Synthesis and Antimicrobial Activity of 1-Aryl-4-(arylimino)-6-iminohexahydro-1,3,5-triazine-2-thione Derivatives

Article abstract of DOI:10.1134/S1070363219040303

A series of 6-imino-1-aryl-4-(arylimino)-1,3,5-triazinane-2-thione derivatives are synthesized by cyclization of 1-aryl-3-cyanoguanidine with aryl isothiocyante in the presence of sodium methoxide under MW irradiation. Structures of the synthesized compou

Full text of DOI:10.1134/S1070363219040303

ISSN 1070-3632, Russian Journal of General Chemistry, 2019, Vol. 89, No. 4, pp. 824–830. © Pleiades Publishing, Ltd., 2019.
Synthesis and Antimicrobial Activity
of 1-Aryl-4-(arylimino)-6-iminohexahydro-1,3,5-triazine-2-thione
Derivatives
T. Siva Sankara Babua, N. Srinivasua*, B. Sahab, and S. Venkat Reddyb
a Division of Chemistry, Department of Science and Humanities,
Vignan’s Foundation for Science, Technology and Research University, Guntur, India
*e-mail: navulurisrinivasu@gmail.com
b NACL Industries Limited (R&D Center), Hyderabad, India
Received February 2, 2019; revised March 30, 2019; accepted April 3, 2019
Abstract—A series of 6-imino-1-aryl-4-(arylimino)-1,3,5-triazinane-2-thione derivatives are synthesized by
cyclization of 1-aryl-3-cyanoguanidine with aryl isothiocyante in the presence of sodium methoxide under MW
1
irradiation. Structures of the synthesized compounds 3a–j are elucidated from H and 13C NMR, MS, and IR,
data. The synthesized compounds are evaluated for their antimicrobial activity against B. subtilis, S. aureus, P.
aeruginosa, and E. Coli. Some compounds demonstrate promising activity against the tested strains.
Keywords: 1,3,5-triazinane-2-thione, isothiocyante, micro-wave irradiation, anti microbial activity
DOI: 10.1134/S1070363219040303
INTRODUCTION
4,6-diimino-2-thio-hexahydro-1,3,5-triazine derivatives
for evaluation of their antimicrobial properties.
Among heterocyclic structures that compose
significant building blocks for many functionalized
molecules [1], 1,3,5-triazine derivatives represent an
important class of compounds due to broad spectrum
of their biological activities [2–6].
RESULTS AND DISCUSSION
The trial reaction of 1-aryl-3-cyano guanidine
(1.0 mmol) with aryl isothiocyante (1.0 mmol) at 70–
80°C gave the desired product in 38% yield along with
the unreacted starting compounds, even after
prolonged reaction time (24 h). The following
application of MW irradiation at 50°C led to the higher
yield (84%) of the process. Further optimization of the
method indicated 80°C and MW irradiation to be the
most efficient in the synthesis of compounds 3a–3j
(Scheme 1, Table 1).
Several synthetic approaches to 6-imino-1-aryl-4-
iminoaryl-1,3,5-triazine-2-thione derivatives were
proposed. Kurzer and co-workers [7] synthesized
triazines by reaction of substituted diguanides with
isothiocyanate esters. Kaiser and co-workers [8]
synthesized similar 1,3,5-triazines by reaction of
thiocyanic acid with l-phenyl-3-cyano-guanidine. Rao
et al. [9] used strong alkali to prepare 1-phenyl-4,6-
diimino-2-thio-hexahydro-1,3,5-triazine from dicyan-
amide and an appropriate isothiocyanate. However,
some disadvantages of the above methods stimulated
development of an efficient and environmentally
benign protocol [10] for the synthesis of 1-phenyl-4,6-
diimino-2-thio-hexahydro-1,3,5-triazine derivatives.
MW promoted synthesis is one of such approaches
[11, 12].
Structures of thus synthesized compounds were
characterized by 1H and 13C NMR, MS, and IR spectra.
A possible pathway of the reaction is presented in
Scheme 2. The initial attack of isothiocyanate by the
imino group of cyanoguanidine results it formation of
the intermediate A, cyclization of which leads to
formation of the intermediate anion B. Its following
protonation leads to the desired molecule C.
Biological activity. The compounds 3a–3j were
screened in vitro for their antibacterial activity against
Gram-positive Bacillus subtilis (ATCC 6633) and
In view of the above and in continuation of our
study of biologically active heterocyclic compounds,
we report herein the MW assisted synthesis of 1-phenyl-
824

SYNTHESIS AND ANTIMICROBIAL ACTIVITY
825
Scheme 1. Synthesis of 6-imino-1-aryl-4-(arylimino)-1,3,5-triazinane-2-thione derivatives.
CN
HN
NH
R1
R1
NH
NaOMe
acetone
NH
HN
N
+
S
R
C
R
MWI, 4−5 min
N
N
N
S
H
2
3
1
Staphylococcus aureus (ATCC 6538) and Gram-
negative Escherichia coli (ATCC 11229), and P.
aeruginosa (ATCC 29213) bacteria. Agar well-
diffusion method [13] was used to assay the
antibacterial activity using chloramphenicol as a
standard antibacterial drug (Table 2).
60 (F524) and visualized under UV light and/or by
spraying 5% solution of H2SO4 in ethanol followed by
heating. Column chromatography was performed on
Silica Gel 60 (60–120 mesh). Melting points were
determined in open capillary tubes and are
uncorrected. IR spectra were recorded for KBr pellets
1
on a JASCO FT-IR-4100 spectrophotometer. H and
Among the synthesized compounds 2-trifluoro-
methoxy-1,3,5-triazines 3i and 3j demonstrated potent
activity against both Gram-positive bacterial strains.
Compound 3c exhibited moderate activity against
Gram-positive S. aureus and Gram-negative E. coli
bacterial strains. The compounds 3g and 3d
demonstrated moderate activity against S. aureus,
B. subtilis, P. aeruginosa, and E. Coli.
13C NMR spectra were measured on a JEOL 400 MHz
spectrometer in DMSO-d6 using TMS as the internal
standard. MS were measured on a SHIMADZU LC-
2010EV spectrometer. Microwave reactions were
carried out in a Milestone multi SYNTH series (ATC-
FO 300) multimode microwave equipped with a twin
magnetron (2x800 W, 2.45 GHz), a maximum
delivered power 1,000 W (10 W increments pulsed
irradiation).
EXPERIMENTAL
Synthesis of 1-aryl-4-(arylimino)-6-imino hexa-
hydro-1, 3, 5-triazine-2-thione derivatives (3a–3j).
A mixture of substituted aryl cyanoguanidine 1a–1d
(1.0 mmol) with aryl isothiocyanate (1.0 mmol) and
sodium methoxide (1.0 mmol) in dry acetone (10 mol)
was loaded in a quartz tube and inserted into a capped
All reagent grade chemicals were purchased from
Sigma-Aldrich Chemicals Co. and Spectrochem Pvt.
Ltd. and used without further purification. Solvents
were dried according to standard methods. All
reactions were monitored by TLC on Merck Kieselgel
Scheme 2. Possible pathway of the reaction.
−
S
N
NH
NH
C
NH−
−H+
N
N
+NH
H
N
N
N
H
H
H
N
N
H
N
N−
S
S
S
C
H+
C
C
NH
N
NH
N
NH
−N
N
H
N
N
N
N
HN
N
H
N
H
B
A
C
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 4 2019

826
SIVA SANKARA BABU et al.
Table 1. Synthesis of 1-aryl-4-(arylimino)-6-iminohexahydro-1,3,5-triazine-2-thione derivatives 3a–3j under MW irradiation
Substrate 1a
Substrate 2b
Product
Time, min
5.0
Yieldc, %
84
1a
2a
O
NH
HN
N
N
N
S
S
H
3a
1a
1b
2b
2a
4.5
4.0
91
89
NH
HN
N
N
N
H
3b
O
NH
N
Cl
Cl
HN
N
N
H
S
3c
1b
1c
2b
2a
5.0
5.0
90
88
NH
HN
N
N
N
H
3d
S
O
NH
HN
N
N
N
S
S
H
3e
1c
2b
4.5
92
NH
HN
N
N
N
H
3f
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 4 2019

SYNTHESIS AND ANTIMICROBIAL ACTIVITY
Product
827
Table 1. (Contd.)
Substrate 1a
1d
Substrate 2b
Time, min
5.0
Yieldc, %
2a
88
O
NH
HN
N
N
N
S
S
H
3g
1d
1e
2b
2a
4.5
5.0
92
84
NH
HN
N
N
N
H
3h
O
NH
HN
N
N
N
S
H
O
F3C
3i
1e
2b
4.5
91
NH
HN
N
N
N
S
H
O
F3C
3j
a
CN
NH
CN
NH
CN
NH
CN
NH
H
H
N
H
N
H
N
N
(1c),
(1b),
(1d),
(1a),
NH
NH
NH
NH
Cl
F3C
O
CN
H
N
NH
(1e).
NH
b
O
S
S
C
(2a),
(2b).
C
N
N
c Isolated yield.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 4 2019

828
SIVA SANKARA BABU et al.
Table 2. Antibacterial activity data for the synthesized 1,3,5-triazine derivatives 3a–3j
Gram-positive strains
Gram-negative strains
Staphylococcus aureus Pseudomonas aeruginosa Escherichia coli
Compound
Bacillus subtilis
11.0
3a
10.0
11.0
16.0
15.0
10.0
11.0
16.0
10.0
19.5
20.0
24.0
17.0
16.0
15.0
11.0
11.0
14.0
18.0
13.0
14.0
18.0
22.0
18.0
15.0
17.0
12.0
10.0
13.0
19.0
11.0
13.0
21.0
20.0
3b
11.0
3c
15.0
3d
16.0
3e
11.0
3f
10.0
3g
17.0
3h
11.0
3i
3j
18.0
21.0
Chloramphenicol
25.0
teflon vial and MW irradiated at 80°C for 4–5 min.
After completion of the reaction (as indicated by
TLC), 5% of methanol in dichloromethane (100 mL)
and water (25 mL) were added. The organic layer was
dried over sodium sulfate and concentrated in vacuum.
The crude product was purified by making slurry with
dichloromethane (25 mL) and ethyl acetate (25 mL).
Upon filtration the corresponding titled compound 3a–
3j was isolated as off white solid.
1H, С6H5), 7.27–7.33 m (4H, С6H5), 7.42–7.53 m (3H,
С6H5), 7.79 d (J = 7.2 Hz, 2H, С6H5), 8.20 s (1H, NH),
10.10 s (1H, NH). 13C NMR spectrum, δ, ppm: 30.7,
120.4, 121.2, 122.8, 128.6, 128.8, 138.2, 139.2, 157.5,
158.1, 183.2. ESI-MS: 296.04 [M + H]+. Calculated for
C15H14N5S.
4-[(3-Chlorophenyl)imino]-1-(2,6-diisopropyl-4-
phenoxyphenyl)-6-imino-1,3,5-triazinane-2-thione
(3c). mp 283–284°C. IR spectrum, ν, cm–1: 3644,
3625, 3429, 3310, 3212, 2932, 2354, 1983, 1865,
1-(2,6-Diisopropyl-4-phenoxyphenyl)-6-imino-4-
(phenylimino)-1,3,5-triazinane-2-thione (3a). mp
270–275°C. IR spectrum, ν, cm–1: 3425, 3285, 1626,
1599, 1489, 1372, 1268, 1089, 999, 866, 693. 1H NMR
spectrum, δ, ppm: 1.11 d (J = 6.8 Hz, 6H), 1.15 d (J =
6.8 Hz, 6H), 2.52–2.60 m (2H), 6.73 s (1H, NH), 6.88
s (2H, С6H5), 7.04 t (J = 7.6 Hz, 1H, С6H5), 7.13–7.18
m (3H, С6H5), 7.30 t (2H, J =7.6 Hz, С6H5), 7.41–7.45
m (2H, С6H5), 7.79 d (J = 7.6 Hz, 2H, С6H5), 8.31 s
(1H, NH), 10.10 s (1H, NH). 13C NMR spectrum, δ,
ppm: 23.6, 23.7, 28.5, 114.8, 118.4, 120.5, 122.9,
123.4, 128.1, 128.4, 129.9, 139.1, 147.1, 156.4, 157.2,
157.9, 158.2, 183.4. ESI-MS: 472.26 [M + H]+.
Calculated for C27H30N5OS.
1
1745, 1602, 1386, 1255, 1092, 967, 770, 622, 439. H
NMR spectrum, δ, ppm: 1.11 d (J = 6.8 Hz, 6H), 1.15
d (J = 6.8 Hz, 6H), 2.59–2.52 m (2H), 6.79 s (1H,
NH), 6.89 s (2H, С6H5), 7.13–7.18 m (3H, С6H5), 7.33–
7.35 m (2H, С6H5), 7.41–7.45 m (2H, С6H5), 7.84 d
(J = 8.4 Hz, 2H, С6H5), 8.37 s (1H, NH), 10.25 s (1H,
NH). 13C NMR spectrum, δ, ppm: 29.7, 34.6, 120.8,
124.5, 127.9, 129.4, 132.6, 134.0, 134.3, 136.0, 144.3,
153.2, 16.5, 163.3, 164.0, 164.2, 189.6. ESI-MS:
506.25 [M + H]+. Calculated for C27H29ClN5OS.
4-[(3-Chlorophenyl)imino]-6-imino-1-phenyl-
1,3,5-triazinane-2-thione (3d). mp 220–223°C. IR
spectrum, ν, cm–1: 3694, 3583, 3460, 3322, 2959,
2629, 2319, 1987, 1864, 1788, 1516, 1327, 1168, 994,
755, 575, 442. 1H NMR spectrum, δ, ppm: 6.40 s (1H,
NH), 7.00–7.20 m (3H, С6H5), 7.25–7.50 m (5H,
С6H5), 7.80–7.91 m (1H, С6H5), 8.25 s (1H, NH),
6-Imino-1-phenyl-4-(phenylimino)-1,3,5-triazi-
nane-2-thione (3b). mp 264–267°C. IR spectrum, ν,
cm–1: 3625, 3613, 2966, 2868, 1955, 1894, 1787, 1694,
1
1519, 1384, 1238, 1075, 947, 809, 662, 486. H NMR
13
spectrum, δ, ppm: 6.38 s (1H, NH), 7.03 t (J =7.6 Hz,
10.17 s (1H, NH). C NMR spectrum, δ, ppm: 121.0,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 4 2019

SYNTHESIS AND ANTIMICROBIAL ACTIVITY
829
122.3, 123.3, 126.9, 128.8, 129.0, 129.1, 129.4, 130.4,
131.3, 138.7, 138.9, 139.7, 158.0, 158.6. ESI-MS:
330.06 [M + H]+. Calculated for C15H13ClN5OS.
spectrum, δ, ppm: 18.3, 25.2, 126.4, 126.6, 127.6,
127.7, 128.7, 129.7, 135.2, 135.3, 135.8, 138.3, 138.4,
157.1, 157.6, 158.6, 159.4, 183.2, 184.4. ESI-MS:
324.68 [M + H]+. Calculated for C17H18N5S.
1-(2,6-Diisopropyl-4-phenoxyphenyl)-4-[(3,4-
dimethylphenyl)imino]-6-imino-1,3,5-triazinane-2-
thione (3e). mp 269–270°C. IR spectrum, ν, cm–1:
3656, 3594, 3582, 3208, 2867, 2354, 2088, 1713,
1-(2,6-Diisopropyl-4-phenoxyphenyl)-6-imino-4-
{[2-(trifluoromethoxy)phenyl]imino}-1,3,5-triazi-
nane-2-thione (3i). mp 254–256°C. IR spectrum, ν,
cm–1: 3594, 3437, 3216, 3080, 2929, 2422, 2083, 1895,
1715, 1554, 1370, 1212, 1045, 883, 753, 648, 521,
1
1488, 1295, 1105, 1009, 872, 737, 515, 405. H NMR
spectrum, δ, ppm: 1.11 d (J = 7.0 Hz, 6H), 1.15 d (J =
6.5 Hz, 6H), 2.55–2.59 m (2H), 6.66 s (1H, NH), 6.88
s (2H, С6H5), 7.04 d (J = 8.0 Hz, 1H, С6H5), 7.13–7.24
m (3H, С6H5), 7.58–7.61 m (1H, С6H5), 8.26 s (1H,
NH), 9.94 s (1H, NH). 13C NMR spectrum, δ, ppm:
18.7, 19.6, 23.6, 23.7, 28.5, 114.6, 118.0, 118.4, 121.6,
123.3, 128.1, 129.3, 129.9, 130.6, 136.2, 136.7, 147.2,
156.4, 157.2, 157.8, 158.1, 183.2. ESI-MS: 500.91
[M + H]+. Calculated for C29H34N5OS.
1
407. H NMR spectrum, δ, ppm: 1.09 d (J = 6.5 Hz,
6H), 1.14 d (J = 6.5 Hz, 6H), 2.19–2.23 m (6H), 2.52–
2.57 m (2H), 6.13 s (1H, NH), 6.87 s (2H, С6H5), 7.12–
7.16 m (3H, С6H5), 7.30–7.33 m (1H, С6H5), 7.38–7.43
m (4H, С6H5), 7.75 d (J = 7.5 Hz, 1H, С6H5), 8.08 s
(1H, NH), 9.56 s (1H, NH). 13C NMR spectrum, δ,
ppm: 14.0, 20.5, 20.6, 20.7, 23.6, 24.7, 26.3, 28.5,
34.1, 54.8, 59.7, 114.9, 118.3, 120.7, 121.1, 123.2,
126.4, 127.2, 128.0, 128.1, 129.9, 130.6, 142.5, 147.1,
156.5, 157.1, 157.9, 159.1, 184.2. ESI-MS: 556.85
[M + H]+. Calculated for C28H29F3N5O2S.
4-[(3,4-Dimethylphenyl)imino]-6-imino-1-phenyl-
1,3,5-triazinane-2-thione (3f). mp 206–210°C. IR
spectrum, ν, cm–1: 3665, 3643, 3456, 3332, 2921,
1942, 1715, 1452, 1264, 1107, 966, 756, 609, 444,
6-Imino-1-phenyl-4-{[2-(trifluoromethoxy)phenyl]-
imino}-1,3,5-triazinane-2-thione (3j). mp 233– 235°C.
IR spectrum, ν, cm–1: 3592, 3426, 3371, 3167, 2886,
2329, 1955, 1808, 1654, 1338, 1182, 1049, 955, 775,
628, 498, 407. 1H NMR spectrum, δ, ppm: 6.32 s (1H,
NH), 7.04–7.30 m (3H, С6H5), 7.38–7.44 (m, 3H,
С6H5), 7.50 t (J = 7.0 Hz, 2H, С6H5), 7.80 d (J =
7.5 Hz, 1H, С6H5), 8.02 s (1H, NH), 9.60 s (1H, NH).
13C NMR spectrum, δ, ppm: 21.1, 117.0, 119.1, 121.1,
126.2, 127.3, 127.8, 128.1, 128.6, 128.9, 129.8, 130.8,
138.2, 142.1, 157.6, 159.0, 172.2, 184.1. ESI-MS:
380.59 [M + H]+. Calculated for C16H13F3N5OS.
1
401. H NMR spectrum, δ, ppm: 2.17 s (3H), 2.20 s
(3H), 6.38 s (1H, NH), 7.02–7.04 (m, 1H, С6H5), 7.26–
7.30 (m, 2H, С6H5), 7.42–7.57 m (4H, С6H5), 7.79 d
(J = 7.5 Hz, 1H, С6H5), 8.19 s (1H, NH), 9.94 s (1H,
NH). ESI-MS: 324.65 [M + H]+. Calculated for
C17H18N5S.
1-(2,6-Diisopropyl-4-phenoxyphenyl)-4-[(2,6-di-
methylphenyl)imino]-6-imino-1,3,5-triazinane-2-thione
(3g). mp 263–265°C. IR spectrum, ν, cm–1: 3576,
3414, 3303, 3167, 3074, 2670, 2085, 1841, 1585,
1
1332, 1162, 1030, 879, 718, 579, 499, 427. H NMR
spectrum, δ, ppm: 1.07-1.17 m (12H), 2.19–2.23 m
(6H), 2.53–2.57 m (2H), 6.41 s (1H, NH), 6.87 s (2H,
С6H5), 7.11–7.16 m (6H, С6H5), 7.38–7.43 m (2H,
С6H5), 8.00 s (1H, NH), 9.29 s (1H, NH). 13C NMR
spectrum, δ, ppm: 18.1, 18.2, 23.5, 23.6, 28.5, 114.7,
115.0, 118.1, 118.3, 123.1, 126.6, 127.7, 127.8, 129.8,
129.9, 135.1, 135.7, 147.1, 147.2, 156.7, 156.9, 157.9,
159.3, 183.3. ESI-MS: 500.91 [M + H]+. Calculated for
C29H34N5OS.
CONCLUSIONS
A mild and highly efficient protocol for the
synthesis of 1-aryl-4-(arylimino)-6-iminohexahydro-
1,3,5-triazine-2-thione
derivatives
under
MW
irradiation is developed. The method is characterized
by short reaction time and high yields. The synthesized
1,3,5-triazine derivatives 3a–3j are evaluated for their
antimicrobial activity. Among these 3i and 3j
demonstrate very good antibacterial activity. The other
products show moderate microbial activity against the
tested organisms.
4-[(2,6-Dimethylphenyl)imino]-6-imino-1-phenyl-
1,3,5-triazinane-2-thione (3h). mp 246-248°C. IR
spectrum, ν, cm–1: 3583, 3501, 3303, 3158, 3008,
2674, 2327, 1970, 1841, 1558, 1154, 1001, 837, 661,
471, 424, 411. 1H NMR spectrum, δ, ppm: 2.19 s (3H),
2.22 s (3H), 6.10 s (1H, NH), 7.08–7.10 (m, 3H,
С6H5), 7.22–7.25 (m, 2H, С6H5), 7.38–7.48 m (3H,
С6H5), 8.00 s (1H, NH), 9.30 s (1H, NH). 13C NMR
AKNOWLEDGMENTS
The authors are thankful to the Chairman, Vignan
University, Guntur, India and the Managing Director,
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SIVA SANKARA BABU et al.
5. Sączewski, F., Bułakowska, A., Bednarski, P., and
Grunert, R., Eur.J. Med. Chem. 2006, vol. 41, p. 219.
doi 10.1016/j.ejmech.2005.10.013
NACL Industries Ltd., Hyderabad, India, for providing
laboratory facilities to carry out the research work.
6. Joseph, K.M., Patent EP0834507A1.
7. Kurzer, F. and Pitchfork, E.D., J. Chem. Soc., C, 1964,
CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
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