Synthesis of (2-chloroquinolin-3-yl)-1,3,4-thiadiazole-2-carboxamides

Article abstract of DOI:10.1007/s11172-021-3194-3

(2-Chloroquinolin-3-yl)-1,3,4-thiadiazole-2-carboxamides were synthesized from hydrazones obtained via the reaction of 3-formyl-2-chloroquinoline with oxamic acid thiohydrazides.

Full text of DOI:10.1007/s11172-021-3194-3

Russian Chemical Bulletin, International Edition, Vol. 70, No. 6, pp. 1131—1134, June, 2021
1131
Synthesis of (2-chloroquinolin-3-yl)-1,3,4-thiadiazole-2-carboxamides*
A. N. Aksenov, M. M. Krayushkin, and V. N. Yarovenko
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
E-mail: yarov@ioc.ac.ru
(2-Chloroquinolin-3-yl)-1,3,4-thiadiazole-2-carboxamides were synthesized from hydr-
azones obtained via the reaction of 3-formyl-2-chloroquinoline with oxamic acid thiohydrazides.
Key words: heterocyclic compounds, quinolines, hydrazones, 1,3,4-thiadiazoles, oxamic
acid thiohydrazides.
Scheme 1
Quinolines are applied in the synthesis of various drugs
(Ofloxacin, Norfloxacin, Ciprofloxacin, Chloroquine, etc.)
and some compounds possessing a wide range of biologi-
cal activity.1,2 A quinoline derivative (hydroxychloroquine)
has been proposed for the treatment of COVID-19.3
Considerable attention is paid to the synthesis and bio-
logical activity of 2-chloroquinolines, starting from which
substances exhibiting antimicrobial, antimalarial, anti-
inflammatory, antitumor, and antiparasitic activities have
been obtained.4,5 It is known6,7 that 1,3,4-thiadiazole
derivatives are employed as promising pharmacophore
moieties in the design of antibacterial, antifungal, anti-
tuberculosis, and antitumor drugs. Taking into account
the wide range of biological activity of these heterocycles,
it seems reasonable to design compounds containing both
quinoline and thiadiazole moieties in one molecule.8—10
In the present work, we proposed a method for the syn-
thesis of new (i.e., never reported) (2-chloroquinolin-3-
yl)-1,3,4-thiadiazoles bearing carboxamide groups.
We have earlier demonstrated11 a high synthetic po-
tential of oxamic acid thiohydrazides in the synthesis of
various heterocyclic compounds. According to our12 ap-
proach (Scheme 1) that involves the reaction of hydrazine
hydrate with 2-morpholinothioxoacetamides 3a—d, which
were obtained from α-chloroacetamides 2a—d and a prel-
iminarily prepared solution of elemental sulfur in mor-
pholine, oxamic acid thiohydrazides 4a—d were synthesized.
It has been demonstrated13 that hydrazones of oxamic
acid thiohydrazides can exist in a solution as an equilibrium
mixture of the two forms, linear A and cyclic B, due to the
ring-chain tautomerism (Scheme 2). The ratio of isomers
depends on the nature of moieties in the thiohydrazide
group in the hydrazones.
1—4: R1 = R2 = H (a); R1 = H, R2 = Cl (b); R1 = H, R2 = Me (c);
1 = R2 = Me (d)
R
Scheme 2
The reaction of 3-formyl-2-chloroquinoline 5 with
oxamic acid thiohydrazides 4a—d in ethanol leads to
* Dedicated to Academician of the Russian Academy of Sciences
V. N. Charushin on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1131—1134, June, 2021.
1066-5285/21/7006-1131 © 2021 Springer Science+Business Media LLC

Aksenov et al.
1132
Russ. Chem. Bull., Int. Ed., Vol. 70, No. 6, June, 2021
dihydrothiadiazoles 6a—d (Scheme 3). The interaction
proceeds regioselectively, whereas the chlorine atom does
not react with thiohydrazides.
azoles 6a—d into the corresponding thiadiazoles does
not occur. It was possible to convert compounds 6a—d
into (2-chloroquinolin-3-yl)-1,3,4-thiadiazole-2-carbox-
amides 8a—d upon their treatment with DDQ in ethanol
(Scheme 5).
Scheme 3
Scheme 5
8: R1 = R2 = H (a); R1 = H, R2 = Cl (b); R1 = H, R2 = Me (c);
R
1 = R2 = Me (d)
In summary, we have proposed and verified a method
for the preparation of previously unknown (2-chloroquino-
lin-3-yl)-1,3,4-thiadiazole-2-carboxamides from oxamic
acid thiohydrazides.
6: R1 = R2 = H (a); R1 = H, R2 = Cl (b); R1 = H, R2 = Me (c);
R
1 = R2 = Me (d)
Analysis of spectral data revealed that compounds
6a—d exist in a DMSO solution in the form of a single
cyclic tautomer, viz., 4,5-dihydrothiadiazole-2-carbox-
amide. Instead of a hydrazinyl proton in the 1H NMR
spectrum, there is a singlet of proton at the C(5) atom of
dihydrothiadiazole, observed in the range of  6.88—6.95.
The 13C NMR spectrum contains a signal from the thia-
diazolic C(5) atom in the range of  71.10—71.69, while
there is no any signal of C=S groups in the range of
 180—200.
Experimental
NMR spectra of compounds 6—8 were recorded on a Bruker
AM-300 instrument (at 300 (1H) and 75 (13C) MHz) in DMSO-d6.
Mass spectra were recorded on a Varian MAT CH-6 instrument
with a direct sample injection into the radiation source, the
ionization energy was 70 eV, and the control voltage was 1.75 kV.
High resolution mass spectra (HRMS) were recorded on a Bruker
micrOTOF II instrument using electrospray as the ionization
method. Melting points were measured using a Boetius appara-
tus without corrections. The reactions were monitored by TLC
using Merck 60 F254 UV-254 chromatographic plates.
Synthesis of dihydrothiadiazoles 6a—d (general procedure).
A mixture of chloroquinolinecarbaldehyde 5 (3.1 mmol) and
thiohydrazide 4а—d (3.5 mmol) in ethanol (25 mL) was stirred
for 12 h. The precipitate was filtered off and washed with a mini-
mal amount of ethanol. This crude product was recrystallized
from ethanol.
The reaction of dihydrothiadiazoles 6a—d with either
acetic anhydride or acetyl chloride gave corresponding
acylated dihydrothiadiazoles 7a—d (Scheme 4).
Scheme 4
5-(2-Chloro-6-methoxyquinolin-3-yl)-4,5-dihydro-N-phenyl-
1,3,4-thiadiazole-2-carboxamide (6a). The yield was 63%, tile red
powder, m.p. 157—159 C. 1H NMR (DMSO-d6, 300.13 MHz),
: 10.28 (s, 1 H, NH in PhCONH); 9.51 (s, 1 H, NH in the
thiadiazole moiety); 8.33 (s, 1 H, H(4) in the quinoline moiety);
7.90 (d, 1 H, J = 9.1 Hz); 7.73 (d, 2 H, J = 7.9 Hz); 7.52 (d, 1 H,
J = 2.6 Hz); 7.47 (dd, 1 H, J = 9.3 Hz, J = 2.8 Hz); 7.31 (t, 2 H,
J = 7.9 Hz); 7.08 (t, 1 H, J = 7.4 Hz); 6.88 (s, 1 H, H(5) in the
thiadiazole moiety); 3.90 (s, 3 H, MeO). 13C NMR (DMSO-d6,
75 MHz), : 158.61, 158.30, 144.86, 143.02, 139.09, 138.62,
135.55, 133.12, 129.48, 129.08, 128.64, 124.33, 124.15, 120.69,
106.70, 71.10 (C(5) in the thiadiazole moiety), 56.20 (MeO).
Found (%): C, 57.39; H, 3.84; Cl, 8.72; N, 14.15; S, 8.11.
i. Ac2O or AcCl, DMF.
7: R1 = R2 = H (a); R1 = H, R2 = Cl (b); R1 = H, R2 = Me (c);
R
1 = R2 = Me (d)
A singlet of methyl protons of the acetyl group appears
in the 1H NMR spectra of compounds 7a—d.
It should be noted that in contrast to our previous
work14 on the reactions of aromatic aldehydes with oxamic
acid thiohydrazides, the autoxidation of dihydrothiadi-
C
19H15ClN4O2S. Calculated (%): C, 57.21; H, 3.79; Cl, 8.89;
N, 14.05; S, 8.04.
5-(2-Chloro-6-methoxyquinolin-3-yl)-N-(2-chlorophenyl)-
4,5-dihydro-1,3,4-thiadiazole-2-carboxamide (6b). The yield
was 89%, slightly pink powder, m.p. 199—201 C. 1H NMR

Chloroquinolinyl-1,3,4-thiadiazole-2-carboxamides
Russ. Chem. Bull., Int. Ed., Vol. 70, No. 6, June, 2021
1133
(DMSO-d6, 300.13 MHz), : 9.62 (s, 1 H, NH in PhCONH);
9.58 (s, 1 H, NH in the thiadiazole moiety); 8.35 (s, 1 H, H(4)
in the quinoline moiety); 7.89 (d, 1 H, J = 9.2 Hz); 7.87 (d, 1 H,
J = 7.0 Hz); 7.59—7.44 (m, 3 H); 7.36 (t, 1 H, J = 7.8 Hz); 7.22
(t, 1 H, J = 7.7 Hz); 6.95 (s, 1 H, H(5) in the thiadiazole moiety);
3.91 (s, 3 H, MeO). 13C NMR (DMSO-d6, 75 MHz), : 158.61,
158.08, 144.81, 143.02, 138.00, 135.64, 134.42, 132.96, 129.93,
129.46, 128.64, 128.25, 126.91, 126.42, 125.01, 124.15, 106.78,
71.69 (C(5) in the thiadiazole moiety), 56.21 (MeO). Found (%):
C, 52.78; H, 3.34; Cl, 16.21; N, 12.81; S, 7.56. C19H14Cl2N4O2S.
Calculated (%): C, 52.67; H, 3.26; Cl, 16.36; N, 12.93; S, 7.40.
5-(2-Chloro-6-methoxyquinolin-3-yl)-4,5-dihydro-N-(2-
methylphenyl)-1,3,4-thiadiazole-2-carboxamide (6c). The yield
was 91%, beige powder, m.p. 213—214 C. 1H NMR (DMSO-d6,
300.13 MHz), : 9.67 (s, 1 H, NH in PhCONH); 9.44 (s, 1 H,
NH in the thiadiazole moiety); 8.37 (s, 1 H, H(4) in the quino-
line moiety); 7.90 (d, 1 H, J = 9.1 Hz); 7.54 (d, 1 H, J = 2.6 Hz);
7.48 (dd, 1 H, J = 9.3 Hz, J = 2.8 Hz); 7.39 (d, 1 H, J = 7.6 Hz);
7.28—7.09 (m, 3 H); 6.89 (s, 1 H, H(5) in the thiadiazole moiety);
3.90 (s, 3 H, MeO); 2.21 (s, 3 H, CH3 arom.). 13C NMR
(DMSO-d6, 75 MHz), : 158.62, 158.29, 144.97, 143.00, 138.96,
135.91, 135.60, 133.13, 133.02, 130.78, 129.50, 128.64, 126.53,
126.30, 125.88, 124.11, 106.74, 71.29 (C(5) in the thiadiazole
moiety), 56.22 (MeO), 18.17 (CH3 arom.). Found (%): C, 58.29;
H, 4.30; Cl, 8.72; N, 13.69; S, 7.87. C20H17ClN4O2S. Calculat-
ed (%): C, 58.18; H, 4.15; Cl, 8.59; N, 13.57; S, 7.77.
5-(2-Chloro-6-methoxyquinolin-3-yl)-4,5-dihydro-N-(2,6-
dimethylphenyl)-1,3,4-thiadiazole-2-carboxamide (6d). The yield
was 47%, light yellow powder, m.p. 197—199 C. 1H NMR
(DMSO-d6, 300.13 MHz), : 9.72 (s, 1 H, NH in PhCONH);
9.35 (s, 1 H, NH in the thiadiazole moiety); 8.43 (s, 1 H, H(4)
in the quinoline moiety); 7.91 (d, 1 H, J = 9.2 Hz); 7.56 (d, 1 H,
J = 2.6 Hz); 7.49 (dd, 1 H, J = 9.1 Hz, J = 2.8 Hz); 7.08 (s, 3 H);
6.89 (s, 1 H, H(5) in the thiadiazole moiety); 3.92 (s, 3 H, MeO);
2.14 (s, 6 H, 2 CH3). 13C NMR (DMSO-d6, 75 MHz), : 158.64,
158.31, 145.17, 142.98, 139.07, 136.09, 135.69, 134.90, 133.13,
129.50, 128.65, 128.14, 127.29, 124.08, 106.75, 71.34 (C(5) in
the thiadiazole moiety), 56.50, 56.23, 19.00 (CH3), 18.52 (CH3).
Found (%): C, 59.24; H, 4.65; Cl, 8.45; N, 13.37; S, 7.70.
C21H19ClN4O2S. Calculated (%): C, 59.08; H, 4.49; Cl, 8.30;
N, 13.12; S, 7.51.
J = 7.3 Hz); 7.17 (t, 1 H, J = 7.3 Hz); 3.89 (s, 3 H, MeO); 2.58
(s, 3 H, MeCO). 13C NMR (DMSO-d6, 75 MHz), : 170.31
(C=O in СH3CO), 158.62, 157.06, 147.74, 143.99, 143.05,
137.73, 134.97, 131.91, 131.51, 129.29, 128.72, 125.34, 124.49,
121.57, 106.72, 68.19 (C(5) in the thiadiazole moiety), 56.14
(CH3O), 22.68 (CH3 in СH3CO). Found (%): C, 57.29; H, 3.91;
Cl, 8.22; N, 12.84; S, 7.38. C21H17ClN4O3S. Calculated (%):
C, 57.21; H, 3.89; Cl, 8.04; N, 12.71; S, 7.27.
4-Acetyl-5-(2-chloro-6-methoxyquinolin-3-yl)-N-(2-chloro-
phenyl)-4,5-dihydro-1,3,4-thiadiazole-2-carboxamide (7b). The
yield was 87% (A), 90% (B), light yellow powder, m.p. 252—253 C
(MeCN). 1H NMR (DMSO-d6, 300.13 MHz), : 10.27 (s, 1 H,
NH in PhCONH); 8.25 (s, 1 H, H(4) in the quinoline moiety);
7.90 (d, 1 H, J = 9.2 Hz); 7.69 (d, 1 H, J = 7.0 Hz); 7.62—7.29
(m, 6 H); 3.90 (s, 3 H, CH3O); 2.55 (s, 3 H, CH3CO). 13C NMR
(DMSO-d6, 75 MHz), : 170.23 (C=O in СH3CO), 158.62,
157.17, 146.90, 143.95, 143.04, 135.03, 133.88, 131.33, 130.18,
129.47, 129.00, 128.73, 128.49, 128.32, 127.60, 124.50, 106.77,
68.64 (C(5) in the thiadiazole moiety), 56.16 (CH3O), 22.61
(CH3 in СH3CO). Found (%): C, 53.16; H, 3.44; Cl, 14.79;
N, 11.89; S, 6.81. C21H16Cl2N4O3S. Calculated (%): C, 53.06;
H, 3.39; Cl, 14.92; N, 11.79; S, 6.75.
4-Acetyl-5-(2-chloro-6-methoxyquinolin-3-yl)-4,5-dihydro-
N-(2-methylphenyl)-1,3,4-thiadiazole-2-carboxamide (7c). The
yield was 88% (A), 79% (B), white powder, m.p. 193—194 C
1
(EtOH). H NMR (DMSO-d6, 300.13 MHz), : 10.22 (s, 1 H,
NH in PhCONH); 8.24 (s, 1 H, H(4) in the quinoline moiety);
7.90 (d, 1 H, J = 9.1 Hz); 7.56 (s, 1 H); 7.50 (dd, 1 H, J = 9.2 Hz,
J = 2.6 Hz); 7.42 (s, 1 H); 7.38—7.17 (m, 4 H); 3.91 (s, 3 H,
CH3O); 2.56 (s, 3 H, CH3CO); 2.24 (s, 3 H, CH3). 13C NMR
(DMSO-d6, 75 MHz), : 170.28 (C=O in СH3CO), 158.62,
157.12, 147.40, 144.01, 143.02, 135.18, 134.97, 134.13, 131.42,
130.96, 129.46, 128.73, 127.26, 126.77, 126.71, 124.46, 106.77,
68.39 (C(5) in the thiadiazole moiety), 56.16 (CH3O), 22.61
(CH3 in СH3CO), 18.23 (CH3). Found (%): C, 58.14; H, 4.29;
Cl, 7.89; N, 12.38; S, 7.24. C22H19ClN4O3S. Calculated (%):
C, 58.08; H, 4.21; Cl, 7.79; N, 12.32; S, 7.05.
4-Acetyl-5-(2-chloro-6-methoxyquinolin-3-yl)-4,5-dihydro-
N-(2,6-dimethylphenyl)-1,3,4-thiadiazole-2-carboxamide (7d).
The yield was 78% (A), 69% (B), white powder, m.p. 153—155 C
1
(EtOH). H NMR (DMSO-d6, 300.13 MHz), : 10.20 (s, 1 H,
Synthesis of acylthiadiazoles 7a—d (general procedure A).
Thiohydrazide 4a—d (0.75 mmol) was heated in acetic anhydride
(3 mL) at 90 C for 4 h. The reaction mixture was treated with
cold water (20 mL). Sodium carbonate was added until pH 6—7,
and the precipitate was filtered off and washed with water. The
resulting products were recrystallized from ethanol or acetonitrile.
Synthesis of acylthiadiazoles 7a—d (general procedure B).
Acetyl chloride (0.04 g, 0.45 mmol) was added to a solution of
thiohydrazide 4a—d (0.3 mmol) in DMF (1 mL). The mixture
was stirred for 1 h, water (10 mL) was added, and the formed
precipitate was filtered off and washed on the filter with water,
sodium carbonate solution (5% aq.), and water. The resulting
products were recrystallized from ethanol or acetonitrile.
4-Acetyl-5-(2-chloro-6-methoxyquinolin-3-yl)-4,5-dihydro-
N-phenyl-1,3,4-thiadiazole-2-carboxamide (7а). The yield was
85% (А), 70% (B), gray powder, m.p. 203—205 C (EtOH).
1H NMR (DMSO-d6, 300.13 MHz), : 10.52 (s, 1 H, NH in
PhCONH); 8.20 (s, 1 H, H(4) in the quinoline moiety); 7.90
(d, 1 H, J = 8.9 Hz); 7.70 (d, 2 H, J = 8.0 Hz); 7.51 (s, 1 H);
7.48 (d, 1 H, J = 8.9 Hz); 7.51 (s, 1 H); 7.42 (s, 1 H); 7.38 (t, 1 H,
NH in PhCONH); 8.25 (s, 1 H, H(4) in the quinoline moiety);
7.91 (d, 1 H, J = 9.2 Hz); 7.59 (d, 1 H, J = 2.6 Hz); 7.50 (dd, 1 H,
J = 9.2 Hz, J = 2.7 Hz); 7.42 (s, 1 H); 7.14 (s, 3 H); 3.91 (s, 3 H,
CH3O); 2.55 (s, 3 H, CH3CO); 2.19 (s, 6 H, 2 CH3). 13C NMR
(DMSO-d6, 75 MHz), : 170.51 (C=O in СH3CO), 158.65,
157.09, 147.18, 144.06, 142.96, 135.98, 135.01, 134.01, 131.29,
129.45, 128.68, 128.35, 127.86, 124.49, 106.70, 68.46 (C(5) in
the thiadiazole moiety), 56.17 (CH3O), 22.57 (CH3 in СH3CO),
18.44 (CH3 arom.), 18.23 (CH3 arom.). Found (%): C, 58.81;
H, 4.62; Cl, 7.74; N, 11.85; S, 6.94. C23H21ClN4O3S. Calculat-
ed (%): C, 58.91; H, 4.51; Cl, 7.56; N, 11.95; S, 6.84.
Synthesis of thiadiazoles 8a—d (general procedure). A mixture
of thiadiazole 6a—d (1 mmol) and DDQ (1 mmol) in ethanol
(10 mL) was refluxed for 3—4 h (TLC monitoring, AcOEt—hex-
ane (1 : 1)). After cooling down to room temperature, the pre-
cipitate was filtered off and washed with aqueous ethanol (1 : 1).
The resulting products were recrystallized from ethanol.
5-(2-Chloro-6-methoxyquinolin-3-yl)-N-phenyl-1,3,4-thia-
diazole-2-carboxamide (8a). The yield was 85%, beige powder,
m.p. 214—215 C. 1H NMR (DMSO-d6, 300.13 MHz), : 11.32

Aksenov et al.
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Russ. Chem. Bull., Int. Ed., Vol. 70, No. 6, June, 2021
(s, 1 H, NH in PhCONH); 9.16 (s, 1 H, H(4) in the quinoline
moiety); 7.98 (d, 1 H, J = 9.2 Hz); 7.88 (d, 2 H, J = 7.9 Hz);
7.70 (d, 1 H, J = 2.8 Hz); 7.60 (dd, 1 H, J = 9.2 Hz, J = 2.7 Hz);
7.41 (t, 2 H, J = 7.9 Hz); 7.19 (t, 1 H, J = 7.4 Hz); 3.94 (s, 3 H,
CH3O). 13C NMR (DMSO-d6, 75 MHz), : 167.59, 166.92,
158.91, 156.55, 144.09, 143.96, 140.16, 138.10, 129.64, 129.24,
128.09, 125.94, 125.28, 123.06, 121.39, 107.23, 56.32 (CH3O).
HRMS, found: m/z 397.0511. Calculated for C19H14ClN4O2S+:
397.0521 [М + H]+.
5-(2-Chloro-6-methoxyquinolin-3-yl)-N-(2-chlorophenyl)-
1,3,4-thiadiazole-2-carboxamide (8b). The yield was 93%, gray
powder, m.p. 208—209 C. 1H NMR (DMSO-d6, 300.13 MHz),
: 10.71 (s, 1 H, NH in PhCONH); 9.14 (s, 1 H, H(4) in the
quinoline moiety); 7.98 (d, 1 H, J = 9.1 Hz); 7.84 (d, 1 H,
J = 8.0 Hz); 7.67 (s, 1 H); 7.61 (d, 2 H, J = 8.3 Hz); 7.45 (t, 1 H,
J = 7.6 Hz); 7.37 (d, 1 H, J = 7.6 Hz); 3.96 (s, 3 H, CH3O).
13C NMR (DMSO-d6, 75 MHz), : 167.19, 166.66, 158.91,
156.66, 144.08, 143.98, 140.23, 134.01, 130.19, 129.65,
129.03, 128.48, 128.28, 128.09, 127.64, 126.01, 123.00, 107.21,
56.33 (CH3O). HRMS, found: m/z 431.0119. Calculated for
C19H13Cl2N4O2S+: 431.0131 [М + H]+.
5-(2-Chloro-6-methoxyquinolin-3-yl)-N-(2-methylphenyl)-
1,3,4-thiadiazole-2-carboxamide (8c). The yield was 72%, gray
powder, m.p. 205—207 C. 1H NMR (DMSO-d6, 300.13 MHz),
: 10.84 (s, 1 H, NH in PhCONH); 9.14 (s, 1 H, H(4) in the
quinoline moiety); 7.97 (d, 1 H, J = 9.2 Hz); 7.68 (d, 1 H,
J = 2.5 Hz); 7.60 (dd, 1 H, J = 9.2 Hz, J = 2.7 Hz); 7.45 (d, 1 H,
J = 8.2 Hz); 7.37—7.20 (m, 3 H); 3.94 (s, 3 H, CH3O); 2.31
(s, 3 H, CH3). 13C NMR (DMSO-d6, 75 MHz), : 167.35, 166.88,
158.90, 156.70, 144.11, 143.95, 140.17, 135.34, 134.11, 130.95,
129.65, 128.10, 127.21, 126.88, 126.66, 125.96, 123.09, 107.18,
56.32 (CH3O), 18.28 (CH3). HRMS, found: m/z 411.0669.
Calculated for C20H16ClN4O2S+: 411.0677 [М + H]+.
5-(2-Chloro-6-methoxyquinolin-3-yl)-N-(2,6-dimethylphen-
yl)-1,3,4-thiadiazole-2-carboxamide (8d). The yield was 70%,
light yellow powder, m.p. 287—288 C. 1H NMR (DMSO-d6,
300.13 MHz), : 10.85 (s, 1 H, NH in PhCONH); 9.15 (s, 1 H);
7.99 (d, 1 H, J = 9.2 Hz); 7.70 (d, 1 H, J = 2.7 Hz); 7.62 (d, 1 H,
J = 9.2 Hz); 7.19—7.13 (m, 3 H); 3.95 (s, 3 H); 2.24 (s, 6 H,
2 CH3). 13C NMR (DMSO-d6, 75 MHz), : 167.19, 166.89,
158.93, 156.58, 144.18, 143.97, 140.28, 136.01, 134.33, 129.69,
128.34, 128.14, 127.78, 125.98, 123.19, 107.21, 56.35 (CH3O),
18.53 (CH3). HRMS, found: m/z 425.0834. Calculated for
C21H18ClN4O2S+: 425.0834 [М + H]+.
This paper does not contain descriptions of studies on
animals or humans.
The authors declare no competing interests.
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Received December 22, 2020;
in revised form February 4, 2021;
accepted March 29, 2021