Synthesis of potassium 4-(1-azol-1-yl)-2,3,5,6- tetrafluorophenyltrifluoroborates from K[C6F5BF 3] and alkali metal azol-1-ides. the dramatic distinction in nucleophilicity of alkali metal azol-1-ides and dialkylamides

Article abstract of DOI:10.1016/j.jfluchem.2013.07.011

Nucleophilic substitution of fluorine atom in K[C₆F ₅BF₃] with alkali metal azol-1-ides in polar aprotic solvent (DMF, DMSO) at 60-130 C gives potassium 4-(azol-1-yl)-2,3,5,6- tetrafluorophenyltrifluoroborates, K[4-AzC₆F₄BF ₃] (AzH = pyrrole, pyrazole, imidazole, indole, and benzimidazole). Unexpectedly, diethylamine and morpholine do not react with K[C ₆F₅BF₃] under the same conditions while pentafluorobenzene and R₂NC₆F₄H form at 150 C. Reaction of K[C₆F₅BF₃] with Na[NR₂] in diglyme or DMSO proceeds similar way. The assumed reason is the relatively low nucleophilicity of both secondary amines and alkali metal dialkylamides which results in destructive by-reaction with K[C₆F ₅BF₃] rather than in its aminodefluorination. This is confirmed by the competitive nucleophilic aminodefluorination of a model substrate, C₆F₅Ph, with sodium indolide/sodium morpholinide.

Full text of DOI:10.1016/j.jfluchem.2013.07.011

Accepted Manuscript
Title: Synthesis of potassium
4-(1-azol-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborates
from K[C6F5BF3] and alkali metal azol-1-ides. The
dramatic distinction in nucleophilicity of alkali metal
azol-1-ides and dialkylamides
Author: Anton Yu. Shabalin Nicolay Yu. Adonin Vadim V.
Bardin Oksana P. Taran Artemiy B. Ayusheev Valentin N.
Parmon
PII:
S0022-1139(13)00266-2
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.jfluchem.2013.07.011
FLUOR 8160
To appear in:
FLUOR
Received date:
Revised date:
Accepted date:
27-5-2013
9-7-2013
15-7-2013
Please cite this article as: A.Yu. Shabalin, N.Yu. Adonin, V.V. Bardin,
O.P. Taran, A.B. Ayusheev, V.N. Parmon, Synthesis of potassium 4-(1-azol-
1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborates from K[C6F5BF3] and alkali
metal azol-1-ides. The dramatic distinction in nucleophilicity of alkali
metal azol-1-ides and dialkylamides, Journal of Fluorine Chemistry (2013),
http://dx.doi.org/10.1016/j.jfluchem.2013.07.011
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*Graphical Abstract - Pictogram
R1
M N
R1
N
F
F
F
F
F
F
F
F
R2
R2
i or ii
+
K
F
BF3
K
BF3
Y
Y
X
X
M = Na, K; X, Y = CH, N; R1, R2 = H,
Conditions: i: (M = K) DMF, 80 °C.
ii: (M = Na) 1. Dipolar aprotic solvent, 80-130 °C; 2. KHF2, 25 °C
Page 1 of 22

Nucleophilic substitution of fluorine atom in K[C6F5BF3] with alkali metal azol-1-ides in polar
aprotic solvent (DMF, DMSO) at 60–130 C gives potassium 4-azolino-2,3,5,6-
tetrafluorophenyltrifluoroborates, K[4-AzC6F4BF3] (AzH = pyrrol, pyrazol, imidazol, indol, and
benzimidazol).
Diethylamine and morpholine as well as the corresponding sodium amides do not react with
K[C6F5BF3] under the same conditions while at 150 C pentafluorobenzene and R2NC6F4H
forms.
In any cases the N-nucleophiles attack a carbon atom in the para-position to BF3 group of
K[C6F5BF3].
Page 2 of 22

*Manuscript
Synthesis of potassium 4-(1-azol-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborates from
K[C6F5BF3] and alkali metal azol-1-ides. The dramatic distinction in nucleophilicity of alkali
metal azol-1-ides and dialkylamides
Anton Yu. Shabalin,a Nicolay Yu. Adonin,a* Vadim V. Bardin,a,b Oksana P. Taran,a Artemiy B.
Ayusheev,a Valentin N. Parmon a
a G.K. Boreskov Institute of Catalysis, SB RAS, Acad. Lavrentjev Ave. 5, 630090 Novosibirsk,
Russian Federation
b N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, SB RAS,
Acad. Lavrentjev Ave. 9, 630090 Novosibirsk, Russian Federation
Received:
Abstract. Nucleophilic substitution of fluorine atom in K[C6F5BF3] with alkali metal azol-1-ides
in polar aprotic solvent (DMF, DMSO) at 60–130 C gives potassium 4-(azol-1-yl)-2,3,5,6-
tetrafluorophenyltrifluoroborates, K[4-AzC6F4BF3] (AzH = pyrrole, pyrazole, imidazole, indole,
and benzimidazole). Unexpectedly, diethylamine and morpholine do not react with K[C6F5BF3]
under the same conditions while pentafluorobenzene and R2NC6F4H form at 150 C. Reaction of
K[C6F5BF3] with Na[NR2] in diglyme or DMSO proceeds similar way. The assumed reason is the
relatively low nucleophilicity of both secondary amines and alkali metal dialkylamides which
results in destructive by-reaction with K[C6F5BF3] rather than in its aminodefluorination. This is
confirmed by the competitive nucleophilic aminodefluorination of a model substrate, C6F5Ph, with
sodium indolide/sodium morpholinide.
Keywords. Pentafluorophenyltrifluoroborate, N-Nucleophile, Nucleophilic substitution, NMR
spectroscopy
* Corresponding author.
Tel.: +7 383 326 9674; fax: +7 383 330 8056
E-mail address: adonin@catalysis.ru (N. Yu. Adonin).
1
Page 3 of 22

1. Introduction
Nucleophilic aminodefluorination of pentafluorobenzenes C6F5X with dialkylamine
(excess) or dialkylamine in the presence of a base is the well-studied routine preparation of fluoro-
containing dialkylaminobenzenes. Constitution of products is determined by many factors although
the main of ones are the nature of substituent X and N-nucleophile [1-3]. When X is an
organoelement substituent, it can behave as an alternative reactive centre. For instance, C6F5X (X =
SiMe3, GeEt3) reacts with lithium piperidin-1-ide (THF, –20 C) giving 4-XC6F4NC5H10 whereas
the reaction with piperidine (2 equivalents) (THF, 20 C) leads to 4-XC6F4NC5H10 and C6F5H
(25:75) [4-6]. The formation of (4-H2NNHC6F4)2Hg from bis(pentafluorophenyl)mercury and
NH2NH2 is accompanied by partial hydrodemercuration, too [7]. The high electrophilicity of the
silicon atom in C6F5SiMe2Y (Y = Cl, Br) [8-10] or C6F5SiF3 [11] results in C6F5SiMe2NAlk2 (Alk
= Me, Et) and C6F5SiF2NC5H10, respectively, under the action of N-nucleophiles rather than
substitution of aromatically bonded fluorine atom. Pentafluorophenylboranes C6F5BX2 (X = F, Cl,
C6F5) form adducts C6F5BX2·N-base with amines and azoles (for more detail see reviews [12, 13]).
Recently we have reported the preparation of K[4-ROC6F4BF3] (R = Me, Et, Pr, i-Pr, Bu, t-
Bu, PhCH2, CH2=CHCH2, Ph) by alkoxydefluorination of K[C6F5BF3] with the corresponding O-
nucleophiles MOR (M = Na, K) in polar aprotic solvents [14]. To continue the exploration of
synthetic routes to polyfluoroorganyltrifluoroborates via modification of the organic moiety, we
studied aminodefluorination of easily available salt K[C6F5BF3] [15] with N-nucleophiles derived
from either secondary amines and azoles [16].
2. Results
Potassium pentafluorophenyltrifluoroborate (1) does not react with diethylamine or
morpholine (>3 equivalents) in DMF at 130 C over a period of 4 h (Scheme 1). Heating with
morpholine at 150 C for 4 h caused the incomplete consumption (33%) of 1 and formation of 4-
(2,3,5,6-tetrafluorophenyl)morpholine (2), N,N-dimethyl-2,3,5,6-tetrafluoroaniline (3) and C6F5H
instead of K[R2NC6F4BF3]. A higher conversion of K[C6F5BF3] was achieved in diglyme or
DMSO, but potassium 4-(morpholin-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborate was not found
again (according to 19F NMR data) (Scheme 2).
2
Page 4 of 22

F
F
F
F
X
X
DMF
No reaction
K
F
BF3
+
H N
130 °C, 4 h
1
>3 equ
X, X = Et, Et; CH2CH2OCH2CH2
Scheme 1. Interaction of 1 with morpholine and diethylamine
F
F
F
F
F
F
F
F
F
F
DMF
+
+
F
N
O
NMe2
150 °C, 4 h
Conversion 33 %
F
F
2
3
F
F
F
F
F
F
F
F
F
Diglyme
+
O
+
F
K
F
BF3
H N
O
F
N
150 °C, 4 h
Conversion 63 %
F
F
1
> 2 equ
F
F
F
F
F
F
F
F
F
DMSO
+
+
F
N
O
F
N
O
150 °C, 4 h
Conversion 79 %
F
F
Scheme 2. Interaction of 1 with morpholine in different solvents
Attempted aminodefluorination of K[C6F5BF3] in the presence of other bases was
unsuccessful, too. Stirring 1 with morpholine and K2CO3 in DMF as well in DMA, NMP or DMSO
at 130 C for 4 h results in C–B bond cleavage at a low conversion of starting salt 1 (Scheme 3).
Moreover, the similar results were obtained using both sodium morpholinide and sodium
diethylamide (Scheme 4).
F
F
F
F
F
F
F
F
F
F
F
F
DMF, DMA, NMP or DMSO
K2CO3
+
+
F
K
F
BF3
H N
O
N
O
130 °C, 4 h
Conversion 5-7 %
1
> 2 equ
Scheme 3. Interaction of 1 with morpholine in different solvents
3
Page 5 of 22

Na N
O
F
F
F
F
F
F
F
F
Diglyme or DMSO
or
Na[NEt2]
+
+ etc.
K
F
BF3
F
130 °C, 4 h
Conversion <10 %
1
Scheme 4. Interaction of 1 with sodium morpholinide or sodium diethylamide
In contrast, heating of K[C6F5BF3] with sodium pyrrol-1-ide (1.4 equivalent) at 130 C in
DMF followed by treatment with K[HF2] gives potassium 4-(pyrrol-1-yl)-2,3,5,6-
tetrafluorophenyltrifluoroborate (4) in 86% yield (Scheme 5).
F
F
F
F
F
F
F
F
1. DMF, 130 °C, 4 h
+
K
F
BF3
Na N
K
N
BF3
2. K[HF2]
1
4
Scheme 5. Interaction of 1 with sodium pyrrol-1-ide
Treatment of K[C6F5BF3] with sodium imidazol-1-ide (generated in situ from imidazole
and NaH) in DMF at 80 C for 8 h gives potassium 4-(imidazol-1-yl)-2,3,5,6-tetrafluorophenyl-
trifluoroborate (5) and admixture of potassium 3,4-bis(imidazol-1-yl)trifluorophenyltrifluoroborate
(6) (after work up with K[HF2]) (Scheme 6). Using individually prepared potassium imidazol-1-ide
instead of sodium salt in DMF, NMP or DMSO has no noticeable effect (93% yield of 5) (Scheme
7). Aminodefluorination in DMF at 60 C over a period of 4 h allowed to avoid the formation of 6
but reduced conversion of 1 from 93 to 60%. In methanol, acetonitrile and DME conversion of 1
was 60, 23 and 0%, respectively (60 C, 4 h).
F
F
F
F
F
F
F
F
1. DMF, 80 °C, 8 h
N
N
+
K
F
BF3
Na N
K
N
BF3
2. K[HF2]
1
5
Scheme 6. Interaction of 1 with sodium imidazol-1-ide
4
Page 6 of 22

F
F
F
F
F
F
F
F
DMF, 80 °C, 8 h
N
N
+
K
F
BF3
K N
K
N
BF3
1
5
Scheme 7. Interaction of 1 with potassium imidazol-1-ide
Potassium 4-(pyrazol-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborate (7) was prepared from
1 and K[C6F5BF3] at 80 C in 64% yield. Like 5, product contained small admixture of potassium
3,4-bis(pyrazol-1-yl)-2,5,6-trifluorophenyltrifluoroborate (8) (Scheme 8).
F
F
F
F
F
F
F
F
N
N
1. DMF, 80 °C, 7 h
+
K
F
BF3
Na N
K
N
BF3
2. K[HF2]
1
7
Scheme 8. Preparation of potassium 4-(pyrazol-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborate (7)
Substitution of fluorine atom in 1 with more spatially hindered N-nucleophiles, such as
sodium indol-1-ide and sodium benzimidazol-1-ide, proceeds like substitution with alkali metal
azolides but complicated by subsequent reaction with the second equivalent of the nucleophilic
reagent. Thus, heating of K[C6F5BF3] with sodium indol-1-ide in DMF at 130 C forms 4-(indol-1-
yl)-2,3,5,6-tetrafluorophenyltrifluoroborate (9) contaminated with residual borate 1 and 3,4-
bis(indol-1-yl)-2,5,6-trifluorophenyltrifluoroborate (10) (ratio 9:1:10 = 88:6:6) (19F NMR). After
cation metathesis with excess K[HF2], borate 9 was isolated at 74% yield (Scheme 9). Decreasing
temperature from 130 to 100 C and usage of stoichiometric ratio K[C6F5BF3]: N-nucleophile
results in the absence of 10, but conversion of 1 diminishes, too.
F
F
F
F
F
F
F
1. DMF, 130 °C, 4 h
+
K
F
BF3
Na
K
N
BF3
N
2. K[HF2]
F
1
9
Scheme 9. Interaction of 1 with sodium indol-1-ide
Reaction of K[C6F5BF3] with sodium benzimidazol-1-ide (1.4 equivalent) in DMF at 130
C for 4 h gives 4-(benzimidazol-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborate (11), 3,4-
5
Page 7 of 22

bis(benzimidazol-1-yl)-2,5,6-trifluorophenyltrifluoroborate (12) and by-products (C6F5H and 1-
(2,3,5,6-tetrafluorophenyl)benzimidazole (13)) (Table 1, run 1). These by-products disappeared
when the reaction was performed at 100 and 80 C but, instead, unreacted borate 1 remained
(Table 1, runs 2, 3) in a significant quantity. Lengthening the reaction period from 4 to 8 h does not
affect on the composition of products (Table 1, run 4). Practically total conversion of 1 was
achieved at 100 C using 2.8-fold excess of nucleophile, although this lead to the further
aminodefluorination of 11 (Table 1, run 5) (Scheme 10).
F
F
F
F
F
F
F
F
F
F
F
1. DMF, 80-110 °C, 4 h
+
K
F
BF3
Na[BIm]
K
BIm
BF3
+
K
BIm
BIm
BF3
2. K[HF2]
N
1
11
12
BIm =
N
Scheme 10. Interaction of 1 with sodium benzimidazol-1-ide
<Here is place for Table 1>
3. Discussion
The obtained results show that aminodefluorination of K[C6F5BF3] with alkali metal
azolides MAz in polar solvents occurs at 60–130 C and leads to substitution of a fluorine atom at
para-position to BF3 group. The other isomers K[AzC6F4BF3] are not detected. When Az is pyrrol-
1-yl, the subsequent replacement of fluorine atom in K[4-AzC6F4BF3] does not occur or negligible.
This process becomes noticeable with other nucleophiles: pyrazol-1-ide, imidazol-1-ide, indol-1-
ide, and in peculiar, benzimidazol-1-ide. Although these minor by-products were not isolated, the
constitution of them in a mixture with the precursor, K[4-AzC6F4BF3] was deduced from 19F NMR
spectra. Thus, the reaction mixture derived from K[C6F5BF3] and sodium imidazol-1-ide produces
resonances at –116.7, –125.9, –152.2 and –133.9 ppm in ratio 1:1:1:3 which were assigned to
fluorine atoms F2, F6, F5, and BF3 of K[3,4-Im2C6F3BF3] (Im = imidazol-1-yl), respectively. An
incremental calculation of chemical shifts based on 19F NMR spectra of K[C6F5BF3] [15] and 1-
(pentafluorophenyl)imidazole C6F5Im [17] gives magnitudes (F) = –115 (F2), –121 (F6), and –146
(F5) ppm, respectively, these are in agreement with experimentally observed ones. For comparison,
the experimental/predicted chemical shifts of K[4-ImC6F4BF3] are –132.2/–131 (F2, 6) and –152.5/–
149 (F3, 5) ppm. The predicted chemical shifts of fluorine atoms bonded to aryl moiety in
alternative izomers are –121 (F6), –142 (F4), and –153 (F5) ppm (K[2,3-Im2C6F3BF3]), –128 (F6), –
133 (F3), and –139 (F5) ppm (K[2,4-Im2C6F3BF3]), and –115 (F6), –142 (F4) and –146 (F3) ppm
6
Page 8 of 22

(K[2,5-Im2C6F3BF3]). This allows the presence of these borates to be rejected. The predicted 19F
NMR spectra of symmetric borates K[2,6-Im2C6F3BF3] and K[3,5-Im2C6F3BF3] consist of two
groups of resonances in 2:1 ratio besides signal of BF3 group which also were not found. The
closely related picture is obtained for borate K[3,4-Az2C6F3BF3] (Az = pyrazin-1-yl) using
spectrum of 1-(pentafluorophenyl)pyrazole [18].
Predicted chemical shifts for K[3,4-Az2C6F3BF3] (Az = indol-1-yl 10 and benzimidazol-1-
yl 12) are –115 (F2), –127 (F6), and –149 (F5) ppm (from 19F NMR spectra of K[C6F5BF3] and 1-
(pentafluorophenyl)indole (14)). However, despite similarity with 19F NMR spectra of 6 and 8, the
spectra of borates 10 and 12 have remarkable peculiarity. Spectrum of 10 contains signals at –
114.1, –114.4, –126.6, –149.6, –149.7 (1:1:2:1:1) and –135.0 (BF3) ppm. Spectrum of 12 is
characterized by signals at –114.6, –114.9, –124.3, –148.8, –149.5 (1:1:2:1:1) and –135.1 (BF3)
ppm. Resonances at ca. –114 ppm have identical fine structure (multiplet) as well as resonances at
ca. –149 ppm (doublet of doublet). We assume that these groups of signals belong to two
stereomers with different mutual arrangement of bulky neighbouring substituents Az. In one of
them both phenyl moieties locate at one side of planar polyfluorinated aryl ring ("cis"
arrangement). In the other stereomer phenyl moieties locate at opposite sides ("trans"
arrangement).
In contrast to alkali metal azolides, secondary amines and their sodium salts do not react
with K[C6F5BF3] up to 130 C whereas at higher temperature hydrodeboration of 1 produces
C6F5H and by-products derived from it. Generally, nucleophilicity of secondary amines R2NH is
higher of the nucleophilicity of azoles AzH and alkali metal amides, MNR2 and MAz, are more
reactive than their parent amines [18-22]. To our knowledge, the relative reactivity of alkali metal
dialkylamide and alkali metal azolides are not compared up to date, and reported results on
nucleophilic aminodefluorination of polyfluoroarenes cannot be interpreted unambiguously
without kinetic measurements. For instance, the reaction of C6F5I with morpholine or with 2-
methylimidazole in DMSO in the presence of KOH (2.5 equivalent) (120 C, 24 h) gives 4-
(2,3,5,6-tetrafluorophenyl)morpholine (90%) and 1-(2,3,5,6-tetrafluorophenyl)-2-methylimidazole
(85%), respectively [23] (the reductive hydrodeiodination and hydrodebromination of
polyhalogenobenzenes in polar aprotic solvents is the result of the halogenophilic attack, see
review [24]). Aminodefluorination of C6F6 with NaAz (AzH = pyrazole [22], pyrrole [25]) (DMF,
rt, 2–10 h) and with LiNR2 (R2NH = Me2NH, pyrrolidine, piperidine) (THF, rt, 24 h) [21] occurs
similar way. Qualitatively, the closely related reactivity of both sorts of N-nucleophiles, MNR2 and
MAz, can be outlined from these experiments. To get more accurate data on the relative
nucleophilicity of sodium azolide vs sodium dialkylamide, we explored the competitive
nucleophilic aminodefluorination of 2,3,4,5,6-pentafluorobiphenyl (15) (model substrate) with
7
Page 9 of 22

sodium indolide / sodium morpholinide. In the first experiment, indole and morpholine (1:1) were
treated with NaH (1.5 equivalent) and the formed salts were introduced in the reaction with 15 in
DMF at 130 C for 4 h. The 19F NMR spectrum of solution showed 1-(2,3,5,6-tetrafluoro-4-
phenylphenyl)indole (16), the absence of 15 and 4-(2,3,5,6-tetrafluoro-4-phenylphenyl)morpholine
(17). After work up, 16 was isolated at 88% yield. When biphenyl 15 (2 equivalents) reacts with N-
nucleophiles prepared from morpholine (1 equivalent), indole (1 equivalent) and NaH (3
equivalents), only substituted indole 16 is formed again whereas the corresponding morpholine
derivative is not produced (19F NMR) (Scheme 11).
F
F
N
N
O
F
F
F
F
Na N
O
F
F
F
F
DMF
17
+
F
125 °C, 4 h
Na
N
15
F
F
16
Scheme 11. Reaction of biphenyl 15 with a mixture of sodium morpholinide and sodium indolide
These results demonstrate a lower nucleophilicity of sodium morpholinide towards 15 with
respect to the nucleophilicity of sodium indolide. So that, the conversion of 1 into K[4-AzC6F4BF3]
by the action of MAz and the failure of the related substitution with R2NH and NaNR2 can be
explained by kinetic reasons: the rate of substitution by MNR2 (M = H, Na) is too slow at ≤130 C
whereas at higher temperature by-reactions (hydrodeboration etc) proceed rather than substitution
of aromatically bonded fluorine atom.
For reliable identification of some unknown polyfluoroarenes or those described without 1H
and 19F NMR spectra, we prepared the required substances in compliance with Schemes 12-14.
F
F
F
F
F
DMSO
+
F
H N
O
N
O
160 °C, 1 h
F
F
F
17 (84 %)
15
2 equ
Scheme 12. Preparation of biphenyl 17
8
Page 10 of 22

F
F
F
F
F
F
F
F
F
F
F
F
DMF
+
+
F
F
Na
F
N
N
N
N
110 °C, 4 h
14
18
Scheme 13. Preparation of 1-(pentafluorophenyl)indole (14)
F
F
F
F
F
F
N
N
DMF
+
F
Na
N
N
75 °C, 1 h
F
F
13 (29 %)
Scheme 14. Preparation of 13
4. Conclusions
Aminodefluorination of K[C6F5BF3] with alkali metal azolides, AzM, in polar solvents at
60–130 C gives borates K[4-AzC6F4BF3] at a high yield along with admixture of K[3,4-
Az2C6F3BF3]. Isomers K[2-AzC6F4BF3] and K[3-AzC6F4BF3] are not found. Potassium 4-
diethylamino-2,3,5,6-tetrafluorophenyltrifluoroborates and potassium 4-morpholino-2,3,5,6-
tetrafluorophenyltrifluoroborate are not obtained this way because of the low substitution rate and
competitive by-reactions. The lower nucleophilicity of R2NNa vs AzNa was confirmed by the
competitive reaction with C6F5Ph.
4. Experimental
4.1. General considerations
The NMR spectra were recorded using a Bruker AVANCE 300 spectrometer (1H at 300.13
MHz, 19F at 282.40 MHz, and 11B at 96.29 MHz). The chemical shifts are referenced to TMS (1H),
CCl3F (19F, with C6F6 as secondary reference (162.9 ppm)), and BF3∙OEt2/CDCl3 (15% v/v) (11B),
respectively. IR spectra were measured on a Shimadzu FTIR-8300, Varian 640-IR and Tensor 27
spectrometers. GC-MS analysis was done using a Hewlett-Packard 1800A (with HP-5MS column)
instrument. High resolution mass spectra were recorded using a Thermo Scientific DFS
spectrometer in EI mode (70 eV). These analyses as well as elemental analysis were performed in
the Collective Service Center of SB RAS (Novosibirsk).
DMF was distilled over P4O10 at reduced pressure. Diglyme (Acros), 1,2-dimethoxyethane
(Acros), N-methylpyrrolidone (Acros), dimethylacetamide (Acros), and dimethyl sulfoxide
(Panreac) were stirred with CaH2 and distilled. Methanol was refluxed with CaO and distilled. NaH
(60% dispersion in oil) (Sigma-Aldrich), pyrrole (Fluka), pyrazole (Acros), imidazole (Acros),
9
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indole (Acros) were used as supplied. K2CO3 was calcinated at 450 C for 4 h before use.
Morpholine and diethylamine were stirred with CaH2 for 6–8 hs and distilled. Potassium
pentafluorophenyltrifluoroborate [15], benzimidazole [26] and 2,3,4,5,6-pentafluorobiphenyl [27]
were prepared as described.
All reactions with NaH were performed under an atmosphere of dry argon.
4.2. Reaction of K[C6F5BF3] with secondary amines
4.2.1. Solution of K[C6F5BF3] (137 mg, 0.50 mmol) with diethylamine (117 mg, 1.60 mmol) in
DMF (1 mL) was kept in a sealed tube at 130 C for 4 h. No reaction occurred (19F NMR).
4.2.2. Reaction of K[C6F5BF3] (50 mg, 0.18 mmol) and morpholine (51 mg, 0.59 mmol) in DMF
(0.8 mL) (130 C, 4 h) gave the same result.
4.2.3. Solution of K[C6F5BF3] (50 mg, 0.18 mmol) and morpholine (51 mg, 0.59 mmol) in DMF
(0.8 mL) was kept in a sealed tube at 150 C for 4 h. After cooling, resonances of K[C6F5BF3]
(0.12 mmol) (33% conversion), 4-(2,3,5,6-tetrafluorophenyl)morpholine (0.03 mmol), and N,N-
dimethyl-2,3,5,6-tetrafluoroaniline [28] (0.04 mmol) besides K[BF4] (0.09 mmol) and C6F5H
(trace) were detected (19F NMR).
4.2.4. Solution of K[C6F5BF3] (44 mg, 0.16 mmol) and morpholine (82 mg, 0.94 mmol) in diglyme
(0.8 mL) was kept in a sealed tube at 150 C for 4 h to form C6F5H (0.10 mmol) and 4-(2,3,5,6-
tetrafluorophenyl)morpholine (0.01 mmol) at 63% conversion of K[C6F5BF3] (residual 0.06 mmol)
(19F NMR).
4.2.5. Solution of K[C6F5BF3] (123 mg, 0.45 mmol) and morpholine (93 mg, 0.107 mmol) in
DMSO (1 mL) was kept in a sealed tube at 150 C for 4 h to form C6F5H (0.01 mmol), 4-(2,3,5,6-
tetrafluorophenyl)morpholine (0.30 mmol) and 4-(2,3,4,5-tetrafluorophenyl)morpholine 19 (0.05
mmol) at 79% conversion of K[C6F5BF3] (residual 0.09 mmol) (19F NMR). The solution was
diluted with water (15 mL), and the products were steam distilled. The distillate was acidified with
5% HCl, extracted with CHCl3, and the extract was dried with MgSO4. The solvent was removed
under reduced pressure to give a mixture of tetrafluorophenylmorpholines 2 and 19 (white solid)
(53 mg) (96:4).
4-(2,3,5,6-Tetrafluorophenyl)morpholine (2) (mixture with 19). 1H NMR (CH2Cl2):  6.66
(tt, 4J(H4, F2,6) = 7 Hz, 3J(H4, F3,5) = 10 Hz, 1H, H4), 3.69 (m, 4H, Hβ), 3.17 (m, 4H, Hα). 19F NMR
(CH2Cl2):  –141.9 (ddd, 3J(F3, F2) = 20 Hz, 5J(F3, F6) = 10 Hz, 3J(F3, H4) = 10 Hz, 2F, F3,5), –
151.8 (ddd, 3J(F2, F3) = 20 Hz, 5J(F2, F5) = 10 Hz, 4J(F2, H4) = 8 Hz, 2F, F2,6) (lit. [23]: 1H NMR
(CDCl3):  6.71 (tt, 3J(H, F) = 7.2 Hz, 2J(H, F) = 9.8 Hz, 1H), 3.82 (m, 4H), 3.27-3.29 (m, 4H). 19F
NMR (CDCl3):  –140.7 (m, 2F), –151.6 (m, 2F)).
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4-(2,3,4,5-Tetrafluorophenyl)morpholine (19) (mixture with 2). 1H NMR (CH2Cl2):  6.50
(dddd, 3J(H6, F 5) = 12 Hz, 4J(H6, F4) = 8 Hz, 4J(H6, F2) = 8 Hz, 5J(H6, F3) = 3 Hz, 1H, H6), 3.73
(m, 4H, Hβ), 2.94 (m, 4H, Hα). 19F NMR (CH2Cl2):  –141.2 (ddd, 3J(F5, F4) = 22 Hz, 5J(F5, F2) =
11 Hz, 3J(F5, H6) = 11 Hz, 1F, F5), –150.9 (ddd, 3J(F2, F3) = 19 Hz, 5J(F2, F5) = 11 Hz, 4J(F2, H6) =
8 Hz, 1F, F2), –157.9 (dd, 3J(F3, F2) = 19 Hz, 3J(F3, F4) = 20 Hz, 1F, F3), –167.6 (ddd, 3J(F4, F5) =
22 Hz, 3J(F4, F3) = 20 Hz, 4J(F4, H6) = 8 Hz, 1F, F4). HRMS (ESI), m/z: calcd. for C10H9F4NO
235,0620; found 235.0614 (isomer mixture).
4.2.6. K[C6F5BF3] (137 mg, 0.50 mmol), morpholine (104 mg, 1.2 mmol) and K2CO3 (138 mg, 1.0
mmol) were kept in DMF (1 mL) at 150 C for 4 h. The 19F NMR spectrum showed signals of
K[C6F5BF3] and 2 (93:7) besides C6F5H (trace). Similar results were obtained in DMAс, NMP and
DMSO.
4.3. Reaction of K[C6F5BF3] with sodium diethylamide
Diethylamine (58 mg, 0.80 mmol), NaH (28 mg, 0.70 mmol) and DMSO (1 mL) were
stirred at 25 C for 1 h. K[C6F5BF3] (137 mg, 0.50 mmol) and C6H5F (48 mg, 0.50 mmol)
(quantitative internal reference) were added, the suspension was stirred at 130 C for 4 h in a
sealed tube, cooled to 25 C and filtered. The solution contained K[C6F5BF3] besides minor
unknown products (19F NMR).
4.4. Reaction of K[C6F5BF3] with sodium morpholinide
4.4.1. Morpholine (38 mg, 0.44 mmol) and NaH (15 mg, 0.37 mmol) in diglyme (0.4 mL) were
stirred at 25 C for 1.5 h, diluted with diglyme (2 mL), and K[C6F5BF3] (107 mg, 0.39 mmol) and
C6H5F (48 mg, 0.50 mmol) (quantitative internal reference) were added. The suspension was
stirred at 130 C for 4 h in a sealed tube, cooled to 25 C and filtered. The solution contained
K[C6F5BF3] (>0.35 mmol) besides minor unknown products (19F NMR).
4.4.2. The reaction of sodium morpholinide [from morpholine (70 mg, 0.8 mmol) and NaH (28 mg,
0.7 mmol)] with K[C6F5BF3] (137 mg, 0.5 mmol) in DMSO (1 mL) was performed similar way.
The 19F NMR spectrum showed signals of K[C6F5BF3], C6F5H and K[BF4] (90:5:5).
4.5. Preparation of potassium 4-(pyrrol-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborate (4)
A 10 mL flask was charged with NaH (56 mg, 1.4 mmol), DMF (2 mL), and pyrrole (115
mg, 1.6 mmol). The reaction mixture was stirred at 25 C for 30 min in the atmosphere of dry
argon and K[C6F5BF3] (274 mg, 1.0 mmol) was added. The flask was closed with a stopper and the
reaction mixture was magnetically stirred at 130 C for 4 h. After cooling to 25 C, the solvent was
11
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evaporated at reduced pressure. The residue was stirred at 25 °С for 8 h with water (0.2 mL) and
K[HF2] (780 mg, 10 mmol), diluted with MeCN (5 mL) and stirred with K2CO3 (50 mg) for 1–2 h.
The suspension was filtered through silica gel (60 μm), which was washed additionally with
acetonitrile (10 mL). The combined solution was evaporated at reduced pressure to yield 4 (white
solid) (276 mg, 86%).
K[4-C4H4NC6F4BF3] (4). 1H NMR (CH3CN):  6.92 (m, 2H), 6.32 (m, 2H). 1H NMR
(acetone):  7.11 (m, 2H), 6.45 (m, 2H). 11B NMR (acetone):  1.82 (q, 1J(B, F) = 41 Hz, BF3). 19F
NMR (CD3CN):  –133.7 (ddq, 3J(F2, F3) = 23 Hz, 5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F,
F2,6), –135.0 (q (1:1:1:1), 1J(F, B) = 42 Hz, 3F, BF3), –152.9 (dd, 3J(F3, F2) = 23 Hz, 5J(F3, F6) = 12
Hz, 2F, F3,5). 19F NMR (acetone):  –134.3 (m, 2F, F2,6), –133.4 (m, 3F, BF3), –153.5 (m, 2F, F3, 5).
19F NMR (DMF):  –133.2 (q (1:1:1:1), 1J(F, B) = 45 Hz, 3F, BF3), –133.9 (ddq, 3J(F2, F3) = 23
Hz, 5J(F2, F5) = 12 Hz, 4J(F2, BF3) = 12 Hz, 2F, F2,6), –153.0 (dd, 3J(F3, F2) = 24 Hz, 5J(F3, F6) =
11 Hz, 2F, F3, 5). IR (KBr): 3147 (w), 1656 (m), 1529 (m), 1454 (vs), 1397 (w), 1380 (w), 1332
(w), 1302 (w), 1251 (m), 1231 (s), 1112 (m), 1069 (m), 1038 (m), 1003 (m), 974 (s), 950 (vs), 852
(w), 778 (m), 760 (w), 726 (m), 712 (m), 637 (w), 597 (w), 446 (w) cm-1.
Anal. calcd for C10H4BF7KN (321.04): C, 37.41; H, 1.26; F, 41.42; found: C, 37.6; H, 1.50;
F, 41.7.
4.6. Preparation of potassium 4-(indol-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborate (9)
4.6.1. A 10 mL flask was charged with DMF (5 mL), NaH (71 mg, 1.77 mmol) and indole (220
mg, 1.86 mmol), and the reaction mixture was stirred at 25 C for 1 h at the atmosphere of dry
argon to form yellowish solution. K[C6F5BF3] (423 mg, 1.54 mmol) was added, and the reaction
mixture was magnetically stirred at 100 C for 4 h. The 19F NMR spectrum showed resonances of
[C6F5BF3]– and [4-C8H6NC6F4BF3]– (2:8). K[HF2] (838 mg, 10.7 mmol) were added, and the
mixture was stirred at 25 °С for 24 h. The suspension was filtered through a glass filter, the flask
and the filter cake were washed with acetone (2x5 mL) and washings were combined with filtrate.
The solvent was distilled off at reduced pressure. The residual solid was washed with ether (10
mL) and dried. The white solid (327 mg) consisted of 9 and 1 (9:1).
4.6.2. A 10 mL flask was charged with DMF (5 mL), NaH (54 mg, 1.35 mmol) and indole (163
mg, 1.39 mmol), and the reaction mixture was stirred at 25 C for 1 h in the atmosphere of dry
argon to form yellowish solution. Then K[C6F5BF3] (278 mg, 1.0 mmol) was added, and reaction
mixture was magnetically stirred at 130 C for 4 h. The 19F NMR spectrum of the mother liquor
contained resonances of [C6F5BF3]–, [4-C8H6NC6F4BF3]–, [3,4-(C8H6N)2C6F4BF3]– (6:88:6).
K[HF2] (788 mg, 10 mmol) was added, and the mixture was stirred at 25 °С for 19 h. The
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suspension was filtered through a glass filter, the flask and filter cake were washed with acetone
(3x3 mL) and washings were combined with filtrate. The solvent was distilled off at reduced
pressure, and the residue was washed with ether (3x4 mL). After recrystallization from MeOH the
residual white solid was dried in air to yield 9 (273 mg, 74%).
K[4-C8H6NC6F4BF3] (9). 1H NMR (acetone):  7.65 (d, 3J(H4, H5) = 7 Hz, 1H, H4), 7.41 (d,
3J(H2, H3) = 3 Hz, 1H, H2), 7.20–7.14 (m, 3H, H5,6,7), 6.74 (d, 3J(H3, H2) = 3 Hz, 1H, H3). 19F
NMR (acetone):  –133.5 (m, 2F, F2,6), –133.8 (q (1:1:1:1), 1J(F, B) = 43 Hz, 3F, BF3), –150.3 (dd,
3J(F3, F2) = 21 Hz, 5J(F3, F6) = 11 Hz, 2F, F3,5). 19F NMR (DMF):  –133.1 (q (1:1:1:1), 1J(F, B) =
43 Hz, 3F, BF3), –133.5 (m, 2F, F2,6), –150.4 (dd, 3J(F3, F2) = 21 Hz, 5J(F3, F6) = 11 Hz, 2F, F3,5).
IR (KBr): 3058 (vw), 1651 (m), 1533 (m), 1514 (w), 1450 (vs), 1369 (w), 1304 (w), 1251 (m),
1265 (m), 1198 (s), 1130 (w), 1103 (m), 1070 (m), 1024 (m), 953 (vs), 854 (w), 785 (w), 769 (w),
746 (m), 714 (m), 640 (w), 422 (vw) cm-1.
Anal. calcd for C14H6BF7KN (371.11): C, 45.31; H, 1.63; F, 35.84, N, 3.77; found: C, 44.7;
H, 1.90; F, 35.9, N, 3.75.
4.7. Preparation of potassium imidazol-1-ide
A 250 mL flask was charged with imidazole (68.1 g, 1 mol), KOH (56.1 g, 1 mol), and
intensively shaken until all mixture liquidified. Then it was warmed for 30 min in a boiling water
bath and volatiles were evaporated to dryness at 130–140 C (bath) in high vacuum. Potassium
imidazol-1-ide (104 g, 98%) was stored in dry argon atmosphere before use.
4.8. Reaction of K[C6F5BF3] with alkali imidazol-1-ide
4.8.1. Preparation of potassium 4-(imidazol-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborate (5)
A 10 mL flask equipped with a magnetic stir bar was charged with potassium imidazol-1-
ide (64 mg, 0.6 mmol), DMF (1 mL), and K[C6F5BF3] (137 mg, 0.5 mmol) and mounted in a pre-
heated oil bath (80 C). The reaction mixture was stirred for 8 h, cooled to 25 C, and the solvent
was evaporated at reduced pressure. The residue was suspended in MeCN, filtered through silica
gel (60 m) and the filtrate was evaporated to dryness in vacuum to give 5 (white solid) (153 mg,
93%).
K[4-C3H3N2C6F4BF3] (5). 1H NMR (CH3CN):  7.72 (s, 1H, H2), 7.28 (s, 1H, H5), 7.31 (s,
1H, H4). 1H NMR (acetone):  8.02 (s, 1H, H2), 7.55 (s, 1H, H5), 7.33 (s, 1H, H4). 11B NMR
(acetone):  1.74 (q, 1J(B, F) = 42 Hz, BF3). 19F NMR (CD3CN):  –133.7 (m, 2F, F2,6), –133.9 (q
(1:1:1:1), 1J(F, B) = 42 Hz, 3F, BF3), –152.1 (dd, 3J(F3, F2) = 22 Hz, 5J(F3, F6) = 11 Hz, 2F, F3,5).
19F NMR (acetone):  –132.2 (m, 2F, F2,6), –133.9 (q (1:1:1:1), 1J(F, B) = 41 Hz, 3F, BF3), –152.5
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(dd, 3J(F3, F2) = 24 Hz, 5J(F3, F6) = 12 Hz, 2F, F3,5). IR (KBr): 3139 (w), 2927 (w), 1655 (m), 1632
(m), 1522 (m), 1457 (vs), 1404 (w), 1350 (w), 1291 (w), 1256 (m), 1211 (s), 1111 (m), 1085 (m),
1059 (m), 1033 (m), 998 (s), 958 (vs), 907 (w), 880 (w), 863 (w), 817 (w), 784 (m), 760 (w), 745
(m), 654 (m), 636 (m), 613 (w) cm-1.
Anal. calcd for C9H3BF7KN2 (322.03): C, 33.57; H, 0.94; F, 41.30; N, 8.70; found: C, 35.1;
H, 1.33; F, 41.1; N, 9.24.
4.8.2. The reaction of potassium imidazol-1-ide (64 mg, 0.6 mmol) with K[C6F5BF3] (137 mg, 0.5
mmol) in NMP or DMSO (1 mL) was performed similar way at 80 C for 8 h to give the same
result (19F NMR, quantitative internal standard C6H5CF3 (10 μL, 0.082 mmol)). When the reaction
was performed at 60 C for 4 h in DMF, MeOH, MeCN or DME, the conversion of K[C6F5BF3]
was 62, 60, 23 and 0 %, respectively.
4.8.3. A 10 mL flask was successively charged with DMF (2.5 mL), NaH (54 mg, 1.35 mmol) and
imidazole (80 mg, 1.17 mmol). The suspension was stirred at 25 C for 1 h in the atmosphere of
dry argon to form a solution. K[C6F5BF3] (236 mg, 0.86 mmol) was added, and the reaction
mixture was magnetically stirred at 80 C for 8 h. After cooling to ambient temperature, K[HF2]
(0.8 g, 10 mmol) was added. The suspension was stirred for 19 h and filtered through a glass filter.
The solvent was evaporated at reduced pressure to give a 232 mg mixture of 5 (0.72 mmol), 1
(0.06 mmol) and 6 (0.06 mmol) (19F NMR).
4.9. Reaction of K[C6F5BF3] with alkali benzimidazol-1-ide
4.9.1. A 10 mL flask was charged with DMF (1 mL), NaH (14 mg, 0.35 mmol) and benzimidazole
(47 mg, 0.40 mmol). After stirring at 25 C for 1 h in the atmosphere of dry argon, K[C6F5BF3] (69
mg, 0.25 mmol) was added in one portion, the flask was closed with a stopper, mounted in a pre-
heated oil bath, and the reaction mixture was stirred at 80–130 C over a period of 4–8 h (Table 1).
The conversion of K[C6F5BF3] and the yield of 11 were determined from 19F NMR spectra with
C6H5CF3 (10 μL, 0.082 mmol) as the quantitative internal standard after cooling to 25 C. The
reaction at 130 C was performed with K[C6F5BF3] (137 mg, 0.50 mmol), NaH (28 mg, 0.70
mmol) and benzimidazole (95 mg, 0.80 mmol) in 1 mL of DMF, and gave M[C6F5BF3] (0.02
mmol) (96% conversion), M[4-C7H5N2C6F4BF3] (0.15 mmol), C6F5H (0.03 mmol), 1-(2,3,5,6-
tetrafluorophenyl)benzimidazole (0.12 mmol) and 12 (0.06 mmol).
4.9.2. A 30 mL flask was charged with DMSO (7 mL), benzimidazole (250 mg, 2.13 mmol) and
NaH (124 mg, 3.10 mmol) was added in one portion. The reaction mixture was stirred at 25 C for
1 h. K[C6F5BF3] (423 mg, 1.54 mmol) was added into the solution, and the reaction set was
mounted into a pre-heated (100 C) oil bath. The solution was magnetically stirred at 100 C for 5
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h. After cooling to 25 C, K[HF2] (2 g) was added, and the suspension was stirred at 25 °С
overnight. The suspension was filtered through a glass filter, and the filtrate was poured out onto
CHCl3 (15 mL). The precipitate was separated by centrifugation, washed with CHCl3 (8 mL), and
dried in a vacuum desiccator yielding white powder (410 mg) which consisted of 11 and 12 (91:9).
K[4-C7H5N2C6F4BF3] (11). 1H NMR (acetone):  8.29 (m, 1H, H2), 7.75 (m, 1H), 7.37 (m,
1H), 7.29 (m, 2H). 11B NMR (acetone):  1.75 (q, 1J(B, F) = 42 Hz, BF3). 19F NMR (acetone):  –
132.8 (m, 2F, F2,6), –133.9 (q (1:1:1:1), 1J(F, B) = 40 Hz, 3F, BF3), –150.4 (dd, 3J(F3, F2) = 23 Hz,
5J(F3, F6) = 11 Hz, 2F, F3,5). IR (KBr): 3124 (w), 2924 (vw), 1651 (w), 1614 (m), 1587 (s), 1495
(s), 1468 (vs), 1305 (m), 1290 (m), 1261 (s), 1217 (s), 1196 (m), 1152 (w), 1128 (m), 1101 (m),
1026 (s), 964 (vs), 895 (w), 875 (w), 858 (w), 781 (m), 764 (m), 742 (s), 636 (w) cm-1.
K[3,4-(C7H5N2)2C6F3BF3] (12) (mixture with 11). 1H NMR (acetone):  8.11 and 7.96 (s,
2H, H2), 7.50–7.46 (m, 2H), 7.38–7.33 (m, 2H), 7.21–6.96 (m, 4H) (stereomer A); 8.07 and 7.94
(s, 2H, H2), 7.50–7.46 (m, 2H), 7.38–7.33 (m, 2H), 7.21–6.96 (m, 4H) (stereomer B). 19F NMR
(acetone):  –114.6 (m, 1F, F2), –124.3 (m, 1F, F6), –135.1 (m, 3F, BF3), –148.8 (m, 1F, F5)
(stereomer A); –114.9 (m, 1F, F2), –124.3 (m, 1F, F6), –135.1 (m, 3F, BF3), –149.5 (m, 1F, F5)
(stereomer B) (tentitive assignment).
4.10. Preparation of potassium 4-(pyrazol-1-yl)-2,3,5,6-tetrafluorophenyltrifluoroborate (7)
A 100 mL two-necked flask was equipped with a magnetic stir bar and topped with a T-
piece. The reactor was evacuated and filled with dry argon. It was charged with DMF (20 mL),
NaH (327 mg, 8.2 mmol), and pyrazole (454 mg, 6.6 mmol) was added in portion with stirring.
After 30–40 min a clear solution was formed. K[C6F5BF3] (1.515g, 5.5 mmol) was added In the
atmosphere of dry argon. The flask was mounted into a hot oil bath and the reaction mixture was
stirred at 80 C for 7 h. K[HF2] (2.15 g, 27 mmol) was added, and the suspension was stirred at 25
°С overnight. The solvent was removed at 15–17 Torr and 55–65 C (bath), the residual oil was
washed with hexane (3x20 mL), dried at reduced pressure and extracted with acetone (4x10 mL).
The solvent was removed from an evaporator, brownish oil was washed with CH2Cl2 (6x5 mL) and
the formed white solid was dried on air. Yield of 7 was 1.14 g (64%) (contaminated with ≤8% of
8).
K[4-C3H3N2C6F4BF3] (7). 1H NMR (acetone):  7.94 (d, 3J(H3, H4) = 2.4 Hz, 1H, H3), 7.73
(d, 3J(H5, H4) = 2.0 Hz, 1H, H5), 6.52 (dd, 3J(H4, H3) = 2.4 Hz, 3J(H4, H5) = 2.0 Hz, 1H, H4). 11B
NMR (acetone-d6):  1.76 (q, 1J(B, F) = 40 Hz, BF3). 19F NMR (acetone):  –134.0 (m, 5F, F2,6 and
BF3), –151.9 (m, 2F, F3,5). IR (KBr): 3132 (w), 1657 (m), 1537 (m), 1510 (m), 1464 (vs), 1416
(w), 1402 (m), 1327 (w), 1269 (m), 1211 (s), 1198 (m), 1097 (s), 1036 (s), 1024 (s), 995 (s), 961
15
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(vs), 916 (w), 880 (w), 862 (w), 843 (w), 779 (s), 762 (m), 748 (m), 633 (m), 608 (w), 446 (w) cm-
1
.
Anal. calcd for C9H3BF7KN2 (322.03): C, 33.57; H, 0.94; F, 41.30, N, 8.70; found: C, 33.1;
H, 0.92; F, 41.2, N, 8.50.
K[3,4-(C3H3N2)2C6F3BF3] (8) (mixture with 7). 1H NMR (acetone):  7.49 (md, 3J(H3, H4)
= 2.4 Hz, 1H, H3), 7.46 (md, 3J(H5, H4) = 2.0 Hz, 1H, H5), 6.24 (dd, 3J(H4, H3) = 2.4 Hz, 3J(H4, H5)
= 2.0 Hz, 1H, H4) (pyrazolino group at position 3), 7.53 (md, 3J(H3, H4) = 2.4 Hz, 1H, H3), 7.50
(md, 3J(H5, H4) = 2.0 Hz, 1H, H5), 6.25 (dd, 3J(H4, H3) = 2.4 Hz, 3J(H4, H5) = 2.0 Hz, 1H, H4)
(pyrazolino group at position 4) (tentitive assignment). 19F NMR (acetone):  –116.6 (m, 1F, F2), –
125.9 (m, 1F, F6), –134 (m, 3F, BF3), –151.2 (m, 1F, F5).
4.11. Competitive reaction of C6F5C6H5 with sodium morpholin-1-ide and sodium indol-1-ide
4.11.1. A 20 mL flask was charged with DMF (5 mL) and NaH (59 mg, 1.47 mmol). Solution of
indole (122 mg, 1.04 mmol) and morpholine (103 mg, 1.18 mmol) in DMF (1 mL) was added in
one portion, and the reaction mixture was stirred at 25 C for 1 h in the atmosphere of dry argon.
C6F5C6H5 (236 mg, 0.96 mmol) was added, and the reaction mixture was magnetically stirred at
130 C for 4 h. After cooling to 25 C, the solution was poured out onto water (20 mL), the
precipitate was filtered off, washed with water and dried in a vacuum desiccator over Sicapent®.
Yield of 1-(2,3,5,6-tetrafluoro-4-phenylphenyl)indole (16) was 291 mg (88%).
1-(2,3,5,6-Tetrafluoro-4-phenylphenyl)indole (16). 1H NMR (acetone):  7.71 (d, 3J(H4, H5)
= 8 Hz, 1H, H4), 7.61 (d, 3J(H2, H3) = 3 Hz, 1H, H2), 7.62–7.52 (5H), 7.34–7.17 (3H), 6.83 (d,
3J(H3, H2) = 3 Hz, 1H, H3). 19F NMR (acetone):  –143.1 (dd, 3J(F3', F2') = 22 Hz, 5J(F3', F6') = 10
Hz, 2F, F3',5'), –147.2 (dd, 3J(F2', F3') = 22 Hz, 5J(F2', F5') = 10 Hz, 2F, F2',6'). IR (KBr): 3054 (w),
2924 (w), 2854 (w), 1651 (w), 1614 (w), 1529 (s), 1491 (vs), 1456 (m), 1438 (s), 1303 (w), 1279
(m), 1215 (m), 1151 (m), 978 (s), 791 (w), 766 (m), 744 (m), 725 (m), 696 (m), 648 (w) cm-1.
HRMS (ESI), m/z: calcd. for C20H11F4N 341.0827; found 341.0821.
4.11.2. A 20 mL flask was charged with DMF (5 mL) and NaH (130 mg, 3.25 mmol). The solution
of indole (113 mg, 0.96 mmol) and morpholine (87 mg, 1.00 mmol) in DMF (1 mL) was added in
one portion, and the reaction mixture was stirred at 25 C for 1 h in the atmosphere of dry argon.
C6F5C6H5 (508 mg, 2.08 mmol) was added, and the reaction mixture was magnetically stirred at
125 C for 4 h. The solution contained tetrafluorophenylindole 16 (1.0 mmol) while 4-(2,3,5,6-
tetrafluoro-4-phenylphenyl)morpholine was not detected (19F NMR).
4.12. Preparation of 4-(2,3,5,6-tetrafluoro-4-phenylphenyl)morpholine (17)
16
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C6F5C6H5 (190 mg, 0.77 mmol), morpholine (159 mmol, 1.82 mmol) and DMSO (1.5 mL)
were heated at 160 C for 1 h in a sealed tube. The semi-solid reaction mixture was poured out
onto water, the precipitate was filtered off, washed with water and dried in a vacuum desiccator
over Sicapent® to yield 17 (202 mg, 84%).
4-(2,3,5,6-Tetrafluoro-4-phenylphenyl)morpholine (17). 1H NMR (acetone):  7.44 (m, 5H,
C6H5), 3.72 (m, 4H, H3,5), 3.26 (m, 4H, H2,6). 19F NMR (acetone):  –145.6 (dd, 3J(F3', F2') = 21
Hz, 5J(F3', F6') = 9 Hz, 2F, F3',5'), –150.9 (dd, 3J(F2', F3') = 21 Hz, 5J(F2', F5') = 9 Hz, 2F, F2',6'). 19F
NMR (DMF):  –145.7 (dd, 3J(F3', F2') = 21 Hz, 5J(F3', F6') = 9 Hz, 2F, F3',5'), –151.0 (dd, 3J(F2', F3')
= 21 Hz, 5J(F2', F5') = 9 Hz, 2F, F2',6'). IR (KBr): 3057 (w), 2964 (m), 2912 (w), 2895 (w), 2855
(m), 1652 (w), 1516 (w), 1483 (vs), 1438 (s), 1400 (w), 1377 (w), 1363 (w), 1336 (w), 1285 (w),
1271 (m), 1256 (m), 1203 (w), 1178 (w), 1113 (s), 1072 (w), 1034 (w), 1011 (m), 974 (vs), 914
(m), 887 (m), 802 (w), 789 (w), 752 (m), 729 (m), 694 (m), 673 (w), 650 (w), 548 (w), 505 (w) cm-
1. HRMS (ESI), m/z: calcd. for C16H13F4NO 311,0933; found 311.0928.
4.13. Preparation of 1-(2,3,5,6-tetrafluorophenyl)benzimidazole (13)
NaH (117 mg, 2.92 mmol) was added to a solution of benzimidazole (252 mg, 2.15 mmol)
in DMF (5 mL) under stirring. The reaction mixture was stirred at 25 C for 1 h in the atmosphere
of dry argon. Pentafluorobenzene (313 mg, 1.86 mmol) was injected with a syringe. After stirring
at 25 C for 20 min, the flask was mounted in a pre-heated bath (70–75 C) for 1 h. The solution
was cooled to 25 C, poured into 5% HCl (20 mL), extracted with ether (2x15 mL), the extract was
washed with water, and dried with MgSO4. The solvent was evaporated at reduced pressure and the
residue was dried in a vacuum desiccator over Sicapent® to yield 13 (white solid) (142 mg, 29%).
1-(2,3,5,6-Tetrafluorophenyl)benzimidazole (13). 1H NMR (acetone):  8.33 (m, 1H, H2),
7.77 (m, 2H), 7.34 (m, 2H), 7.42 (m, 1H, H4'). 19F NMR (acetone):  –137.8 (m, 2F, F3',5'), –146.5
(m, 2F, F2',6'). HRMS (ESI), m/z: calcd. for C13H6F4N2 266.0467; found 266.0463.
4.14. Reaction of C6F6 with sodium indol-1-ide
An ampoule was flushed with dry argon, charged successively with DMF (5 mL), indole
(198 mg, 1.69 mmol) and NaH (70 mg, 1.75 mmol). In 1 h, hexafluorobenzene (1.11 g, 6 mmol)
was added, the ampoule was sealed and heated at 110 C for 4 h. The reaction mixture was poured
into 5% HCl (50 mL) and extracted with ether (2x15 mL). The extract was washed with brine,
dried with MgSO4, and the solvent was evaporated at reduced pressure to yield 1-
(pentafluorophenyl)indole (14) and 1,4-bis(indol-1-yl)tetrafluorobenzene (18) (1:1) (330 mg).
17
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1-(Pentafluorophenyl)indole (14) (mixture with 18). 1H NMR (acetone):  7.62 (d 8 Hz,
1H), 7.41 (m, 1H), 7.15–7.05 (3H), 6.67 (d, 3J(H3, H2) = 3 Hz, 1H, H3). 19F NMR (acetone):  –
146.4 (m, 2F, F2',6'), –156.0 (t, 3J(F4', F3',5') = 21 Hz, 1F, F4'), –162.3 (m, 2F, F3',5').
1,4-Bis(indol-1-yl)tetrafluorobenzene (18) (mixture with 14). 1H NMR (acetone):  7.54 (d
8 Hz, 1H), 7.41 (m, 1H), 7.15–7.05 (3H), 6.73 (d, 3J(H3, H2) = 3 Hz, 1H, H3). 19F NMR (acetone):
 –146.2 (s, 4F, F2',3',5',6'). HRMS (ESI), m/z: (mixture of 14 and 18). calcd. for C14H6F5N 14
283.0420; found 283.0421; calcd. for C22H12F4N2 18 380.0936; found 380.0946.
Acknowledgements
The study was supported by The Ministry of Education and Science of Russian Federation,
project 2012-1.2.1-12-000-1004-038.
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Table 1. Reaction of K[C6F5BF3] 1 with sodium benzimidazolide (1.4 equiv) in DMF
Run
Temperature, °С
Time, h Conversion of 1, % Ratio 11 : 12
1
130
100
80
4
4
4
8
4
96
84
60
86
96
71 : 29a
75 : 25
88 : 12
78 : 22
66 : 34
2
3
4
5b
100
100
a Besides C6F5H and 1-(2,3,5,6-tetrafluorophenyl)benzimidazole.
b 2.8 equivalent of sodium benzimidazolide.
20
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