Regioselective synthesis of novel perfluoroalkylated fused pyridines and 3-(Aminomethylene)thiochroman-4-ones from 3-(Perfluoroalkanoyl)thiochromenones and Amines

Article abstract of DOI:10.1055/s-0029-1218586

The regioselectivity of reactions of 3-(perfluoroacyl)-4H-thiochromen-4- ones with a range of hetaryl, aryl, and alkyl amines was examined. The reactions provide ready access to polyfluoroalkylated fused pyridines and thiochromen-4-ones. Georg Thieme Verlag Stuttgart New York.

Full text of DOI:10.1055/s-0029-1218586

PAPER
671
Regioselective Synthesis of Novel Perfluoroalkylated Fused Pyridines and
3-(Aminomethylene)thiochroman-4-ones from 3-(Perfluoroalkanoyl)thio-
chromenones and Amines
S
ome Reactions of
n
3-(Perfluoro
t
alkano
o
yl)Thiochr
o
n
enones Kotljarov,a,b Dmitri V. Sevenard,c Viktor O. Iaroshenko,*d,e Roman A. Irgashev,f Dmitriy M. Volochnyuk,d
Peter Langer,g Andrei A. Tolmachev,d,e Vyacheslav Ya. Sosnovskikh*f
a
Formerly Fachbereich Chemie der Universität Konstanz, Fach M-720, Universitätsstr. 10, 78457 Konstanz, Germany
Institute of Organic and Bioorganic Chemistry, University of Tartu, Jakobi 2, 50014 Tartu, Estonia
Hansa Fine Chemicals GmbH, BITZ, Fahrenheitstr. 1, 28359 Bremen, Germany
‘Enamine Ltd.’, 23 A. Matrosova st., 01103 Kyiv, Ukraine
b
c
d
Fax +380(44)5373253; E-mail: yaroshenko@enamine.net
National Taras Shevchenko University, 62 Volodymyrska st., Kyiv 33, 01033, Ukraine
Department of Chemistry, Ural State University, 51 Lenina Ave., 620083 Ekaterinburg, Russian Federation
e
f
E-mail: Vyacheslav.Sosnovskikh@usu.ru
Institut für Chemie, Universität Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany
g
Received 3 September 2009; revised 26 October 2009
Dedicated to Dr. Holger Feist on the occasion of his 50th birthday
yl polyfluoroalkanoates.7 We regarded the thiochromen-
ones 2 as desirable targets because of their relationship to
naturally occurring benzopyran derivatives and their use-
fulness as perfluoroalkylated building blocks for the prep-
aration of more complex partially fluorinated
heterocycles and other highly functionalized biologically
and medicinally important products. However, after a de-
tailed study of the chemical behavior of 2 with various
mononucleophiles and 1,3-dinucleophiles, we found that
these compounds are less reactive than the corresponding
3-(perfluoroalkanoyl)chromenones 1. Nevertheless, they
react with amidines and guanidines salts to afford 5-(2-
sulfanylbenzoyl)-4-(polyfluoroalkyl)pyrimidines in good
yields.8
Abstract: The regioselectivity of reactions of 3-(perfluoroacyl)-
4H-thiochromen-4-ones with a range of hetaryl, aryl, and alkyl
amines was examined. The reactions provide ready access to poly-
fluoroalkylated fused pyridines and thiochromen-4-ones.
Key words: heterocycles, amines, fused-ring systems, thiochrom-
enones, perfluoroalkyl compounds
4H-1-Benzopyran-4-ones (chromenones) are one of the
most widely distributed classes of natural compounds
found in the plant kingdom.1 Many natural and synthetic
chromenone derivatives exhibit various biological activi-
ties and find use as substrates in the preparation of a vari-
ety of rearranged products and new heterocyclic
systems.1,2 Furthermore, the presence of fluorine atoms in
biologically active molecules can enhance their lipophi-
licity and thus their in vivo uptake and transport. In partic-
ular, the trifluoromethyl group, in addition to its high
electronegativity, confers increased stability and lipophi-
licity.3
Here, we report on the reactions of thiochromenones 2
with some mononucleophiles, and on their applications in
pyridine ring annulation with electron-rich heterocyclic
amines. We recently prepared a wide range of fluorinated
fused pyridines by the reaction of 3-(perfluoroal-
kanoyl)chromenones 1 with heterocyclic amines and, al-
though four competitive routes were observed, the
reaction pathways could be controlled with respect to the
prevalent pyridine derivatives.9 As an extension of this re-
sult, and in view of the unique biological properties dis-
played by many fluorinated compounds,3 we decided to
investigate whether this reaction could be applied to 3-
(perfluoroalkanoyl)thiochromenones 2.
Whereas the chemical properties of perfluoroalkylated
chromenones have been extensively studied,4 little atten-
tion has been paid to the synthesis and reactivity of perflu-
oroalkylated thiochromenones.5 In a continuation of our
studies on the synthesis and chemical properties of 3-
(polyfluoroacyl)chromenones 1, which turned out to be
highly reactive toward mono- and dinucleophiles,6 we
now report the results of our studies on the reactivity of
their thio analogues, the 3-(polyfluoroacyl)thiochromen-
ones 2. We recently reported a simple and convenient
method for the synthesis of these compounds through a
halogenation–dehydrohalogenation sequence, starting
from commercially available thiochroman-4-one and eth-
Note that 3-(polyfluoroacyl)chromenones 1, especially 3-
(trifluoroacetyl)-4H-chromen-4-one, react readily with
water to form stable covalent hydrates (gem-diols), and
with alkyl orthoformates to give the corresponding
hemiketals.6a The thio analogues 2a (RF = CF3) and 2b
(RF = CF2CF3), prepared by treating the corresponding 3-
(perfluoroalkanoyl)-2H-thiochromen-4-ols with sulfuryl
chloride,7 showed analogous behavior, and they exist as a
mixture of the nonhydrate form 2 and the hydrate form 3.
(In the case of 2a in CDCl3 and DMSO-d6, these are
SYNTHESIS 2010, No. 4, pp 0671–0677
x
x
.
x
x
.2
0
1
0
Advanced online publication: 07.12.2009
DOI: 10.1055/s-0029-1218586; Art ID: P12209SS
© Georg Thieme Verlag Stuttgart · New York

672
A. Kotljarov et al.
PAPER
O
S
O
SH
O
O
O
HO OH
RF
RF
RF
Het
H2N
H2O
O
X
O
5a–e
– H2O
X
Het
3
4
2a,b
RF
A
H2N
O
HO OMe
RF
HC(OMe)3
MeOH
Het
RF
1 X = O
2 X = S
SH
O
X
N
S
N
OH
RF
Scheme 1 Reactions of chromenones 1 and thiochromenones 2 with
Het
water and methanol
6a–i
7
Scheme 2 Possible route for the formation of pyridines 6
present in a 3:2 ratio.) As expected, the reaction of thio-
chromenone 2a with methyl orthoformate in methanol
containing concentrated hydrochloric acid resulted in the
formation of hemiketal 4 (X = S; RF = CF3) in a 95% yield
(Scheme 1).
Table 1 Isolated Yields of Heteroannulated Pyridines 6a–i
Thiochromenone 2 RF
Heterocycle 5 Product 6 Yield (%)
On extending our studies to the reaction of thiochromen-
ones 2 with 1,3-dinucleophiles, such as electron-rich het-
erocyclic amines 5 (Figure 1), we found that 2a and 2b
reacted with 5a–e in N,N-dimethylformamide solution at
110 °C for 54–84 hours, as reported previously for the 3-
(perfluoroalkanoyl)chromenones 1.9
2a
2b
2a
2b
2a
2a
2b
2a
2b
CF3
5a
5a
5b
5b
5c
5d
5d
5e
5e
6a
6b
6c
6d
6e
6f
60
64
75
78
92
58
63
80
82
C2F5
CF3
CF2CF3
CF3
O
CF3
S
N
N
Ph
Et2N
O
NH2
NC
CF2CF3
CF3
6g
6h
6i
NH2
NH2
N
N
H
N
5c
Me
5a
5b
CF2CF3
Me
O
N
with heterocyclic amines makes this class of compounds
very useful for the synthesis of novel polyfluoroalkylated
fused pyridines with potential biological activity.
N
NH2
N
NH2
t-Bu
Me
5e
The structures of the compounds 6 were deduced by ele-
Figure 1 Structures of the aminoheterocycles 5
mental analysis; by 1H, F, and C NMR spectroscopy;
and by mass spectrometry. In the 1H NMR spectra of 6, a
singlet corresponding to the pyridine proton appeared at
d = 7.9–8.8 ppm. In addition, all the protons of the ben-
zene ring were shifted to a higher field, showing that
opening of the thiopyrone ring took place under the action
of 5. This is in accordance with data for the salicyloyl an-
alogues of compounds 6, which we have described previ-
ously.6b,9
19
13
In contrast to the case of 1, the reaction of 2 with hetaryl-
amines 5 proceeded under harsher conditions and ap-
peared to be more regioselective, giving the set of diverse
heteroannulated pyridines 6a–i, bearing the perfluoro-
alkyl substituent at the a-position of the pyridine core, as
the sole isolated products in 60–92% yields (Scheme 2,
Table 1).
The first step of the reaction leading to 6 (Scheme 2) ap-
parently involves an attack at the C-2 atom of 2 by the in-
ternal b-carbon of the enamine (in general, this atom is
more nucleophilic than the primary amino group), with
opening of the thiopyrone ring (1,4-addition; intermediate
A). Finally, intramolecular attack by the amino group at
the polyfluoroacyl group leads to fused pyridines 6. The
alternative cyclization of A, involving the amino group
and the carbonyl carbon atom connected to the benzene
ring, does not occur, and no formation of the correspond-
ing 5H-thiochromeno[4,3-b]pyridin-5-ols 7 was detected.
The reaction of 3-(polyfluoroacyl)thiochromenones 2
We also found that the reaction of thiochromenone 2a
with primary aromatic and aliphatic amines in refluxing
benzene for five hours afforded 3-(substituted amino-
methylene)-2-hydroxy-2-(trifluoromethyl)thiochromen-4-
ones 8a–d in good-to-excellent yields (Table 2). Note that
only aromatic amines with electron-donating groups can
be used; naphthalen-2-amine failed to react with 2a under
a range of conditions. The reaction involves the nucleo-
philic 1,4-addition of the amine with concomitant opening
of the thiopyrone ring and subsequent intramolecular cy-
clization of the intermediate at the trifluoroacetyl group.
The driving force for the process is the stabilization of the
Synthesis 2010, No. 4, 671–677 © Thieme Stuttgart · New York

PAPER
Some Reactions of 3-(Perfluoroalkanoyl)thiochromenones
673
enaminones 8 by a hydrogen bond between the thiopyra- A somewhat unexpected result was obtained from the re-
none carbonyl oxygen and the hydrogen of the NH group action of thiochromenone 2a with N-methylpyrrole. In
(Scheme 3). This finding is in line with some results re- this case, the reaction proceeded without cleavage of the
ported for 3-(polyfluoroacyl)chromenones 1, which react thiopyrone ring to give a 9:1 mixture of the methylpyrro-
with primary aliphatic and aromatic amines under milder lyl derivatives 9a and 9b in 61% yield; in other words, the
reaction conditions (methanol, ~20 °C) to give 3-(substi- major tautomer had the enolic structure (Scheme 3). Note
tuted
aminomethylene)-2-hydroxy-2-(trifluorometh- that the starting compound 2a was unaffected when it was
yl)chromen-4-ones.6a
heated with an excess of indole at 90 °C for 10 h. In the 1H
NMR spectrum, the H-2 and H-3 protons of 9b appeared
at d = 5.63–5.73 ppm as an AB-system with a vicinal cou-
pling constant 3JH2,H3 = 13.0 Hz, which indicates an axial
arrangement for the H-2 and H-3 atoms. Tautomer 9b is
therefore in the half-chair conformation with a trans-
diequatorial arrangement of the substituents. Note that the
reaction between 3-(perfluoroalkanoyl)chromenones and
N-methylpyrrole resulted in the formation of the rear-
ranged products, the 2-hydroxy-3-(1-methylpyrrol-2-yl-
methylene)-2-(polyfluoroalkyl)chromen-4-ones.10
Table 2 Isolated Yields of Thiochromenones 8a–d, 9a, and 9b
R
Thiochromenone
Yield (%)
4-MeC6H4
4-MeOC6H4
Bn
8a
91
88
98
57
61
8b
8c
PhCH2CH2
8d
a
–
9a + 9b
All our attempts to obtain perfluoroalkylated heterocycles
from thiochromenone 2a and 1,2-dinucleophiles, such as
hydroxylamine, hydrazine, or methylhydrazine, under the
same conditions that had previously been used for the cor-
responding reactions of 3-(polyfluoroacyl)chromenones
a The reactant was N-methylpyrrole.
H
R
N
O
O
S
O
1
6c,11 failed to give useful results. This appears to be con-
RNH2
CF3
nected with the difficulty met by the nucleophile in cleav-
ing the thiopyrone S–C bond. Also, in contrast with the 3-
(perfluoroalkanoyl)chromenones 1,6d thiochromenone 2a
did not react with enol ethers (ethyl vinyl ether, 2,3-dihy-
drofuran, or 3,4-dihydro-2H-pyran). In all cases, the start-
ing material was recovered with a small amount of the
desired adduct. The failure of the hetero-Diels–Alder re-
action probably arises from the less electronegative char-
acter of the sulfur atom, which strongly reduces the
electrophilicity of the C-2 atom as compared with
chromenones.
OH
S
CF3
2a
8a–d
N
Me
OH
S
O
O
O
CF3
CF3
+
S
9a
9b
N
N
Me
Me
It is known that the introduction of a nitro group at the 6-
position of chromenones or the transformation of thio-
chromenones into thiochromenone 1,1-dioxides can in-
crease the electrophilicity of the C-2 atom.12,13 Bearing
these facts in mind, we decided to prepare 3-(perfluoro-
propanoyl)thiochromenone 1,1-dioxide (10) and 6-nitro-
3-(trifluoroacetyl)thiochromenone (11) as potentially
more reactive substrates. Attempts to synthesize 10 by di-
rect oxidation of 2 with hydrogen peroxide failed. Thio-
chromenol 12b7 was oxidized by treatment with hydrogen
peroxide in glacial acetic acid to give the expected thio-
chromenol 1,1-dioxide 13 in 32% yield; however, all our
attempts to obtain 10 by a chlorination–dehydrochlorina-
tion sequence from 13 were fruitless, and only complex
reaction mixtures were obtained. We also found that nitra-
tion of 2a with a 1:1 mixture of concentrated sulfuric acid
and 98% nitric acid at 90 °C for 1 h afforded a mixture of
the products 11, 14, and 15 in a ratio of 72:23:5 in only
18% yield (Scheme 4).
Scheme 3 Reactions of thiochromenone 2a with primary amines or
N-methylpyrrole
The structures of products 8a–d were determined by com-
parison of their spectra with those reported for related
compounds.6a The IR spectra of 8a–d showed absorption
bands associated with OH and NH groups of the amino-
enone fragment in the ranges 3350–3200 and 1636–1587
cm–1, respectively. A characteristic spectral feature of the
1H NMR spectrum 8 is a chemical shift of the NH proton
in the range d = 11.2–12.8 ppm with a coupling constant
with the olefinic proton of 3J = 12.9–13.3 Hz. The doublet
of the olefinic proton was observed at d = 8.1 ppm for 8a
and 8b, and at 7.6–7.8 ppm for 8c and 8d. In the 13C NMR
spectra, a signal for the carbon atom adjacent to the trifluo-
romethyl substituent appeared at about d = 81.6 ppm as a
distinctive quartet (2JC,F = 32.3 Hz). This confirmed that
the trifluoromethyl group is bonded to the sp3-hybridized
carbon atom. The chemical shift of the trifluoromethyl
group was observed at d = –83 ppm, and a quartet for the
carbon atom was observed at d = 125 ppm (1JC,F = 285
Hz).
In conclusion, we have developed an easy and regioselec-
tive one-step synthesis of novel perfluoroalkylated fused
pyridines starting from readily obtainable 3-(polyfluoro-
acyl)thiochromenones and heterocyclic amines. Because
Synthesis 2010, No. 4, 671–677 © Thieme Stuttgart · New York

674
A. Kotljarov et al.
PAPER
7.91 (d, J = 8.1 Hz, 1 H, H-8), 8.44 (dd, J = 8.1, 1.4 Hz, 1 H, H-5),
9.20 (s, 1 H, H-2); d (hydrate 3, 41%) = 7.69 (ddd, J = 8.1, 7.0, 1.0
Hz, 1 H, H-6), 7.80 (ddd, J = 8.1, 7.0, 1.4 Hz, 1 H, H-7), 7.91 (d,
J = 8.1 Hz, 1 H, H-8), 8.37 (s, 2 H, 2 OH), 8.51 (dd, J = 8.1, 1.4 Hz,
1 H, H-5), 8.90 (s, 1 H, H-2).
13C NMR (CDCl3): d (nonhydrate 2a) = 115.9 (q, 1JC,F = 289.7 Hz,
CF3), 126.9, 129.2, 129.4, 129.5, 132.7, 132.9, 135.0, 148.4 (C-2),
176.4 (C-4), 181.8 (q, 2JC,F = 38.5 Hz, C = O); d (hydrate 3) = 94.4
(q, 2JC,F = 33.9 Hz, C–CF3), 122.9 (q, 1JC,F = 289.4 Hz, CF3), 126.7,
127.4, 128.7, 129.1, 131.3, 132.4, 137.0, 143.6 (C-2), 180.7 (C-4).
OH
O
OH
O
RF
C2F5
H2O2
12b
S
12a,b
S
13
O
O
X
SO2Cl2
O
SO2Cl2
O
O
O
H2O2
X
RF
C2F5
19F NMR (CDCl3): d (nonhydrate 2a) = –74.50 (s, CF3); (hydrate 3)
d = –86.6 (s, CF3).
S
2a,b
S
10
O
O
Anal. Calcd for C11H5F3O2S·0.25H2O: C, 50.38; H, 2.11. Found: C,
50.29; H, 1.71.
HNO3
O
2a
3-(2,2,2-Trifluoro-1-hydroxy-1-methoxyethyl)-4H-thio-
chromen-4-one (4)
O
S
O
S
HO OH
CF3
O2N
CF3
Concd aq HCl (0.3 mL) was added dropwise to a refluxing soln of
thiochromenone 2a (300 mg, 1.16 mmol) and HC(OMe)3 (2.0 g,
18.9 mmol) in MeOH (8 mL). After the initial exothermic reaction
had subsided, the mixture was allowed to stand at r.t. for 24 h. The
solid that formed was filtered and washed with PE. Product 4 was
isolated without recrystallization as analytically pure colorless crys-
tals. Yield: 320 mg (95%); mp 139–140 °C.
+
O2N
11
14 (6-NO2)
15 (8-NO2)
a RF = CF3
b RF = C2F5
Scheme 4 Possible routes for the activation of thiochromenones 2
IR (KBr): 1588, 1489 cm–1.
1H NMR (DMSO-d6): d = 3.33 (s, 3 H, MeO), 7.67 (ddd, J = 8.1,
7.0, 1.0 Hz, 1 H, H-6), 7.77 (ddd, J = 8.1, 7.0, 1.4 Hz, 1 H, H-7),
7.84 (dd, J = 8.1, 1.0 Hz, 1 H, H-8), 8.53 (dd, J = 8.1, 1.4 Hz, 1 H,
H-5), 8.74 (s, 1 H, H-2), 9.43 (s, 1 H, OH).
of the presence of the 2-sulfanylbenzoyl moiety, these
compounds are of considerable interest as reactive precur-
sors for the synthesis of other useful organic materials
containing polyfluoroalkyl groups.
19F NMR (DMSO-d6): d = –84.6 (s, CF3).
Compounds 6a–i; General Procedure
NMR spectra were recorded on Jeol JNM-LA 400, Bruker DRX-
400, Varian VXR-300, or Varian Mercury-400 spectrometers: H
A conical flask was charged with thiochromenone 2 (1 mmol), the
appropriate aminoheterocycle 6 (1 mmol), and DMF (10 mL). In the
case of dinucleophile hydrochlorides, NaOAc (1 mmol) was also
added. The flask was fitted with a reflux condenser and the contents
were heated for 54–84 h. The solvent was removed in vacuo and the
product was purified by flash chromatography (silica gel) or recrys-
tallization. The yields refer to the amounts of isolated products.
1
signals (300 or 400 MHz) and 13C-signals (100 MHz) were recorded
with TMS as an internal standard; 19F signals (282 or 376 MHz)
were recorded with CFCl3 as internal standard. IR spectra were re-
corded on a Perkin-Elmer Spectrum BX-II instrument as KBr disks.
Elemental analyses were performed at the Microanalysis Services
of the Institute of Organic Synthesis, Ural Branch, Russian Acade-
my of Sciences. Mass spectra were recorded on a Hewlett-Packard
HPGC/MS 5890/5972 instrument (EI, 70 eV) with a GC inlet, or on
an MX-1321 instrument (EI, 70 eV) with a direct inlet. Column
chromatography was performed on silica gel (63–200 mesh,
Merck). Merck 60F254 silica gel plates were used for TLC. Melting
points are uncorrected. All the solvents used were dried and distilled
according to standard procedures. Satisfactory microanalyses were
obtained: C 0.35; H 0.25; N 0.25.
2,3-Dimethyl-6-(2-sulfanylbenzoyl)-5-(trifluoromethyl)-3H-im-
idazo[4,5-b]pyridine (6a)
Reaction conditions: DMF, 110 °C, 84 h.
Reddish solid; yield: 192 mg (60%); mp 164–167 °C; Rf = 0.24
(Et2O–MeOH, 5:2).
1H NMR (DMSO-d6): d = 2.69 (s, 3 H), 3.85 (s, 3 H), 7.32 (t,
3J = 7.7 Hz, 1 H), 7.51 (d, 3J = 8.0 Hz, 1 H), 7.67 (t, 3J = 7.7 Hz, 1
H), 7.86 (d, 3J = 8.1 Hz, 1 H), 8.34 (s, 1 H).
1
13C NMR (DMSO-d6): d = 13.9, 28.5, 121.8 (q, JC,F = 275 Hz),
3-(Trifluoroacetyl)-4H-thiochromen-4-one (2a)
Freshly distilled SO2Cl2 (3.6 g, 26.7 mmol) was added carefully to
125.8, 125.9, 126.0, 126.1, 127.9 (q, JC,F = 1.2 Hz), 134.0, 134.3 (q,
JC,F = 1 Hz), 135.6, 135.8 (q, JC,F = 34 Hz), 139.9, 147.9 (q,
2
a
well-stirred soln of 2,2,2-trifluoro-1-(4-hydroxy-2H-thio-
chromen-3-yl)ethanone7 (5.7 g, 21.9 mmol) in CHCl3 (200 mL),
and the mixture was stirred at r.t. for 24 h. The resulting yellow soln
was evaporated under reduced pressure to give a yellow solid that
was purified by recrystallization (heptane) as pale yellow needles.
Yield: 5.3 g (94%); mp 126–127 °C.
JC,F = 0.8 Hz), 159.6, 194.2.
19F NMR (DMSO-d6): d = –59.4 (s, CF3).
MS (EI, 70 eV): m/z (%) = 351 (22) [M]+, 350 (78) [M – 1]+, 336
(24), 283 (100) [M + 1 – CF3]+, 266 (15) [M – 1 – CF3 – CH3]+, 136
(15) [SC6H4CO]+, 109 (16) [HSC6H4]+, 95 (22).
IR (KBr): 3243, 3029, 1705, 1633, 1600, 1588, 1557, 1510 cm–1.
1H NMR (CDCl3): d (nonhydrate 2a, 60%) = 7.62–7.75 (m, 3 H, H-
6, H-7, H-8), 8.57–8.62 (m, 1 H, H-5), 8.68 (s, 1 H, H-2); d (hydrate
3, 40%) = 6.66 (br s, 2 H, 2 OH), 7.62–7.75 (m, 3 H, H-6, H-7, H-
8), 8.57–8.62 (m, 1 H, H-5), 8.65 (s, 1 H, H-2).
1H NMR (DMSO-d6): d (nonhydrate 2a, 59%) = 7.71 (ddd, J = 8.1,
7.0, 1.0 Hz, 1 H, H-6), 7.81 (ddd, J = 8.1, 7.0, 1.4 Hz, 1 H, H-7),
2,3-Dimethyl-5-(pentafluoroethyl)-6-(2-sulfanylbenzoyl)-3H-
imidazo[4,5-b]pyridine (6b)
Reaction conditions: DMF, 110 °C, 48 h.
Light red-grey solid; yield: 234 mg (64%); mp 131–133 °C;
Rf = 0.18 (PE–Et2O, 1:1).
Synthesis 2010, No. 4, 671–677 © Thieme Stuttgart · New York

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Some Reactions of 3-(Perfluoroalkanoyl)thiochromenones
675
1H NMR (DMSO-d6): d = 2.70 (s, 3 H), 3.85 (s, 3 H), 7.38 (t,
3J = 7.6 Hz, 1 H), 7.54 (d, 3J = 8.0 Hz, 1 H), 7.61 (t, 3J = 7.6 Hz, 1
H), 7.91 (d, 3J = 8.0 Hz, 1 H), 8.48 (s, 1 H).
1-tert-Butyl-5-(2-sulfanylbenzoyl)-6-(trifluoromethyl)-1H-pyr-
rolo[2,3-b]pyridine-3-carbonitrile (6f)
Reaction conditions: DMF, 110 °C, 84 h.
1
13C NMR (DMSO-d6): d = 13.9, 28.5, 115.8 (tq, JC,F = 259 Hz,
Reddish solid; yield: 213 mg (58%); mp 170–172 °C; Rf = 0.55
(PE–Et2O, 1:1).
2JC,F = 38 Hz), 117.0 (qt, JC,F = 287 Hz, JC,F = 38 Hz), 125.8,
1
2
126.9, 127.0, 127.3 (q, JC,F = 0.9 Hz), 134.1 (q, JC,F = 1.1 Hz),
134.4, 136.3 (q, JC,F = 0.8 Hz), 137.4, 139.0, 139.4 (t, JC,F = 28
Hz), 141.4, 149.7, 193.3.
MS (EI, 70 eV): m/z (%) = 401 (8) [M]+, 385 (14) [M – 1 – CH3]+,
283 (100) [M + 1 – C2F5]+, 265 (16) [M – 2 – C2F5 – CH3]+, 256 (33),
136 (27) [SC6H4CO]+, 109 (19) [HSC6H4]+, 95 (14), 73 (19).
1H NMR (CDCl3): d = 1.86 (s, 9 H), 7.35 (dd, 3J = 7.8, 7.5 Hz, 1 H),
7.60 (d, 3J = 7.5 Hz, 1 H), 7.71 (t, 3J = 7.5 Hz, 1 H), 7.86 (d, 3J = 7.8
Hz, 1 H), 8.78 (s, 1 H), 9.00 (s, 1 H).
13C NMR (CDCl3): d = 28.3 (3 C), 59.5, 82.2, 113.7 (q, JC,F = 1 Hz),
114.8 (q, JC,F = 2 Hz), 122.4 (q, 1JC,F = 275 Hz), 125.9 (2 C), 126.4
(q, JC,F = 2.5 Hz), 133.9, 134.2, 134.3 (q, JC,F = 1 Hz), 139.7, 140.8,
142.0, 143.2 (q, 2JC,F = 35 Hz), 147.8, 193.7.
2
2-Phenyl-5-(2-sulfanylbenzoyl)-6-(trifluoromethyl)-1,2-dihy-
dropyrazolo[3,4-b]pyridin-3-one (6c)
19F NMR (CDCl3): d = –64.9 (s, CF3).
MS (EI, 70 eV): m/z (%) = 404 (18) [M + 1]+, 403 (54) [M]+, 402
(100) [M – 1]+, 347 (26) [M + 1 – C4H9]+, 346 (50) [M – C4H9]+, 334
(23) [M – CF3]+, 326 (22), 278 (33) [M + 1 – C4H9 – CF3]+, 137 (13)
[HSC6H4CO]+, 136 (13) [SC6H4CO]+, 57 (45) [C4H9]+.
Reaction conditions: DMF, 110 °C, 54 h.
Pink solid; yield: 282 mg (75%); mp 179–182 °C; Rf = 0.75 (Et2O).
3
3
1H NMR (CDCl3): d = 7.34 (t, J = 7.8 Hz, 1 H), 7.37 (d, J = 7.2
Hz, 1 H), 7.56 (dd, 3J = 8.4, 7.2 Hz, 2 H), 7.68 (t, 3J = 7.8 Hz, 1 H),
3
3
7.72 (d, J = 7.8 Hz, 1 H), 7.88 (d, J = 7.8 Hz, 1 H), 7.92 (d,
3J = 8.4 Hz, 2 H), 8.65 (s, 1 H).
1-tert-Butyl-6-(pentafluoroethyl)-5-(2-sulfanylbenzoyl)-1H-
pyrrolo[2,3-b]pyridine-3-carbonitrile (6g)
Reaction conditions: DMF, 110 °C, 84 h.
13C NMR (CDCl3): d = 110.8, 120.5 (2 C), 121.1 (q, 1JC,F = 276 Hz),
126.0 (q, JC,F = 1.2 Hz), 126.4, 129.2 (2 C), 133.7 (q, JC,F = 0.8 Hz),
134.1, 134.3, 136.3, 136.5, 139.8, 146.8 (q, JC,F = 34 Hz), 154.6,
156.8, 193.2.
Reddish solid; yield: 286 mg (63%); mp 160–163 °C; Rf = 85 (PE–
Et2O, 1:1).
1H NMR (CDCl3): d = 1.89 (s, 9 H), 7.33 (dd, 3J = 7.8, 7.4 Hz, 1 H),
7.62 (d, 3J = 7.4 Hz, 1 H), 7.69 (t, 3J = 7.4 Hz, 1 H), 7.83 (d, 3J = 7.8
Hz, 1 H), 8.76 (s, 1 H), 9.07 (s, 1 H).
2
19F NMR (CDCl3): d = –66.7 (s, CF3).
MS (EI, 70 eV): m/z (%) = 415 (26) [M]+, 414 (27) [M – 1]+, 413
(98) [M – 2]+, 399 (25), 366 (22), 347 (66) [M + 1 – CF3]+, 346 (100)
[M – CF3]+, 330 (23), 279 (37) [M – SC6H4CO]+, 250 (16), 136 (17)
[SC6H4CO]+, 109 (15) [HSC6H4]+, 77 (85).
13C NMR (CDCl3): d = 28.0 (3 C), 59.9, 82.7, 114.2 (t, JC,F = 1.5
1
2
Hz), 115.4 (t, JC,F = 2.7 Hz), 115.8 (tq, JC,F = 258 Hz, JC,F = 36
Hz), 117.0 (qt, 1JC,F = 287 Hz, 2JC,F = 36 Hz), 125.9, 126.1, 126.7 (t,
JC,F = 2.2 Hz), 133.3, 134.7, 135.5 (t, JC,F = 1.3 Hz), 139.2, 140.1,
142.9, 143.7 (t, 2JC,F = 29 Hz), 147.7, 193.0.
6-(Pentafluoroethyl)-2-phenyl-5-(2-sulfanylbenzoyl)-1,2-dihy-
dropyrazolo[3,4-b]pyridin-3-one (6d)
Reaction conditions: DMF, 110 °C, 54 h.
1,3-Dimethyl-6-(2-sulfanylbenzoyl)-7-(trifluoromethyl)pyri-
do[2,3-d]pyrimidine-2,4(1H,3H)-dione (6h)
Colorless solid; yield: 288 mg (80%); mp 128–131 °C; Rf = 0.85
(EtOAc).
Colorless solid; yield: 330 mg (78%); mp 151–154 °C; Rf = 0.65
(PE–Et2O, 1:1).
1H NMR (CDCl3): d = 7.07 (t, J = 7.4 Hz, 1 H), 7.18 (t, J = 7.4 Hz,
1 H), 7.21 (d, J = 7.4 Hz, 1 H), 7.33 (t, J = 7.2 Hz, 1 H), 7.41 (d,
J = 7.4 Hz, 1 H), 7.53 (dd, J = 8.4, 7.2 Hz, 2 H), 7.88 (d, J = 8.4 Hz,
2 H), 8.54 (s, 1 H).
1H NMR (CDCl3): d = 3.36 (s, 3 H), 3.65 (s, 3 H), 7.36 (ddd,
4
3
4
3J = 7.8, 7.2 Hz, J = 0.8 Hz, 1 H), 7.58 (dd, J = 7.8 Hz, J = 1.2
3
4
Hz, 1 H), 7.68 (ddd, J = 8.1, 7.2 Hz, J = 1.2 Hz, 1 H), 7.90 (dd,
3J = 8.1 Hz, 4J = 0.8 Hz, 1 H), 8.67 (s, 1 H).
1
2
13C NMR (CDCl3): d = 110.9 (tq, JC,F = 258 Hz, JC,F = 38 Hz),
112.4, 117.9 (qt, 1JC,F = 287 Hz, 2JC,F = 36 Hz), 120.5 (2 C), 126.3,
126.4 (q, J = 0.9 Hz), 127.4, 129.2 (2 C), 129.5, 134.1, 134.2, 135.8,
137.9, 138.6, 144.2 (t, 2JC,F = 28 Hz), 154.7, 157.0, 193.1.
13C NMR (CDCl3): d = 28.2, 29.2, 112.7, 120.4 (q, 1JC,F = 276 Hz),
3
126.1, 126.2, 127.7 (q, JC,F = 1.2 Hz), 133.7, 134.4 (2 C), 139.1,
140.1, 145.8 (q, 2JC,F = 35 Hz), 150.6, 150.9, 159.5, 192.3.
19F NMR (CDCl3): d = –63.1 (s, CF3).
2-(Diethylamino)-6-(2-sulfanylbenzoyl)-5-(trifluorometh-
yl)[1,3]thiazolo[4,5-b]pyridine (6e)
Reaction conditions: DMF, 110 °C, 60 h.
MS (EI, 70 eV): m/z (%) = 395 (19) [M]+, 394 (100) [M – 1]+, 380
(54) [M – CH3]+, 351 (59), 326 (56) [M – CF3]+, 310 (12), 295 (19)
[M – 1 – CF3 – 2CH3]+, 136 (12) [SC6H4CO]+, 109 (12) [HSC6H4]+,
98 (24), 97 (19).
Pale red solid; yield: 343 mg (92%); mp 141–143 °C; Rf = 0.28
(PE–Et2O, 1:1).
3
3
1H NMR (CDCl3): d = 1.34 (t, J = 7.1 Hz, 6 H), 3.60 (q, J = 7.1
Hz, 4 H), 7.18 (t, 3J = 7.6 Hz, 1 H), 7.42 (d, 3J = 8.0 Hz, 1 H), 7.48
(t, 3J = 7.6 Hz, 1 H), 7.91 (s, 1 H), 7.95 (d, 3J = 8.0 Hz, 1 H).
1,3-Dimethyl-7-(pentafluoroethyl)-6-(2-sulfanylbenzoyl)pyri-
do[2,3-d]pyrimidine-2,4(1H,3H)-dione (6i)
Colorless solid; yield: 330 mg (82%); mp 113–116 °C; Rf = 0.16
(PE–Et2O, 1:1).
1H NMR (CDCl3): d = 3.32 (s, 3 H), 3.57 (s, 3 H), 4.44 (s, 1 H, SH),
7.32 (ddd, 3J = 7.8, 7.3 Hz, 4J = 0.8 Hz, 1 H), 7.57 (dd, 3J = 7.8 Hz,
4J = 1.2 Hz, 1 H), 7.71 (ddd, 3J = 7.8, 7.3 Hz, 4J = 1.2 Hz, 1 H), 7.93
(dd, 3J = 7.8 Hz, 4J = 0.8 Hz, 1 H), 8.30 (s, 1 H).
13C NMR (CDCl3): d = 12.6 (2 C), 46.8 (2 C), 118.3, 120.5 (q,
1JC,F = 275 Hz), 125.8, 128.3, 131.1, 135.7, 137.2, 140.2, 140.5,
143.8 (q, 2JC,F = 35 Hz), 147.7, 167.4, 173.2, 184.1.
19F NMR (CDCl3): d = –62.6 (s, CF3).
MS (EI, 70 eV): m/z (%) = 411 (49) [M]+, 410 (17) [M – 1]+, 381
(20) [M – 1 – Et]+, 343 (32) [M + 1 – CF3]+, 342 (100) [M – CF3]+,
313 (44) [M – CF3 – Et]+, 270 (15), 221 (16), 146 (68), 136 (23)
[SC6H4CO]+, 109 (14) [HSC6H4]+, 77 (63).
1
13C NMR (CDCl3): d = 28.7, 29.7, 111.8 (tq, JC,F = 258 Hz,
1
2
2JC,F = 38 Hz), 118.5 (qt, JC,F = 287 Hz, JC,F = 36 Hz), 124.6,
3
130.7, 131.4 (t, JC,F = 1.6 Hz), 132.0, 133.6, 134.4, 139.2, 139.8,
137.8, 148.2 (t, 2JC,F = 28 Hz), 150.3, 150.9, 159.8, 192.1.
Synthesis 2010, No. 4, 671–677 © Thieme Stuttgart · New York

676
A. Kotljarov et al.
PAPER
MS (EI, 70 eV): m/z (%) = 445 (6) [M]+, 327 (34) [M + 1 – C2F5]+,
326 (100) [M – C2F5]+, 189 (14) [M – C2F5 – HSCOC6H4]+, 136 (14)
[SC6H4CO]+.
2-Hydroxy-3-{[(2-phenylethyl)amino]methylene}-2-(trifluoro-
methyl)-2,3-dihydro-4H-thiochromen-4-one (8d)
This compound was prepared in a manner analogous to that used to
prepare 8c.
2-Hydroxy-3-{[(4-methylphenyl)amino]methylene}-2-(trifluo-
romethyl)-2,3-dihydro-4H-thiochromen-4-one (8a)
A mixture of thiochromenone 2a (70 mg, 0.27 mmol) and p-tolui-
dine (90 mg, 0.81 mmol) was heated at 90 °C for 3 h. The resulting
mixture was cooled and diluted with MeOH (2 mL), and the solid
that formed was filtered and washed with MeOH to give yellow
crystals. Yield: 90 mg (91%); mp 174–175 °C.
Colorless crystals; yield: 250 mg (57%); mp 154–155 °C.
IR (KBr): 3350, 3270, 3060, 1630, 1590, 1571, 1535 cm–1.
1H NMR (DMSO-d6): d = 2.94 (m, 2 H, CH2), 3.64 (m, 2 H, NCH2),
7.12–7.30 (m, 8 H, H-6, H-8, H-7, Ph), 7.60 (d, J = 13.1 Hz, 1
H, =CH), 7.93 (d, J = 7.7, 1.3 Hz, 1 H, H-5), 8.30 (br s, 1 H, OH),
11.21 (dt, J = 13.1, 6.3 Hz, 1 H, NH).
IR (KBr): 3256, 1636, 1611, 1590, 1571, 1523 cm–1.
2-(1-Methyl-1H-pyrrol-2-yl)-3-(trifluoroacetyl)-2H-thio-
chromen-4-ol (9a) and trans-2-(1-Methyl-1H-pyrrol-2-yl)-3-
(trifluoroacetyl)-2,3-dihydro-4H-thiochromen-4-one (9b)
A mixture of thiochromenone 2a (100 mg, 0.39 mmol) and
N-methylpyrrole (65 mg, 0.80 mmol) was heated at 90 °C for 40
min. The resulting mixture was treated with hexane and the solid
that formed was recrystallized (toluene) as yellow crystals. Yield:
80 mg (61%); mp 194–195 °C.
1H NMR (DMSO-d6): d = 2.31 (s, 3 H, Me), 7.23–7.36 (m, 6 H, H-
6, H-8, Ar), 7.46 (ddd, J = 7.9, 7.2, 1.4 Hz, 1 H, H-7), 8.01 (dd,
J = 7.9, 1.4 Hz, 1 H, H-5), 8.12 (d, J = 12.9 Hz, 1 H, =CH), 8.56 (s,
1 H, OH), 12.75 (d, J = 12.9 Hz, 1 H, NH).
19F NMR (DMSO-d6): d = –82.9 (s, CF3).
Anal. Calcd for C18H14F3NO2S: C, 59.17; H, 3.86; N, 3.83. Found:
C, 59.14; H, 3.79; N, 3.83.
IR (KBr): 1708, 1616, 1589, 1542, 1491, 1464 cm–1.
2-Hydroxy-3-{[(4-methoxyphenyl)amino]methylene}-2-(tri-
fluoromethyl)-2,3-dihydro-4H-thiochromen-4-one (8b)
Method A. A soln of thiochromenone 2a (100 mg, 0.39 mmol) and
p-anisidine (130 mg, 1.04 mmol) in benzene (10 mL) was refluxed
for 5 h. The resulting mixture was cooled and diluted with heptane
(10 mL). The solid that formed was filtered, washed with heptane,
and air-dried to give yellow crystals.
1H NMR (DMSO-d6): d (9a, 88%) = 3.67 (s, 3 H, Me), 5.44 (s, 1 H,
H-2), 5.47 (dd, J = 3.8, 1.7 Hz, 1 H, H-5¢), 5.65 (dd, J = 3.8, 2.7 Hz,
1 H, H-4¢), 6.67 (t, J = 2.2 Hz, 1 H, H-3¢), 7.31 (dd, J = 7.8, 1.0 Hz,
1 H, H-8), 7.35 (td, J = 7.5, 1.0 Hz, 1 H, H-6), 7.47 (td, J = 7.5, 1.4
Hz, 1 H, H-7), 8.05 (dd, J = 7.9, 1.4 Hz, 1 H, H-5); d (9b,
12%) = 3.64 (s, 3 H, Me), 5.63 (d, J = 13.0 Hz, 1 H, H-3/2), 5.73 (d,
J = 13.0 Hz, 1 H, H-2/3), 5.98 (dd, J = 3.8, 2.7 Hz, 1 H, H-4¢), 6.20
(dd, J = 3.8, 1.7 Hz, 1 H, H-5¢), 6.72 (dd, J = 1.7, 2.7 Hz, 1 H, H-3¢),
7.41 (d, J = 8.0 Hz, 1 H, H-8), 7.30–7.35 (m, 1 H, H-6), 7.61 (ddd,
J = 8.2, 7.2, 1.4 Hz, 1 H, H-7), 8.02 (dd, J = 8.0, 1.4 Hz, 1 H, H-5).
Method B. A soln of thiochromenone 2a (100 mg, 0.39 mmol) and
p-anisidine (130 mg, 1.04 mmol) in MeOH (3 mL) was refluxed for
3 h then cooled. The yellow solid that formed was filtered, washed
with cooled MeOH, and air-dried to give yellow crystals.
19F NMR (DMSO-d6): d (9a, 90%) = –71.0 (s, CF3); d (9b, 10%) =
–78.4 (s, CF3).
Yield: 130 mg (88%, method A), 120 mg (81%, method B); mp
177–178 °C.
IR (KBr): 3202, 1629, 1587, 1572, 1514 cm–1.
Anal. Calcd for C16H12F3NO2S: C, 56.63; H, 3.56; N, 4.13. Found:
C, 56.47; H, 3.67; N, 4.14.
1H NMR (DMSO-d6): d = 3.77 (s, 3 H, MeO), 7.00–7.04 (m, 2 H,
H-2¢, H-6¢), 7.29–7.38 (m, 4 H, H-6, H-8, H-3¢, H-5¢), 7.45 (ddd,
6-Nitro-3-(trifluoroacetyl)-4H-thiochromen-4-one (11), 6-Ni-
tro-3-(2,2,2-trifluoro-1,1-dihydroxyethyl)-4H-thiochromen-4-
one (14), and 8-Nitro-3-(2,2,2-trifluoro-1,1-dihydroxyethyl)-
4H-thiochromen-4-one (15)
A mixture of thiochromenone 2a (810 mg, 3.14 mmol), concd
H2SO4 (2.5 mL), and 98% HNO3 (2.5 mL) was heated at 90 °C for
1 h, then cooled and poured with stirring onto crushed ice (50 g).
The solid that formed was filtered, washed with H2O, dried, and re-
crystallized (toluene–hexane, 1:1). Yield: 170 mg (18%); mp 165–
166 °C.
1H NMR (400 MHz, DMSO-d6): d (11, 72%) = 8.38 (dd, J = 8.9,
0.4 Hz, 1 H, H-8), 8.60 (dd, J = 8.9, 2.6 Hz, 1 H, H-7), 9.03 (dd,
J = 2.6, 0.4 Hz, 1 H, H-5), 9.39 (s, 1 H, H-2); d (14, 23%) = 8.26 (s,
2 H, 2 OH), 8.36 (dd, J = 8.9, 0.4 Hz, 1 H, H-8), 8.57 (dd, J = 8.9,
2.6 Hz, 1 H, H-7), 9.10 (dd, J = 2.6, 0.4 Hz, 1 H, H-5), 9.14 (s, 1 H,
H-2); d (15 hydrate, 5%) = 7.96 (t, J = 8.2 Hz, 1 H, H-6), 8.25 (s, 2
H, 2 OH), 8.87 (dd, J = 8.2, 1.5 Hz, 1 H, H-5/7), 8.93 (dd, J = 8.2,
1.5 Hz, 1 H, H-7/5), 9.09 (s, 1 H, H-2).
4
3
3J = 7.9, 7.2 Hz, J = 1.4 Hz, 1 H, H-7), 8.01 (dd, J = 7.9 Hz,
4J = 1.4 Hz, 1 H, H-5), 8.06 (d, J = 12.9 Hz, 1 H, =CH), 8.53 (s, 1
H, OH), 12.82 (d, J = 12.9 Hz, 1 H, NH).
2
13C NMR (DMSO-d6): d = 55.6, 81.6 (q, JC,F = 32.3 Hz), 101.8,
1
115.3, 119.2, 125.1 (q, JC,F = 285.6 Hz), 125.9, 126.1, 128.6,
129.4, 131.7, 132.2, 133.3, 135.1, 137.7, 147.7, 157.2, 183.1.
19F NMR (DMSO-d6): d = –83.0 (s, CF3).
Anal. Calcd for C18H14F3NO3S: C, 56.69; H, 3.70; N, 3.67. Found:
C, 56.66; H, 3.45; N, 3.70.
3-[(Benzylamino)methylene]-2-hydroxy-2-(trifluoromethyl)-
2,3-dihydro-4H-thiochromen-4-one (8c)
This compound was prepared by Method A described for 8b.
Colorless crystals; yield: 210 mg (98%); mp 128–130 °C.
IR (KBr): 3070, 1630, 1587, 1570, 1518 cm–1.
1H NMR (DMSO-d6): d = 4.63 (d, AB-system, J = 14.8, 6.3 Hz, 2
H, CH2), 7.15–7.40 (m, 8 H, H-6, H-8, H-7, Ph), 7.78 (d, J = 13.3
Hz, 1 H, =CH), 7.91 (d, J = 7.8 Hz, 1 H, H-5), 7.98 (s, 1 H, OH),
11.42 (dt, J = 13.3, 6.3 Hz, 1 H, NH).
Anal. Calcd for C11H4F3NO4S·0.25H2O: C, 42.94; H, 1.47; N, 4.55.
Found: C, 42.67; H, 1.47; N, 4.37.
2,2,3,3,3-Pentafluoro-1-(4-hydroxy-1,1-dioxido-2H-thio-
chromen-3-yl)propan-1-one (13)
A 35% soln of H2O2 (1.5 g, 16 mmol) was added carefully to a well
stirred soln of thiochromenol 12b (1.0 g, 3.2 mmol) in AcOH (15
mL). The mixture was refluxed for 1 h then cooled to r.t. and poured
onto H2O (100 mL). The precipitated solid was filtered and air-dried
to give yellowish crystals. Yield: 0.35 g (32%); mp 135–137 °C.
2
13C NMR (DMSO-d6): d = 53.1, 81.6 (q, JC,F = 32.3 Hz), 99.3,
1
125.2 (q, JC,F = 285.1 Hz), 125.6, 125.9, 127.8, 128.4, 128.5,
128.9, 131.7, 132.0, 134.8, 138.4, 156.0, 182.1.
19F NMR (DMSO-d6): d = –83.2 (s, CF3).
Synthesis 2010, No. 4, 671–677 © Thieme Stuttgart · New York

PAPER
Some Reactions of 3-(Perfluoroalkanoyl)thiochromenones
677
IR (KBr): 1619, 1592, 1544 cm–1.
(5) (a) Tamura, K.; Ishihara, T.; Yamanaka, H. J. Fluorine
Chem. 1994, 68, 25. (b) Usachev, B. I.; Sosnovskikh, V.
Ya.; Shafeev, M. A.; Röschenthaler, G.-V. Phosphorus,
Sulfur Silicon Relat. Elem. 2005, 180, 1315. (c) Usachev,
B. I.; Shafeev, M. A.; Sosnovskikh, V. Ya. Russ. Chem. Bull.
2006, 55, 523.
1H NMR (CDCl3): d = 4.36 (s, 2 H, H-2), 7.79–7.90 (m, 2 H, H-6,
H-7), 8.04–8.10 [m, 1 H, H-5(8)], 8.21–8.25 [m, 1 H, H-8(5)], 15.93
(s, 1 H, OH).
3
19F NMR (CDCl3): d = –116.9 (m, CF2), –82.2 (t, CF3, JF,F = 1.5
Hz).
(6) (a) Sosnovskikh, V. Ya.; Irgashev, R. A.; Barabanov, M. A.
Synthesis 2006, 2707. (b) Sosnovskikh, V. Ya.; Irgashev, R.
A.; Kodess, M. I. Tetrahedron 2008, 64, 2997.
(c) Sosnovskikh, V. Y.; Moshkin, V. S.; Kodess, M. I.
Tetrahedron 2008, 64, 7877. (d) Sosnovskikh, V. Ya.;
Khalymbadzha, I. A.; Irgashev, R. A.; Slepukhin, P. A.
Tetrahedron 2008, 64, 10172.
(7) Sevenard, D. V.; Vorobyev, M.; Sosnovskikh, V. Ya.;
Wessel, H.; Kazakova, O.; Vogel, V.; Shevchenko, N. E.;
Nenajdenko, V. G.; Lork, E.; Röschenthaler, G.-V.
Tetrahedron 2009, 65, 7538.
Anal. Calcd for C12H7F5O4S: C, 42.11; H, 2.06. Found: 42.08; H,
2.14.
References
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Eswarakrishnan, S. Fluorine in Bioorganic Chemistry;
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(f) Hiyama, T. Organofluorine Compounds: Chemistry and
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D. V.; Sosnovskikh, V. Ya. Synthesis 2009, 3233.
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Irgashev, R. A.; Sosnovskikh, V. Ya. Synthesis 2009, 3869.
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Trans. 1 1988, 1829.
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