Microwave Assisted Synthesis and Antibacterial Activity of New 1,3,4-Thiadiazoles and 1,2,4-Triazoles Derived from 2-{2-[2-(4-Fluorophenyl)-4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}acetohydrazide

Article abstract of DOI:10.1134/S1070363220090200

Abstract: A series of novel derivatives of1-(2-{2-[2-(4-fluorophenyl)-4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}acetyl)-4-phenylthiosemicarbazide,5-({2-[2-(4-fluorophenyl)-4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}methyl)-4-phenyl-4H-1,2,4-triaz

Full text of DOI:10.1134/S1070363220090200

ISSN 1070-3632, Russian Journal of General Chemistry, 2020, Vol. 90, No. 9, pp. 1721–1726. © Pleiades Publishing, Ltd., 2020.
Microwave Assisted Synthesis and Antibacterial Activity
of New 1,3,4-Thiadiazoles and 1,2,4-Triazoles Derived
from 2-{2-[2-(4-Fluorophenyl)-4-methylthiazol-5-yl]-
1H-benzo[d]imidazol-1-yl}acetohydrazide
N. R. Darekara,b, B. K. Karalea, H. N. Akolkara, and A. S. Burungaleb,*
a P.G. and Research, Department of Chemistry, Rayat Shikshan Sanstha’s Radhabai Kale Mahila Mahavidyalaya,
Maharashtra, Ahmednagar, 414001 India
b P.G. and Research, Department of Chemistry, Rayat Shikshan Sanstha’s S. M. Joshi College,
Hadapsar, Maharashtra, Pune, 411028 India
*e-mail: hemantakolkar@gmail.com
Received July 7, 2020; revised August 18, 2020; accepted August 31, 2020
Abstract—Aseries of novel derivatives of 1-(2-{2-[2-(4-fluorophenyl)-4-methylthiazol-5-yl]-1H-benzo[d]imidazol-
1-yl}acetyl)-4-phenylthiosemicarbazide, 5-({2-[2-(4-fluorophenyl)-4-methylthiazol-5-yl]-1H-benzo[d]imidazol-
1-yl}methyl)-4-phenyl-4H-1,2,4-triazole-3-thiol and 5-({2-[2-(4-fluorophenyl)-4-methylthiazol-5-yl]-1H-benzo[d]-
imidazol-1-yl}methyl)-N-phenyl-1,3,4-thiadiazol-2-amine have been synthesized by the conventional method as
well as using MW irradiation.All newly synthesized compounds have been tested for antibacterial activity. Several
products have demonstrated moderate activity against gram positive and gram negative bacterial strains.
Keywords: 1,3,4-thiadiazole, 1,2,4-triazole, microwave irradiation, antibacterial activity
DOI: 10.1134/S1070363220090200
1
Antimycobacterial and antimicrobial activities have
been well established and studied in depth for benz-
imidazole [1, 2], thiazole [3, 4], 1,3,4-thiadiazole [5–7],
and 1,2,4-triazole [8, 9] derivatives.
IR, H and 13C NMR spectra. Reaction of compounds
7a–7e in presence of NaOH under conventional
conditions or MW irradiation gave 1,2,4-triazole
derivatives 8a–8e [10, 13]. In IR spectra of the products
8a–8e no bands at ca. 3100 cm–1 characteristic for
–NH group were recorded. In 1H NMR spectra of those
compounds characteristic singlets of S–H were recorded
at ca. 14.00 ppm. Similar reaction of compounds 7a–7e
in acidic media under conventional conditions or MW
irradiation gave 1,3,4-thiadiazoles 9a–9e [10, 13]. The
NH group of compound 9a was recorded in IR spectrum
by the band at 3201 cm–1 and in 1H NMR spectrum by a
singlet at 9.50 ppm.
Pharmacological importance associated with those
compounds inspired us to synthesize novel benzimidazole
and thiazole containing 1,3,4-thiadiazoles and 1,2,4-
triazoles under conventional and MW irradiation. All
newly synthesized compounds were evaluated for their
antibacterial activity.
RESULTS AND DISCUSSION
Synthesis of 2-{2-[2-(4-fluorophenyl)-4-methyl-
thiazol-5-yl]-1H-benzo[d]imidazol-1-yl}acetohydrazide
6 was carried out by the known method (Scheme 1)
[10–12].
The MW irradiation method proved to be more
efficient in the synthesis of thiosemicarbazides 7a–7e,
1,2,4-triazoles 8a–8e and 1,3,4-thiadiazoles 9a–9e
derivatives than the conventional heating. It reduced
the reaction time from hours to 5–10 min and increased
the products yield up to 77–88% over the conventional
method (60–74%) (Table 1).
A novel series of 1-(2-{2-[2-(4-fluorophenyl)-4-
methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}acetyl)-
4-phenylthiosemicarbazide 7a–7e was synthesized from
the intermediate 6 and substituted aryl isothiocyanates
by conventional method and under MW irradiation
[10, 13]. Their molecular structures were supported by
In vitro antibacterial activity. All the synthesized
compounds were tested against gram positive bacterial
1721

1722
DAREKAR et al.
Scheme 1. Synthesis of derivatives of thiosemicarbazide (7a–7e), 1,2,4-triazole (8a–8e), and 1,3,4-thiadiazole (9a–9e).
strains Staphylococcus aureus (NCIM 2079), Bacillus
subtilis (NCIM 2063), and gram negative bacterial strains
Escherichia coli (NCIM 2810), Salmonella abony (NCIM
2257). The zone of inhibition in mm was determined by
the well diffusion method at concentration of 1 mg/ mL,
and Ciprofloxacin was used as the reference drug
(Table 2). Compounds 7a, 7d, 7e, 8d, and 9e demonstrated
moderate activity against both gram positive and
gram negative bacteria while other compounds were
characterized by low activity or none.
EXPERIMENTAL
All organic solvents and reagents were acquired
from commercial sources and used as received. The
melting points were measured on a DBK melting point
apparatus and are uncorrected. Microwave irradiation
was carried out in a Raga’s synthetic microwave oven.
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MICROWAVE ASSISTED SYNTHESIS AND ANTIBACTERIAL ACTIVITY
Table 1. Synthesis data for the products
1723
Conventional method
Microwave method
Comp. no.
Ar
time, min
yield, %
74
time, min
yield, %
88
7a
7b
7c
7d
7e
8a
8b
8c
8d
8e
9a
9b
9c
9d
9e
3-Chlorophenyl
2-Chlorophenyl
2,4-Dichlorophenyl
4-Chlorophenyl
3,4-Dichlorophenyl
3-Chlorophenyl
2-Chlorophenyl
2,4-Dichlorophenyl
4-Chlorophenyl
3,4-Dichlorophenyl
3-Chlorophenyl
2-Chlorophenyl
2,4-Dichlorophenyl
4-Chlorophenyl
3,4-Dichlorophenyl
90
90
7.0
6.5
7.5
8.0
9.5
8.5
9.0
8.0
7.5
8.5
9.0
9.5
8.5
8.5
8.0
70
85
84
82
87
80
78
81
83
90
75
90
68
90
72
150
150
150
150
150
240
240
240
240
240
65
68
62
66
70
68
62
67
79
77
85
83
78
81
60
66
Table 2. Antibacterial tests data for the synthesized compounds
Zone of inhibition, mm
Compound
S. aureus
B. subtilis
E. coli
S. abony
7a
7b
7c
7d
7e
8a
8b
8c
8d
8e
9a
9b
9c
9d
9e
16
15
15
15
16
–
–
–
15
–
11
13
12
11
13
23
15
11
14
13
16
–
–
–
17
–
12
12
12
12
15
28
14
–
–
14
17
–
11
13
13
10
12
14
14
12
14
26
17
15
13
15
16
12
10
–
18
10
16
13
–
13
16
40
Ciprofloxacin
FTIR spectra were recorded on a Shimadzu IR Affinity
1S (ATR) spectrophotometer. 1H and 13C NMR spectra
were measured on a Bruker Advance 400 spectrometer
using TMS as an internal standard and DMSO-d6 as a
solvent. Mass spectra were measured on a Waters, Q-TOF
micromass (ESI-MS) mass spectrometer.
in 15 mL of ethanol and refluxed for 90 min. Reaction
progress was monitored by TLC. Upon completion of the
reaction the solid product was filtered off and crystallized
from ethanol to give the corresponding pure compounds
7a–7e (Table 1).
Microwave method. The mixture of equimolar amounts
(0.01 mmol) of acid hydrazide 6 and aryl isothiocyanates
5 was dissolved in 15 mLof ethanol and subjected to MW
irradiation for 5 to 10 min at 350 W. Reaction progress
was monitored by TLC. Upon completion of the reaction
the precipitated product was filtered off and crystallized
Synthesis of 1-(2-{2-[2-(4-fluorophenyl)-4-
methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}acetyl)-
4-phenylthiosemicarbazide (7a–7e). Conventional
method. Equimolar amounts (0.01 mmol) of acid
hydrazide 6 and aryl isothiocyanate 5 were dissolved
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DAREKAR et al.
from ethanol to give the corresponding pure compounds
7a–7e (Table 2).
166.25, 162.28, 155.02, 145.42, 142.49, 137.91, 135.88,
129.16, 128.67, 128.58, 128.09, 123.18, 122.54, 119.31,
118.94, 116.51, 116.29, 110.98, 45.57, 16.48. LC-MS:
m/z: 551 [M + H]+.
4-(3-Chlorophenyl)-1-(2-{2-[2-(4-fluorophenyl)-4-
methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}acetyl)-
thiosemicarbazide (7a). White solid, mp 194–196°C.
IR spectrum, ν, cm–1: 3367 (N–H), 3277 (N–H), 3248
4-(3,4-Dichlorophenyl)-1-(2-{2-[2-(4-fluoro-
phenyl)-4-methylthiazol-5-yl]-1H-benzo[d]imidazol-
1-yl}acetyl)thiosemicarbazide (7e). White solid, mp
188–190°C. IR spectrum, ν, cm–1: 3367 (N–H), 3276
(N–H), 3244 (N–H), 1671 (C=O), 1231 (C–F). 1H NMR
spectrum, δ, ppm: 10.51 s (1H, NH), 10.07 s (1H, NH),
9.88 s (1H, NH), 7.29–8.05 m (11H, ArH), 5.07 s (2H,
CH2), 2.50 s (3H, CH3). 13C NMR spectrum, δС, ppm:
166.21, 164.73, 162.25, 154.99, 145.38, 142.48, 139.09,
135.84, 129.95, 129.10, 128.62, 128.53, 123.14, 122.52,
119. 29, 118.90, 116.47, 116.25, 110.95, 45.55, 16.45.
LC-MS: m/z: 585 [M + H]+.
1
(N–H), 1672 (C=O), 1232 (C–F). H NMR spectrum,
δ, ppm: 10.51 s (1H, NH), 9.99 s (1H, NH), 9.80 s (1H,
NH), 8.05 d. d (2H, J = 5.6 and 8.8 Hz, ArH), 7.75 d (1H,
J = 8 Hz, ArH), 7.58 d (2H, J = 8 Hz, ArH), 7.19–7.40 m
(7H,ArH), 5.07 s (2H, CH2), 2.51 s (3H, CH3). 13C NMR
spectrum, δС, ppm: 166.22, 162.25, 155.01, 145.38,
142.48, 140.42, 135.87, 132.21, 129.76, 129.14, 128.64,
128.55, 123.14, 122.52, 119.29, 118.91, 116.50, 116.27,
110.98, 45.56, 16.47. LC-MS: m/z: 551.06 [M + H]+.
4-(2-Chlorophenyl)-1-(2-{2-[2-(4-fluorophenyl)-4-
methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}acetyl)-
thiosemicarbazide (7b). White solid, mp 226–228°C.
IR spectrum, ν, cm–1: 3365 (N–H), 3277 (N–H), 3245
(N–H), 1674 (C=O), 1231 (C–F). 1H NMR spectrum, δ,
ppm: 10.55 s (1H, NH), 9.98 s (1H, NH), 9.60 s (1H, NH),
8.05 d. d (2H, J = 5.2 and 8.8 Hz, ArH), 7.75 d (1H, J =
8 Hz, ArH), 7.29–7.57 m (9H, ArH), 5.06 s (2H, CH2),
2.52 s (3H, CH3). 13C NMR spectrum, δС, ppm: 166.22,
155.01, 145.37, 142.48, 135.87, 129.39, 129.14, 128.66,
128.57, 127.21, 123.09, 122.51, 119.27, 118.94, 116.48,
116.26, 111.01, 45.50, 16.48. LC-MS: m/z: 551.06
[M + H]+.
Synthesis of 5-({2-[2-(4-fluorophenyl)-4-methyl-
thiazol-5-yl]-1H-benzo[d]imidazol-1-yl}methyl)-4-
phenyl-4H-1,2,4-triazole-3-thiol (8a–8e). Conventional
method. The mixture of an appropriate thiosemicarbazide
7a–7e (0.001 mol) with 10 mLof 2 N NaOH solution was
refluxed for 2.5 h. Progress of the reaction was monitored
by TLC.After completion of the reaction, the mixture was
poured onto crushed ice and acidified with acetic acid. The
product was filtered off and crystallized from ethanol to
give the corresponding pure compound 8a–8e (Table 1).
Microwave method. The mixture of an appropriate
thiosemicarbazide 7a–7e (0.01 mol) with 2 N NaOH
solution was subjected to MW irradiation at 350W for
5–10 min. Progress of the reaction was monitored by
TLC. After completion of the process, the mixture was
poured onto crushed ice and acidified with dilute acetic
acid. The product was filtered off and crystallized from
DMF/water to afford the corresponding pure compound
8a–8e (Table 1).
4-(2,4-Dichlorophenyl)-1-(2-{2-[2-(4-fluoro-
phenyl)-4-methylthiazol-5-yl]-1H-benzo[d]imidazol-
1-yl}acetyl)thiosemicarbazide (7c), White solid, mp
220–222°C. IR spectrum, ν, cm–1: 3366 (N–H), 3275
(N–H), 3246 (N–H), 1671 (C=O), 1232 (C–F). 1H NMR
spectrum, δ, ppm: 10.52 s (1H, NH), 10.03 s (1H, NH),
9.58 s (1H, NH), 8.01 d. d (2H, J = 5.6 and 8.4 Hz, ArH),
7.71 d (1H, J = 8 Hz,ArH), 7.66 s (1H,ArH), 7.25–7.52 m
(7H, ArH), 5.02 s (2H, CH2), 2.48 s (3H, CH3). LC-MS:
m/z: 585 [M + H]+.
4-(3-Chlorophenyl)-5-({2-[2-(4-fluorophenyl)-
4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}-
methyl)-4H-1,2,4-triazole-3-thiol (8a). White solid,
mp 230–232°C. IR spectrum, ν, cm–1: 2939 (=C–H),
4-(4-Chlorophenyl)-1-(2-{2-[2-(4-fluorophenyl)-4-
methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}acetyl)-
thiosemicarbazide (7d). White solid, mp 160–162°C.
IR spectrum, ν, cm–1: 3367 (N–H), 3278 (N–H), 3247
1
1640 (C=N), 1218 (C–F). H NMR spectrum, δ, ppm:
6.99–8.01 m (12H, ArH), 5.50 s (2H, CH2), 2.41 s (3H,
CH3). 13C NMR spectrum, δС, ppm: 168.42, 165.99,
162.27, 154.71, 146.50, 144.53, 142.42, 135.27, 135.13,
133.19, 130.51, 128.94, 128.63, 128.54, 127.65, 126.28,
123.15, 122.51, 119.22, 118.71, 116.55, 116.32, 111.21,
40.50, 16.62. LC-MS: m/z: 533.11 [M + H]+.
1
(N–H), 1672 (C=O), 1232 (C–F). H NMR spectrum,
δ, ppm: 10.46 s (1H, NH), 9.89 s (1H, NH), 9.74 s (1H,
NH), 8.01 d. d (2H, J = 5.6 and 8.8 Hz, ArH), 7.71 d (1H,
J = 7.6 Hz, ArH), 7.54 d (1H, J = 8 Hz, ArH), 7.41 d (2H,
J = 7.6 Hz, ArH), 7.25–7.36 m (6H, ArH), 5.04 s (2H,
CH2), 2.48 s (3H, CH3). 13C NMR spectrum, δС, ppm:
4-(2-Chlorophenyl)-5-({2-[2-(4-fluorophenyl)-
4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}-
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MICROWAVE ASSISTED SYNTHESIS AND ANTIBACTERIAL ACTIVITY
1725
methyl)-4H-1,2,4-triazole-3-thiol (8b). White solid,
mp 226–228°C. IR spectrum, ν, cm–1: 2936 (=C–H),
1638 (C=N), 1219 (C–F). H NMR spectrum, δ, ppm:
7.13–7.99 m (12H, ArH), 5.31 s (2H, CH2), 2.40 s (3H,
CH3). 13C NMR spectrum, δС, ppm: 165.87, 154.76,
142.49, 130.81, 129.92, 128.51, 127.92, 122.43, 119.16,
116.57, 116.35, 111.35, 40.12, 16.63. LC-MS: m/z: 532.98
[M + H]+.
Microwave method. The mixture of an appropriate
thiosemicarbazide 7a–7e (0.01 mol) with 5 mL of conc.
H2SO4 was subjected to MW irradiation for 5 to 10 min
at 350 W.After completion of the process the mixture was
poured onto crushed ice and neutralized with liquid NH3.
The precipitated solid was filtered off and crystallized
from water–DMF to afford the corresponding pure
thiadiazole 9a–9e (Table 1).
1
N-(3-Chlorophenyl)-5-({2-[2-(4-fluorophenyl)-
4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}-
methyl)-1,3,4-thiadiazol-2-amine (9a). White solid,
mp 130–132°C. IR spectrum, ν, cm–1: 3201 (N–H), 3039
4-(2,4-Dichlorophenyl)-5-({2-[2-(4-fluorophenyl)-
4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}-
methyl)-4H-1,2,4-triazole-3-thiol (8c). White solid,
mp 230–232°C. IR spectrum, ν, cm–1: 2938 (=C–H),
1
1
(=C–H), 1606 (C=N), 1232 (C–F). H NMR spectrum,
1635 (C=N), 1221 (C–F). H NMR spectrum, δ, ppm:
δ, ppm: 9.5 s (1H, NH), 7.05–8.18 m (12H, ArH), 5.85 s
(2H, CH2), 2.40 s (3H, CH3). 13C NMR spectrum, δС,
ppm: 165.80, 165.01, 154.67, 144.15, 142.18, 134.57,
129.11, 128.54, 128.19, 127.31, 123.71, 123.02, 122.35,
121.10, 118.99, 118.11, 116.07, 115.85, 110.74, 42.31,
15.98. LC-MS: m/z: 533.15 [M + H]+.
7.23–7.97 m (11H, ArH), 5.38 s (2H, CH2), 2.40 s (3H,
CH3). LC-MS: m/z: 567.00 [M + H]+.
4-(4-Chlorophenyl)-5-({2-[2-(4-fluorophenyl)-
4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}
methyl)-4H-1,2,4-triazole-3-thiol (8d). White solid, mp
210–212°C. IR spectrum, ν, cm–1: 2935 (=C–H), 1639
(C=N), 1219 (C–F). 1H NMR spectrum, δ, ppm: 14.00 s
(1H, SH), 7.17–8.01 m (12H, ArH), 5.51 s (2H, CH2),
2.41 s (3H, CH3). 13C NMR spectrum, δС, ppm: 168.51,
166.04, 154.75, 147.24, 144.53, 142.39, 135.16, 134.44,
131.49, 129.41, 129.31, 129.03, 128.65, 128.56, 123.29,
122.65, 119.33, 118.58, 116.59, 116.37, 111.09, 38.88,
16.57. LC-MS: m/z: 533.05 [M + H]+.
N-(2-Chlorophenyl)-5-({2-[2-(4-fluorophenyl)-
4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}
methyl)-1,3,4-thiadiazol-2-amine (9b). White solid,
mp 140–142°C. IR spectrum, ν, cm–1: 3203 (N–H), 3038
1
(=C–H), 1607 (C=N), 1232 (C–F). H NMR spectrum,
δ, ppm: 9.2 s (1H, NH), 8.17 d (1H, J = 8.8 Hz, ArH),
8.01–8.02 m (2H, ArH), 7.72 d. d (2H, J = 13.2 and
8 Hz, ArH), 7.26–7.44 m (6H, ArH), 7.03 t (1H, J =
7.2 Hz, ArH), 5.84 s (2H, CH2), 2.47 s (3H, CH3). 13C
NMR spectrum, δС, ppm: 166.30, 165.51, 162.30, 155.75,
155.17, 144.65, 142.69, 136.91, 135.08, 129.61, 129.05,
128.69, 128.61, 127.81, 124.22, 123.52, 122.86, 122.70,
121.61, 119.50, 118.61, 116.57, 116.35, 111.25, 42.81,
16.48. LC-MS: m/z: 533.10 [M + H]+.
4-(3,4-Dichlorophenyl)-5-({2-[2-(4-fluorophenyl)-
4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}-
methyl)-4H-1,2,4-triazole-3-thiol (8e). White solid, mp
220–222°C. IR spectrum, ν, cm–1: 2938 (=C–H), 1637
(C=N), 1222 (C–F). 1H NMR spectrum, δ, ppm: 14.00 s
(1H, SH), 7.17–8.01 m (12H, ArH), 5.51 s (2H, CH2),
2.41 s (3H, CH3). 13C NMR spectrum, δС, ppm: 168.53,
166.09, 162.30, 154.68, 146.94, 144.47, 142.35, 135.08,
132.63, 131.74, 131.15, 129.54, 129.03, 128.67, 128.59,
127.86, 123.25, 122.67, 119.32, 118.57, 116.55, 116.33,
111.09, 16.64. LC-MS: m/z: 567.05 [M + H]+.
N-(2,4-Dichlorophenyl)-5-({2-[2-(4-fluorophenyl)-
4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}-
methyl)-1,3,4-thiadiazol-2-amine (9c). White solid, mp
230–232°C. IR spectrum, ν, cm–1: 3201 (N–H), 3037
(=C–H), 1608 (C=N), 1231 (C–F). 1H NMR spectrum, δ,
ppm: 9.2 s (1H, NH), 8.29 d (1H, J = 8.4 Hz,ArH), 8.04 m
(2H,ArH), 7.74 d. d (2H, J = 14.8 and 7.2 Hz,ArH), 7.60 s
(1H, ArH), 7.32–7.38 m (5H, ArH), 5.86 s (2H, CH2),
2.49 s (3H, CH3). 13C NMR spectrum, δС, ppm: 166.30,
165.04, 156.19, 155.16, 144.64, 142.68, 136.09, 135.06,
128.89, 128.69, 128.61, 127.80, 126.60, 123.52, 123.02,
122.86, 122.12, 119.50, 118.59, 116.57, 116.35, 111.25,
42.78, 16.49. LC-MS: m/z: 567.05 [M + H]+.
Synthesis of 5-({2-[2-(4-fluorophenyl)-4-
methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}-
methyl)-N-phenyl-1,3,4-thiadiazol-2-amine (9a–9e).
Conventional method. The mixture of an appropriate
thiosemicarbazide 7a–7e (0.001 mol) with 5 mL of conc.
H2SO4 was stirred for 4 h at RT. After completion of
process, the mixture was poured onto crushed ice and
neutralized with liquid NH3, a solid product was formed.
It was filtered off and washed with methanol to afford the
corresponding pure compound 9a–9e (Table 1).
N-(4-Chlorophenyl)-5-({2-[2-(4-fluorophenyl)-
4-methylthiazol-5-yl]-1H-benzo[d]imidazol-1-yl}-
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DAREKAR et al.
methyl)-1,3,4-thiadiazol-2-amine (9d). White solid,
mp 210–212°C. IR spectrum, ν, cm–1: 3202 (N–H), 3039
(=C–H), 1605 (C=N), 1232 (C–F). 1H NMR spectrum, δ,
ppm: 10.2 s (1H, NH), 8.04 m (1H, ArH), 7.73 d. d (2H,
J = 17 and 7.6 Hz, ArH), 7.56 d (1H, J = 8 Hz, ArH),
7.33–7.50 m (4H, ArH), 5.86 s (2H, CH2), 2.49 s (3H,
CH3). 13C NMR spectrum, δС, ppm: 166.30, 164.66,
162.29, 155.16, 154.64, 144.63, 142.68, 139.13, 135.06,
129.01, 128.84, 128.68, 128.59, 125.41, 123.50, 122.84,
119.49, 118.89, 118.60, 116.55, 116.33, 111.23, 42.80,
16.48. LC-MS: m/z: 533.05 [M + H]+.
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ACKNOWLEDGMENTS
Authors are thankful to Department of Science and
Technology, New Delhi for providing financial assistance for
research facilities under FIST programme.
CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
SUPPLEMENTARY MATERIAL
Supplementary material are available for this article at
https://doi.org/10.1134/S1070363220090200 and are accessible
for authorized users.
https://doi.org/10.1134/S1070363219070259
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 90 No. 9 2020