Fluorine-containing heterocycles: VIII. Transformations of 2-polyfluorobenzoylacrylates having a thiosemicarbazide fragment

Article abstract of DOI:10.1023/A:1022523915232

Depending on the conditions, 3-(4-R-thiosemicarbazido)-2-polyfluorobenzoylacrylates can be converted into the corresponding potassium salts, [1,3,4]thiadiazino[6,5,4-ij]quinolines, and pyrazole or 1,3,4-thiadiazole derivatives.

Full text of DOI:10.1023/A:1022523915232

Russian Journal of Organic Chemistry, Vol. 38, No. 12, 2002, pp. 1790 1796. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 12, 2002,
pp. 1851 1856.
Original Russian Text Copyright
2002 by Lipunova, Nosova, Sidorova, Charushin, Chasovskikh, Tkachev.
Fluorine-Containing Heterocycles:
VIII.* Transformations of 2-Polyfluorobenzoylacrylates
Having a Thiosemicarbazide Fragment**
G. N. Lipunova1, E. V. Nosova1, L. P. Sidorova1, V. N. Charushin1,
O. M. Chasovskikh1, and A. V. Tkachev2
1
Ural State Technical University, ul. Mira 19, Yekaterinburg, 620002 Russia
2
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 9, Novosibirsk, 630090 Russia
Received January 16, 2002
Abstract Depending on the conditions, 3-(4-R-thiosemicarbazido)-2-polyfluorobenzoylacrylates can be
converted into the corresponding potassium salts, [1,3,4]thiadiazino[6,5,4-ij]quinolines, and pyrazole or
1,3,4-thiadiazole derivatives.
We previously showed that 3-hydrazino-2-poly-
fluorobenzoylacrylates are convenient synthons for
the preparation of [ij]-fused fluoroquinolinones and
other fluorinated nitrogen-containing heterocycles
[2, 3]. We also reported that heating of 3-(4-R-thio-
semicarbazido)-2-polyfluorobenzoylacrylates I in
benzene or toluene leads to formation of tricyclic
fluoroquinolinones, 9,10-difluoro-7H-[1,3,4]thiadi-
azino[6,5,4-ij]quinolin-7-one derivatives III [4]. The
reaction is relatively fast, and it requires no catalyst to
occur [5]. We failed to isolate bicyclic intermediates
like fluoroquinolinones II.
to ester and ketone carbonyl groups were present in
the IR spectrum. By heating in boiling toluene for 1 h,
compound IIe was converted into tricyclic thiadi-
azinoquinoline III.
Acrylates I are also capable of undergoing intra-
molecular cyclizations with participation of the C O
groups. When acrylate Ia was heated in boiling
toluene, apart from compound IIIa, we isolated 70%
of a product with a lower melting point. The product
1
is readily soluble in toluene, and its H and 19F NMR
spectra correspond to the structure of 1,4,5-trisub-
1
stituted pyrazole IV. The H NMR spectrum of IV
contained signals from protons of the ethyl group and
morpholine, tetrafluorobenzoyl, and pyrazole frag-
ments (Table 1). Signals from four fluorine nuclei
The goal of the present work was to study intra-
molecular cyclizations of acrylates I with participation
of the carbonyl groups, as well as to synthesize
fluoroquinolinones II. Heating of ethyl 3-(4-cyclo-
hexylthiosemicarbazido)-2-pentafluorobenzoylacrylate
(Ie) in ethanol gave a product which was assigned
were present in the 19F NMR spectrum. Compound
IV showed in the IR spectrum only one carbonyl
absorption band located at a lower frequency, as com-
pared with acrylate Ia. Taking into account published
data [6], this band was assigned to ketone carbonyl. In
the mass spectrum of IV we observed only fragment
ion peaks, the most abundant being that with m/z 177.
It corresponds to elimination of the tetrafluorobenzoyl
fragment from the molecular ion (Table 2). Pyrazole
IV was also obtained in 40% yield (in a mixture with
products III and VIII) by heating of acrylate Ia in
boiling toluene in the presence of KF. Heating of Ia
in ethanol also yields product IV. According to our
previous data [2], pyrazoles like IV are characterized
1
structure IIe on the basis of its H and 19F NMR
spectra. The 1H NMR spectrum of IIe contained
signals from the 2-H proton, protons of the ethyl and
cyclohexyl groups, and two NH protons (Table 1). In
the 19F NMR spectrum of IIe we observed signals
from four fluorine atoms. Absorption bands belonging
____________
*
For communication VII, see [1].
**
This study was financially supported by the Russian Founda-
tion for Basic Research (project nos. 00-03-32785a and 01-
03-96427) and by the CRDF program (grant no. REC-005).
1070-4280/02/3812-1790$27.00 2002 MAIK Nauka/Interperiodica

FLUORINE-CONTAINING HETEROCYCLES: VIII.
1791
Scheme 1.
X = H, R = morpholino (a); X = F, R = morpholino (b); X = H, R = thiomorpholino (c); X = H, R = perhydroazepin-1-yl (d);
X = F, R = cyclohexylamino (e); X = H, R = cyclohexylamino (f).
by a more downfield signal from 3-H, as compared to
pyrazoles like V and VI. In fact, an analogous pattern
was observed in the present work (Table 1).
pound V shows in the mass spectrum the molecular
ion peak and also fragment ion peaks corresponding
to elimination of OEt, COOEt, and thiomorpholino
groups (minus one or two hydrogen atoms); the latter
peaks are the most intense in the spectrum (Table 2).
Heating of compound Ic for 1.5 h in boiling ben-
zene in the presence of a catalytic amount of such
a strong base as 1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU) afforded 1,4,5-trisubstituted pyrazole V as
a result of cyclization involving the ketone carbonyl
4,5-Disubstituted pyrazole VI was obtained by
heating of acrylate Ic in benzene containing traces
of water; obviously, compound VI is formed from
pyrazole V as a result of hydrolysis at the thioamide
group. Unlike compound V, pyrazole VI has a higher
melting point and is characterized by a lower solubil-
ity in organic solvents. The IR spectrum of VI, as
well as of V, contains a high-frequency ester carbonyl
absorption band. In the mass spectrum of VI we
observed the molecular ion peak and those resulting
from elimination of ethoxy group (base peak) and
nitrogen molecule (Table 2). The fragmentation
patterns of pyrazoles V and VI under electron impact
differ from that observed for compound IV. Pyrazole
VI was synthesized previously from 3-hydrazino-
pyridyl-2-tetrafluorobenzoylacrylates [3].
1
group. The H NMR spectrum of V contain signals
from all protons present therein, and four fluorine
signals were observed in the 19F NMR spectrum
(Table 1). Protons of the (CH2)2N fragment in the
1
thiomorpholino group appear in the H NMR spec-
trum as two multiplets, and one fluorine signal is
an unresolved multiplet. This pattern suggests
coupling between hydrogen and fluorine nuclei
through 8 bonds or through space, which is possible
in the structure with , -arrangement of the tetra-
fluorophenyl and thiomorpholino groups. The IR
spectrum of V contains only one high-frequency car-
bonyl absorption band due to the ester group. Com-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 12 2002

1792
LIPUNOVA et al.
Table 1. IR, UV, and 1H and 19F NMR spectra of compounds I VIII
1H NMR spectrum, , ppm, J, Hz
Compound
no.
3-H
NH
CH3, t OCH2, q 6-H, m
R
3
3
Ia
8.33 d, J = 11.9 Hz
12.94 d, J = 12.2 Hz,
1.04
1.33
4.00
4.25
7.43
3.32 m [4H, N(CH2)2],
3.74 m [4H, O(CH2)2]
11.43 br.d
IIe
8.10 s
8.4 br.s, 10.5 br.s
1.2 1.4 m [6H, (CH2)3],
1.6 1.9 m [4H, (CH2)2],
4.1 br. s (1H, CHNH)
IV
V
8.82 s
8.12 s
1.18
1.21
4.12
4.17
7.84
7.40
3.60 m [4H, N(CH2)2],
3.70 m [4H, O(CH2)2]
2.83 m [4H, N(CH2)2],
3.72 m (2H, NCH2),
4.32 m (2H, NCH2)
VI
8.38 s
13.71 br.s
1.16
4.15
7.55
8.06
VII
3.43 m [4H, N(CH2)2],
3.76 m [4H, O(CH2)2]
3
3
VIIIa
VIIIb
VIIIc
VIIId
8.18 d, J = 14.1 Hz
13.62 d, J = 12.7 Hz
1.01
1.06
1.07
1.01
3.92
4.02
3.93
3.95
7.25
3.55 m [4H, N(CH2)2],
3.71 m [4H, O(CH2)2]
3
3
8.33 d, J = 12.7 Hz
13.11 d, J = 12.7 Hz
3.68 m [4H, N(CH2)2],
3.84 m [4H, O(CH2)2]
3
3
8.15 d, J = 13.7 Hz
13.6 d, J = 12.8 Hz
7.15
7.30
2.71 m [4H, S(CH2)2],
4.16 m [4H, N(CH2)2]
3
8.21 d, J = 13.6 Hz
13.23 d, 3J 11.9 Hz
1.53 m [4H, (CH2)2],
1.69 m [4H, (CH2)2],
3.76 m [4H, N(CH2)2]
Compound
no.
IR spectrum,
(C O), cm
UV spectrum,
max, nm
19F NMR spectrum, F, ppm
1
Ia
IIe
IV
V
1700, 1620
1710, 1630
1630
345
312
270
140.5 m (1F), 142.5 m (1F), 156.8 m (1F), 158.0 m (1F)
143.7 m (1F), 150.5 m (1F), 155,2 m (1F), 162,1 m (1F)
137.0 m (1F), 138.5 m (1F), 148.5 m (1F), 155.0 m (1F)
138.0 m (1F), 140.3 m (1F), 154.1 m (1F), 157.1 m (1F)
134.5 m (1F), 141.1 m (1F), 157.0 m (1F), 157.9 m (1F)
140.0 m (1F), 140.7 m (1F), 155.8 m (1F), 156.5 m (1F)
142.2 m (1F), 143.4 m (1F), 159.3 m (1F), 160.2 m (1F)
145.2 m (2F), 156.0 m (1F), 163.1 m (1F)
1720
1720
250, 298
264
VI
VII
VIIIa
VIIIb
VIIIc
VIIId
322
384
384
384
1630, 1680
1710, 1630
1680, 1620
1630, 1670
384
141.1 m (1F), 143.1 m (1F), 158.3 m (1F), 158.6 m (1F)
2,5-Disubstituted thiadiazole VII was obtained in
55% yield by heating of acrylate Ia in boiling benzene
in the presence of a catalytic amount of DBU. Com-
pound VII is characterized by a strong UV band with
its maximum at 322 nm. The IR spectrum of VII
lacks carbonyl absorption band. Its H NMR spectrum
contains signals from morpholine protons and 6-H of
the aromatic fragment, and four fluorine signals are
present in the 19F NMR spectrum. Thiadiazole VII
shows the molecular ion peak in the mass spectrum.
Compound VII was also obtained (together with salt
VIIIa) by heating of acrylate Ia in boiling toluene
in the presence of K2CO3. It should be noted that the
fragmentation pattern of Ia at 120 C resembles that
of pyrazole IV, whereas at 200 C it is similar to that
of thiadiazole VII.
1
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 12 2002

FLUORINE-CONTAINING HETEROCYCLES: VIII.
1793
Table 2. Melting points, mass spectra, and elemental analyses of compounds I VIII
Found, %
Calculated, %
Comp.
no.
mp,
C
Mass spectrum, m/z (Irel, %)
Formula
C
H
N
C
H
N
Ia
104 106 120 C: 264 (11), 219 (7), 177 46.8
(100), 149 (14)
3.9 10.4 C17H17F4N3O4S
46.90 3.91 9.66
220 C: 318 (74), 261 (62), 192
(100), 174 (23)
IIe
IV
195 197
55 57
55.4
4.5 10.0 C19H19F4N3O3S
3.9 10.3 C17H15F4N3O3S
55.21 4.63 10.17
48.92 3.62 10.07
50 C: 265 (11), 264 (77), 219 48.5
(57), 218 (66), 177 (100), 149
(36)
V
78 80
90 C: 433 (24, M+), 386 (12), 46.8
289 (8), 243 (14), 200 (10),
146 (49), 145 (100), 144 (99)
3.2
3.2
9.4 C17H15F3N3O2S2
9.9 C12H8F4N2O2
47.11 3.49 9.70
50.09 2.80 9.72
45.14 2.82 13.16
VI
140 142 90 C: 288 (76, M+), 260 (30), 50.4
244 (63), 243 (100), 240 (76),
216 (41)
VII
158 160 120 C: 319 (100, M+), 262 (98), 45.3
3.0 13.0 C12H9F4N3OS
193 (100), 175 (40)
VIIIa
225 227 120 C: 417 (41), 264 (51), 219 43.4
(42), 177 (100), 149 (47)
3.3
9.1 C17H16F4KN3O4S 43.15 3.29 8.90
VIIIb 214 216
VIIIc 202 204
VIIId 178 180
41.8
41.5
46.6
3.4
3.6
4.2
8.7 C17H15F5KN3O4S 41.54 3.05 8.50
8.8 C17H17F4KN3O3S2 41.62 3.49 8.57
8.5 C19H20F4KN3O3S 47.00 4.15 8.65
Table 3. Experimental 13C chemical shifts of compounds Ia and VIIIa and calculated chemical shifts of structures A D
13C NMR spectrum, C, ppm
Calculated chemical shifts
C
Atom
no.
Ia
VIIIa
A
B
C
D
C1
165.20
110.50
151.96
183.98
178.29
42.22
65.52
59.38
13.92
179.11
110.74
145.61
167.25
181.16
48.03
67.23
59.11
14.31
165.0
111.6
158.3
185.0
187.0
58
71
59.6
13.7
165.0
111.6
158.3
154.0
187.0
53
72
59.6
13.7
87.0
118.6
142.5
184
187.0
57.6
71.5
59
15
58.0
118.6
142.5
154
187.0
49.6
71.2
60
14
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
127.50
140.82
142.68
143.91
141.56
119.92
130.61
138.77
143.14
147.97
141.14
129.26
122.5
147.5
138.2
143.5
146.8
115.5
122.5
147.5
138.2
143.5
146.8
115.5
122.5
147.5
138.2
143.5
146.8
115.5
122.5
147.5
138.2
143.5
146.8
115.5
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 12 2002

1794
LIPUNOVA et al.
Scheme 2.
By heating of acrylate Ia in acetonitrile in the
trum of VIIIa (Table 3). The mass spectrum of VIIIa
contained ion peaks with m/z 264, 219, 177, and 149,
which were also typical of acrylate Ia (at 120 C) and
pyrazole IV (Table 2).
presence of KF or K2CO3 we obtained high-melting
water-soluble product VIIIa which showed in the
electron absorption spectrum a strong band with its
maximum at 384 nm, i.e., at a longer wavelength
than that observed for acrylate Ia. In the IR spectrum
of VIIIa, the ketone and ester carbonyl absorption
bands were located closer to each other (1630 and
The above data led us to presume the structure of
potassium salt VIIIa in which the negative charge
is delocalized mainly over the S C N fragment.
This structure is consistent with the chemical shift
of C4 in the experimental 13C NMR spectrum. Similar
salts were obtained from acrylates Ib, Id, and Ie by
heating in acetonitrile in the presence of KF. Salts
VIII are fairly stable. For example, salt VIIIa remains
unchanged on heating in toluene for 2 h. Using UV
spectroscopy, we detected formation of salts of
acrylates I with triethylamine. However, these salts
turned out to be less stable than VIII.
We previously showed [2, 3] that heating of 3-R-
hydrazino-2-polyfluorobenzoylacrylates (R = aroyl,
benzazolyl) in acetonitrile in the presence of KF gives
rise to pyrazoles together with penta- and tricyclic
quinolinone derivatives. No salt formation was ob-
served in these reaction. Presumably, increased acidity
of the SH group in the thiol form of acrylates I favors
formation of stable salts. The formation of stable
potassium salts from symmetric polyfluorinated -di-
ketones was reported in [7].
1
1600 cm ), as compared to the corresponding bands
1
of acrylate Ia (1700 and 1620 cm ; Table 1). Its
1H NMR spectrum contained signals from protons of
morpholino group and 6-H in tetrafluorobenzoyl frag-
ment, and signals from the CH and NH protons
1
appeared as doublets (as well as in the H NMR spec-
trum of Ia). Four fluorine signals were present in
the 19F NMR spectrum. Product VIIIa dissolved on
addition of acetic acid, but after a time a solid pre-
cipitated from the solution. All spectral parameters of
the latter were identical to those of acrylate Ia. We
compared the 13C NMR spectrum of VIIIa with the
calculated spectra of several hypothetical structures
A D (Scheme 2; the calculations were performed with
the use of ChemDraw Ultra 6.0.1 program; Table 3).
The upfield region of the 13C spectrum of VIIIa
contains no other signals belonging to tetrahedral
carbon atoms than those from ethoxy group and
morpholine residue. Therefore, compound VIIIa
cannot be a product of intramolecular addition of the
NH or SH moiety of Ia to the carbonyl group. Thus
structures C and D can be ruled out. The data corre-
sponding to a superposition of structures A and B
turned out to be the closest to the experimental spec-
EXPERIMENTAL
1
The H and 19F NMR spectra were recorded on
Bruker WP-250 and Bruker WP-80SY spectrometers
1
(250.135 MHz for H and 75.38 MHz for 19F) from
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 12 2002

FLUORINE-CONTAINING HETEROCYCLES: VIII.
1795
solutions in DMSO-d6. Tetramethylsilane was used
1,8-Diazabicyclo[5.4.0]undec-7-ene, 10 drops, was
added to a suspension of 0.75 g (1.65 mmol) of ester
Ic in 15 ml of benzene. The mixture was stirred for
1.5 h at 80 and evaporated almost to dryness, 4 drops
of acetic acid was added, and the precipitate was
filtered off. Recrystallization from ethanol gave 0.5 g
(62%) of pyrazole V.
1
as internal reference for H NMR spectra, and 19F
chemical shifts were measured relative to hexafluoro-
benzene. The 13C NMR spectra were obtained on
a Bruker WP-500 instrument at 125 MHz using
CDCl3 as solvent and reference. The mass spectra
were recorded on a Varian MAT 311A spectrometer
(accelerating voltage 3 kV, cathode emission current
300 A, direct sample admission into the ion source).
The UV spectra were measured on a Specord UV-Vis
spectrophotometer in ethanol, and the IR spectra were
obtained on a Specord 75IR instrument from samples
pelleted with KBr. The solvents (96% ethanol, ben-
zene, toluene, and acetonitrile) were preliminarily
dried over sodium sulfate and distilled. 3-(4-R-Thio-
semicarbazido)-2-polyfluorobenzoylacrylates I were
synthesized by the procedure reported in [4].
Ethyl 1-cyclohexylaminothiocarbonylamino-
5,6,7,8-tetrafluoro-4-oxo-1,4-dihydroquinoline-3-
carboxylate (IIe). A solution of 0.4 g (0.92 mmol)
of compound Ie in 12 ml of ethanol was heated for
1 h at 80 C. It was then cooled and evaporated, and
the residue was recrystallized from ethanol. Yield
0.3 g (79%).
Ethyl 2-cyclohexylamino-8,9,10-trifluoro-7-oxo-
7H-[1,3,4]oxadiazino[6,5,4-ij]quinoline-6-carbo-
xylate (III). A solution of 0.1 g (0.24 mmol) of ester
IIe in 8 ml of toluene was heated for 1.5 h under
reflux. The mixture was cooled, and the precipitate
was filtered off and recrystallized from ethanol. Yield
0.07 g (74%).
5-Ethoxy-2-morpholinothiocarbonyl-4-(2,3,4,5-
tetrafluorobenzoyl)pyrazole (IV). a. A solution of
1.0 g (2.3 mmol) of ester Ia in 12 ml of toluene was
heated for 2 h under reflux. The mixture was cooled,
and the precipitate of quinolinone IIa, 0.1 g (11%),
was filtered off. The filtrate was evaporated, and the
residue was recrystallized from ethanol. Yield of
pyrazole IV 0.6 g (63%).
Ethyl 5-(2,3,4,5-tetrafluorophenyl)-1H-pyrazole-
4-carboxylate (VI). a. A solution of 2.0 g (4.4 mmol)
of ester Ic in 30 ml of wet benzene was heated for 2 h
at 80 C. The mixture was cooled, and the precipitate
was filtered off and recrystallized from ethanol. Yield
1.3 g (38%).
b. A solution of 0.18 g (0.4 mmol) of ester If
in 8 ml of ethanol was heated for 2 h at 80 C. The
mixture was evaporated, and the residue was recrys-
tallized from ethanol. Yield 0.09 g (78%).
2-Morpholino-5-(2,3,4,5-tetrafluorophenyl-1,3,4-
thiadiazole (VII). a. A 0.1-ml portion of DBU was
added to a suspension of 0.5 g (1.15 mmol) of ester
Ia in 10 ml of dry benzene, and the mixture was
heated for 2 h at 80 C and evaporated. The residue
was recrystallized from ethanol. Yield 0.2 g (55%).
b. Potassium carbonate, 1.0 g (7.25 mmol), was
added to a suspension of 1.6 g (4.0 mmol) of ester Ia
in 15 ml of toluene, and the mixture was heated for
2 h under reflux and filtered while hot. The precipitate
was washed with water and recrystallized from
acetone to obtain 0.4 g (21%) of potassium salt VIIIa.
The toluene solution was evaporated, and the residue
was recrystallized from ethanol to obtain 0.9 g (71%)
of thiadiazole VII.
Ethyl 3-[2-(R-thiocarbonyl)hydrazino]-2-tetra-
(penta)fluorobenzoylacrylate potassium salts VIII.
a. Potassium fluoride, 0.3 g (4.6 mmol), was added
to a solution of 1.0 g (2.3 mmol) of ester Ia in 15 ml
of acetonitrile, and the mixture was heated for 1 h
under reflux. It was then cooled, and the precipitate
of salt VIIIa was filtered off and recrystallized from
acetone. Yield 0.45 g (41%). Salts VIIIb and VIIId
were synthesized in a similar way.
b. Potassium fluoride, 0.6 g (9.2 mmol), was
added to a solution of 2.0 g (4.6 mmol) of ester Ia
in 18 ml of toluene. The mixture was heated for 2 h
under reflux and cooled, and the precipitate was fil-
tered off and washed with water to obtain 0.5 g (23%)
of compound VIIIa. The toluene solution was
evaporated, and the residue was recrystallized from
ethanol. Yield of IV 1.3 g (68%).
c. A solution of 0.5 g (1.15 mmol) of ester Ia in
15 ml of ethanol was heated for 1 h under reflux.
The mixture was evaporated, and the residue was
recrystallized from ethanol. Yield 0.35 g (73%).
b. Potassium carbonate, 0.64 g (4.6 mmol), was
added to a solution of 1.0 g (2.3 mmol) of ester Ia
in 12 ml of acetonitrile. The mixture was heated for
2 h under reflux and cooled, and the precipitate of
salt VIIIa was filtered off and recrystallized from
acetonitrile. Yield 0.5 g (46%). Salt VIIIb was ob-
tained in a similar way.
c. Ethyl 3-ethoxy-2-(2,3,4,5-tetrafluorobenzoyl)-
acrylate, 1.4 g (4.3 mmol), and potassium fluoride,
Ethyl 5-(2,3,4,5-tetrafluorophenyl)-1-thiomor-
pholinothiocarbonylpyrazole-4-carboxylate (V).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 12 2002

1796
LIPUNOVA et al.
0.5 g (8.0 mmol), were added to a suspension of 0.6 g
(4 mmol) of 4-morpholinothiosemicarbazide in 10 ml
of acetonitrile. The mixture was heated for 1 h under
reflux and evaporated, 10 ml of acetone was added
to the residue, and the precipitate of salt VIIIa was
filtered off and recrystallized from acetone. Yield
0.9 g (47%).
2. Lipunova, G.N., Mokrushina, G.A., Nosova, E.V.,
Chasovskikh, O.M., Rusinova, L.I., and Aleksand-
rov, G.G., Russ. J. Org. Chem., 1997, vol. 33, no. 10,
pp. 1576 1486.
3. Lipunova, G.N., Nosova, E.V., Charushin, V.N., and
Chasovskikh, O.M., Khim. Geterotsikl. Soedin., 2001,
no. 10 (412), pp. 1396 1406.
4. Lipunova, G.N., Sidorova, L.P., Nosova, E.V., Pero-
va, N.M., Charushin, V.N., and Aleksandrov, G.G.,
Russ. J. Org. Chem., 1999, vol. 35, no. 11, pp. 1698
1705.
d. Potassium carbonate, 0.5 g (3.6 mmol), was
added to a suspension of 0.8 g (1.8 mmol) of ester Ic
in 10 ml of toluene. The mixture was heated for 2 h
under reflux and cooled, and the precipitate of salt
VIIIc was filtered off and recrystallized from ethanol.
Yield 0.55 g (61%).
5. Mokrushina, G.A., Alekseev, S.G., Charushin, V.N.,
and Chupakhin, O.N., Zh. Vses. Khim. Ob-va, 1991,
vol. 36, no. 4, pp. 447 455.
6. Bellamy, L.J., The Infra-red Spectra of Complex
Molecules, London: Methuen, 1958.
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1. Kotovskaya, S.K., Romanova, S.A., Charushin, V.N.,
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7. Pashkevich, K.I., Latypov, R.R., and Filyakova, V.I.,
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 12 2002