Synthesis of substituted 3-[(4-oxocyclohexa-2,5-dien-1-ylidene)-hydrazinylidene]-1,3-dihydro-2H-indol-2-ones and their reactions with hydrogen chloride

Article abstract of DOI:10.1134/S1070428016050067

4-Hydroxyphenylhydrazones of isatin derivatives were synthesized and oxidized with lead compounds to the corresponding azines. The introduction of isatin fragment in a quinoid system increases the redox potential of the system compared with 1,4-benzoquino

Full text of DOI:10.1134/S1070428016050067

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2016, Vol. 52, No. 5, pp. 650–654. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © B.V. Murashevich, N.A. Nichik, A.K. Zamyatina, N.V. Toropin, K.S. Burmistrov, 2016, published in Zhurnal Organicheskoi Khimii,
2
016, Vol. 52, No. 5, pp. 665–669.
Synthesis of Substituted 3-[(4-Oxocyclohexa-2,5-dien-1-ylidene)-
hydrazinylidene]-1,3-dihydro-2H-indol-2-ones and Their
Reactions with Hydrogen Chloride
B. V. Murashevich, N. A. Nichik, A. K. Zamyatina,
N. V. Toropin, and K. S. Burmistrov
Ukrainian State University of Chemical Technology, pr. Gagarina 8, Dnepropetrovsk, 49005 Ukraine
е-mail: murashevich@yahoo.com
Received October 7, 2015
Abstract—4-Hydroxyphenylhydrazones of isatin derivatives were synthesized and oxidized with lead
compounds to the corresponding azines. The introduction of isatin fragment in a quinoid system increases the
redox potential of the system compared with 1,4-benzoquinone thus presumably resulting in the prevalence of
1
,4-addition process. By an example of the reaction of N-methylisatins with hydrogen chloride it was shown
that the reaction proceeded in keeping with the theoretically predicted direction. Azines, derivatives of isatin
unsubstituted at the nitrogen atom, do not react with hydrogen chloride because of the presence of a strong
intramolecular hydrogen bond.
DOI: 10.1134/S1070428016050067
Quinone imines are nitrogen analogs of quinones
HX type. HCl is one of these reagents. N-Substituted
quinone imines are known to react readily with
hydrogen chloride and bromide along the scheme of
1,4- or 6,3-addition [3–6]. The direction of addition
(1,4- or 6,3-) is governed by relative feasibility of the
quinoid intermediate A or B (Scheme 1).
In its turn the energy advantage of structures A and
B may be estimated from the comparison of the redox
potentials of the quinone imines. If the replacement of
the carbonyl group С=О in quinone by an imino group
С=NR results in increased redox potential, then the
scheme of 1,4-addition is operating due to the relative
and like quinones take part in metabolic processes of
living organisms exhibiting a high biologic activity.
Among quinone imine derivatives found in natural
objects compounds are present with anticancer and
antibacterial action [1]. In the human body these
compounds undergo diverse transformations, and some
of intermediates may be very toxic. For instance, the
metabolite of paracetamol considered as endowing the
drug with hepatotoxicity is N-acetyl-1,4-benzoquinone
imine [2]. The most characteristic reactions of quinone
imines are redox processes and addition of reagents of
Scheme 1.
H
Cl
Cl
1
,4-
RHN
O
RHN
RHN
OH
OH
A
HCl
RN
O
H
Cl
Cl
6
,3-
RN
OH
B
6
50

SYNTHESIS OF SUBSTITUTED 3-[(4-OXOCYCLOHEXA-2,5-DIEN-1-YLIDENE)...
651
advantage of intermediate A. When this replacement
leads to the reduced redox potential, intermediate B
becomes more feasible and the reaction takes the path
of 6,3-addition. The efficiency of this approach was de-
cisively demonstrated by examples of reactions N-aryl-
The aim of this study was the synthesis and
reactivity investigation of azines with the structure free
of СН=N moiety. We selected as such structures isatin
derrivatives, 3-[(4-oxocyclohexa-2,5-dienylidene)hyd-
razinylidene]-1,3-dihydro-2H-indol-2-ones 1a–1d that
were synthesized by the reaction of 4-hydroxyphe-
nylhydrazine with the corresponding isatins followed
by oxidation by procedure described before [9].
1
,4-benzoquinone imines with HCl and HBr [4–6].
It was recently found that arenalazines of quinones
containing in the molecule an azomethine fragment
reacted with the reagents of the НХ type along the
scheme of 1,8-addition [7, 8] (Scheme 2).
The reaction was carried out without isolation of 4-
hydroxy-phenylhydrazine, and hydrazones 1a–1d were
obtained in 60–85% yields. Their subsequent oxidation
with lead dioxide in dichloroethane afforded the target
azines 2a–2d in a fair yield (Scheme 3).
Scheme 2.
ArHC
N
N
O
The structure of hydrazones 1a–1d and azines 2a–2d
1
was confirmed by the data of Н NMR spectra. In the
spectra of azines 2a–2d a nonequivalence of the
protons of the quinoid ring was observed because of
hindered isomerization near the nitrogen atom.
HX
ArXHC
N
N
OH
By the method of potentiometric titration of solu-
tions of hydrazones 1a–1d with lead tetraacetate in
0.5 M sodium acetate solution in acetic acid we measu-
red the redox potentials of the systems 1a–1d/2a–2d.
The values of redox potentials of compounds 1a–1d
are 0.614, 0.611, 0.602, 0.615 V.
Evidently the reaction of 1,8-addition occurs due to
the energy advantage of intermediate C having aroma-
tic nature.
H
Ar
N
N
OH
The reactivity of obtained azines 2a–2d we studied
by an example of the reaction with hydrogen chloride.
In this case evidently intermediates D–F may arise.
Cl
C
Scheme 3.
OH
OH
OH
HNO2
SnCl2
_
+
2
NH2
N Cl
NHNH2
R'
R'
O
R'
O
N
R
H
N
PbO
2
RN
N
OH
RN
N
N
O
O
O
a_1d
2a 2d
_
1
2
R = R' = H (a); R = Me, R' = H (b), Br (c), NO (d).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 5 2016

6
52
MURASHEVICH et al.
R'
R'
R'
H
Cl
Cl
N
H
N
RN
RN
N
OH
RN
N
N
OH
N
OH
Cl
O
O
O
H
D
E
F
Since the redox potential of the systems 1/2
In order to exclude the possible influence of the
hydrogen bond on the reactivity we studied HCl
addition to azines 2b–2d. In contrast to compound 2a,
the IR spectrum of compound 2b contains a strong
absorption band in the region 1727 cm confirming
the existence of the substance in the amide form.
Actually, these compounds as has been predicted from
the values of redox potentials readily add hydrogen
chloride in 1,4-positions.
insignificantly exceeds the redox potential of the
system quinone–hydroquinone (0.583 V [10]), the
addition of hydrogen chloride most probably would
occur by the scheme of 1,4-addition. The substrates,
isatin derivatives having the CONH moiety, in
particular, compound 2a, did not react with hydrogen
chloride. The low reactivity apparently is due to the
prevailing existence of compound 2a in tautomeric
imidol form with an intramolecular hydrogen bond.
–
1
The addition is accompanied by a partial reduction
of azines 2b–2d to hydrazones 1b–1d, thus somewhat
decreasing the yield of the reaction products. The
reason of the partial reduction of azines is the fact that
the introduction of chlorine in the quinoid ring caused
the decrease in the redox potential, namely, the
mesomeric effect of chlorine dominates over the
inductive effect evidently because of the long
conjugation chain of the quinoid ring with the isatin
fragment. Therefore the initial azines 2b–2d partially
oxidize in the course of the reaction the addition
products 3b–3d (Scheme 4). The structure of addition
N
N
O
.
.
.
H
N
O
2
a
This assumption is confirmed by the IR spectrum of
compound 2a, which contains a strong absorption band
–
1
in the region 3432 cm corresponding to the stretching
vibrations of the imidol OH group involved in the
formation of the hydrogen bond, whereas the
absorption band of the stretching vibrations of the
С=О group of the imide isatin fragment in the region
1
products 3b–3d is confirmed by the H NMR spectra,
and for compound 3b also by an independent synthesis
from 4-hydroxy-2-chlorophenylhydrazine.
–
1
1
730 cm is very weak.
EXPERIMENTAL
The presence of a hydrogen bond with the
exocyclic nitrogen atom of the quinoid system reduces
its basicity thus impeding the protonation which is the
primary act of the hydrogen halide addition [6].
1
Н NMR spectra were registered on a spectrometer
Varian Gemini 2000 (400 MHz), internal reference
TMS. IR spectra were recorded on a spectrophoto-
meter Perkin Elmer Spectrum BX II from pellets with
KBr. The mixtures were separated by column chro-
matography on silica gel ROCC, fraction 60–200 µm,
eluent chloroform–2-propanol, 1 : 9. The qualitative
analysis of reaction mixtures was performed by
TLC using plates with fixed layer of silica gel
Kieselgel 60 F254 (Merck) on a polymer sublayer and
Sorbfil (IMID) on an aluminum sublayer, eluent
chloroform or mixtures chloroform–2-propanol in
various ratios.
Scheme 4.
R'
Cl
H
HCl
b_2d
2
N
OH
MeN
N
O
b_3d
3
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 5 2016

SYNTHESIS OF SUBSTITUTED 3-[(4-OXOCYCLOHEXA-2,5-DIEN-1-YLIDENE)...
653
4
-Hydroxyphenylhydrazones of substituted isa-
tins 1a–1d. General procedure. A solution of 6 g
0.05 mol) of 4-aminophenol in a mixture of 50 mL of
NH), 12.72 s (1Н, ОН). Found, %: С 52.01; Н 3.48; Br
23.12; N 12.16. C H BrN O . Calculated, %: С
1
5
12
3
2
(
52.02; Н 3.47; Br 23.12; N 12.14.
-[2-(4-Hydroxyphenyl)hydrazinylidene]-1-
methyl-5-nitro-1,3-dihydro-2H-indol-2-one (1d). Yield
water and 15 mL of 32% hydrochloric acid was cooled
on an ice bath to 0°С. At continuous stirring maintain-
ing the temperature below 5°С a solution was added of
3
1
8
2%, orange crystals, mp 242–244°С. Н NMR spec-
4
g (0.055 mol) of sodium nitrite in 15 mL of water.
trum (DMSO-d ), δ, ppm: 3.26 s (3Н, СН ), 6.80 d (1Н,
6
3
The obtained solution of a diazonium salt was stirred
for 40 min. It was then added to a cooled to –5°С
solution of tin(II) chloride obtained by dissolving 30 g
of tin in a mixture of 50 mL of water and 100 mL of
C H ОН, J 8.4 Hz), 7.20 d (1H, C H NO , J 8.5 Hz),
6
4
6
4
2
7
.33 d (1H, C H ОН, J 8.4 Hz), 8.10 d (1H, C H NO ,
6 4 6 4 2
J 8.5 Hz), 8.15 s (1H, C H NO ), 9.41 s (1H, NH), 12.64
6
4
2
s (1Н, ОН). Found, %: С 57.70; Н 3.83; N 17.96.
C H N O . Calculated, %: С 57.69; Н 3.85; N 17.95.
3
2% hydrochloric acid. After stirring for 2 h to the
1
5
12
4
4
reaction mixture was added a solution of 0.05 mol of
an appropriate isatin in a sufficient amount of 2-
propanol, also a solution was added of 6 g (0.07 mol)
of sodium acetate in 35 mL of water. The mixture
obtained was stirred for 2 h, heated to 50°С, and left
standing for crystallization. The separated precipitate
was filtered off and several times washed with water
on the filter. The filtrate was additionally diluted with
water, the separated precipitate was filtered off,
washed with water on the filter, the precipitates were
combined and dried.
3-[(4-Oxocyclohexa-2,5-dien-1-ylidene)hyd-
razinylidene]-1,3-dihydro-2H-indol-2-ones 2a–2d. To
a solution of 5.8 mmol of hydrazone 1a–1d in a suffi-
cient amount of 1,2-dichloroethane was added 5 g of an-
hydrous sodium sulfate, 10 g of lead dioxide, and 1.5 g
of lead tetraacetate. The mixture was stirred for 30 min,
filtered, and the filtrate was evaporated till dryness, the
residue was crystallized from benzene and dried.
3
-[(4-Oxocyclohexa-2,5-dien-1-ylidene)hyd-
razinylidene]-1,3-dihydro-2H-indol-2-one (2a). Yield
1
3
-[2-(4-Hydroxyphenyl)hydrazinylidene]-1,3-di-
60%, brown crystals, mp 120–123°С. Н NMR spec-
hydro-2H-indol-2-one (1a). Yield 84%, yellow crys-
trum (CDCl
6.93 d (1Н, С
7.8, 1.5 Hz), 7.05 t (1Н, С
, J 7.8, 1.5 Hz), 7.44 d (1Н, С
7.49 d (1Н, С O, J 10, 2 Hz), 7.59 d (1Н, С
10, 2 Hz). Found, %: С 66.94; Н 4.60; N 16.70.
C H N O . Calculated, %: С 66.93; Н 3.58; N 16.73.
14 9 3 2
3
), δ, ppm: 6.53 d (1Н, С
O, J 10, 2 Hz), 6.93 d (1Н, С
, J 7.8, 1.5 Hz), 7.41 t (1Н,
, J 7.8, 1.5 Hz),
O, J
6
Н
4
O, J 10, 2 Hz),
1
tals, mp 220°С. Н NMR spectrum (DMSO-d ), δ, ppm:
6
Н
4
Н
6 4
, J
6
6
7
6
.80 d (1Н, С Н OH, J 8.8 Hz), 6.91 d (1Н, C H , J
Н
6 4
6
4
6
4
.8 Hz), 7.03 t (1Н, C H , J.8 Hz), 7.20 t (1Н, C H , J
С
6
Н
4
Н
6 4
6
4
6
4
.3 Hz), 7.27 d (1Н, С Н OH, J 8.8 Hz), 7.50 d (1H,
6
Н
4
Н
6 4
6
4
C H , J 6.3 Hz), 9.29 s (1H, NH-Ar), 10.91 s (1H, NH),
6
4
12.78 s (1H, OH). Found, %: С 66.40; Н 4.36; N 16.59.
C H N O . Calculated, %: С 66.40; Н 4.35; N 16.60.
1
4
11
3
2
1
-Methyl-3-[(4-oxocyclohexa-2,5-dien-1-ylidene)-
3
-[2-(4-Hydroxyphenyl)hydrazinylidene]-1-
hydrazinylidene]-1,3-dihydro-2H-indol-2-one (2b).
Yield 91%, brown crystals, mp 170–172°С. Н NMR
1
methyl-1,3-dihydro-2H-indol-2-one (1b). Yield 60%,
orange crystals, mp 214–216°С. Н NMR spectrum
DMSO-d ), δ, ppm: 3.26 s (3Н, СН ), 5.74 d (1H, C H ,
J 7.1 Hz), 6.79 d.d (2H, C H ОН, J 8.8 Hz), 7.10 t
1H, C H , J 6.6 Hz), 7.10 d (1H, C H , J 6.6 Hz), 7.29
d.d (2H, C H ОН, J 8.8 Hz), 7.30 t (1H, C H , J
.1 Hz), 9.36 s (1H, NH), 12.72 s (1Н, ОН). Found, %:
1
spectrum (CDCl
(1Н, С O, J 10, 2.1 Hz), 6.67 d.d (1Н, С
2.1 Hz), 6.88 d (1Н, С
J 7.8 Hz), 7.47 t (1Н, С
), δ, ppm: 3.22 s (3Н, СН
), 6.51 d.d
O, J 10,
, J 7.8 Hz), 7.05 t (1Н, С
, J 7.4 Hz), 7.48 d.d (1Н,
, J 7.4 Hz),
O, J 10.4, 2.5 Hz). Found, %: С
3
3
(
6
Н
4
6 4
Н
6
3
6
4
Н
4
Н ,
6 4
6
4
6
(
Н
6 4
6
4
6
4
С
6
Н
4
O, J 10.4, 2.5 Hz), 7.56 d (1Н, С
Н
6 4
6
4
6
4
7
7.57 d.d (1Н, С
6
Н
4
С 67.39; Н 5.85; N 15.74. C H N O . Calculated, %:
С 67.41; Н 4.86; N 15.73.
67.92; Н 4.15; N 15.84. C15
67.92; Н 4.15; N 15.85.
H N O . Calculated, %:
11 3 2
1
5
13
3
2
5
-Bromo-3-[2-(4-hydroxyphenyl)hydrazinyl-
5-Bromo-1-methyl-3-[(4-oxocyclohexa-2,5-dien-
idene]-1-methyl-1,3-dihydro-2H-indol-2-one (1c).
Yield 66%, bright orange crystals, mp 205–208°С. Н
1-ylidene)hydrazinylidene]-1,3-dihydro-2H-indol-2-
1
one (2c). Yield 77%, dark brown crystals, mp 127–
1
NMR spectrum (DMSO-d ), δ, ppm: 3.24 s (3Н, СН ),
130°С. Н NMR spectrum (CDCl
3
), δ, ppm: 3.29 s
O, J 10.2, 2.4 Hz),
O, J 9.4, 1.8 Hz), 7.49–7.52
Н O, J 10.2, 1.8 Hz), 7.57–7.63 m (d.d + d,
6 4
6
3
6
.79 d (1H, C H ОН, J 8.1 Hz), 7.05 d (1H, C H ОН,
(3Н, СН
6.69–6.72 d.d (1Н, С
d.d (1Н, С
3 6 4
), 6.53–6.56 d.d (1Н, С Н
6
4
6
4
J 8.3 Hz), 7.35 d (1H, C H Br, J 11.4 Hz), 7.44 d (1H,
Н
6 4
6
4
C H Br, J 9.8 Hz), 7.66 s (1H, C H Br), 9.41 s (1H,
6
4
6
4
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 5 2016

6
2
54
MURASHEVICH et al.
Н). Found, %: С 52.38; Н 2.93; Br 23.23; N 12.21.
(3d). Yield 62%, dark crystals, mp 214–218°С (from
1
C H BrN O . Calculated, %: С 52.33; Н 2.90; Br
benzene). Н NMR spectrum (DMSO-d ), δ, ppm: 3.26
1
5
10
3
2
6
2
3.25; N 12.20.
s (3Н, СН
3
), 6.96 d (1H, C H ClOH, J 8.7 Hz), 7.22 d
6 3
(
8
8
1H, C H ClOH, J 8.5 Hz), 7.29 d (1Н, С Н NO , J
.5 Hz), 12.52 s (1Н, ОН), 7.54 s (1H, C H ClOH),
6 3
6
3
6
3
2
1
-Methyl-5-nitro-3-[(4-oxocyclohexa-2,5-dien-1-
ylidene)hydrazinylidene]-1,3-dihydro-2H-indol-2-
one (2d). Yield 65%, dark brown crystals, mp 152–
55°С. Н NMR spectrum (CDCl ), δ, ppm: 3.36 s
3Н, СН ), 6.55 d.d (1Н, С Н O, J 9.5 Hz), 7.05 d.d
.13 d (1Н, С Н NO , J 8.1 Hz), 8.20 s (1Н,
6
3
2
С Н NO ), 10.09 s (1H, NH). Found, %: С 51.98; Н
3
С 51.95; Н 3.17; Cl 10.24; N 16.16.
1
6
3
2
1
(
(
3
.18; Cl 10.21; N 16.15. C H ClN O . Calculated, %:
15 11 4 4
3 6 4
1Н, С Н O, J 8.7 Hz), 7.32 d (1Н, С Н NO ), 7.60
6
4
6
3
2
d.d (1Н, С Н O, J 9.5 Hz), 8.40–8.56 m (d.d + d, 2Н).
Independent synthesis of 3-[2-(4-hydroxy-3-chlo-
rophenyl)hydrazinylidene]-1-methyl-1,3-dihydro-
6
4
Found, %: С 58.03; Н 3.20; N 18.10. C H N O .
1
5
10
4
4
2
H-indol-2-one (3b). To a solution of 8 g (0.05 mol)
Calculated, %: С 58.06; Н 3.23; N 18.06.
of 4-amino-2-chlorophenol in a mixture of 50 mL of
water and 15 mL of 32% hydrochloric acid cooled to
Addition of hydrogen chloride to reagents 3b–3d
general procedure). To a solution of 3 mmol of azine
b–2d in a sufficient amount of 1,2-dichlo-roethane
was added 2 mL of 32% hydrochloric acid, the mixture
was strongly shaken for 3 min and was stirred at room
temperature for 1 h. Afterwards it was diluted with
(
2
0
5
°С while continuous stirring at the temperature below
°С was added a solution of 4 g (0.055 mol) of sodium
nitrite in 15 mL of water, and the mixture was stirred
for 40 min. Further reaction was performed as
described for the synthesis of 4-hydroxyphenyl-
substituted isatins. Yield 63%, mp 215–216°С. The
melting of a sample mixed with the product obtained
from azine 2b did not show a melting point depression.
1
00 mL of water, the organic layer was separated, the
water layer was several times extracted with 1,2-
dichloroethane. The dichloroethane extracts were
combined, dried with anhydrous sodium sulfate, the
solvent was distilled off, the residue was purified by
column chromatography.
ACKNOWLEDGMENTS
The authors express their gratitude to Doctor of
Chemical Sciences, Professor Alexander Vasilievich
Prosyanik for valuable recommendations and constant
interest in the study.
3
-[2-(4-Hydroxy-3-chlorophenyl)hydrazinyl-
idene]-1-methyl-1,3-dihydro-2H-indol-2-one (3b).
Yield 64%, orange crystals, mp 215–216°С (from
1
benzene). Н NMR spectrum (DMSO-d ), δ, ppm: 3.25
6
s (3Н, СН ), 6.98 d (1H, C H , J 8.8 Hz), 7.10 d (1Н,
REFERENCES
3
6
3
С Н , J 6.8 Hz), 7.10 t (1Н, С Н , J 6.8 Hz), 7.25 d.d
6
4
6
4
1
. Molinski, T.F., Chem. Rev., 1993, vol. 93, p. 1825.
(
1H, C H , J 8.8, 2.7 Hz), 7.31 t (1Н, С Н , J 7.3 Hz),
6 3 6 4
2. Koenigs, L.L., Thompson, S.J., Peter, R.M., Rettie, A.E.,
7
9
.50 d (1H, C H , J 2.7 Hz), 7.58 d (1Н, С Н , J 7.3 Hz),
6 3 6 4
.97 s (1H, NH), 12.6 s (1Н, ОН). Found, %: С 59.73;
Trager, W.F., and Nelson, S.D., Chem. Res. Toxicol.,
1
998, vol. 11, p. 295.
. Adams, R. and Reifschneider, W., Bull. Soc. Chim.,
958, p. 23.
. Burmistrov, K.S. and Toropin, N.V., Zh. Org. Khim.,
983, vol. 19, p. 1576
. Burmistrov, K.S. and Yurchenko, A.G., Zh. Org. Khim.,
985, vol. 21, p. 575.
. Toropin, N.V., Burmistrov, K.S., Burmistrov, S.I., and
Zaichenko, N.L., Zh. Org. Khim., 1986, vol. 12, p. 999.
. Burmistrov, K.S., Murashevich, B.V., and Toropin, N.V.,
Russ. J. Org. Chem., 2011, vol. 47, p. 140.
Н 4.00; Cl 11.75; N 13.94. C H ClN O . Calculated,
1
5
12
3
2
3
4
5
6
7
8
9
%: С 59.70; Н 3.98; Cl 11.77; N 13.93.
1
5
-Bromo-3-[2-(4-hydroxy-3-chlorophenyl)hyd-
1
razineylidene]-1-methyl-1,3-dihydro-2H-indol-2-
one (3c). Yield 88%, dark orange crystals, mp 185–
1
1
1
87°С (from benzene). Н NMR spectrum (DMSO-d ),
6
δ, ppm: 3.22 s (3Н, СН ), 6.97 d (1Н, С Н Br, J 8.3 Hz),
3
6
3
7
.05 d (1H, C H ClOH, J 7.3 Hz), 7.28 d (1H,
6 3
C H ClOH, J 7.6 Hz), 7.43 d (1Н, С Н Br, J 9.2 Hz),
6
3
6
3
7
.58 s (1H, C H ClOH), 7.69 s (1Н, С Н Br), 10.08 s
6 3 6 3
. Murashevich, B.V., Burmistrov, K.S., and Toropin, N.V.,
Vopr. Khim. Khim. Tekhnol., 2011, vol. 3, p. 16.
. Burmistrov, K.S., Toropin, N.V., and Burmistrov, S.I.,
Ukr. Khim. Zh., 1992, vol. 58, p. 575.
(
1H, NH), 12.53 s (1Н, ОН). Found, %: С 52.21; Н
3
.20; Br 23.16; N 12.15. C H BrN O . Calculated,
15 11 3 2
%: С 52.17; Н 3.18; Br 23.18; N 12.17.
3
-[2-(4-Hydroxy-3-chlorophenyl)hydrazinyl-
10. Burmistrov, S.I., Burmistrov, K.S., and Malinovskii, M.S.,
idene]-1-methyl-5-nitro-1,3-dihydro-2H-indol-2-one
Zh. Org. Khim., 1976, vol. 12, p. 2193.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 5 2016