Stable gem-trifluoromethyl anionic σ-complexes based on 1,3,5-tris(sulfonyl)benzene derivatives and their transformations

Article abstract of DOI:10.1016/j.jfluchem.2010.09.005

A convenient synthetic procedures is described to obtain gem-trifluoromethyl anionic σ-complexes of 1,3,5-tris(fluorosulfonyl) benzene, 1,3,5-tris(β,β,β-trifluoroethoxysulfonyl)benzene, 1,3,5-tris(trifluoromethylsulfonyl)benzene as well as of 1,3,5-trinot

Full text of DOI:10.1016/j.jfluchem.2010.09.005

Journal of Fluorine Chemistry 131 (2010) 1344–1352
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Stable gem-trifluoromethyl anionic
s-complexes based
on 1,3,5-tris(sulfonyl)benzene derivatives and their transformations
a
a,b
Oksana M. Holovko-Kamoshenkova a, Nataliia V. Kirij a, , Vladimir N. Boiko , Alexander B. Rozhenko
,
*
Yurii L. Yagupolskii a
a Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Murmanskaya Str. 5, UA-02094 Kiev, Ukraine
b
¨
¨
¨
Fakultat fur Chemie der Universitat, Postfach 10 01 31, 33501 Bielefeld, Germany
A R T I C L E I N F O
A B S T R A C T
Article history:
A convenient synthetic procedures is described to obtain gem-trifluoromethyl anionic
s-complexes of
Received 1 July 2010
1,3,5-tris(fluorosulfonyl)benzene, 1,3,5-tris(b,b,b-trifluoroethoxysulfonyl)benzene, 1,3,5-tris(trifluor-
omethylsulfonyl)benzene as well as of 1,3,5-trinotrobenzene. Conditions for easy oxidation of these
adducts into corresponding 2,4,6-tris(substituted)benzotrifluorides have been found. It is shown that
Received in revised form 13 September 2010
Accepted 17 September 2010
Available online 25 September 2010
the latter add trifluoromethyl anion to the 1 and 3 positions of the aromatic ring forming new anionic s-
complexes in different ratio. Structures and relative stabilities of the anionic adducts are discussed based
on RI-MP2 quantum chemical calculations.
Keywords:
Anionic
s-complexes
ß 2010 Elsevier B.V. All rights reserved.
Trifluoromethylation
Oxidation
Quantum chemical investigation
1. Introduction
mixture. Trifluoromethyl ion was generated in situ by the
termolysis of potassium trifluoroacetate [2h]. Noteworthy, the
As a matter of fact anionic
s
-complexes of the Meisenheimer
practical application of this method is rather limited, due to the
type are steel of grate interest as intermediates in the reactions of
aromatic nucleophilic substitution. Their grate importance is
caused by the possibility of further transformation into the final
high reaction temperature (>150 8C), which can cause partial
decomposition of the initial substrates and the formed anionic
complexes.
s-
novel products in many ways [1]. The chemistry of anionic
s
-
The modern method to generate [CF3ꢀ] is deal with using a very
popular and easily available Ruppert reagent, Me3SiCF3/Fꢀ [5].
complexes is widely investigated for the aromatic compounds with
strong electron withdrawing groups. In particular, the reactions of
1,3,5-trinitrobenzene [2] and 1,3,5-tris(trifluoromethylsulfonyl)-
benzene [2f,2i, 3] with different C-nucleophiles are well docu-
mented in literature. Most of these adducts were isolated and
successfully oxidized into the corresponding 1,2,4,6-tetrasubsti-
tuted benzenes [2,3].
Thus the formation of trifluoromethyl-containing anionic
s-
complexes was postulated in the reactions of some nitroarenes
with Me3SiCF3 in the presence of fluoride ion. The subsequent
oxidation of these adducts led to the formation of a mixture of
isomeric trifluoromethyl-containing benzene derivatives [2l]. Also
using the Me3SiCF3/TASF system in the reaction with 1,2,4,5-
tetrakis(trifluoromethyl)benzene enabled preparing under mild
We focus our attention on the
s-complexes with CF3 group at
the sp3-carbon atom. These adducts attract our interest because
trifluoromethyl-containing aromatic molecules are known to be
valuable starting material in preparing new drugs and other
biologically active compounds [4].
conditions a stable anionic s-complex containing two trifluor-
omethyl groups at the geminal center [6].
Our scientific group is interested in aromatic compounds
activated by very strong electron-withdrawing substituents, SO2F
and SO2CF3. Recently we have developed a suitable method for
preparation of 1,3,5-tris(fluorosulfonyl)benzene and its deriva-
tives [7,8]. It is pertinent to remark here that to best of our
knowledge in the literature there are no examples of organic
molecules containing both CF3 and above mentioned groups. That
is why it seems to us interesting and important to check the
possibility of their formation.
However, up to now there are only few examples in literature
for the synthesis and study of further transformations of the
s-
complexes with the extremely unstable perfluoroakyl anions. In
particular, CF3-containing anionic
s-complex of 1,3,5-trinitroben-
zene was detected by 1H NMR spectroscopy in the reaction
In the present paper we report our systematic investigation on
the reactions of the 1,3,5-tris(trifluoromethylsulfonyl)benzene 1,
* Corresponding author. Tel.: +38 044 4994615; fax: +38 044 5732643.
E-mail address: kirij@yandex.ru (N.V. Kirij).
0022-1139/$ – see front matter ß 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2010.09.005

[
O.M. Holovko-Kamoshenkova et al. / Journal of Fluorine Chemistry 131 (2010) 1344–1352
1345
H
CF3
H
CF3
F3CO2S
SO2CF3
+ Cat[Me3Si(CF3)2]
F3CO2S
CF3
F3CO2S
SO2CF3
DME
-Me3SiF
_
_
+
Cat+
Cat+
SO2CF3
SO2CF3
4
SO2CF3
5
1
Cat = [Me4N], [Cs([15]crown-5)2]
Scheme 1.
1,3,5-tris(fluorosulfonyl)benzene 2 and 1,3,5-tris(
b
,
b
,
b
-trifluor-
spectra CF3H and Me3SiF, the products of Me3SiCF3 transformations
were the main products in the reaction mixture. Using other fluoride
ion sources, such as potassium and cesium fluorides in combination
with crown ethers, as well as increasing of the reaction temperature
does not improve the result.
oethoxysulfonyl)benzene 3 with the Me3SiCF3/Fꢀsystem, aimed on
preparing of new trifluoromethyl-containing anionic s-complexes
and studying on their transformation to the corresponding novel
aromatic products.
Me3SiCF3 is known to react with fluoride ion to form
pentacoordinated silicon complex Cat[Me3Si(CF3)2], which is a
convenient source of trifluoromethyl anion excluding the presence
of Fꢀ [13]. Our experiments have shown that in contrast to the
above mentioned Me3SiCF3/Me4NF system, the generated in situ
silicate [Me4N][Me3Si(CF3)2] reacts with sulfone 1 in DME at
ꢀ60 ꢁ 5 8C smoothly forming a mixture of anionic s-complexes 4 and
5 in ratio 4:1 (Scheme 1).
Probably, along with the reaction at the free position of the
aromatic ring, the ipso-attack of the [CF3ꢀ] intermediate takes
place followed by elimination of SO2CF3 group and forming 5. A
similar nucleophilic substitution of SO2CF3 group was previously
reported in the reactions of the sulfone 1 with S-nucleophiles [3b].
A conversion of the initial substrate does not exceed 60%, probably
due to the low solubility of 1 under the reaction conditions.
Increasing the reaction temperature is however not possible,
because the silicate [Me4N][Me3Si(CF3)2] is unstable at tempera-
tures above ꢀ55 8C. In order to increase a conversion degree of 1
the silicate [Cs([15]crown-5)2][Me3Si(CF3)2] [14] was synthesized
that is stable in the solution up to ꢀ5 8C. In the reaction of 1 with
this silicate in DME in temperature range from ꢀ50 8C to ꢀ15 8C,
2. Results and discussion
At the beginning it should be noted that among above
mentioned 1,3,5-tris(sulfonyl)benzene derivatives 1–3, the reac-
tions of complex formation were widely investigated only for
1,3,5-tris(trifluoromethylsulfonyl)benzene 1. In particular, the
interaction between substrate 1 and a number of non-fluorinated
organosilicon compounds (Me3SiCH2COOMe, Me3SiC(O)Me,
PhCH2SiMe3SiCH2Ph, etc.) in the presence of fluoride ion in THF
at 25 8C was substantially explored [2f]. Surprisingly it was found
that sulfon 1 does not demonstrate the C–C bond formation under
these reaction conditions. An adduct with fluoride ion was
postulated as the only product.
Our idea was to test the possibility of CF3-containing complex
formation by the reaction between compound 1 and Me3SiCF3/Fꢀ
system.
We have found that sulfone 1 interacts with Me3SiCF3 at
ꢀ60 ꢁ 5 8C in the presence of tetramethylammonium fluoride
forming anionic s-complex 4. Unfortunately the yield of adduct 4
was very low under these reaction conditions. According to 19F NMR
Table 1
1H and 19F NMR data of the anionic
s
-complexes 4–6, 8, 10, 14–19 (DMSO-d6), (
d
/ppm, J/Hz). The numbering of the C-atoms see in Scheme 6.
Compound
1H*
19F
1-H
3,5-H
CF3
R
3
3
4
5
4.68 (q, JH,F = 7.5)
7.87 (s)
7.80 (s)
ꢀ78.31a (d, JF,H = 7.5)
ꢀ81.43b (s); ꢀ81.8c, (s)
ꢀ81.87 (s); ꢀ81.84 (s)
3
4.45 (q, JH,F = 6.9)
ꢀ77.28a (m);
5
ꢀ63.12d (q, JF,F =5.6)
7.22 (s)
8.27 (s)
3
5
4
6
5.36 (q, JH,F = 7.7)
ꢀ77.57a, tm, (5JF,F = 9.5)
67.5b (qd, JF,F = 9.5; JF,H = 1.7);
68.7c (s)
2
3
3
3
8f
4.92 (q, JH,F = 7.7)
7.80 (s)
8.49 (s)
8.34 (s)
8.14 (s)
ꢀ76.60a (d, JF,H = 7.7)
ꢀ75.69b (t, JF,H = 9); ꢀ75.89c (t, JF,H = 9)
3
10
14
15
5.8 (q, 3JH,F = 6.3)
ꢀ71.39a (d, JF,H = 6.3)
ꢀ66.70a (m)
66.57b (q, JF,F =12); 68.6c (s)
5
3
5
5
5
5.34 (q, JH,F = 9)
ꢀ77.71a (t, JF,F = 12);
63.49 (q, JF,F = 12); 66.98 (q, JF,F = 12)
ꢀ54.4e (t, JF,F = 12)
69.14 (q, JF,F = 12)
5
5
16f
17f
7.95 (s)
7.65 (s)
ꢀ66.80a (m)
ꢀ75.21 (m); ꢀ75.52 (m)
ꢀ73.63 (m); ꢀ74.03 (m)
3
3
5.03 (q, JH,F = 8.8)
ꢀ75.95a (d, JF,H = 8.8);
ꢀ53.5e (s)
18
19
8.72 (s)
8.47 (s)
ꢀ65.04 (m)
3
3
5.84 (q, JH,F = 8.8)
ꢀ74.66a (d, JF,H = 8.8);
ꢀ53.5e (s)
a
CF3 in position 1.
b
2,6-R.
c
4-R.
d
CF3 in position 2.
e
CF3 in position 3.
d
f
3
3
3
H CH2 for compound 8: 4.6 (q, JH,F =9 Hz, 2H, o-SO3CH2CF3), 4.53 (q, JH,F = 9 Hz, 2H, o-SO3CH2CF3), 4.42 (q, JH,F = 9 Hz, 2H, p-SO3CH2CF3); for compound 16: 4.62 (q,
J = 8.2 Hz, 4H, o-SO3CH2CF3), 4.53 (q, J = 8.2 Hz, 2H, p-SO3CH2CF3); for compound 17: 4.60 (q, J = 8.2 Hz, 4H, o-SO3CH2CF3), 4.51 (q, J = 8.2 Hz, 2H, p-SO3CH2CF3.
*
d
H (CH3)4N for compounds 4–6, 8, 10, 14–19: 3.31 (12H, CH3).

1346
O.M. Holovko-Kamoshenkova et al. / Journal of Fluorine Chemistry 131 (2010) 1344–1352
Table 2
13C NMR data of the anionic
s-complexes 6, 8, 10, 14–16 (THF-d8), (d/ppm, J/Hz). The numbering of the C-atoms see in Scheme 6.
Compound
1-C
2,6-C
3,5-C
4-C
CF3
2
2
2
1
6
41.03 (q, JC,F = 33)
95.62 (d, JC,F = 27)
94.39 (s)
142.29 (s)
140.93 (s)
130.18 (s)
145.48 (s)
98.33 (q, JC,F = 27)
98.66 (s)
126.48a (q, JC,F = 288)
2
1
8c
10
14
15
41.79 (q, JC,F = 32)
127.12a(q, JC,F = 290)
2
1
42.74 (q, JC,F = 31)
125.18 (s)
122.94 (s)
126,6a (q, JC,F = 288)
2
2
1
89.82 (d, JC,F = 31)
101.49 (d, JC,F =31)
123.57a (q, JC,F = 290)
2
2
2
2
1
42.43 (q, JC,F = 33)
95.57 (d, JC,F = 28)
139.65 (q, JC,F = 35, 3-C)
142.09 (s, 5-C)
99.51 (d, JC,F =28)
123.7a (q, JC,F = 288)
b
1
125.89 (q, JC,F = 285)
2
1
16c
59.51 (q, JC,F = 31)
97.77 (s)
143.47 (s)
94.68 (s)
122.54a (sep, JC,F = 290)
a
CF3 in position 1.
b
CF3 in position 3.
c
1
2
1
2
d
C (OCH2CF3) for compound 8 124.28 (q, JC,F = 277, o-OCH2CF3), 64.99 (q, JC,F = 37, o-OCH2CF3); 124.38 (q, JC,F = 277, p-OCH2CF3), 64.61 (q, JC,F = 37, p-OCH2CF3); for
1
2
1
2
compound 16 122.41 (q, JC,F = 278, o-OCH2CF3); 63.57 (q, JC,F = 37, o-OCH2CF3); 122.55 (q, JC,F =278, p-OCH2CF3) 63.15 (q, JC,F = 37, p-OCH2CF3).
[()TD$FIG]
_
H
CF3
FO2S
SO2F
FO2S
SO3
Me3SiCF3 + CatF
FO2S
SO2F
DME
_
-50 oC, 1h
+
Cat+
Cat+
SO2F
-Me3SiF
SO2F
6
SO2F
2
7
Cat[Me3Si(CF3)2]
6
Cat = [Me4N], [Cs([15]crown-5)2]
65-70%
Scheme 2.
the conversion of the starting compound increases from 60 to 95%
and the total yield of the anionic complexes 4 and 5 with the same
ratio (4:1) has been brought to 65%.
Unfortunately, the complexes 4 and 5 have been not separated
therefore they are characterized in mixture by 1=, 19F NMR spectra
(Tables 1 and 2).
base and on the other hand Fꢀ is known to interact with glass
producing some moisture. To confirm our assumption the reaction
of 2 with CatF was carried out to produce sulfonate 7. Also it should
be noted that the same product was obtained as a result of
interaction between substrate 2 and KHCO3 in DMSO. Its structure
was proved by 1=, 19F
4
13E NMR spectral data.
We next examined the reactivity of 1,3,5-tris(fluorosulfonyl)-
In order to decrease the yield of the co-product, the reactions of
the sulfonyl fluoride 2 with several trifluoromethylsilicates have
been investigated. Thus, 2 reacts with the generated in situ silicates
Cat[Me3Si(CF3)2] in DME at ꢀ50 ꢁ 5 8C forming the stable anionic s-
complex 6 in 65–70% yield (Scheme 2). The conversion of the
substrate 2 in the reaction with the silicates is 100% and the by-
benzene 2 in the context of the CF3-containing
formation. Fluorosulfonyl group is very similar by its electronic
properties ( p = 1.01 [9]) to the trifluoromethylsulfonyl substitu-
ent ( p = 1.04 [9]), thus it can be supposed that compound 2 is
activated enough to form anionic -complex and recently we have
s-complex
s
s
s
provided experimental evidence for this fact [10]. It is pertinent to
remark here that sulfonylfluoride 2 presents interesting possibili-
ties in the sense that it has two potential electrophilic centers for
reaction with nucleophile – SO2F group and a free position of the
aromatic ring.
Continue our investigations we have found that 2 reacts with
Me3SiCF3 in the presence of fluoride ion in DME at ꢀ50 ꢁ 5 8C
forming anionic s-complex 6 (ꢂ45 mol.%) and 3,5-bis(fluorosulfo-
nyl)benzenesulfonate 7 as a by-product (Scheme 2). The overall
conversion of the substrate under these conditions does not exceed
80%.
product 7 is not formed. However, the formation of another
unidentified species (about 10–15 mol. %) alongside with the main
product 6 has been detected by 19F NMR spectrum. Unfortunately we
failed to isolate pure anionic s-complex 6 and it was characterized
only in the mixture by means of 1=, 19F and 13E NMR spectra (Tables 1
and 2).
The next object of our investigation, 1,3,5-tris(b,b,b-trifluor-
oethoxysulfonyl)benzene 3 was obtained in our laboratory during
the course of investigation of the sulfonyl center reactivity in
compound 2 [12]. It should be noted that SO2OCH2CF3 group is a
rather electron withdrawing substituent (sp-SO2OCH2CF3 = 0.88
We consider that product 7 is a result of hydrolyses of SO2F
group caused by the presence of fluoride ion in the reaction
mixture. Because on the one hand [Me4N]F, for example, is a strong
[11]). Furthermore, in contrast to the compounds containing non-
fluorinated alkoxysulfonyl groups, which are strong alkylating
agents, the derivatives including SO2OCH2CF3 groups are stable
[()TD$FIG]
H
CF3
Me3SiCF3 + Me4NF
DME
-60 oC, 1 h
R
R
R
R
_
[Me4N] [Me3Si(CF3)2]
Me4N+
-Me3SiF
R
R
90-95%
3, 9
8, 10
R = SO2OCH2CF3 (3, 8); NO2 (9, 10)
Scheme 3.

[
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1347
CF
3
The prepared 2,4,6-trisubstituted benzotrifluorides 11–13 are
more electrophilic than the starting 1,3,5-trisubstituted benzenes
2, 3 and 9, due to the presence of an additional electron
withdrawing CF3 group, and can be also expected to form stable
H
CF
3
R
R
R
R
t-BuOCl
_
+
o
Me N
DME / 0-25 C
4
anionic
s-complexes. In the reactions with Me3SiCF3 in the
75-90%
R
R
presence of Me4NF as well as with silicate [Me4N][Me3Si(CF3)2]
they undergo the nucleophilic addition of the [EF3ꢀ] both at
position 1 and 3 of the aromatic ring producing the corresponding
6, 8, 10
11-13
R=SO F (6, 11); SO OCH CF (8, 12); NO (10, 13)
isomeric anionic
s-complexes 14–19 (Scheme 5).
2
2
2
3
2
The reaction of 11 with silicate [Me4N][Me3Si(CF3)2] yields a
mixture of 14 and 15 in ratio 1:2 with the total yield 85%.
Compound 12 interacts with the Me3SiCF3/Fꢀ system and under-
goes EF3-addition mainly at the first position of the aromatic ring
forming the anionic complex 16 as a major product. In contrast,
Scheme 4.
and exhibit significantly lower alkylating properties [11]. From the
above it can be seen that compound 3 presents interesting
trinitrobenzotrifluoride 13 forms predominantly the anionic s-
possibilities as a substrate for anionic
s
-complex formation.
complex 19 with addition of the trifluoromethyl anion mainly at
the third position of the aromatic ring.
We have found that in contrast to the sulfone 1 and sulfonyl
fluoride 2, sulfonyl ester 3 reacts selectively both with Me3SiCF3 in
the presence of fluoride ion and with the silicates Cat[Me3Si(CF3)2]
in DME at ꢀ50 ꢁ 5 8C producing the stable trifluoromethyl-contain-
ing anionic s-complex 8 in quantitative yield (Scheme 3).
The adduct 16 is stable and has been isolated in pure form as a
yellow solid with mp 109–110 8C. Complexes 14 and 15 are also
stable but unfortunately we were not able to separate them. At the
same time the trinitro-derivatives 18 and 19 are unstable and can
be detected only in the reaction mixture by means of the 19F and 1H
NMR spectra (Table 1).
Taking into account that trifluoromethyl-containing s-complex
of 1,3,5-trinitrobenzene 9 was not isolated as individual compound
we examined the complexation reaction of TNB with Me3SiCF3/Fꢀ
in DME at ꢀ60 8C.
3. Quantum chemical investigation of anionic
s-complexes
It has been found that under these reaction conditions stable
anionic s-complex 10 is formed with quantitative yield (Scheme 3).
The structures of all the anionic -complexes, as well as the
s
Anion 8 has been isolated as yellow solid with mp 71–72 8C,
whereas 10 is a dark-red solid with mp 170 8C. The structures of 8
and 10 agree with the data of elemental analysis and 1=, 19F, 13E
NMR spectra (Tables 1 and 2).
corresponding starting aromatic compounds have been fully
optimized at the DFT and RI-MP2 levels of theory. There are special
peculiarities inherent to all investigated anion structures are
deviations from planarity of the ring and H-bounding of all
hydrogens to oxygen atoms. Additionally, in all anion structures
Anionic s-complexes 6, 8 and 10 have been further oxidized to
˚
2,4,6-trisubstituted benzotrifluorides 11–13. The oxidation has
been carried out using t-BuOCl in DME in temperature range 0–
25 8C and usually was completed within a few minutes (Scheme 4).
the C2–C3 (C5–C6) bonds are shorter (1.36–1.39 A) than the C3–C4
˚
and C4–C5 ones (1.41–1.42 A) and these in turn are shorter than the
bonds at the formally sp3-hybridized C1 atom, C1–C2 and C1–C6
˚
Although the anionic
s-complex 6 has not been isolated in the
(1.49–1.50 A), hence most correct representation of the anion
pure form, we had a success to obtain 2,4,6-tris(fluorosulfonyl)-
benzotrifluoride 11 in 75% yield by the oxidation of the mixture of
6 with the co-product and subsequent purification.
The oxidation of the compounds 8 and 10 proceeds with high
yields with the formation of 2,4,6-tris(b,b,b-trifluoroethoxysul-
fonyl)benzotrifluoride 12 and 2,4,6-trinitrobenzotrifluoride 13,
respectively. It should be noted that the yield of product 13 in the
proposed reaction (85%) is higher compared to those reported
previously (33% [2l] and 40% [2h]) and hence this method can be
used for a suitable preparative synthesis of 13.
Unfortunately, numerous attempts to carry out the oxidation of
complexes 4 and 5 have been resulted in inseparable and
unidentifiable product mixtures.
structures best agrees with the mesomeric form shown in Scheme 6.
RI-MP2 energy optimization predicts for anion 10 Cs symmet-
rical structure shown in Fig. 1. The six-membered ring in 10
indicates a slight boat-type distortion from the planar conforma-
tion. Four carbon atoms (C2, C3, C5 and C6) form a plane whereas
C1 and C4 are out of plane, the former deviates more
(nC1C2C3C5 = 17.78) than the latter (nC4C3C2C6 = ꢀ8.18). An
equatorial position of the C1–H hydrogen is favored by forming
hydrogen bonds with oxygens of the ortho-NO2 substituents. The
CF3 group is axial, diminishing an unfavorable closeness of the
latter to the NO2 moieties. Similar to 10, a structure of the
unsymmetrical CF3-disubstituted
s-complex 19 is boat-like
distorted, too (nC1C2C3C5 = ꢀ17.18, nC1C6C5C3 = 21.98,
[()TD$FIG]
CF3
CF3
F3C
CF3
Me3SiCF3/ Me4NF
DME
-55 oC, 1 h
R
R
R
R
R
R
_
_
+
H
[Me3Si(CF3)2] [Me4N]
Me4N+
Me4N+
CF3
R
R
R
11-13
14, 16, 18
1
15, 17, 19
R = SO2F (11, 14, 15)
:
:
:
2
1
9
R = SO2OCH2CF3 (12, 16, 17)
R = NO2 (13, 18, 19)
Scheme 5.
9
1

[
O.M. Holovko-Kamoshenkova et al. / Journal of Fluorine Chemistry 131 (2010) 1344–1352
F3C
Increasing the substituent to OCH2CF3 does not significantly
Y
change the most favorable gas-phase conformation for 8 (Fig. 4).
The optimized structure still keeps Cs symmetry. As already
mentioned by discussing the experimental results, the anions
based on the tris-CF3CH2OSO2-substituted benzene are especially
1
R
R
Z
6
R= NO2, SO2F, SO2CF3, SO2OCH2CF3
Y=Z=H; Y=H, Z=CF3; Y=CF3, Z=H
2
stable. As it is seen from Fig. 4, in the anionic
s-complex 8 the CF3
5
3
group attached to the ring is shielded with the CF3CH2O
substituents. The latter are acid enough to build H-bonds towards
fluorine atoms, resulting in additional stabilization of 8.
4
R
An introduction of an additional CF3 group into the fluorinated
trifluromethyl derivatives 4, 6 and 8 provides more diversity for
the structures of the corresponding anions. Three main factors
affect the structures of anions investigated. These are (a) forming a
maximal number of the H-bonds; (b) mutual repulsion between
the electron acceptor groups and (c) keeping the in-plane
Scheme 6. Binding and atom numeration in calculated anionic
s-complexes.
(nC4C3C2C6 = 10.4, C4C5C6C2 = ꢀ6.08). The CF3 group in the ring
requires more place than the hydrogen atom. Therefore, in the
structure calculated for 19 two nitro groups in positions 2 and 4
(Fig. 1) are noticeably rotated out of the ring plane (approx. by 44–
48 and 26–28 degrees, respectively). Such a conformation is quite
different to that found for the gem-bis-CF3-substituted derivative
18 (Fig. 1) for which an almost planar ring has been found with all
conformation for the electron acceptor groups, providing
a
maximal delocalization of the negative charge. The combination
of these, sometimes oppositely influencing factors provides
interesting structural effects.
The gem-disubstituted anion 14 (Fig. 2) keeps Cs symmetry as
well as the overall structure of the starting compound 6. It
possesses the boat-like distorted geometry (nC1C2C3C5 = 20.08,
NO2 groups almost co-planar with the ring
p-system. It belongs to
the C2 symmetry point group, with the rotational axis going trough
C1 and C4 atoms. Two equivalent C-CF3 bonds are slightly
nC4C3C2C6 = ꢀ7.48). The isomeric
s-complex 15 is even more
˚
elongated (1.598 A).
boat-like distorted (nC1C2C3C5 = 26.88, nC1C6C5C3 = ꢀ26.18,
nC4C3C2C6 = ꢀ5.28, nC4C5C6C2 = 10.88). While the CF3 group
attached to carbon C3 is not so strongly pressed out from the ring
level as it was found for 19 (nC(CF3)C3C4C5 = 167.08), another type
of distortion, deviations of SC4C3 and SC4C5 bond angle values
from 120 degrees (126.8 and 113.3 degrees, respectively) has been
predicted by calculations.
In contrast to the NO2 substituent, the SO2F group is not planar,
and hence, sterically more demanding. In 6 (Cs symmetrical
structure, Fig. 2) the mutual repulsion between the CF3 group and
fluorine atoms of the ortho-SO2F substituents increases the boat-
type distortion at the rostrum of the boat (nC1C2C3C5 = 20.68,
nC4C3C2C6 = ꢀ8.68). Noteworthy, another (unsymmetrical) con-
formational form of 6 with one SO2F group rotated by 180 degrees
(6a, not shown here, see Supplementary Materials for detailed
data) possesses almost the same total energy.
Structures 20 and 21, while not synthesized, have been
investigated theoretically, too. Two most favorable conformations
have been found for the bis-substituted gem-derivative, 20 (Fig. 3)
and 20a (see Supplementary Material), which lie very close in
energy (DE(RI-MP2) = 0.1 kcal/mol). The structures differ only in
conformations of the SO2CF3 group in positions 4. Both structures
indicate the almost ideally planar rings and slightly different C1–
The SO2CF3 groups in 4 are sterically more demanding than the
SO2F groups in 6. In the most favored equilibrium structure of 4
(Fig. 3) the SO2CF3 substituents are trans-oriented relative to the
trifluoromethyl moiety attached to the ring. The Cs symmetrical
equilibrium structure of 4 is also boat-like (nC1C2C3C5 = 20.18,
nC4C3C2C6 = ꢀ8.48) and therefore similar to that of 6.
˚
CF3 bond lengths (approx. 1.55 and 1.58 A for the CF3 group cis- and
trans-oriented relative to the o-(SO2)CF3 moieties. The isomeric
[()TD$FIG]
Fig. 1. VMD view for equilibrium (RI-MP2/TZVP) structures of 10, 18 and 19.
[()TD$FIG]
Fig. 2. VMD view for equilibrium (RI-MP2/TZVP) structures of 6, 14 and 15.

[
O.M. Holovko-Kamoshenkova et al. / Journal of Fluorine Chemistry 131 (2010) 1344–1352
1349
Fig. 3. VMD view for equilibrium (RI-MP2/TZVP) structures of 4, 20 and 21.
[()TD$FIG]
Fig. 4. VMD view for equilibrium (RI-MP2/TZVP) structures 8, 16 and 17.
anion 21 is again boat-like distorted (nC1C2C3C5 = 24.28,
nC1C6C5C3 = ꢀ24.58, nC4C3C2C6 = ꢀ9.78, nC4C5C6C2 = 9.98,
nSC4C3 = 129.68, nSC4C5 = 114.58), probably due to the larger
volume of the SO2CF3 group compared to the SO2F moiety.
The corresponding gem-bis-CF3-substituted derivative 16 can
probably exist in several different conformations possessing
similar (within 1 kcal/mol) total energies. Taking into account
the restricted accuracy inherent to the used DFT calculation level
or even to the MP2 approach we cannot make a final choice
between the various isomers arising due to rotation of substi-
tuents. As the examples, two different structures of 16 have been
localizedasmainminimainenergy.OneofthemisshowninFig.4and
possesses the Cs symmetrical boat conformation (nC1C2C3
C5 = 20.98, nC4C3C2C6 = ꢀ7.88). Another one, 16a (see Supplemen-
tary Material) differs from 16 only by trans-orientation of the ortho-
O-CH2CF3 groups. Most likely, the conformation of 16 results from a
combination of several effects such as a favorable H-bonding, and a
sterical repulsion between electronegative atoms.
3.1. Relative stabilities of the anionic s-complexes
We have compared stabilities of all calculated adducts
involving SO2X substituents with those inherent to the
corresponding trinitro-derivatives (Table 3), estimated from
the isodesmic reaction (1). As expected, the former are in all
cases more stable than the latter (negative vales of
D
E1, Table 3),
due to the more pronounced electron withdrawing properties of
the SO2X substituents compared to those of NO2. The most
stable mono-CF3 adduct is 4 (
introducing a second trifluoromethyl group is more favorable in
D
E1 = ꢀ11.0 kcal/mol), however
the case of the SO2F-substituted species 14 and 15 than for 20
and 21 involving SO2CF3 groups (
D
E1 ꢀ9.4 vs. ꢀ4.8 kcal/mol for
the corresponding gem-disubstituted adducts 14 and 20 and
ꢀ15.3 vs. ꢀ13.6 kcal/mol for the unsymmetrical adducts 15 and
21). Probably, the SO2CF3 indicates a stronger sterical repulsion
from the CF3 groups attached to the ring than that inherent to
the SO2F–CF3 pair.
Y
H
CF
3
Y
CF
3
O N
NO
2
O N
2
NO
2
R
R
R
R
Z
2
_
_
ð1Þ
+ΔE1
+
+
NO
NO
2
R
R
2
Similarly, for the isomeric unsymmetrical
s
-complex 17 some
For all considered cases the unsymmetrically substituted
anions are thermodynamically more stable than the isomeric
gem-bis-CF3 anionic species (see Table 3,
qualitatively in line with the experimental data. The reaction of
2,4,6-trinitrobenzotrifluoride 13 with Me3SiCF3/Me4NF results in
thermodynamically more stable 19 as a main product and the
isomeric gem-disubstituted anion 18 arises only as traces.
Similarly, 2,4,6-tris(fluorosulfonyl)benzotrifluoride 11 yields in
the same reaction 15 in the large excess. Only for sulfonyl ester 12
the formation of the gem-disubstituted product 16 (90 mol.%) was
different conformations can be also localized as the favorable gas-
phase structures, depending on the position of the ortho-CF3CH2O
groups. One of them is shown in Fig. 4, the slightly less favored ones
are showninSupplementary Material. Again, the conformation of17
indicates significant difference of the sp2 bond angles
(SC4C3 = 127.5 and SC4C5 = 112.8 degrees). Noteworthy is the
D
E2 magnitudes). This is
˚
significant different lengths of the C2–C3 (1.396 A) and C5–C6 bonds
˚
(1.364 A) that can also be resulted from the mutual repulsion
between the electron withdrawing CF3CH2O and CF3 moieties.

1350
O.M. Holovko-Kamoshenkova et al. / Journal of Fluorine Chemistry 131 (2010) 1344–1352
Table 3
5.1. Interaction of 1,3,5-tris(trifluoromethylsulfonyl)benzene 1 with
[Cs([15]crown-5)2][Me3Si(CF3)2]
Relative energy values calculated at the RI-MP2/TZVP//RI-BP86/TZVP level of
theory.
To a well-stirred mixture of CsF (0.24 g, 1.58 mmol) and 15-
E1, kcal/mol
D
E2, kcal/mol
crown-5 (0.7 g, 3.16 mmol) in DME (15 mL) at ꢀ60 8C Me3SiCF3
(0.50 g, 3.48 mmol) was added slowly dropwise. The mixture was
stirred for 2 h at ꢀ30 ꢃ ꢀ40 8C and then 1,3,5-tris(trifluoromethyl-
sulfonyl)benzene 1 (0.60 g, 1.26 mmol) was added. The mixture
formed was stirred for 2 h at ꢀ50 ꢃ ꢀ40 8C and then for 2 h at
ꢀ30 ꢃ ꢀ15 8C. After that the reaction mixture was allowed to warm
to the room temperature with stirring in bath overnight. The solvent
and other volatile materials were evaporated in vacuo at room
temperature. The oily residue was washed with Et2O (3 ꢄ 5 mL) and
the mixture of cesium 1-trifluoromethyl-2,4,6-tris(trifluoromethylsul-
fonyl)cyclohexadienate (4) and cesium 1,2-bis(trifluoromethyl)-4,6-
bis(trifluoromethylsulfonyl)cyclohexadienate (5) (total yield 75%, in
ratio 4:1) was precipitated from Et2O solution as a dark-orange solid.
1H, 19F and 13C NMR data, see Tables 1 and 2.
Structure
R
D
10
18
19
6
NO2
0.00
7.9
–
0.0
1.0
ꢀ6.8
–
SO2F
ꢀ10.0
ꢀ9.4
14
15
4
0.0
ꢀ6.0
–
ꢀ15.3
ꢀ11.0
ꢀ4.8
SO2CF3
20
21
8
0.0
ꢀ9.0
–
ꢀ13.6
ꢀ1.8
SO2OCH2CF3
16
17
ꢀ1.8
0.0
ꢀ3.6
ꢀ5.4
proved, while the RI-MP2 calculations still predict a slightly higher
stability for the isomeric unsymmetrically substituted anion 17. At
the first look, the experimental data are in contradiction with the
relative energy values calculated theoretically. We can exclude
that our gas phase RI-MP2/TZVP calculations yield enough exact
total energy values, on the other hand, it is noteworthy that the
predicted differences in total energies favoured the unsymmetri-
cally disubstituted product, in accord with the experimentally
observed trend, decreasing in the order X = SO2CF3 > NO2 >
SO2F > SO2OCH2CF3. The preferred formation of 16 vs. 17 could
mean the mixed (thermodynamic and kinetic) control of the
trifluoromethylation reaction, the detailed investigation of this
aspect is however beyond the scope of the current paper and can
be a subject of future investigations.
5.2. Interaction of 1,3,5-tris(fluorosulfonyl)benzene 2 with
[Me4N][Me3Si(CF3)2]
To a well-stirred mixture of Me4NF (0.05 g, 0.53 mmol) in DME
(5 mL) at ꢀ60 8C Me3SiCF3 (0.17 g, 1.17 mmol) was added slowly
dropwise. The mixture was stirred for 1 h at ꢀ60 ꢁ 5 8C and then
1,3,5-tris(fluorosulfonyl)benzene2 (0.15 g, 0.46 mmol) was added. The
mixture formed was stirred for 1 h at ꢀ50 ꢁ 5 8C and then was allowed
to warm to the room temperature with stirring in bath overnight. The
solvent and other volatile materials were evaporated in vacuo at room
temperature. The oily residue was washed with Et2O (3 ꢄ 5 mL) and
tetramethylammonium 1-trifluoromethyl-2,4,6-tris(fluorosulfonyl)cyclo-
hexadienate (6) with inseparable and unidentified impurity was
precipitated from Et2O solution as a yellow solid. The content of the
major product 6 is 85–90%. The yield of 6 is 65% relative to C6H5F as
internal standard. 1H, 19F and 13C NMR data, see Tables 1 and 2.
4. Conclusions
A convenient synthetic procedures have been described to
5.3. Tetramethylammonium or potassium 3,5-
obtain gem-trifluoromethyl anionic -complexes of 1,3,5-tris(-
s
bis(fluorosulfonyl)benzenesulfonate (7)
fluorosulfonyl)benzene, 1,3,5-tris(b,b,b-trifluoroethoxysulfonyl)-
benzene, 1,3,5-tris(trifluoromethylsulfonyl)benzene as well as of
1,3,5-trinitrobenzene. Conditions for easy oxidation of these
adducts into corresponding 2,4,6-tris(substituted)benzotrifluor-
ides have been found. The latter add trifluoromethyl anion to the 1
To a well-stirred solution of appropriate reagent (Me4NF
(0.31 mmol) in DME (2 mL) or KHCO3 (0.31 mmol) in DMSO-d6
(2 mL)) 1,3,5-tris(fluorosulfonyl)benzene 2 (0.10 g, 0.31 mmol)
was added. The mixture was stirred at room temperature
overnight. The product formation was monitored by 1H, 19F and
13C NMR spectrometry. (In the case of the reaction in DME solvent
was evaporated in vacuo and the residue was dissolved in DMSO-
and 3 positions of the aromatic ring forming new anionic
s-
complexes (gem-disubstituted and unsymmetrical ones, respec-
tively) in different ratio. Quantum chemical calculations predict
d6). 1H NMR (299.9 MHz, DMSO-d6):
H-2 and H-6). 19F NMR (188.1 MHz, CCl3F):
NMR (100.623 MHz, DMSO-d6): 53.11 (s, C-1), 134.61 (d,
2JC,F = 28.1 Hz, C-3,5), 132.26 (s, C-2,6), 128.92 (s, C-4).
d
8.73 (1H, s, H-4), 8.57 (2H, s,
66.05 (s, 2F, SO2F). 13
different equilibrium structures for the anionic
s-complexes,
depending on the nature of the acceptor groups in the ring. The
unsymmetrical bis-trifluoromethylated anionic adducts seem in
all cases to be significantly more stable than the corresponding
gem-disubstituted isomers, while the both structures have been
identified in the experiment. This makes it possible to suggest the
reaction of trifluoromethylation to be kinetically controlled.
d
C
d
5.4. General procedure for the synthesis of the anionic
s-complexes
(8) and (10)
To a well-stirred solution of appropriate substrate 3 or 9
(0.35 mmol) in DME (4 mL) at ꢀ60 8C Me3SiCF3 (0.06 g, 0.45 mmol)
and Me4NF (0.04 g, 0.42 mmol) were added. The mixture was stirred
for 1 h at ꢀ50 ꢁ 5 8C and allowed to warm to room temperature with
stirring in bath overnight. The solvent and other volatile materials were
evaporated in vacuo at room temperature. The oily residue was washed
with Et2O (3 ꢄ 5 mL) and the product was precipitated from Et2O
solution.
5. Experimental section
General: All reactions were carried out under a dry argon
atmosphere by using Schlenk techniques. Me3SiCF3 was purchased
from ABCR. Me4NF was synthesized according to literature
procedure [15]. All solvents were purified according to procedures
described in reference [16]. 1H, 19F, 13C NMR spectra were recorded
on the Varian VXR 300 (299.9 MHz), Varian Gemini 200
(188.1 MHz), and Bruker Avance DRX 400 (100.623 MHz) spectro-
meters, respectively. Chemical shift values are given in ppm
relative to Me4Si and CCl3F as external standards. Melting points
were measured on the electro-thermal apparatus and are
uncorrected.
5.4.1. Tetramethylammonium 1-trifluoromethyl-2,4,6-tris(b,b,b-
trifluoroethoxysulfonyl)cyclohexa-dienate (8)
Yield: 0.23 g (95%), a yellow solid, mp 71–72 8C. Anal. Calcd. for
C17H21F12NO9S3: C, 28.84; H, 2.99; F, 32.24; N, 1.9; S, 13.6. Found:

O.M. Holovko-Kamoshenkova et al. / Journal of Fluorine Chemistry 131 (2010) 1344–1352
1351
C, 28.61; H, 3.12; N, 2.1; F, 32.51; S, 13. 48. 1H, 19F and 13C NMR, see
Tables 1 and 2.
vacuo at room temperature. The oily residue was washed with Et2O
(3 ꢄ 5 mL) and the mixture of tetramethylammonium 1,1-bis
(trifluoromethyl)-2,4,6-tris(fluorosulfonyl)cyclohexadienate (14) and tet-
ramethylammonium 1,3-bis(trifluoromethyl)-2,4,6-tris(fluorosulfonyl)-
cyclohexadienate (15) in ratio 1:2 correspondingly in total yield 85%
relative to C6H5F as an internal standard were precipitated from Et2O
solution as a yellow solid. 1H, 19F and 13C NMR data, see Tables 1 and 2.
5.4.2. Tetramethylammonium 1-trifluoromethyl-2,4,6-
trinitrocyclohexadienate (10)
Yield: 0.11 g (95%), dark-red solid, mp 170–171 8C. Anal. Calcd.
for C11H15F3N4O6: C, 37.06; H, 4.24; F, 16; N, 15.73. Found: C, 36.9;
H, 4.17; F, 15.92; N, 15.54. 1H, 19F and 13C NMR data, see Tables 1
and 2.
5.7. General procedure for the interaction of benzotrifluorides 12 and
13 with Me3SiCF3/Fꢀ system
5.5. General procedure for the oxidation of the anionic
s-complexes
(6), (8) and (10)
To a well-stirred solution of appropriate substrate 12 or 13
(0.47 mmol) in DME (10 mL) at ꢀ60 8C Me3SiCF3 (0.08 g,
0.59 mmol) and Me4NF (0.05 g, 0.54 mmol) were added. The
mixture was stirred for 1 h at ꢀ50 ꢁ 5 8C and allowed to warm to
room temperature with stirring in bath overnight. The solvent and
other volatile materials were evaporated in vacuo at room tempera-
ture. In the case of 12 the oily residue was washed with Et2O
(3 ꢄ 5 mL) and the product was precipitated from Et2O solution.
To a well-stirred solution of appropriate substrate 6, 8 or 10
(1.1 mmol) in DME (10 mL) at 0 ꢁ 5 8C t-BuOCl (0.15 g, 1.43 mmol)
was added. The mixture was stirred for 5–10 min at present
temperature and allowed to warm to room temperature with stirring.
The residue formed was filtered off and the solid was washed with
DME (2 ꢄ 5 mL). The solvent was evaporated in vacuo. The crude
product was crystallized from appropriate solvent.
5.7.1. Tetramethylammonium 1,1-bis(trifluoromethyl)-2,4,6-
5.5.1. 2,4,6-Tris(fluorosulfonyl)benzotrifluoride (11)
tris(b,b,b-trifluoroethoxysulfonyl)cyclohexadienate (16) and
The crude product was crystallized from CCl4. Yield: 0.32 g
tetramethylammonium 1,3-bis(trifluoromethyl)-2,4,6-tris(b,b,b-
trifluoroethoxysulfonyl)cyclohexadienate (17)
(75%), white solid, mp 103–105 8C. 1H NMR (299.9 MHz, THF-d8):
d
9.2 (2H, s, H-3 and H-5). 19F NMR (188.1 MHz, CCl3F):
5JF,F = 16 Hz, 3F, CF3), 64.86 (s, 1F, p-SO2F), 64.31 (q, 5JF,F = 16 Hz, o-
SO2F). 13C NMR (100.623 MHz, THF-d8):
139.28 (s, C-3 and C-5),
d
ꢀ53.45 (t,
The products 16 and 17 were obtained in ratio 9:1 correspond-
ingly in total yield 95% relative to C6H5F as an internal standard.
Product 16 was precipitated from Et2O solution. Yield: 0.25 g
(67%), yellow solid, mp 109–110 8C. Anal. Calcd. for C18H20F15O9S3:
C, 29.69; H, 2.77; F, 39.18; S, 13.22. Found: C, 23.21; H, 2.81; F,
39.63; S, 13. 33. 1H, 19F and 13C NMR data, see Tables 1 and 2.
d
139.13 (d, 2JC,F = 31.7 Hz, C-4), 138.72 (d, 2JC,F = 31.7 Hz, C-2 and C-
6), 136.548 (q, 2JC,F = 38.24 Hz, C-1). 121.38 (q, 1JC,F = 277 Hz, CF3).
Anal. Calcd. for C7H2F6O6S3: C, 21.42; H, 0.5; F, 29.06; S, 24.53.
Found: C, 21.21; H, 0.42; F, 29.23; S, 24.67.
5.7.2. Tetramethylammonium 1,1-bis(trifluoromethyl)-2,4,6-
trinitrocyclohexadienate (18) and tetramethylammonium 1,3-
bis(trifluoromethyl)-2,4,6-trinitrocyclohexadienate (19)
The products 18 and 19 were obtained in ratio 1:9 correspond-
ingly in total yield 70% relative to C6H5F as an internal standard. 1H
and 19F NMR data, see Table 1.
5.5.2. 2,4,6-Tris(
b,b,b-trifluoroethoxysulfonyl)benzotrifluoride (12)
The crude product was crystallized from benzene. Yield: 0.63 g
(90%), white solid, mp 164–165 8C. 1H NMR (299.9 MHz, THF-d8):
d
9.01 (2H, s, H-3 and H-5), 5.27 (4H, q, 3JH,F = 8.4 Hz, o-SO3CH2CF3),
3
5.12 (2H, q, JH,F = 8.4 Hz, p-SO3CH2CF3). 19F NMR (188.1 MHz,
CCl3F):
(100.623 MHz, THF-d8):
d
ꢀ53.99 (s, 3F, CF3), ꢀ75.08 (m, 9F, SO3CH2CF3). 13C NMR
d
141.51 (s, C-4), 141.4 (q, 3JC,F = 1.9 Hz C-2
6. Theoretical section
2
and C-6), 137.09 (s, C-3 and C-5), 134.48 (q, JC,F = 37.73 Hz, C-1),
123.53 (q, 1JC,F = 277.22 Hz, p-SO3CH2CF3), 123.52 (q,
All the structures were first optimized using TURBOMOLE
(version 6.02) program packet [17], and the implemented
Resolution Identity (RI) [18] algorithm. RI-BP86 functional
[19,20] and standard triple-zeta basis sets [21] (TZVP) were used.
The contraction of the basis functions were (14s9p)/
[5s4p] ! {73211/6111} for S, (11s6p)/[5s3p] ! {62111/411} for
C, N,O and F and (5 s)/[3 s] ! {311} for H. One set of (five) d-
functions was added for every non-hydrogen atom and one set of
p-functions was used for H’s. For all the structures vibrational
analyses were performed computing numerically first and second
order derivatives, checking the equilibrium structures to be true
local minima in energy. The most favorable structures were re-
optimized using the more superior RI-MP2 method [22,23] within
the frozen core approximation. The same (TZVP) basis sets were
used. No frequency analyses were performed at this level of
approximation. The relative energy values were calculated from
the total RI-MP2/TZVP energy magnitudes without zero-point
energy corrections. The optimized structures were pictured using
the VMD program [24].
1JC,F = 277.5 Hz, o-SO3CH2CF3), 121.82 (q, JC,F = 277.5 Hz, CF3),
1
2
2
67.68 (q, JC,F = 38 Hz, o-SO3CH2CF3), 67.41 (q, JC,F = 38 Hz, p-
SO3CH2CF3). Anal. Calcd. for C13H8F12O9S3: C, 24.7; H, 1.27; F, 36.1;
S, 15.2. Found: C, 24.91; H, 1.33; F, 35.93; S, 15. 43.
5.5.3. 2,4,6-Trinitrobenzotrifluoride (13)
The crude product was crystallized from benzene. Yield: 0.27 g
(85%); a white solid; mp 87–88 8C. 1H NMR (299.9 MHz, DMSO-d6):
d
8.78 (2H, s, H-3 and H-5). 19F NMR (188.1 MHz, CCl3F):
d
ꢀ59.62
(s, 3F, CF3). 13C NMR (100.623 MHz, DMSO-d6):
d 150.63 (s, C-2 and
C-6), 150.1 (s, C-4), 122.86 (s, C-3 and C-5), 126.6 (q,
1JC,F = 288.28 Hz, CF3), 122.68 (q, 2JC,F = 36.02 Hz, C-1). Anal. Calcd.
for C7H2F3N3O6: C, 29.89; H, 0.72; F, 20.28; N, 14.95. Found: C,
30.05; H, 0.84; F, 20.52; N, 15.03.
5.6. Interaction of 2,4,6-tris(fluorosulfonyl)benzotrifluoride 11 with
[Me4N][Me3Si(CF3)2]
To a well-stirred mixture of Me4NF (0.08 g, 0.88 mmol) in DME
(9 mL) at ꢀ60 8C Me3SiCF3 (0.27 g, 1.93 mmol) was added slowly
dropwise. The mixture was stirred for 1 h at ꢀ60 ꢁ 5 8C and then
1,3,5-tris(fluorosulfonyl)benzotrifluoride 11 (0.3 g, 0.76 mmol) was
added. The mixture formed was stirred for 1 h at ꢀ55 ꢁ 5 8C and then
was allowed to warm to room temperature with stirring in bath
overnight. The solvent and other volatile materials were evaporated in
Acknowledgment
The authors thank Professor Dr. U. Manthe, University of
Bielefeld (Germany) for providing an access to the computer
cluster and TURBOMOLE set of program and Dr. Thorsten To¨nsing
for the technical support for our calculations.

1352
O.M. Holovko-Kamoshenkova et al. / Journal of Fluorine Chemistry 131 (2010) 1344–1352
(d) J.-P. Begue, D. Bonnet-Delpon, Bioorganic and Medicinal Chemistry of
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Supplementary data associated with this article can be found, in
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