Enhanced preparation of aryl and heteryl sulfur pentafluorides using mercury (II) oxide - hydrogen fluoride media as a fluorinating reagent

Article abstract of DOI:10.1016/j.jfluchem.2020.109635

We developed enhanced method for low temperature and good yield preparation of aryl and heteryl sulfur pentafluorides from chlorotetrafluorides using mercury oxide - hydrogen fluoride and mercury oxide - pyridinium poly(hydrogen fluoride) media as the fluorinating reagents.

Full text of DOI:10.1016/j.jfluchem.2020.109635

Journal of Fluorine Chemistry 239 (2020) 109635
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Enhanced preparation of aryl and heteryl sulfur pentafluorides using
mercury (II) oxide - hydrogen fluoride media as a fluorinating reagent
a
,
a
a
a
Olexandr I. Guzyr *, Volodymyr N. Kozel , Eduard B. Rusanov , Alexander B. Rozhenko ,
b
a
Volodymyr N. Fetyukhin , Yuriy G. Shermolovich
a
Institute of Organic Chemistry NAS of Ukraine, Murmanska str. 5, 02660, Kyiv, Ukraine
Life Chemicals Inc., 1A Dixie Avenue, Niagara-on-the-Lake, L0S 1J0, ON, Canada
b
A R T I C L E I N F O
A B S T R A C T
Keywords:
We developed enhanced method for low temperature and good yield preparation of aryl and heteryl sulfur
pentafluorides from chlorotetrafluorides using mercury oxide - hydrogen fluoride and mercury oxide - pyr-
idinium poly(hydrogen fluoride) media as the fluorinating reagents.
Fluorination
Sulfur fluorides
Organyl sulfur pentafluorides
Hydrogen fluoride
Mercury (II) oxide
1
. Introduction
form) with disulphides or thiols in the presence of alkali metal fluorides
[
14,15]. Prepared by this method tetrafluorosulfanyl chlorides RSF
are, in general, stable compounds, and similarly to SF
X (X = Cl, Br), are
undergoing radical promoted addition reactions to carbon-carbon mul-
tiple bonds [16,17]. However, the transformation of RSF Cl derivatives
to RSF by the exchange of the last chlorine atom remains extraordinary
4
Cl
The chemistry of “super-trifluoromethyl” pentafluorosulfanyl group
has reached considerable attention during last decades due to its unique
physical properties such as lipophilicity, large steric volume, and
5
4
electron-withdrawing nature [1–7]. These properties gave SF
rivatives ability to serve as the perspective alternatives to other
fluorine-containing groups (CF , C , CF(CF , CHF , OCF , SCF
SO CF ) in drug development for pharmaceutical and agrochemical
5
de-
5
challenge. Thus, the only reagent suitable for ambient temperature
preparation of aryl sulfur pentafluorides is anhydrous HF [14,18]. Other
3
2
F
5
3
)
2
2
3
3
,
2
3
2 3 5 3 2 3
compounds such as ZnF , SbF , SbF , BF , and Ag CO are rather of
industry [1,2]. An additional importance is that these compounds could
be formally regarded as the organic derivatives of robust and chemically
inert sulfur hexafluoride. Consequently, along with unique electronic
properties, and superior chemical stability to polyfluoroaliphatic coun-
terparts [5], pentafluorosulfanyl compounds have aroused considerable
interest for the application in material science as well [8–10].
seldom usage [14,19]. Moreover, the numbers of the suitable reagents
for the preparation of heteryl sulfur pentafluorides are limited to AgF
and IF
high temperatures, requiring considerable amounts (2 M equiv. for AgF
and up to 6 eq for IF ), and prolonged reaction times.
5
[20–22]. However, both of them are too costly, active only at
5
The common synthetic methods for the preparation of the com-
2. Results and discussion
pounds bearing SF
first is based on the radical addition of pentafluorosulphanyl halides
SF
5
groups were ascertained by two procedures. The
The basic strategies for the synthesis of aryl and heteryl sulfur
chlorotetrafluorides were developed by the research of Umemoto,
Dolbier, and Shibata groups [14,20–23]. They are generally based on the
reaction of excess of chlorine and the solution of disulfide 1 in aceto-
nitrile in the presence of potassium fluoride as fluorinating reagent. The
preparation of chlorotetrafluorides 6 passes through several stages and
includes the formation of intermediate sulfur (II) and sulfur (IV) halides
2 – 5 (Scheme 1). The course of the reaction is generally dependent on
5
X (X = Cl, Br) to carbon-carbon multiple bonds, and implementation
of the obtained products as the building blocks for the further chemical
transformations [2]. The second approach involves oxidative fluorina-
tion of divalent sulfur derivatives using elemental fluorine, or fluorides
in higher oxidation states (AgF
2
, XeF
2
), as the reagents [11–13]. The
modification of the last method is the two-step transformation involving
on the first stage the reaction of chlorine (gaseous or as incorporated
*
Corresponding author.
E-mail address: alexander@ioch.kiev.ua (O.I. Guzyr).
https://doi.org/10.1016/j.jfluchem.2020.109635
Received 19 June 2020; Received in revised form 1 September 2020; Accepted 3 September 2020
Available online 7 September 2020
0
022-1139/© 2020 Elsevier B.V. All rights reserved.

O.I. Guzyr et al.
Journal of Fluorine Chemistry 239 (2020) 109635
the order of the addition of the reagents. Thus, the reaction of disulfide 1
with excess of chlorine rises the generation of sulfur (IV) halides 4 [14].
Maintaining the deficient amount of the chlorine in the reaction mixture
favors the processes based on the disproportionation of intermediate
sulphenyl fluorides 3 [24].
While optimizing the preparation of starting chlorotetrafluorides 6a-
h we observed that use the large excess of chlorine in the earlier stage of
the reaction causes in some cases sequences of side processes such as
carbon-sulfur bond cleavage, and the chlorination of the aromatic ring.
We found, that these side processes could be minimized by maintenance
in the reaction mixture the steady deficient amount of chlorine. This was
realized by the slow addition of solution of chlorine in acetonitrile to the
reaction media. When the formation of aryl or heteryl sulfur trifluoride 5
as an intermediate product had accomplished (Scheme 1), and the ar-
omatic ring becomes deactivated by strong electron withdrawing SF
3
Scheme 2. Preparation of aryl and heteryl sulfur chlorotetrafluorides 6a-h.
substituent, the excess of the chlorine could be applied without any
precautions.
Using both methods, we prepared new as well as previously
described aryl and heteryl sulfur chlorotetrafluorides 6a-h (Scheme 2).
Method a is based on the treatment of the disulfide 1 in CH
the excess of chlorine. By this method we prepared following com-
pounds: p-O NC SF Cl (6b), 2-SF Cl-pyridine (6g), 2-SF Cl-pyrimi-
dine (6h, 2-SCl-pyrimidine was used as a starting material).
Method b is based on the maintenance in the reaction mixture the
deficient amount of the Cl . After the formation of RSF had accom-
plished, the excess of chlorine was applied. By this method we prepared
3
CN with
2
6
H
4
4
4
4
6 4 4
Scheme 3. Equilibrium in the solution of 2-Cl-4-F-C H SF Cl (6e).
2
3
following compounds: C
6
H
5
SF
4
Cl (6a), 3,5-F
SF Cl (6e), 2-SF
2
C
6
H
4
SF
4
Cl (6c), 2,4-
isomer is much lower than such of trans- one. Using this phenomenon we
separate cis- isomer by treatment of the mixture with 5 % water solution
of NaHCO
3
and monitoring the hydrolysis by 19F NMR spectroscopy. To
F
2 6
C H
4
SF Cl (6d), 2-Cl-4-FC
4
6
H
4
4
4
Cl-benzothiazole (6f).
Due to the steric hindrance caused by bulky chlorine substituent in
ortho- position to sulfur atom, the reaction of 2-chloro-4-fluorophenyldi-
sulfide 6e at the same conditions results in 2-chloro-4-fluorophenyl
sulfur trifluoride 5e as a main product. The formation of 2-chloro-4-flu-
orophenyl sulfur chlorotetrafluoride 6e takes place in low yield (8 % by
the best of our knowledge, we provided the first example for the isola-
tion of cis- organylsulfur chlorotetrafluoride from the isomers mixture.
1
9
F NMR spectrum of cis- isomer shows three groups of multiplets in low
field region with the integration 1:2:1, which was assigned to three types
of none-equivalent fluorine nuclei.
1
9
F NMR data). In response to equilibrium [14] in the solution of RSF
4
Cl
(
Scheme 3), addition the large excess of chlorine to the reaction mixture,
Our first attempts to convert novel heteryl sulfur chlorotetrafluorides
to pentafluorides by the methods described earlier in literature were
ambiguous. Thus, the reaction of 2-benzothiazolylsulfur chlorotetra-
fluoride 6f with AgF caused only the formation of decomposition
products. However, we found, that the preparation of aryl and heteryl
sulfur pentafluorides from chlorotetrafluorides could be achieved in
very smooth conditions (at room or low temperatures) by the employing
the mercury (II) oxide – hydrogen fluoride or mercury (II) oxide – pyr-
idinium poly(hydrogen fluoride) mixtures as fluorinating reagents
(Scheme 5). The reaction course could be easily monitored by color
change of the reaction mixture. The completion of the reaction corre-
sponds to change of orange color of mercury (II) oxide suspension to
grey of mercury (II) chloride.
leads to the change in the products distribution to higher amount of
sulfur (VI) derivative 6e (40 % by 19F NMR).
Major part of synthesized aryl and heteryl sulfur chlorotetrafluorides
exhibiting trans- configuration of tetragonal-bipyramidal environment
with four fluorine atoms in equatorial and single chlorine in axial po-
sitions to organic substituent attached to sulfur atom. These structures
were evaluated by the presence of the singlet for four magnetically
equivalent fluorine nuclei at low field region (+ 120 – +150 ppm) [14,
1
9–22].
The preparation of 2-benzothiazolylsulfur chlorotetrafluoride 6f re-
sults in a mixture of cis- and trans- isomers in proportion 4:1 (Scheme 4).
The formation of trans- isomer was concluded by the appearance of the
signal typical for trans- RSF
4
Cl: singlet at low field region (132.21 ppm).
It should be noted, that the first reports for the application of mer-
cury (II) oxide – hydrogen fluoride mixture as the fluorination reagent
The isomer mixture is not possible to separate by any common physical
methods. However, we found, that the rate of the hydrolyses of cis-
2
refers to 1938, when Henne attempts to prepare HgF by the reaction of
4
Scheme 1. Processes taking place in the course of the preparation of RSF Cl.
2

O.I. Guzyr et al.
Journal of Fluorine Chemistry 239 (2020) 109635
Scheme 4. Isolation of cis- 2-benzothiazolylsulfur chlorotetrafluoride 6f from isomers mixture.
HF produces the molecule of water, one could expect that half amount of
RSF Cl to be converted to RSO F as hydrolyses product. However, due to
4
2
the fact that the rate of chlorine-fluorine exchange is much higher, than
the hydrolysis reactions, we did not observed major increase of the
amount of sulfonyl fluoride in the mixture compared to the already
present in starting chlorotetrafluoride.
Our attempts to prepare 2-pyrimidiniumsulfur pentafluoride using
HgO/HF as fluorinating media failed. Instead we obtained 2-fluoropyr-
ymidine as a product of C–S bond cleavage reaction. However, the use of
less acidic pyridinium poly(hydrogen fluoride) as a second additive and
short reaction times, allows to prepare 2-pentafluorosulfanyl pyrimidine
in good yield.
The great advantage of this fluorinating method over described
previously processes is the ability to use stoichiometric amount of HgO
(
0.5 eq). Attempts to use catalytic amount of mercury oxide failed and
led to incomplete conversion of starting chlorotetrafluoride.
Compounds 7a-h were fully characterized by spectroscopic and
analytical methods. Pentafluorosulfanyl compounds exhibiting octahe-
1
9
4
dral environment around sulfur atom and showing AB -type F NMR
spectra at low field region: doublet for four equivalent fluorine nuclei in
equatorial, and quintet for axial fluorine with the correct integration 4:1
and coupling constants 2
J
(Fax–Feq) ranging close to 150 Hz value. The
signals for the ipso-carbon nuclei of aromatic and heterocyclic rings
attached to SF
substituents in 13C NMR spectra for the compounds 7a-h
are observed as multiplets at 140–170 ppm.
5
Scheme 5. Preparation of aryl and heteryl sulfur pentafluorides 7a-h.
3
. X-ray diffraction studies of 7f and 7h
HgO and HF using chloroform or dichloromethane as the solvents [25].
Instead, he obtained the solvent fluorination, and formation of CHF and
CH respectively. Interestingly, HgF itself does not show any reac-
tivity towards CHCl or CH Cl [25]. This method was further verified
Compounds 7f and 7h are low melting crystalline solids, and were
3
characterized by means single crystal X-ray crystallography. Compound
7f crystallizes in monoclinic space group P21/с. The molecular structure
and selected bond lengths and angles of 7f are given in Fig. 1.
The benzothiazole ring is planar. The sulfur atom exhibits distorted
2
F
2
2
3
2
2
on various aliphatic halides, and, later, by Olah, on haloketones using
pyridinium poly(hydrogen fluoride) as the second additive [26].
To the best of our knowledge, the character of reactive species in
HgO/HF and HgO/PPHF mixtures was not studied in details. Possibly,
these heterogeneous reactions are accompanied with the formation of
highly reactive nascent surface mercury fluoride or oxofluoride. Our
own observations partly support this conjecture. Thus, our attempts to
detect reactive species in PPHF/HgO liquid media by 1 F NMR spec-
troscopy showed no signals which could be attributed to mercury fluo-
octahedral environment. The axial and equatorial S
comparable and are 1.55(3) and 1.56 Å respectively.
Compound 7h crystallizes in tetragonal space group P4 2 2. The
–
F bond lengths are
1
1
pyrimidine cycle in 7h is also planar. The C1-S1 bond distance value in
7h is 1.829(4) Å is elongated in comparison to those of 7f (1.719 Å) and
average for Ar-SF5 (ca. 1.8 Å) which, possibly, responds to ease of its
9
cleavage. Average S
The equatorial fluorine atoms in 7h are twisted out of the equatorial
–
F distances values are 1.577(2) Å.
◦
rides. Interestingly, despite the fact that HgF
pyridiniumsulfur chlorotetrafluoride [20], HgO/HF mixture success-
fully converts 2-SF Cl-pyridine to 2-SF -pyridine at room temperature.
2
is inert towards 2-
plane by 3.53 towards the axial fluorine. Similar to 7f the axial and
equatorial S F bond lengths are comparable and are of 1.578 and 1.577
Å respectively (Fig. 2)
–
4
5
Starting aryl and heteryl sulfur chlorotetrafluorides 6a-h after the
work-up could be used as crude products for the next fluorination stage
without any further purification. The minor impurities are sulphonyl
4
. DFT calculations of 2-pentafluorosulfanyl pyrimidine (7h)
2
fluorides RSO F, sulfinil fluorides RSOF, and acetonitrile which does not
The DFT calculations carried out for 2-pentafluorosulfanyl pyrimi-
affects the further fluorination processes.
dine showed that an optimized structure of 7h (Fig. 3) possesses C2v
symmetry with four identical S F equatorial distances (1.614 Å) and
4
It is important to notice, that since the reaction of RSF Cl with HgO/
–
3

O.I. Guzyr et al.
Journal of Fluorine Chemistry 239 (2020) 109635
to the nitrogen lone pairs intrudes between the -MOs of the aromatic
π
moiety in 7a, transposing the HOMO and HOMO-1.
Despite a formal similarity between molecules 7h and 7a, the cor-
responding electrostatic potential surfaces (Fig. 5) differ significantly.
While in the both compounds large negative ESP is associated with
electronegative fluorine atoms, in 7a, another center with negative ESP
5
was unexpectedly found in para- and meta- positions to SF group. In
contrast, large negative electrostatic potential is concentrated on ni-
trogen atoms that is even higher than that found for the fluorine atoms in
5
the SF group, whereas the meta- and para- positions do not show
negative ESP. Thus, the newly synthesized building block 7h will
demonstrate definitely different behavior towards binding sites of
proteins.
Fig. 1. Molecular structure of 2-pentafluorosulfanyl benzothiazole 7f. Selected
bond lengths [Å] and agles [º]: C1-S1 1.716(5) Å, C1-S2A 1.801(6) Å, S2A-F1A
5
. Conclusions
1
.55(3) Å, S1-Feq (av) 1.56 Å, C1-S2A-Feq(av) 89.53, F1A-S2A-Feq(av) 90.75.
In summary, we provided convenient synthetic method for the con-
version of aryl and hereryl sulfur chlorotetrafluorides to pentafluorides
using stoichiometric amount of HgO (0.5 eq), and HF or PPHF as a
second additive as the fluorinating reagents. The presented reaction is
the first example of mild conversion of heteryl sulfur chlorotetra-
fluorides to pentafluorides. X-ray crystallographic analysis of 2-SF
5
-
benzothiazole and 2-SF -pyrimidine showed distorted octahedral envi-
5
ronment of sulfur atom and elongated C
–
S bond length for pyr-
imidinium compound.
6
. Experimental
.1. General
All experiments involving air sensitive compounds were performed
6
under inert atmosphere (dry Ar) using dry solvents and standard Schlenk
techniques. The reactions with corrosive anhydrous HF and pyridinium
poly(hydrogen fluoride) (PPHF) were carried out in sealed Nalgene
Fig. 2. Molecular structure of 7h. Selected bond lengths [Å] and agles [º]: C1-
S1 1.829(4) Å, S1-F3 1.578 Å, S1-Feq(av) 1.577 Å, C1-N1 1.320 Å C2-N1 1.345
◦
(
4) Å. N1-C1-N1A 129.4 , C1-S1-Feq(av) 91.75, F3-S1-Feq(av) 88.22.
6 5 4 2 6 4 4
polypropylene bottles. Starting C H SF Cl (6a), p-O NC H SF Cl (6b),
and 2-SF Cl-pyridine (6g) were obtained according to the known pro-
4
one slightly shorter axial S
–
F bond (1.604 Å) coinciding with the C
2
cedures [14,20]. Commercially available spay-dried KF (Aldrich) was
–
–
S
additionally dried at 220 C in high vacuum (0.03 Torr) for 8 h prior to
◦
axe. The C S bond length (1.872 Å) is definitely longer that the C
bond length calculated under the same conditions for the nitrogen-free
homologue PhSF (7a) (1.832 Å). The NCN bond angle (129.1) is
noticeably increased compared to the expected for the aromatic ring
value of 120 and the magnitude derived for PhSF (121.7). Calculated
NBO charge distribution in 7h demonstrates a slight deficiency of charge
on SF group (0.109 e). Taking into account the high positive charge at
the ipso-carbon (0.229), the found charge transfer cannot be referred
only to a C S bond polarization, but to the charge transfer from SF
group to the aromatic moiety.
use. Acetonitrile was distilled over CaH . Reagent grade mercury (II)
2
◦
5
oxide was dried in high vacuum at 80 C. The toxic Hg-containing wastes
should be handled and recovered using literature described methods
[25] or, alternatively, by authorized mercury waste management facil-
ities. The preparation of aryl and heteryl sulfur chlorotetrafluorides
5
1
13
5
were carried out in Teflon reactors. H (400.08 MHz), C (100.62 MHz),
1
9
F (188.14 and 376.43 MHz) NMR spectra were recorded on Varian
–
VXR-400 and Varian Gemini-200 spectrometers at room temperature,
chemical shift values were measured relative to TMS (internal standard).
5
1
9
The highest occupied molecular orbitals (MOs) of 7h and 7a are
compared in Fig. 4. As one can see, including the electronegative ni-
trogen atoms lowers the occupied MOs. The MO corresponding mainly
6 6
F NMR spectra were recorded using C F as external standard and the
chemical shifts were converted into δ scale relative to CCl F. HPLC/MS
3
analyses were carried out using a system consisting of an Agilent 1100
Fig. 3. Equilibrium (B3LYP/cc-pVTZ) structures of 7h and 7a.
4

O.I. Guzyr et al.
Journal of Fluorine Chemistry 239 (2020) 109635
Fig. 4. The highest occupied molecular orbitals of 7h (top) and 7a (bottoms).
Fig. 5. Electrostatic potential surface calculated for 7h and 7a. Color code: red –negative ESP, blue – positive ESP (For interpretation of the references to colour in
this figure legend, the reader is referred to the web version of this article).
Series high performance liquid chromatography equipped with a diode
matrix and an Agilent LC/MSD SL mass selective detector (ionization
method: electrospray ionization under atmospheric pressure). GC/MS
data were obtained on the Hewlett-Packard 5890/5972 apparatus
δ -105.01 (m, 2 F, aromat F), 137.54 (s, 4 F, S-Feq).
6.1.2. Preparation of 2,4-F SF Cl (6d)
2
C
6
H
3
4
The solution of Cl
2
(23.00 g, 324.00 mmol) in dry CH
3
CN (230 mL)
◦
(
GC/MS) at 70 eV in the electron impact mode. Infrared spectra were
was added dropwise at 20 C over the period of 4 h to the vigorously
recorded on a Bruker Vertex 70 spectrometer. Melting point values were
determined with a Boetius device. Elemental analyses were performed at
the microanalytical laboratory of the Institute of Organic chemistry,
National Academy of Sciences of Ukraine.
stirred solution of (2,4-C
of spay-dried KF (32.02 g, 551.17 mmol) in dry CH
reaction mixture was stirred overnight. The precipitate filtered off, the
filtrate evaporated at 15 Torr leaving crude 2,4-F SF Cl (19.10 g)
6
H
3
S)
2
(10.00 g, 35.45 mmol), and suspension
3
CN (100 mL). The
2 6
C H
3
4
as a pale-yellow liquid. The crude product was distilled in vacuum (8
◦
6
.1.1. Preparation of 3,5-F
2
C
6
H
3
SF
4
Cl (6c)
Torr), collecting fraction boiling at 60 C. Yield: 8.95 g. The distilled
The solution of Cl
2
(15.20 g, 214.36 mmol) in dry CH
3
CN (150 mL)
product according to 19F NMR data was obtained as a mixture of 2,4-
◦
was added dropwise at 20 C over the period of 3 h to the vigorously
F
F
2
C
C
6
H
H
3
SF
SO
4
Cl (88 %), 2,4-F SF
2
C
6
H
3
3
(12 %), and some traces of 2,4-
stirred solution of (3,5-C
spay-dried KF (22.10 g, 38.30 mmol) in dry CH
action mixture was stirred overnight. The precipitate filtered off, the
filtrate evaporated at 15 Torr leaving 3,5-F SF Cl as a pale-yellow
liquid. Yield: 11.81 g (97 %) The crude product which was used for the
next stage without further purification. 19F NMR (376.43 MHz, CH
CN):
6
H
3
S)
2
(6.90 g, 23.77 mmol), and suspension of
2
6
3
2
F and 2,4-F C H SOF, and used for the next stage without
2 6 3
3
CN (200 mL). The re-
further purification. Spectroscopic data for this compound have been
already reported [19].
C
2 6
H
3
4
3
5

O.I. Guzyr et al.
Journal of Fluorine Chemistry 239 (2020) 109635
6
.2. Preparation of 2-Cl-4-F-C
6
H
3
SF
4
Cl (6e)
4
6.5. Preparation of 2-SF Cl-pyrimidine (6h)
The solution of Cl
2
(20.00 g, 282.00 mmol) in dry CH
3
CN (220 mL)
2-SCl-Pyrimidine (6.18 g, 42.00 mmol) was added rapidly via pipette
to the vigorously stirred solution of Cl (6.58 g, 93.00 mmol), and the
◦
was added dropwise at 20 C over the period of 4 h to the vigorously
2
stirred solution of (2-Cl-4-F-C
6
H
3
S)
2
(10.00 g, 30.94 mmol), and sus-
CN (150
suspension of potassium fluoride (17.70 g, 294.00 mmol) in acetonitrile
(80 mL). The reaction mixture was stirred overnight, the precipitate
filtered off, and the filtrate evaporated at 12 Torr. The oily residue was
pension of spay-dried KF (35.00 g, 602.00 mmol) in dry CH
3
mL). The reaction mixture was stirred overnight. The excess of chlorine
gas was introduced into the reaction mixture over the period of 20 min
till the completion of absorption. The suspension was stirred at ambient
conditions for another 20 h.
◦
1
distilled in vacuum. B.p. 60 C/0.07 Torr. Yield: 5.98 g (64 %) H NMR
(300 MHz, CDCl
): δ 7.55 (t, JHH =4.7 Hz, 1H, HetH), 8.88 (d, JHH =4.7
3
1
9
Hz, 2H, HetH). F NMR (188.14 MHz, CH
3
CN): δ 119.17 (s, 4 F, SFeq).
): δ 123.81 (s, HetC), 158.78 (s, HetC),
). Anal. calcd. for C ClF S: C, 21.58;
1
3C NMR (100.62 MHz, CDCl
3
The precipitate was filtered off, the filtrate evaporated at 15 Torr
leaving crude 2-Cl-4-F-C
6
H
SF
3 4
Cl as a pale-yellow liquid. Yield: 10.65 g.
171.04 (q, 2JCF =28.6 Hz, CSF
5
4
H
3
4 2
N
1
9
The crude product according to F NMR data was obtained as a mixture
H, 1.36; N, 12.59; S, 14.41; Cl, 15.93; found: C, 21.64; H, 1.51; N, 12.67;
S, 14.47; Cl, 15.78.
of 2-Cl-4-F-C
of 2-Cl-4-F-C
6
H
H
3
SF
SO
4
Cl (40 %), 2-Cl-4-F-C
F and 2-Cl-4-F-C SOF, and used for the next stage
CN): δ
6 3 3
H SF (60 %), and some traces
6
3
2
6 3
H
1
9
without further purification. F NMR for 6d: (376.43 MHz, CH
107.04 – -107.97 (m, 1 F, aromat F), 138.34 (s, 4 F, S-Feq).
3
6.6. General method for the preparation of aryl and heteryl sulfur
-
pentafluorides 7a-h
6
.3. Preparation of 2-SF
4
Cl-benzothiazole (6f, mixture of cis- and trans-
Aryl or heteryl sulfur chlorotetrafluoride was introduced under the
inert atmosphere (Ar) into the Nalgene plastic bottle equipped with
magnetic stirrer. HgO (0.5 M eq.) was added, the bottle sealed with
isomers)
◦
The solution of Cl
2
(9.60 g, 135.38 mmol) in dry CH
3
CN (180 mL)
rubber stopper, and cooled to -30 C under the inert atmosphere. The 30
◦
was added dropwise at 20 C over the period of 2 h to the vigorously
stirred solution of bis(2-benzothiazolyl) disulfide (5.00 g, 15.04 mmol),
M eq. of anhydrous HF or pyridinium poly(hydrogen fluoride) were
added via syringe at that temperature. The reaction mixture was stirred
◦
◦
and suspension of spay-dried KF (14.41 g, 248.00 mmol) in dry CH
100 mL). The reaction mixture was stirred overnight. The precipitate
filtered off, the filtrate evaporated at 0.03 Torr leaving crude 2-SF Cl-
3
CN
for 0.5 h at -30 C, warmed up to room temperature (20 C), sealed with
(
plastic stopper, and stirred overnight. In the case of 2-SF Cl-pyrimidine
4
4
as a starting material, the reaction mixture was stirred at room tem-
benzothiazole (7.97 g) as a pale-yellow liquid. The crude product was
perature for 1 h, and then immediately subjected to work-up. The work-
up procedures were specific for each compound.
◦
distilled in vacuum. B.p. 90 C/0.03 Torr. Yield: 6.94 g (83 %). The
distilled product according to 19F NMR data was obtained as a mixture of
cis- 6f (79 %), and trans- 6f (21 %), and used for fluorination stage
6.6.1. Preparation of C H SF (7a)
6
5
5
without further purification. 19F NMR (188.14 MHz, CDCl
) for cis- 6f: δ
5.80 (dt, JFeqFeq =91.80 Hz, JFeqFax =158.40 Hz 1 F, SFeq), 101.15 (dd,
3
Obtained from compound 6a (4.58 g, 20.76 mmol), HgO (2.25 g,
6
10.38 mmol), PPHF (17.80 mL, 623.00 mmol). The reaction mixture was
J
FeqFeq =91.80 Hz, JFeqFax =165.00 Hz 2 F, SFeq), 147.72 (dt, JFaxFeq
poured into ice, neutralized, and extracted with CH Cl2 (3 × 20 mL).
2
1
9
=
158.40 Hz, JFaxFeq =165.00 Hz 1 F, SFax). F NMR (188.14 MHz,
) for trans- 6f: 132.21 (s, 4 F, SFax). Anal. calcd. for C ClF NS
CH Cl extract was washed with brine (2 × 20 mL), and stirred with 30
2
2
CDCl
3
7
H
4
4
2
:
6 4 2
mL of 5 % aqueous NaOH till disappearance of the signal of C H SO F at
C, 30.28; H, 1.45; N, 5.04; S, 23.09; Cl, 12.77; found: C, 30.57; H, 1.64;
N, 4.86; S, 23.15; Cl, 12.54.
64 ppm (10 h). Organic layer was separated, washed with brine (20 mL),
dried over Na SO , solvent distilled off at normal pressure using Vigre
2
4
column, and the residue fractionalized. Colorless liquid. B. p.: 151–153
◦
6
.4. Preparation of cis-2-SF
4
Cl-benzothiazole (6f)
C/760 Torr. Yield: 3.16 g (75 %). Spectroscopic data for this compound
have been already reported [14].
The solution of Cl
2
(9.60 g, 135.38 mmol) in dry CH
3
CN (180 mL)
◦
was added dropwise at 20 C over the period of 2 h to the vigorously
stirred solution of bis(2-benzothiazolyl) disulfide (5.00 g, 15.04 mmol),
2 6 4 5
6.6.2. Preparation of p-O NC H SF (7b)
Obtained from compound 6b (0.46 g, 1.73 mmol), HgO (0.19 g, 0.87
and suspension of spay-dried KF (14.41 g, 248.00 mmol) in dry CH
3
CN
mmol), HF (1.1 mL, 55.00 mmol). The reaction mixture was poured into
(
100 mL). The reaction mixture was stirred overnight. The precipitate
ice, neutralized by 10 % aqueous NaHCO
(30 mL). CH Cl extract was stirred with 20 mL of 5 % aqueous NaOH till
disappearance of the signal of p-O NC SO F at 60 ppm (10 h).
Organic layer was separated, washed with brine (20 mL), dried over
Na SO , and evaporated using rotor evaporator. The residue was treated
3 2 2
, and extracted with CH Cl
filtered off, the filtrate evaporated at 0.03 Torr leaving crude 2-SF
benzothiazole (8.43 g) as a pale-yellow liquid. According to 19F NMR
4
Cl-
2
2
2
6
H
4
2
data, the crude product was obtained as a mixture of cis- 6f (80 %), and
trans- 6f (20 %). The mixture was dissolved in CH
aqueous solution of NaHCO
hydrolysis was accompanied with the evolution of CO
by 19F NMR of organic layer. After 20 min the signal of trans- isomer
disappeared. The CH Cl layer was separated, dried over Na SO , and
evaporated using rotor evaporator. The oily residue was distilled in
2
Cl
2
(200 mL), 5 %
2
4
◦
3
added (200 mL), and stirred at 20 C. The
with hexane (30 mL), and stirred overnight. The precipitate was filtered
◦
2
, and monitored
off, and the filtrate evaporated in vacuum. Yellow solid. M.p. 40 C.
Yield: 0.35 g (81 %). Spectroscopic data for this compound have been
already reported [14].
2
2
2
4
◦
1
vacuum. B.p. 69 C/0.03 Torr. Yield: 2.51 g (30 %). H NMR (400 MHz,
2 6 3 5
6.6.3. Preparation of 3,5-F C H SF (7c)
2
CDCl
3
): δ 7.56–7.65 (m, 2H, arom H), 7.92 (doublet of AB, JHH =7.9 Hz,
Obtained from crude compound 6c (11.81 g, 46.03 mmol), HgO
2
19
1
H, arom H), 8.15 (doublet of AB, JHH =7.9 Hz, 1H, arom H). F NMR
188.14 MHz, CDCl
): δ 65.80 (dt, JFeqFeq =91.80 Hz, JFeqFax =158.40 Hz
F, SFeq), 101.15 (dd, JFeqFeq =91.80 Hz, JFeqFax =165.00 Hz 2 F, SFeq),
47.72 (dt, JFaxFeq =158.40 Hz, JFaxFeq =165.00 Hz 1 F, SFax). C NMR
): δ 121.80 (s, aromC), 125.60 (s, aromC), 127.79 (s,
aromC), 128.42 (s, aromC), 135.20 (s, aromC), 146.94 (s, aromC),
(5.00 g, 23.01 mmol), PPHF (26 mL, 1841.07 mmol). The reaction
(
3
mixture was poured into ice, extracted with CH
CH Cl
extract was washed with brine (2 × 100 mL), and stirred with 5
% aqueous solution of NaOH (200 mL), till disappearance of the signal of
3,5-F SO F at 62 ppm (10 h). Organic layer was separated, washed
with brine (100 mL), dried over Na SO , and the solvent distilled off at
760 Torr. The liquid residue was distilled using Vigre column. B.p. 128
2
Cl
2
(3 × 100 mL).
1
1
2
2
1
3
(
75.83 MHz, CDCl
3
C
2 6
H
3
2
2
4
1
1
2
79.57–180.40 (m, C-SF
4 7 4 4 2
Cl). Anal. calcd. for C H ClF NS : C, 30.28; H,
◦
1
.45; N, 5.04; S, 23.09; Cl, 12.77; found: C, 30.34; H, 1.51; N, 4.91; S,
3.12; Cl, 12.62.
C. Yield: 5.31 g (45 %). H NMR (400 MHz, CDCl
3
): δ 6.99–7.04 (m, 1H,
1
9
arom H), 7.29–7.36 (m, 2H, arom H). F NMR (376.43 MHz, CDCl ): δ
3
6

O.I. Guzyr et al.
Journal of Fluorine Chemistry 239 (2020) 109635
2
-
107.46 (m, 2 F, aromat F), 61.56 (d, JFF =151.6 Hz, 4 F, S-Feq), 80.20
over Na
2
SO
4
, evaporated using rotor evaporator, and the residue sub-
2
13
◦
◦
1
(
q,
J
FF =151.6 Hz, 1 F, eq S-Fax). C NMR (100.61 MHz, CDCl
3
): δ
limed at 40 C/0.05 Torr. M.p. 60 C. Yield: 0.25 g (74 %). H NMR (400
2
1
07.62 (t, J =25 Hz), 110.35–110.73 (m), 154.67–155.38 (m), 163.26
MHz, CDCl
3
): δ 7.56–7.64 (m, 2H, arom H), 7.92 (doublet of AB, JHH
+
2
(
(
dm, J =253.0 Hz). EI MS, 70 eV, m/z (rel. int.): 240 (42) [M] , 70
=8.0 Hz, 1H, arom H), 8.17 (doublet of AB, JHH =8.0 Hz, 1H, arom H).
ꢀ 1
19
2
100). IR (KBr, cm ): 509, 546, 563, 588, 603, 665, 772, 834, 910, 998,
106, 1131, 1229, 1303, 1387, 1447, 1611, 3115. Anal. calcd. for
S: C, 30.01; H, 1.26; S, 13.35; found: C, 30.11; H, 1.28; S, 13.15.
F NMR (376.43 MHz, CDCl
3
): δ 61.25 (d, JFF =152.2 Hz, 4 F, S-Feq),
73.02 (q, 2JFF =152.2 Hz, 1 F, eq S-Fax). C NMR (125.71 MHz, CDCl
13
1
3
):
C
H
6 3
F
7
δ 121.77 (s, arom C), 125.50 (s, arom C), 127.68 (s, arom C), 128.19 (s,
arom C), 135.21 (s, arom C), 148.75 (s, arom C), 170.16–171.03 (m,
+
6
.6.4. Preparation of 2,4-F
2
C
6
H
3
SF
5
(7d)
CSF
5
). EI MS, 70 eV, m/z (rel. int.): 261 (100) [M] . Anal. calcd. for
Obtained from the distilled product 6d (8.56 g) which, according to
7 4 5 2
C H F NS : C, 32.18; H, 1.54; N, 5.36; S, 24.55; found: C, 32.22; H, 1.65;
1
9
F NMR data, was obtained as a mixture of 2,4-F
,4-F SF (12 %), and some traces of 2,4-F
SOF, HgO (3.61 g, 16.68 mmol), and PPHF (19 mL, 667.21
Cl
extract was washed with brine (2 × 100 mL), and
stirred with 5 % aqueous solution of NaOH (200 mL), till disappearance
of the signal of 2,4-F SO F at 64 ppm (10 h). Organic layer was
separated, washed with brine (100 mL), dried over Na SO , and the
2
C H
6 3
SF
4
Cl (88 %),
N, 5.38; S, 24.43.
2
F
2
C
H
6 3
3
2 6
C H
SO
3 2
F and 2,4-
2
6
C H
3
5
6.6.7. Preparation of 2-SF -pyridine (7g)
mmol). The reaction mixture was poured into ice, extracted with CH
3 × 100 mL). CH Cl
2
2
Prepared from 6g (1.00 g, 4.51 mmol), HgO (0.49 g, 2.26 mmol), and
HF (2.7 mL, 135.40 mmol). After the completion of the reaction, HF was
partly evaporated at atmospheric pressure, the residue treated with
(
2
2
2
6
C H
3
2
2 2
CH Cl (20 mL), and NaF (1 g), and left overnight. Precipitate was
2
4
filtered off, the filtrate evaporated at atmospheric pressure. The residue
was dissolved in pentane (20 mL), and the precipitate filtered off.
Pentane solution was stirred with 5 % aqueous NaOH, till disappearance
solvent distilled off at 760 Torr. The liquid residue was distilled using
◦
Vigre column. B.p. 140 C. Yield: 4.05 g (51 %). Spectroscopic data for
this compound have been already reported [19]. Anal. calcd. for
of the signal of 2-SO
2
F-pyridine at 55 ppm (10 h). Organic layer was
SO , and the sol-
C
H
6 3
F
7
S: C, 30.01; H, 1.26; S, 13.35; found: C, 30.18; H, 1.31; S, 13.21.
separated, washed with brine (10 mL), dried over Na
2
4
vent distilled off at 760 Torr. The crude product was distilled in vacuum.
◦
6
.6.5. Preparation of 2-Cl-4-F-C
6
H
3
SF
5
(7e)
Boiling point: 104 C/50 Torr. Yield: 0.62 g (67 %). Spectroscopic data
Obtained from crude compound 6e (10.65 g), which, according to
for this compound have been already reported [20].
1
9
F NMR data, was a mixture of 2-Cl-4-F-C
6
H
3
SF
(60 %), and some traces of 2-Cl-4-F-C
SOF, HgO (4.24 g, 19.58 mmol), PPHF (22 mL, 783.29 mmol). The
Cl
(2 × 100
extract was washed with brine (2 × 100 mL), and stirred
with 5 % aqueous solution of NaOH (200 mL), till disappearance of the
signal of 2-Cl-4-F-C SO F at 58 ppm (10 h). Organic layer was sepa-
rated, washed with brine (100 mL), dried over Na SO , and the solvent
distilled off at 760 Torr. The liquid residue was distilled using Vigre
4
Cl (40 %), 2-Cl-4-F-
C
C
6
H
H
3
SF
3
6
H
3
2
SO F and 2-Cl-4-F-
5
6.6.8. Preparation of 2-SF -pyrimidine (7h)
6
3
Prepared from 6h (1.72 g, 7.73 mmol), HgO (0.84 g, 3.86 mmol), and
reaction mixture was poured into ice, extracted with CH
mL). CH Cl
2
2
PPHF (6.6 mL, 232 mmol). After 1 h of the stirring at room temperature
2
2
2 2
reaction mixture was treated with CH Cl (30 mL), NaF (10 g) added,
and stirred for 1 h. Precipitate was filtered off, the filtrate evaporated at
atmospheric pressure. The residue was dissolved in pentane (20 mL),
and the precipitate filtered off. Pentane solution was stirred with 5 %
6
H
3
2
2
4
aqueous NaHCO
at 50 ppm (10 h). Organic layer was separated, washed with brine (10
mL), dried over Na SO , and the solvent distilled off at 760 Torr. The
crude product was sublimed at 50 C/0.04 Torr. M.p. 67 C. Yield: 1.03 g
3 2
, till disappearance of the signal of 2-SO F-pyrimidine
◦
1
column. B.p. 165 C. Yield: 1.54 g (15 %). H NMR (400 MHz, CDCl ): δ
3
7
.07–7.11 (m, 1H, arom H), 7.25–7.27 (m, 1H, arom H), 7.86–7.90 (dd,
2
4
H, arom H). 19F NMR (376.43 MHz, CDCl
): δ -107.06 – -107.00 (m, 1
◦
◦
1
3
2
2
1
F, aromat F), 65.90 (d, JFF =152.0 Hz, 4 F, S-Feq), 81.57 (q, JFF =152.0
(65 %). H NMR (400 MHz, CDCl
3
): δ 7.56 (t, JHH =4.7 Hz, 1H, HetH),
1
3
2
19
Hz, 1 F, eq S-Fax). C NMR (75.83 MHz, CDCl
Hz, arom C), 119.87 (d, 2
arom C), 147.27–148.26 (m, CSF
EI MS, 70 eV, m/z (rel. int.): 256 (35) [M] .). IR (KBr, cm ): 439, 488,
3
): δ 114.33 (d, JCF =22.3
8.93 (d, JHH =4.7 Hz, 2H, HetH). F NMR (188.14 MHz, CDCl
3
): δ 46.17
2
2
J
CF =25.2 Hz, arom C), 131.76–132.10 (m,
(d, JFF =151.6 Hz, 4 F, S-Feq), 73.12 (q, JFF =151.6 Hz, 1 F, eq S-Fax).
1
13
5
), 163.15 (d, JCF =257.1 Hz, arom C).
3
C NMR (75.83 MHz, CDCl ): δ 123.79 (s, HetC), 158.84 (s, HetC),
+
ꢀ 1
2
170.43 (q, JCF =28.5 Hz, CSF
5
). EI MS, 70 eV, m/z (rel. int.): 206 (10)
] . Anal. calcd. for C S: C, 23.31; H, 1.47;
N, 13.59; S, 15.56; found: C, 23.38; H, 1.49; N, 13.65; S, 15.43.
+
+
5
1
1
10, 568, 596, 677, 803, 845, 914, 1037, 1110, 1221, 1289, 1384, 1480,
583, 1603. Anal. calcd. for C ClF S: C, 28.08; H, 1.18; Cl, 13.82; S,
2.50; found: C, 28.16; H, 1.21; Cl, 13.62; S, 12.45.
[M] , 79 (100) [M-SF
5
4 3 5 2
H F N
6
H
3
6
6
.6.8.1. X-ray Structure determination for 7f and 7h. Crystal data for 7f:
6
.6.6. Preparation of 2- SF
5
-benzothiazole (7f)
C H F NS , M = 261.23, monoclinic, space group P2 /с, а = 10.728(6),
7
4
5
2
1
Obtained from the distilled product 6f which, according to 19F NMR
3
b = 6.086(3), c = 14.200(9)Å, β = 94.84(3 )˚ , V = 923.7(9)Å , Z = 4, d =
c
ꢀ
1
data, was obtained as a mixture of cis- and trans- isomers.
1.878,
μ
0.617ММ , F(000) 520, crystal size ca. 0.10 х 0.12 х 0.49 mm.
Using HF as a second additive. Prepared from 6f (0.5 g, 1.80 mmol),
HgO (0.2 g, 0.90 mmol), and HF (1.1 mL, 54.01 mmol). After the
completion of the reaction, HF was partly evaporated at atmospheric
All crystallographic measurements were performed at 183 K on a Bruker
Smart Apex II diffractometer operating in the
tensity data were collected within the θ
ω
scans mode. The in-
◦
max
≤ 26.63 using Mo-K radi-
α
pressure, the residue treated with CH
left overnight. Precipitate was filtered off, the filtrate was stirred with 5
aqueous solution of NaOH (10 mL) till disappearance of the signal for
-SO F-benzothiazole at 60 ppm (10 h). The CH Cl layer was separated,
washed with brine, and dried over Na SO . CH Cl was evaporated
2
Cl
2
(10 mL), and NaF (1 g), and
ation (λ =0.71078 Å). The intensities of 7606 reflections were collected
(1901 unique reflections, R
merg
= 0.0485). The structure were solved by
%
direct methods and refined by the full-matrix least-squares technique in
the anisotropic approximation for non-hydrogen atoms using the Bruker
2
2
2
2
2
4
2
2
SHELXTL program package [27]. The SF group is disordered over two
5
◦
using rotor evaporator, and the residue sublimed at 40 C/0.05 Torr. M.
position A and B with multiplicity 46 and 54 %. All CH hydrogen atoms
◦
p. 60 C Yield : 0.36 g (77 %).
were placed at calculated positions and refined as ‘riding’ model.
Convergence for 7f was obtained at R1 = 0.0669 and wR2 = 0.1555 for
Using PPHF as a second additive. Prepared from 6f (0.3 g, 1.08
mmol), HgO (0.12 g, 0.54 mmol), and PPHF (1.0 mL, 32.41 mmol). After
the completion of the reaction, the reaction mixture was poured into ice,
1188 observed reflections with I ≥ 2σ(I); R1 = 0.1112 and wR2 =
0.1860, GOF = 1.072 for independent reflections, 167 parameters, the
largest and minimal peaks in the final difference map 0.51 and –0.49
extracted with CH
brine (2 × 10 mL), and stirred with 5 % aqueous solution of NaOH (20
mL), till disappearance of the signal of 2-SO F-benzothiazole at 60 ppm
10 h). Organic layer was separated, washed with brine (10 mL), dried
2
Cl
2
(2 × 10 mL). CH
2 2
Cl extract was washed with
3
e/Å .
2
Crystal data for 7h: C H F N S, M = 206.14, tetragonal, space group
4
3 5 2
(
7

O.I. Guzyr et al.
Journal of Fluorine Chemistry 239 (2020) 109635
3
P4
.977,
All crystallographic measurements were performed at room temperature
1
2
1
2, а = 7.0134(3), c = 14.0773(8)Å, V = 692.42(7)Å , Z = 4, d
c
=
9635.
ꢀ 1
1
μ
0.506ММ , F(000) 408, crystal size ca. 0.14 х 0.23 х 0.32 mm.
References
on a Bruker Smart Apex II diffractometer operating in the
ω
scans mode.
◦
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α
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technique in the anisotropic approximation for non-hydrogen atoms
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3
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[
Declaration of Competing Interest
The authors report no declarations of interest.
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8