)ꢀ 2-(perfluoroprop-1-ene-1-yl)malonate (4c) (85 mol%
purity)
1H NMR (401 MHz, CDCl3): δ 4.62 (dd, 3JHF = 26 Hz, 4JHF = 4 Hz,
CH, 1H), 4.28 (q, 3JHH = 7 Hz, C(O)OCH2, 4H), 1.29 (t, 3JHH = 7 Hz, CH3,
6H).
13C NMR (101 MHz, CDCl3): δ 163.2 (s, C(O), 2C), 147.9 (ddq, 1JCF
=
267 Hz, 2JCF = 43 Hz, 3JCF = 2 Hz, CF=CF, 1C), 139.9 (ddq, 1JCF = 246
Hz, 2JCF = 42 Hz, 2JCF = 41 Hz, CF=CF2, 1C), 118.3 (qdd, 1JCF = 272 Hz,
2JCF = 36 Hz, 3JCF = 4 Hz, CF3, 1C), 63.0 (bs, CH2, 2C), 50.9 (d, 2JCF
22 Hz, CH, 1C), 13.8 (bs, CH3, 2C).
=
4.3.2.1. Diethyl (E)ꢀ 2‑chloro-2-(perfluoroprop-1-ene-1-yl)malonate (4b)
(26% yield, 80% purity). 1H NMR (401 MHz, CDCl3): δ 4.35 (q, 3JHH = 7
Hz, C(O)OCH2, 4H), 1.32 (t, 3JHH = 7 Hz, CH3, 6H).
19F NMR (376 MHz, CDCl3): ꢀ 68.1 (dd, 3JFF = 22 Hz, 4JFF = 10 Hz,
CF3, 3F), ꢀ 142.5 (dqd, transJFF = 134 Hz, 4JFF = 22 Hz, 3JFH = 28 Hz,
13C NMR (101 MHz, CDCl3): δ 161.9 (s, C(O), 2C), 147.8 (ddq, 1JCF
=
trans
3
=CF, 1F), ꢀ 167.6 (ddq,
=CF, 1F).
J
FF
= 134 Hz, JFF = 10 Hz, 4JFH = 4 Hz,
265 Hz, 2JCF = 39 Hz, 3JCF = 2 Hz, CF=CF, 1C), 139.5 (ddq, 1JCF = 255
Hz, 2JCF = 46 Hz, 2JCF = 41 Hz, CF=CF2, 1C), 118.2 (qdd, 1JCF = 274 Hz,
2JCF = 36 Hz, 3JCF = 4 Hz, CF3, 1C), 66.7 (dd, 2JCF = 23 Hz, 3JCF = 4 Hz,
CCl, 1C), 64.8 (bs, CH2, 2C), 13.7 (bs, CH3, 2C).
4.6. Reaction of diethyl malonate 1c with hexafluoropropene (HFP) 3
19F NMR (376 MHz, CDCl3): ꢀ 68.0 (dd, 3JFF = 22 Hz, 4JFF = 10 Hz,
CF3, 3F), ꢀ 142.4 (dq, transJFF = 136 Hz, 3JFF = 22 Hz, =CF, 1F), ꢀ 159.6
(dq, transJFF = 136 Hz, 4JFF = 10 Hz, =CF, 1F).
Analogously to the example 4.2., the salt 2c was generated in a glass
ampoule (500 mL) with a PTFE stopper from NaH suspension in mineral
oil (60%, 5.24 g, 131.0 mmol, 1.05 equiv.) and 1c (20.0 g, 124.9 mmol,
ca. 18 mL) in dry DMF (95 mL) for 14 h at 12 - 15 ◦C. The reaction of HFP
4.3.2.2. Diethyl 2,2-dichloromalonate (6) (27% yield, 96% purity). 1H
NMR (401 MHz, CDCl3): δ 4.34 (q, 3JHH = 7 Hz, C(O)OCH2, 4H), 1.31 (t,
3JHH = 7 Hz, CH3, 6H) [11b].
◦
3 (22.5 g, 150.0 mmol, 1.2 equiv.) was carried out at ꢀ 30 C for 2 h
(Method A). The reaction mixture was worked-up analogously as
described above (4.2.) and the crude product (18.5 g) was distilled
under high vacuum. The olefin 4cbis was obtained as a yellow liquid
with b. p. 128 - 132 ◦C / 0.5 mmHg. The yield of 4cbis was 14% (7.6 g;
purity 92%).
13C NMR (101 MHz, CDCl3): δ 162.7 (s, C(O), 2C), 77.4 (s, CCl2, 1C),
64.6 (bs, CH2, 2C), 13.7 (bs, CH3, 2C) [11b].
4.4. Reaction of diethyl 2-bromomalonate 1d with hfp 3 in dmf
4.6.1. Tetraethyl 2-(1,2,2,2-tetrafluoroethyl)prop‑1-ene-1,1,3,3-
tetracarboxylate (4cbis) (92% purity)
Analogously to the example 4.2., the salt 2b was generated in a glass
ampoule (100 mL) with a PTFE stopper from NaH suspension in mineral
oil (60%; 1.51 g, 37.8 mmol, 1.03 equiv.) and 1d (8.76 g, 36.6 mmol, ca.
6.3 mL) in dry DMF (45 mL) for 1.5 h at 2–5 ◦C. The reaction with HFP 3
(6.51 g, 43.4 mmol, 1.2 equiv.) was conducted at -25 ◦C for 2 h (Method
A). The reaction mixture was worked-up according to the method
described above (4.2.) and the crude product (6.1 g) was distilled under
high vacuum. The third fraction (2.7 g) with b.p. 62–65 ◦C / 0.5 mmHg
contained the product 4d’ with 20% yield (90% purity).
1H NMR (401 MHz, CDCl3): δ 6.18 (dq, 2JHF = 45 Hz, 3JHF = 6 Hz,
CFH, 1H), 4.57 (s, CH(COOEt)2, 1H), 4.21 (q, 3JHH = 7 Hz, OCH2, 8H),
1.25 (t, 3JHH = 7 Hz, CH3, 12H).
13C NMR (101 MHz, CDCl3): δ 165.2 (s, COOEt, 2C); 165.2 (s, COOEt,
2C); 163.2 (d, 2JCF = 40 Hz, C = C, 1C); 135.9 (d, 3JCF = 20 Hz, C = C,
1C); 121.5 (qd, 1JCF = 283 Hz, 2JCF = 28 Hz, CF3, 1C); 85.3 (dq, 1JCF
=
186 Hz, 2JCF = 36 Hz, CFH, 1C); 62.5 (s, OCH2, 1C); 62.4 (s, OCH2, 1C);
62.3 (s, OCH2, 1C); 62.2 (s, OCH2, 1C); 49.7 (3JCF = 7 Hz, CH, 1C); 14.0
(s, CH3, 1C); 13.9 (s, CH3, 1C); 13.80 (s, CH3, 1C); 13.78 (s, CH3, 1C).
19F NMR (376 MHz, CDCl3): ꢀ 75.4 (dd, 3JFF = 13 Hz, 3JFH = 6 Hz,
CF3, 3F), ꢀ 200.2 (dq, 2JFH = 45 Hz, 3JFF = 13 Hz, CHF, 1F).
4.4.1. Diethyl 2-(2‑bromo-1,2,3,3,3-pentafluoropropylidene)malonate
(4d’) (90% purity)
1H NMR (401 MHz, CDCl3): δ 4.32 (qd, 3JHH = 7 Hz, 6JHF = 7 Hz, C
(O)OCH2, 4H), 1.30 (t, 3JHH = 7 Hz, CH3, 6H).
4.6.2. Diethyl-2-(1,2,3,3,3-pentafluoropropyliden)malonate (4c‘) (40 mol
% content)
13C NMR (101 MHz, CDCl3): δ 163.2 (s, C(O), 2C), 160.3 (d, 2JCF
=
11 Hz, CF=C, 1C), 155.3 (dd, 1JCF = 248 Hz, 2JCF = 29 Hz, CF=C, 1C),
119.4 (qdd, 1JCF = 286 Hz, 2JCF = 29 Hz, 3JCF = 3 Hz, CF3, 1C), 91.4
(dqui, 2JCF = 40 Hz, CFBr, 1C), 64.8 (bs, CH2, 2C), 13.7 (bs, CH3, 2C).
19F NMR (376 MHz, CDCl3): ꢀ 77.7 (dd, 3JFF = 10 Hz, 4JFF = 11 Hz,
CF3, 3F), ꢀ 105.1 (dq, 3JFF = 29 Hz, 4JFF = 10 Hz, =CF, 1F), ꢀ 135.4 (dq,
3JFF = 28 Hz, 3JFF = 10 Hz, CBrF, 1F).
1H NMR (401 MHz, CDCl3): δ 6.47 (ddq, 2JHF = 43 Hz, 3JHF = 21 Hz,
3JHF = 6 Hz, CFH, 1H), 4.33 (qd, 3JHH = 7 Hz, spJHH = 1 Hz, OCH2, 4H),
1.31 (t, 3JHH = 7 Hz, CH3, 6H).
19F NMR (376 MHz, CDCl3): ꢀ 75.9 (dd, 3JFF = 15 Hz, 3JFH = 6 Hz,
CF3, 3F), ꢀ 103.3 (ddq, 3JFF = 23 Hz, 3JFH = 22 Hz, 4JFF = 6 Hz, =CF, 1F),
ꢀ 209.3 (ddq, 2JFH = 43 Hz, 3JFF = 23 Hz, 3JFF = 15 Hz, CHF, 1F).
4.5. Reaction of diethyl 2-bromomalonate 1d with HFP 3 in THF
4.7. Reaction of diethyl 2-fluoromalonate 1a with perfluoroallyl
fluorosulfate (FAFS) 8
Analogously to the example 4.2., the salt 2d was generated in a glass
ampoule (100 mL) with a PTFE stopper from a NaH suspension in
mineral oil (60%; 1.5 g, 37.5 mmol, 1.03 equiv.) and 1d (8.7 g, 36.4
mmol, ca. 6.1 mL) in dry THF (50 mL) for 0.5 h at 3–6 ◦C. The reaction
with HFP 3 (6.6 g, 44.0 mmol, 1.2 equiv.) was carried out at -40 ◦C for
2.5 h (Method A). The reaction mixture was worked-up in the manner
described above (4.2.) and the crude product (7.1 g) was distilled under
high vacuum. The first fraction (1.82 g) with a b.p. of 44–47 ◦C / 0.5
To a three-neck flask (250 mL) equipped with a thermometer and
condenser, a suspension of NaH in mineral oil (60%, 2.71 g. 67.8 mmol,
1.05 equiv.) and dry MeCN (90 mL) were added. The suspension was
stirred for 20 min at r. t., then cooled to 8–10 ◦C and 1a (11.5 g, 64.5
mmol, 10.0 mL) of was added dropwise at this temperature, so that the
temperature did not exceed 14 ◦C. Then, the ice bath was removed, and
the reaction mixture was stirred for 2 h until it reached room
11

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
temperature. Afterwards, the salt solution 2a was poured into a drop-
ping funnel (100 mL) under inert gas atmosphere and the dropping
funnel was connected to a three-neck flask (250 mL), which was
equipped with a dropping funnel, thermometer and condenser (Method
B). In this flask, FAFS 8 (17.1 g, 74.3 mmol, 1.15 equiv.) and dry
acetonitrile (75 mL) were added, and the reaction solution was cooled to
ꢀ 15 ◦C. The solution of 2a was slowly added dropwise at this temper-
ature. During the addition of solution of 2a, a slight exothermic
37.7 mmol, 1.04 equiv.) and 1d (8.75 g, 36.6 mmol, 6.1 mL) in dry
MeCN (50 mL) for 2 h at 5 - 6 ◦C. The reaction of FAFS 8 (9.71 g, 42.2
mmol, 1.15 equiv.) with salt 2d was carried out in dry DMF (70 mL) at
ꢀ 35 ◦C for 2 h (Method B). The reaction mixture was processed analo-
gously as described above (4.7.) and the crude product (11.9 g) was
distilled in a high vacuum. The compound 7 was obtained as a yellow
liquid with b. p. 70 - 74 ◦C / 0.5 mmHg. The yield of 7 was 25% (2.9 g;
purity 95%).
◦
observed. The r. m. was then stirred at ꢀ 15 C for 3.5 h, then slowly
heated to r. t. and mixed at this temperature for 8 h. The r. m. was
evaporated in vacuo and poured into an ice-cold sulfuric acid (2%, 200
mL) and the lower layer was separated. The water phase was extracted
with MTBE (3 × 100 mL), the organic phases were combined, washed
with saturated NaHCO3 solution (3 × 250 mL) and then dried over
anhydrous Na2SO4. The solvent was evaporated under reduced pressure.
The crude product (18.7 g) was distilled via a short Vigreux column in
high vacuum. The olefin 9a was obtained as a yellowish liquid with b. p.
56 - 59 ◦C / 0.5 mmHg and 72% yield (14.4 g; purity 97%).
4.9.1. Diethyl 2,2-dibromomalonate (7) (95% purity)
1H NMR (401 MHz, CDCl3): δ 4.33 (q, 3JHH = 7 Hz, C(O)OCH2, 4H),
1.30 (t, 3JHH = 7 Hz, CH3, 6H) [11j].
13C NMR (101 MHz, CDCl3): δ 159.7 (s, C(O), 2C), 63.4 (bs, CH2, 2C),
50.7 (s, CBr2, 1C), 14.0 (bs, CH3, 2C) [11j].
4.10. Reaction of diethyl malonate 1c with perfluoroallyl fluorosulfate
(FAFS) 8
Analogously to the example 4.7., the salt 2c was generated in a three-
neck flask (100 mL) from a suspension of NaH in mineral oil (60%; 2.6 g,
65.0 mmol, 1.03 equiv.) and 1c (10.3 g, 64.3 mmol, 9.8 mL) in dry DMF
(50 mL) for 4 h at 5 - 19 ◦C. The reaction of FAFS 8 (37.0 g, 160.8 mmol,
2.5 equiv.) with salt 2c was carried out in dry Et2O (135 mL) at ꢀ 20 ◦C
for 2 h (Method B). The reaction mixture was processed in the manner
described above (4.7.) and the crude product (14.4 g) was distilled in a
high vacuum. The 7 was obtained as a yellow liquid with b. p. 52 - 58 ◦C
/ 0.5 mmHg. The yield of 9c was 50% (9.47 g; purity 92%).
4.7.1. Diethyl 2-fluoro-2-(perfluoroallyl)malonate (9a) (97% purity)
1H NMR (401 MHz, CDCl3): δ 4.36 (q, 3JHH = 7. Hz, OCH2, 4H), 1.32
(t, 3JHH = 7 Hz, CH3, 6H).
2
13C NMR (101 MHz, CDCl3): δ 160.6 (d, JCF = 25 Hz, C(O), 2C),
154.9 (tdt, 1JCF = 293 Hz, 2JCF = 40 Hz, 3JCF = 1 Hz, CF=CF2, 1C), 122.1
(dtt, 1JCF = 241 Hz, 2JCF = 44 Hz, 2JCF = 23 Hz, CF=CF2, 1C), 112.5 (ttt,
1JCF = 258 Hz, 2JCF = 278 Hz, 3JCF = 4.8 Hz, CF2, 1C), 90.9 (dt, 1JCF
=
212 Hz, 2JCF = 30 Hz, CF, 1C), 64.0 (bs, CH2, 2C), 13.7 (bs, CH3, 2C).
19F NMR (376 MHz, CDCl3): ꢀ 90.6 (ddt, 2JFF = 53 Hz, cisJFF = 38 Hz,
4JFF = 6 Hz, =CF2, 1F), ꢀ 105.0 (dquid, transJFF = 116 Hz, 2JFF = 53 Hz,
4JFF = 4 Hz, =CF2, 1F), ꢀ 110.9 (ddt, 3JFF = 16 Hz, 3JFF = 6 Hz, 4JFF = 4
4.10.1. Diethyl 2-(perfluoroallyl)malonate (9c) (92% purity)
1H NMR (401 MHz, CDCl3): δ 4.26 (qd, 3JHH = 7 Hz, 5JHH = 1 Hz,
4
3
OCH2, 4H), 4.17 (td, 3JHF = 13 Hz, 4JHF = 1 Hz, CH, 1H), 1.27 (t, 3JHH
7 Hz, CH3, 6H).
=
Hz, CF2, 2F), ꢀ 171.0 (dt, JFF = 12 Hz, JFF = 6 Hz, CF, 1F), ꢀ 186.3
trans
(ddqd,
1F).
J
FF
= 116 Hz, cisJFF = 38 Hz, 3JFF = 16 Hz, 4JFF = 7 Hz, =CF,
13C NMR (101 MHz, CDCl3): δ 162.7 (t, 3JCF = 4 Hz, C(O), 2C), 154.1
(tdt, 1JCF = 290 Hz, 2JCF = 41 Hz, 3JCF = 4 Hz, CF=CF2, 1C), 124.1 (dtt,
1JCF = 237 Hz, 2JCF = 43 Hz, 2JCF = 21 Hz, CF=CF2, 1C), 114.3 (tdt, 1JCF
= 249 Hz, 2JCF = 30 Hz, 3JCF = 5 Hz, CF2, 1C), 62.7 (bs, CH2, 2C), 56.1 (t,
2JCF = 26 Hz, CH, 1C), 13.8 (bs, CH3, 2C).
4.8. Reaction of diethyl 2-chloromalonate 1b with perfluoroallyl
fluorosulfate (FAFS) 8
Analogously to the example 4.7., the salt 2b was generated in a three-
neck flask (100 mL) from a NaH suspension in mineral oil (60%; 1.51 g,
37.8 mmol, 1.05 equiv.) and 1b (7.1 g, 36.5 mmol, 6.0 mL) in dry MeCN
(50 mL) for 2 h at 4 - 6 ◦C. The reaction of FAFS 8 (9.65 g, 42.0 mmol,
1.15 equiv.) with salt 2b was carried out in dry MeCN (75 mL) at ꢀ 30 ◦C
for 2 h (Method B). The reaction mixture was worked-up analogously as
described above (4.7.) and the crude product (8.9 g) was distilled in a
high vacuum. The olefin 9b was obtained as a yellowish liquid with b. p.
66 - 68 ◦C / 0.5 mmHg. The yield of 9b was 64% (7.6 g; purity 97%).
19F NMR (376 MHz, CDCl3): ꢀ 93.4 (ddt, 2JFF = 58 Hz, cisJFF = 36 Hz,
4JFF = 6 Hz, =CF2, 1F), ꢀ 102.6 (ddt, 3JFF = 19 Hz, 3JFH = 13 Hz, 4JFF = 4
Hz, CF2, 2F), ꢀ 106.7 (dquid, transJFF = 115 Hz, 2JFF = 58 Hz, 4JFF = 4 Hz,
=CF2, 1F), ꢀ 186.8 (ddt, transJFF = 114 Hz, cisJFF = 37 Hz, 3JFF = 15 Hz,
4JFF = 1 Hz, =CF, 1F).
4.11. Reaction of diethyl malonate 1a with 1,1,2,3,3-pentafluoro-3-
(1,1,2,2,3,3-hexafluoro-3-(trifluoromethoxy)propoxy)prop‑1-ene (MA-
31) 12
4.8.1. Diethyl 2‑chloro-2-(perfluoroallyl)malonate (9b) (97% purity)
1H NMR (401 MHz, CDCl3): δ 4.33 (q, 3JHH = 7 Hz, OCH2, 4H), 1.30
(t, 3JHH = 7 Hz, CH3, 6H).
Analogously to the example 4.7., the salt 2a was generated in a three-
necked flask (100 mL) from a suspension of NaH in mineral oil (1.5 g
60%; 37.4 mmol, 1.03 equiv.) and 1a (6.47 g, 36.3 mmol, 5.7 mL) in dry
DMF (50 mL) for 3.5 h at 5 - 6 ◦C. The reaction of MA-31 12 (16.0 g, 41.7
mmol, 1.15 equiv.) with salt 2a was carried out in dry MeCN (100 mL) at
ꢀ 30 ◦C for 1.5 h (Method B). The reaction mixture was worked-up
analogously as described above (4.7.) and the crude product (8.3 g)
was distilled under high vacuum. 9a was obtained as a yellow liquid
with b. p. 51 - 53 ◦C / 0.5 mmHg. The yield of 9a was 19% (2.1 g, purity
94%). 11 was isolated as a yellowish liquid with b. p. 55 - 61 ◦C / 0.5
mmHg. The yield of 11 was 9% (1.1 g; purity 76%).
13C NMR (101 MHz, CDCl3): δ 161.7 (s, C(O), 2C), 154.9 (tdt, 1JCF
=
292 Hz, 2JCF = 42 Hz, 3JCF = 3 Hz, CF=CF2, 1C), 123.0 (dtt, 1JCF = 241
Hz, 2JCF = 42 Hz, 2JCF = 23 Hz, CF=CF2, 1C), 112.5 (tdt, 1JCF = 257 Hz,
2JCF = 26 Hz, 3JCF = 5 Hz, CF2, 1C), 70.2 (t, 2JCF = 29 Hz, CCl, 1C), 64.3
(bs, CH2, 2C), 13.7 (bs, CH3, 2C).
19F NMR (376 MHz, CDCl3): ꢀ 91.3 (ddt, 2JFF = 52 Hz, cisJFF = 38 Hz,
4JFF = 5 Hz, =CF2, 1F), ꢀ 103.4 (dquid, transJFF = 114 Hz, 2JFF = 52 Hz,
4JFF = 3 Hz, =CF2, 1F), ꢀ 104.2 (ddd, 3JFF = 28 Hz, 3JFF = 15 Hz, 4JFF
=
6 Hz, CF2, 2F), ꢀ 182.6 (ddt, transJFF = 114 Hz, cisJFF = 38 Hz, 3JFF = 15
Hz, =CF, 1F).
4.11.1. Diethyl 2-fluoro-2-(perfluoroallyl)malonate (9a) (94% purity)
1H-, 13C- and 19F-NMR spectral data are analogous to Section 4.7.1.
4.9. Reaction of diethyl 2-bromomalonate 1d with perfluoroallyl
fluorosulfate (FAFS) 8
4.11.2. Diethyl (E)ꢀ 2-fluoro-2-(1,2,3,3-tetrafluoro-3-(1,1,2,2,3,3-
hexafluoro-3-(trifluoromethoxy)prop‑oxy)‑prop-1-ene-1-yl)malonate (11)
(76% purity)
Analogously to the example 4.7., the salt 2b was generated in a three-
neck flask (100 mL) from a NaH suspension in mineral oil (60%; 1.51 g,
1H NMR (401 MHz, CDCl3): δ 4.36 (qd, 3JHH = 7 Hz, 5JHF = 2 Hz,
12

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
OCH2, 4H), 1.32 (t, 3JHH = 7 Hz, CH3, 6H).
1F), ꢀ 129.4 (bs, CF2, 2F), ꢀ 156.8 (dd, 4JFF = 22 Hz, 3JFH = 29 Hz, CF,
1F), ꢀ 157.7 (dm, 4JFF = 22 Hz, CF, 1F).
13C NMR (101 MHz, CDCl3): δ 161.1 (dd, 2JCF = 26 Hz, 3JCF = 2 Hz, C
(O), 2C), 147.0 (ddd, 1JCF = 269 Hz, 2JCF = 41 Hz, 2JCF = 23 Hz, CF=CF,
1C), 141.6 (ddtd, 1JCF = 258 Hz, 2JCF = 42 Hz, 2JCF = 38 Hz, 3JCF = 5 Hz,
CF=CF, 1C), 119 (q, 1JCF = 269 Hz, CF3, 1C), 116.2 (tdd, 1JCF = 276 Hz,
2JCF = 34 Hz, 3JCF = 3 Hz, OCF2, 1C), 115.1 (tt, 1JCF = 278 Hz, 2JCF = 41
Hz, OCF2, 1C), 114.5 (tt, 1JCF = 288 Hz, 2JCF = 31 Hz, OCF2, 1C), 106.7
(tqui, 1JCF = 270 Hz, 2JCF = 36 Hz, CF2, 1C), 89.2 (ddd, 1JCF = 204 Hz,
2JCF = 27 Hz, 3JCF = 3 Hz, CF, 1C), 64.3 (bs, CH2, 2C), 13.6 (bs, CH3, 2C).
19F NMR (376 MHz, CDCl3): ꢀ 55.3 (t, 4JFF = 9 Hz, CF3, 3F), ꢀ 71.6
(dtd, 3JFF = 25 Hz, 3JFF = 12 Hz, 4JFF = 3 Hz, OCF2, 2F), ꢀ 83.8 (ttt, 3JFF
= 20 Hz, 4JFF = 6 Hz, 5JFF = 1 Hz, OCF2, 2F), ꢀ 85.7 (dtq, 3JFF = 17 Hz,
4.13.2. Diethyl (E)ꢀ 2-(1,2-difluoro-2-(perfluoropropoxy)vinyl)ꢀ 2-
fluoromalonate (16a) (29 mol% content)
1H NMR (401 MHz, CDCl3): δ 4.32 (q, 3JHF = 7 Hz, C(O)OCH2, 4H),
1.32 (t, 3JHH = 7 Hz, CH3, 6H).
19F NMR (376 MHz, CDCl3): ꢀ 81.4 (t, 3JFF = 7 Hz, CF3, 3F), ꢀ 85.2
(dsix, 2JFF = 146 Hz, 3JFF = 7 Hz, OCF2, 1F), ꢀ 86.9 (dm, 2JFF = 146 Hz,
4JFH = 7 Hz, OCF2, 1F), ꢀ 110.6 (ddt, transJFH =121 Hz, 4JFF = 15 Hz, 4JFF
= 6 Hz, =CF, 1F), ꢀ 129.6 (bs, CF2, 2F), ꢀ 158.6 (dd, 3JFF = 25 Hz, 4JFF
=
15 Hz, CF, 1F), ꢀ 164.8 (ddt, transJFH =121 Hz, 3JFF = 25 Hz, 5JFF = 6 Hz,
=CF, 1F).
4JFF = 9 Hz, 4JFF = 1 Hz, OCF2, 2F), ꢀ 129.4 (s, CF2, 2F), ꢀ 147.9 (ddt,
trans
trans
J
J
= 137 Hz, 3JFF = 25 Hz, 4JFF = 24 Hz, =CF, 1F), ꢀ 160.0 (dtd,
= 137.3 Hz, 3JFF = 10 Hz, 4JFF = 11 Hz, =CF, 1F), ꢀ 160.9 (ddt,
FF
FF
3JFF = 24 Hz, 4JFF = 12 Hz, 5JFF = 3 Hz, CF, 1F).
4.14. Reaction of diethyl malonate 1c with 1,1,1,2,2,3,3-heptafluoro-3-
((1,2,2-trifluorovinyl)-oxy)propane (PPVE-1) 16
4.11.3. 2,2,3,3-tetrafluoro-3-(trifluoromethoxy)propanoic acid (14) (38
mol% content)
4.14.1. Using diethyl ether
1H NMR (401 MHz, CD3CN): δ 14.02 (bs, OH, 1H).
19F NMR (376 MHz, CD3CN): ꢀ 55.1 (t, 4JFF = 9 Hz, OCF3, 3F), ꢀ 86.2
(tq, 3JFF = 9 Hz, 4JFF = 3 Hz, OCF2, 2F), ꢀ 119.1 (t, 3JFF = 9 Hz, CF2, 2F)
[11d].
Analogously to the example 4.7., the salt 2c was generated in a three-
neck flask (100 mL) from a suspension of NaH in mineral oil (60%; 2.65
g, 66.3 mmol, 1.03 equiv.) and 1c (10.3 g, 64.3 mmol, 9.8 mL) in dry
DMF (50 mL) for 3.5 h at 4 - 20 ◦C. The reaction of PPVE-1 16 (34.2 g,
128.6 mmol, 2.0 equiv.) with salt 2c was carried out in 120 mL of dry
Et2O at ꢀ 25 ◦C for 2.5 h (Method B). The reaction mixture was treated
analogously as described above (4.7.) and the crude product (13.7 g)
was distilled under high vacuum. The 16cbis was obtained as a yellowish
liquid with b. p. 132–135 ◦C / 0.5 mmHg in 20% yield (7.1 g; 91%
purity).
4.12. Reaction of diethyl 2-chloromalonate 1b with 1,1,2,3,3-
pentafluoro-3-(1,1,2,2,3,3-hexafluoro-3-(trifluoromethoxy)propoxy)
prop‑1-ene (MA-31) 12
Analogously to the example 4.7., the salt 2b was generated in a three-
neck flask (100 mL) from a suspension of NaH in mineral oil (60%; 1.51
g, 37.8 mmol, 1.03 equiv.) and 1b (7.1 g, 36.5 mmol, 6.0 mL) in dry
MeCN (50 mL) for 1 h at 4 - 5 ◦C. The reaction of MA-31 12 (16.03 g,
42.0 mmol, 1.15 equiv.) with salt 2a was carried out in dry MeCN (100
mL) at ꢀ 25 ◦C for 2.5 h (Method B). The reaction mixture was processed
in the manner described above (4.7.) and the crude product (5.7 g) was
distilled under high vacuum. The 9b was obtained as a yellow liquid
with b. p. 63 - 67 ◦C / 0.5 mmHg in 27% yield (3.0 g; 92% purity).
4.14.1.1. Tetraethyl
2-(fluoro(perfluoropropoxy)methyl)prop‑1-ene-
1,1,3,3-tetracarboxylate (16cbis) (91% purity). 1H NMR (401 MHz,
CDCl3): δ 7.03 (d, 2JHF = 56 Hz, OCFH, 1H), 4.83 (s, CH, 1H), 4.29 (q,
3JHF = 7 Hz, C(O)OCH2, 4H), 4.24 (q, 3JHF = 7 Hz, C(O)OCH2, 4H), 1.25
(t, 3JHH = 7 Hz, CH3, 6H), 1.24 (t, 3JHH = 7 Hz, CH3, 6H).
13C NMR (101 MHz, CDCl3): δ 165.3 (s, C(O), 1C), 165.2 (s, C(O),
1C), 163.1 (s, C(O), 1C), 162.9 (s, C(O), 1C), 137.5 (d, 2JCF = 24 Hz, C =
C, 1C), 134.1 (d, 3JCF = 7 Hz, C = C, 1C), 117.2 (qt, 1JCF = 288 Hz, 2JCF
= 33 Hz, CF3, 1C), 115.8 (tt, 1JCF = 280 Hz, 2JCF = 32 Hz, OCF2, 1C),
106.7 (tsix, 1JCF = 268 Hz, 2JCF = 39 Hz, CF2, 1C), 101.1 (dt, 1JCF = 233
Hz, 3JCF = 5 Hz, CFH, 1C), 62.5 (s, OCH2, 1C), 62.4 (s, OCH2, 2C), 62.3
(s, OCH2, 1C), 50.0 (s, CH, 1C), 13.79 (s, CH3, 1C), 13.75 (s, CH3, 1C),
13.72 (s, CH3, 2C).
4.12.1. Diethyl 2‑chloro-2-(perfluoroallyl)malonate (9b) (92% purity)
1H, 13C and 19F NMR spectral data are analogous to Section 4.8.1.
4.12.2. 2,2,3,3-tetrafluoro-3-(trifluoromethoxy)propanoic acid (14)
(46% content)
19F NMR (376 MHz, CDCl3): ꢀ 81.3 (t, 3JFF = 7 Hz, CF3, 3F), ꢀ 83.7
(dsix, 2JFF = 147 Hz, 3JFF = 7 Hz, OCF2, 1F), ꢀ 88.0 (dm, 2JFF = 147 Hz,
1H and 19F NMR spectral data are analogous to Section 4.11.3.
4JFH = 4 Hz, OCF2, 1F), ꢀ 125.2 (ddd, 2JFH = 56 Hz, 4JFF = 15 Hz, 4JFH
4 Hz, CHF, 1F), ꢀ 129.7 (bs, CF2, 2F).
=
4.13. Reaction of diethyl 2-fluoromalonate 1a with 1,1,1,2,2,3,3-hepta-
fluoro-3-((1,2,2-trifluorovinyl)-oxy)propane (PPVE-1) 16
4.14.2. Using acetonitrile
Analogously to the example 4.7., the salt 2a was generated in a three-
neck flask (100 mL) from a suspension of NaH in mineral oil (60%; 2.66
g, 66.5 mmol, 1.03 equiv.) and 1a (11.5 g, 64.5 mmol, 9.6 mL) in dry
DMF (50 mL) for 3 h at 5 - 6 ◦C. The reaction of PPVE-1 16 (54.9 g, 206.4
mmol, 3.2 equiv.) with salt 2a was carried out in dry MeCN (130 mL) at
Analogously to the example 4.7., the salt 2c was generated in a three-
neck flask (100 mL) from a suspension of NaH in mineral oil (60%; 2.66
g, 66.5 mmol, 1.03 equiv.) and 1c (10.3 g, 64.3 mmol, 9.8 mL) in dry
DMF (50 mL) for 3.5 h at 6 - 20 ◦C. The reaction of PPVE-1 16 (26.0 g,
97.7 mmol, 1.52 equiv.) with salt 2c was carried out in dry MeCN (125
mL) at ꢀ 15 ◦C for 1.5 h (Method B). The reaction mixture was treated
analogously as described above (4.7.) and the crude product (11.5 g)
was distilled under high vacuum. The 16c was obtained as a yellow
liquid with b. p. 59 - 60 ◦C / 0.5 mmHg with 4% yield (1.0 g; 91%
purity).
◦
ꢀ 20 C for 3.5 h (Method B). The reaction mixture was treated analo-
gously as described above (4.7.) and the crude product (13.8 g) was
distilled in a high vacuum. 16a was obtained as a yellowish liquid with
b. p. 59 - 62 ◦C / 0.5 mmHg in 5% yield (1.0 g, 29 mol% content in the
product). 16abis was obtained as a yellow liquid with b. p. 124 - 129 ◦C /
0.5 mmHg in 7% yield (2.7 g, 62 mol% content in the product).
4.13.1. Tetraethyl (E)ꢀ 1,2,4-trifluoro-3-(perfluoropropoxy)but‑2-ene-
1,1,4,4-tetracarboxylate (16abis) (ca. 62 mol% content)
4.14.2.1. Diethyl
(E)ꢀ 2-(1,2-difluoro-2-(perfluoropropoxy)vinyl)malo-
nate (16c) (91% purity). 1H NMR (401 MHz, CDCl3): δ 4.46 (dd, 3JHF
=
1H NMR (401 MHz, CDCl3): δ 4.35 (q, 3JHF = 7 Hz, C(O)OCH2, 4H),
1.30 (t, 3JHH = 7 Hz, CH3, 6H).
26 Hz, 4JHF = 3 Hz, CH, 1H), 4.26 (q, 3JHF = 7 Hz, C(O)OCH2, 4H), 1.27
(t, 3JHH = 7 Hz, CH3, 6H).
19F NMR (376 MHz, CDCl3): ꢀ 81.5 (t, 3JFF = 7 Hz, CF3, 3F), ꢀ 84.5
(six, 3JFF = 7 Hz, OCF2, 2F), ꢀ 96.3 (dd, 3JFF = 28 Hz, 4JFF = 4 Hz, =CF,
13C NMR (101 MHz, CDCl3): δ 163.7 (d, 3JCF = 2 Hz, C(O), 2C), 144.8
(dd, 1JCF = 277 Hz, 2JCF = 43 Hz, CF=CF, 1C), 133.8 (dd, 1JCF = 252 Hz,
13

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
2JCF = 55 Hz, CF=CF, 1C), 117.1 (qt, 1JCF = 287 Hz, 2JCF = 33 Hz, CF3,
1C), 115.5 (tt, 1JCF = 285 Hz, 2JCF = 31 Hz, OCF2, 1C), 106.6 (tsix, 1JCF
= 268 Hz, 2JCF = 39 Hz, CF2, 1C), 65.8 (s, OCH2, 2C), 50.6 (dd, 2JCF = 22
Hz, 3JCF = 2 Hz, CH, 1C), 13.7 (s, CH3, 2C).
(O)OCH2, 4H), 1.23 (t, 3JHH = 7 Hz, CH3, 6H), 1.21 (t, 3JHH = 7 Hz, CH3,
6H).
13C NMR (101 MHz, CDCl3): δ 165.3 (s, C(O), 1C), 165.2 (s, C(O),
1C), 163.0 (s, C(O), 1C), 162.9 (s, C(O), 1C), 137.5 (d, 2JCF = 24 Hz, C =
C, 1C), 134.1 (d, 3JCF = 7 Hz, C = C, 1C), 119.1 (q, 1JCF = 269 Hz, OCF3,
19F NMR (376 MHz, CDCl3): ꢀ 81.5 (t, 3JFF = 7 Hz, CF3, 3F), ꢀ 85.0
(six, 3JFF = 6 Hz, OCF2, 2F), ꢀ 120.0 (ddt, transJFF = 121 Hz, 4JFF = 6 Hz,
4JFH = 3 Hz, =CF, 1F), ꢀ 129.6 (bs, CF2, 2F), ꢀ 159.2 (ddt, transJFF = 121
Hz, 3JFH = 26 Hz, 5JFF = 7 Hz, =CF, 1F).
1C), 115.8 (tt, 1JCF = 282 Hz, 2JCF = 32 Hz, OCF2, 1C), 114.7 (tt, 1JCF
=
287 Hz, 2JCF = 31 Hz, OCF2, 1C), 106.9 (tquin, 1JCF = 269 Hz, 2JCF = 37
Hz, CF2, 1C), 101.0 (dt, 1JCF = 234 Hz, 3JCF = 5 Hz, CFH, 1C), 62.5 (s,
OCH2, 1C), 62.33 (s, OCH2, 2C), 62.29 (s, OCH2, 1C), 50.0 (s, CH, 1C),
13.8 (s, CH3, 1C), 13.71 (s, CH3, 1C), 13.65 (s, CH3, 2C).
4.15. Reaction of diethyl malonate 1c with 1,1,2-trifluoro-2-(trifluoro-
methoxy)ethene 15
19F NMR (376 MHz, CDCl3): ꢀ 55.2 (t, 4JFF = 9 Hz, OCF3, 3F), ꢀ 83.1
(ddt, 2JFF = 147 Hz, 4JFH = 15 Hz, 3JFF = 9 Hz, OCF2, 1F), ꢀ 85.7 (m, 3JFF
= 9 Hz, 4JFF = 4 Hz, OCF2, 2F), ꢀ 87.2 (dm, 2JFF = 147 Hz, 4JFH = 4 Hz,
OCF2, 1F), ꢀ 125.4 (ddd, 2JFH = 56 Hz, 4JFF = 15 Hz, 4JFH = 4 Hz, CHF,
1F), ꢀ 129.1 (bs, CF2, 2F).
Analogously to the example 4.2., the salt 2c was generated in a glass
ampoule (250 mL) with a PTFE stopper from a suspension of NaH in
mineral oil (60%; 2.67 g, 66.8 mmol, 1.04 equiv.) and 1c (10.3 g, 64.2
mmol, ca. 9.8 mL) in dry DMF (75 mL) for 4 h at 5 - 19 ◦C. The reaction of
PMVE 15 (20.2 g, 121.7 mmol, 1.9 equiv.) was carried out at ꢀ 20 ◦C for
2 h (Method A). The reaction mixture was treated analogously as
described above (4.2.) and the crude product (8.5 g) was distilled under
high vacuum. The olefin 15cbis was obtained as a yellowish liquid with
b. p. 133 - 135 ◦C / 0.5 mmHg, in 16% yield (4.5 g; 92% purity). 15c was
detected in the second fraction (b. p. 45 - 50 ◦C / 0.5 mmHg) in 2% yield
(1.0 g; 30% content).
4.16.2. Diethyl (E)ꢀ 2-(1,2-difluoro-2-(1,1,2,2,3,3-hexafluoro-3-
(trifluoromethoxy)propoxy)vinyl)malo-nate (17c) (60 mol% content)
1H NMR (401 MHz, CDCl3): δ 4.48 (dd, 3JHF = 26 Hz, 4JHF = 3 Hz,
CH, 1H), 4.27 (q, 3JHF = 7 Hz, C(O)OCH2, 4H), 1.3 (t, 3JHH = 7 Hz, CH3,
6H).
19F NMR (376 MHz, CDCl3): ꢀ 55.3 (t, 4JFF = 9 Hz, OCF3, 3F), ꢀ 84.2
(tm, 3JFF = 6 Hz, OCF2, 2F), ꢀ 85.8 (six, 3JFF = 9 Hz, OCF2, 2F), ꢀ 120.
(ddt, transJFF = 121 Hz, 4JFF = 6 Hz, 4JFH = 3 Hz, =CF, 1F), ꢀ 129.0 (bs,
CF2, 2F), ꢀ 159.3 (ddt, transJFF = 121 Hz, 3JFH = 26 Hz, 5JFF = 7 Hz, =CF,
1F).
4.15.1. Tetraethyl 2-(fluoro(trifluoromethoxy)methyl)prop‑1-ene-1,1,3,3-
tetracarboxylate (15cbis) (92% purity)
1H NMR (401 MHz, CDCl3): δ 6.85 (d, 2JHF = 57 Hz, OCFH, 1H), 4.99
(s, CH, 1H), 4.28 (q, 3JHF = 7 Hz, C(O)OCH2, 4H), 4.23 (q, 3JHF = 7 Hz, C
(O)OCH2, 4H), 1.28 (t, 3JHH = 7 Hz, CH3, 6H), 1.25 (t, 3JHH = 7 Hz, CH3,
6H).
4.17. Reaction of diethyl malonate 1c with 1,1,2,2,3,3-hexafluoro-1,3-
bis((1,2,2-trifluorovinyl)oxy)-propane (DVE-3) 18
13C NMR (101 MHz, CDCl3): δ 165.4 (s, C(O), 2C), 163.2 (s, C(O),
1C), 162.9 (s, C(O), 1C), 138.1 (d, 2JCF = 24 Hz, C = C, 1C), 133.8 (d,
3JCF = 7 Hz, C = C, 1C), 120.7 (q, 1JCF = 262 Hz, OCF3, 1C), 102.0 (dq,
1JCF = 233 Hz, 3JCF = 3 Hz, CFH, 1C), 62.44 (s, OCH2, 2C), 62.38 (s,
OCH2, 2C), 50.5 (s, CH, 1C), 13.82 (s, CH3, 2C), 13.77 (s, CH3, 2C).
Analogously to the example 4.7., the salt 2c was generated in a three-
neck flask (100 mL) from a suspension of NaH in mineral oil (60%; 2.65
g, 66.3 mmol, 1.03 equiv.) and 1c (10.3 g, 64.3 mmol, 9.8 mL) in dry
DMF (50 mL) for 2.5 h at 6 - 21 ◦C. The reaction of DVE-3 18 (22.1 g,
64.3 mmol, 1.0 equiv.) with salt 2c was carried out in dry MeCN (125
4
19F NMR (376 MHz, CDCl3): ꢀ 59.3 (d, JFF = 5 Hz, OCF3, 3F),
◦
mL) at ꢀ 25 C for 2 h (Method B). The reaction mixture was treated
ꢀ 126.5 (dq, 2JFH = 5 Hz, 4JFF = 5 Hz, CHF, 1F).
analogously as described above (4.7.) and the crude product (9.8 g) was
distilled under high vacuum. The 18cbis was obtained as a yellowish
liquid with b. p. 157 - 161 ◦C / 0.5 mmHg with 9% yield (3.4 g; 75%
purity). 18c was detected in the second fraction (b. p. 77 - 87 ◦C / 0.5
mmHg) in 2% yield (0.72 g; 40 mol% content.
4.15.2. Diethyl (E)ꢀ 2-(1,2-difluoro-2-(trifluoromethoxy)vinyl)malonate
(15c) (30% content)
1H NMR (401 MHz, CDCl3): δ 4.44 (dd, 3JHF = 26 Hz, 4JHF = 3 Hz,
CH, 1H), 4.25 (q, 3JHF = 7 Hz, C(O)OCH2, 4H), 1.26 (t, 3JHH = 7 Hz, CH3,
6H).
4.17.1. Tetraethyl 2-(fluoro(1,1,2,2,3,3-hexafluoro-3-((1,2,2-
trifluorovinyl)oxy)propoxy)methyl)prop‑1-ene-1,1,3,3-tetracarboxylate
(18cbis) (75% purity)
4
19F NMR (376 MHz, CDCl3): ꢀ 59.6 (d, JFF = 4 Hz, OCF3, 3F),
trans
4
4
ꢀ 121.6 (ddq,
J
FF
= 121 Hz, JFF = 7 Hz, JFH = 4 Hz, =CF, 1F),
ꢀ 159.6 (ddq, transJFF = 121 Hz, 3JFH = 26 Hz, 5JFF = 4 Hz, =CF, 1F).
1H NMR (401 MHz, CDCl3): δ 7.02 (d, 2JHF = 56 Hz, OCFH, 1H), 4.81
(s, CH, 1H), 4.29 (q, 3JHF = 7 Hz, C(O)OCH2, 4H), 4.24 (q, 3JHF = 7 Hz, C
(O)OCH2, 4H), 1.25 (t, 3JHH = 7 Hz, CH3, 6H), 1.23 (t, 3JHH = 7 Hz, CH3,
6H).
4.16. Reaction of diethyl malonate 1c with 1,1,2,2,3,3-hexafluoro-1-
(trifluoromethoxy)ꢀ 3-((1,2,2-trifluorovinyl)oxy)propane (MV-31) 17
13C NMR (101 MHz, CDCl3): δ 165.3 (s, C(O), 1C), 165.2 (s, C(O),
Analogously to the example 4.7., the salt 2c was generated in a three-
neck flask (100 mL) from a suspension of NaH in mineral oil (60%; 2.66
g, 66.5 mmol, 1.03 equiv.) and 1c (10.3 g, 64.3 mmol, 9.8 mL) in dry
1C), 163.1 (s, C(O), 1C), 163.0 (s, C(O), 1C), 147.1 (tdt, 1JCF = 279 Hz,
2
2
JCF = 53 Hz, 4JCF = 3 Hz, C CF , 1C), 137.5 (d, JCF = 24 Hz, C = C,
–
–
1C), 134.0 (d, 3JCF = 6 Hz, C = C,21C), 129.6 (dt, 1JCF = 269 Hz, 2JCF
=
DMF (50 mL) for 3 h at 7 - 19 C. The reaction of MV-31 17 (40.1 g,
48 Hz, C CF , 1C), 116.1 (ttt, JCF = 285 Hz, 2JCF = 32 Hz, 4JCF = 4 Hz,
1
◦
–
–
2
1
2
120.8 mmol, 1.9 equiv.) with salt 2c was carried out in dry MeCN (125
OCF2, 1C), 115.9 (tt, JCF = 281 Hz, JCF = 33 Hz, OCF2, 1C), 107.2
(tquin, 1JCF = 269 Hz, 2JCF = 37 Hz, CF2, 1C), 101.0 (dt, 1JCF = 233 Hz,
3JCF = 2 Hz, CFH, 1C), 62.5 (s, OCH2, 1C), 62.4 (s, OCH2, 2C), 62.3 (s,
OCH2, 1C), 50.0 (s, CH, 1C), 13.84 (s, CH3, 1C), 13.79 (s, CH3, 1C),
13.74 (s, CH3, 2C).
◦
mL) at ꢀ 25 C for 2 h (Method B). The reaction mixture was treated
analogously as described above (4.7.) and the crude product (13.2 g)
was distilled under high vacuum. 17cbis was obtained as a yellowish
◦
liquid with b. p. 136 - 139 C / 0.5 mmHg in 16% yield (6.2 g; 90%
purity). 17c was detected in the second fraction (b. p. 62 - 71 ◦C / 0.5
19F NMR (376 MHz, CDCl3): ꢀ 83.0 (ddt, 2JFF = 147 Hz, 4JFH = 15 Hz,
mmHg) in 3% yield (0.96 g; 60 mol% content).
3JFF = 7 Hz, OCF2, 1F), ꢀ 85.2 (m, 3JFF = 6 Hz, 4JFF = 2 Hz, OCF2, 2F),
ꢀ 87.3 (dm, 2JFF = 147 Hz, 4JFH = 4 Hz, OCF2, 1F), ꢀ 113.5 (dd, 2JFF
84 Hz, cisJFF = 65 Hz, =CFF, 1F), ꢀ 121.6 (ddt, 2JFF = 84 Hz, transJFF
=
=
4.16.1. Tetraethyl 2-(fluoro(1,1,2,2,3,3-hexafluoro-3-(trifluoromethoxy)
propoxy)methyl)prop‑1-ene-1,1,3,3-tetracarboxylate (17cbis) (90% purity)
1H NMR (401 MHz, CDCl3): δ 7.01 (d, 2JHF = 56 Hz, OCFH, 1H), 4.78
(s, CH, 1H), 4.26 (q, 3JHF = 7 Hz, C(O)OCH2, 4H), 4.22 (q, 3JHF = 7 Hz, C
113 Hz, 5JFF = 6 Hz, =CFF, 1F), ꢀ 125.1 (ddd, 2JFH = 56 Hz, 4JFF = 15
Hz, 4JFH = 4 Hz, CHF, 1F), ꢀ 128.8 (bs, CF2, 2F), ꢀ 134.8 (ddt, transJFF
113 Hz, cisJFF = 65 Hz, 5JFF = 6 Hz, =CF, 1F).
=
14

S.N. Tverdomed et al.
Journal of Fluorine Chemistry 250 (2021) 109864
Lett 6 (2021) 184–192;
4.17.2. Diethyl (E)ꢀ 2-(1,2-difluoro-2-(1,1,2,2,3,3-hexafluoro-3-((1,2,2-
trifluorovinyl)oxy)propoxy)-vinyl)-malonate (18c) (40 mol% content)
1H NMR (401 MHz, CDCl3): δ 4.48 (dd, 3JHF = 26 Hz, 4JHF = 3 Hz,
CH, 1H), 4.28 (q, 3JHF = 7 Hz, C(O)OCH2, 4H), 1.26 (t, 3JHH = 7 Hz, CH3,
6H).
d) B.H. Thomas, G. Shafer, J.J. Ma, M.-.H. Tu, D.D. DesMarteau, Synthesis of 3,6-
dioxa-Δ7-4-trifluoromethyl perfluorooctyl trifluoromethyl sulfonimide: bis
[(perfluoroalkyl)sulfonyl] superacid monomer and polymer, J. Fluorine Chem. 125
(2004) 1231–1240.
[6] a) T. Okazoe, D. Shirakawa, K. Murata, Application of liquid-phase direct
fluorination: novel synthetic methods for a polyfluorinated coating material and a
monomer of a perfluorinated polymer electrolyte membrane, Appl. Sci. 2 (2012)
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3
19F NMR (376 MHz, CDCl3): ꢀ 84.3 (quin, JFF = 7 Hz, OCF2, 2F),
ꢀ 85.8 (oct, 3JFF = 3 Hz, OCF2, 2F), ꢀ 113.50 (dd, 2JFF = 84 Hz, cisJFF
=
65 Hz, =CFF, 1F), ꢀ 119.9 (ddt, transJFF = 11 Hz, 4JFF = 6 Hz, 4JFH = 3 Hz,
2
trans
=CF, 1F), ꢀ 121.5 (ddt, JFF = 84 Hz,
J
= 113 Hz, =CFF, 1F),
FF
c)K. Murata, T. Okazoe, E. Murotani, Process for preparation of perfluorinated
sulfonyl fluorides, WO 2005003062 A2, (2005).
ꢀ 128.7 (bs, CF2, 2F), ꢀ 135.2 (ddt, transJFF = 113 Hz, cisJFF = 65 Hz, 4JFF
= 6 Hz, =CF, 1F), ꢀ 159.4 (ddt, transJFF = 119 Hz, 3JFH = 25 Hz, 5JFF = 2
Hz, =CF, 1F).
d)A. Watakabe, S. Hommura, S. Kotera, S. Saito, K. Murata, M. Sawaguchi, T.
Hoshino, J. Tayanagi, E. Endoh, Electrolyte material for solid polymer fuel cell, its
manufacture electrolyte membrane, and membrane-electrode assembly, WO
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Declaration of Competing Interest
We declare no conflict of interests.
Supplementary materials
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