Synthesis, crystal structure, and biological activity of a novel 1,2,3-thiadiazole compound containing 1,2,4-triazole moiety

Article abstract of DOI:10.1080/10426507.2013.820186

A new 1,2,3-thiadiazole compound containing 1,2,4-triazole moiety, C1 ₅H1₄FN₅ O₂S₂, has been synthesized and the crystal structure was determined by single crystal X-ray diffraction study. The biological activity of the title compound was determined and the results showed that title compounds 10 showed higher inhibition abilities of rape root than the control cyclopropane-1,1-dicarboxylic acid at 100 μg/mL (73%) and weak activity against Echinochloa crusgalli (28%) and KARI (35%) at 100 μg/mL. [Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: additional text, figures, tables.]

Full text of DOI:10.1080/10426507.2013.820186

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Synthesis, Crystal Structure, and
Biological Activity of A Novel 1,2,3-
Thiadiazole Compound Containing 1,2,4-
Triazole Moiety
Li-Jing Min a , Cheng-Xia Tan b , Jian-Quan Weng b & Xing-Hai Liu b
a College of Life Sciences, Huzhou Teachers College , Huzhou ,
313000 , Zhejiang , China
b College of Chemical Engineering and Materials Science , Zhejiang
University of Technology , Hangzhou , 310014 , Zhejiang , China
Accepted author version posted online: 25 Sep 2013.Published
online: 28 Jan 2014.
To cite this article: Li-Jing Min , Cheng-Xia Tan , Jian-Quan Weng & Xing-Hai Liu (2014) Synthesis,
Crystal Structure, and Biological Activity of A Novel 1,2,3-Thiadiazole Compound Containing 1,2,4-
Triazole Moiety, Phosphorus, Sulfur, and Silicon and the Related Elements, 189:3, 379-386, DOI:
10.1080/10426507.2013.820186
To link to this article: http://dx.doi.org/10.1080/10426507.2013.820186
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Phosphorus, Sulfur, and Silicon, 189:379–386, 2014
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2013.820186
SYNTHESIS, CRYSTAL STRUCTURE, AND BIOLOGICAL
ACTIVITY OF A NOVEL 1,2,3-THIADIAZOLE COMPOUND
CONTAINING 1,2,4-TRIAZOLE MOIETY
Li-Jing Min,1 Cheng-Xia Tan,2 Jian-Quan Weng,2
and Xing-Hai Liu2
1College of Life Sciences, Huzhou Teachers College, Huzhou 313000, Zhejiang,
China
2College of Chemical Engineering and Materials Science, Zhejiang University of
Technology, Hangzhou 310014, Zhejiang, China
GRAPHICAL ABSTRACT
Abstract A new 1,2,3-thiadiazole compound containing 1,2,4-triazole moiety, C15H14FN5
O2S2, has been synthesized and the crystal structure was determined by single crystal X-
ray diffraction study. The biological activity of the title compound was determined and the
results showed that title compounds 10 showed higher inhibition abilities of rape root than
the control cyclopropane-1,1-dicarboxylic acid at 100 μg/mL (73%) and weak activity against
Echinochloa crusgalli (28%) and KARI (35%) at 100 μg/mL.
[Supplementary materials are available for this article. Go to the publisher’s online edition of
Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental
files: additional text, figures, tables.]
Keywords Crystal structure; synthesis; 1,2,3-thiadiazole; 1,2,4-triazole; bioactivity
INTRODUCTION
In recent years, heterocyclic compounds had received considerable attention because
of their pharmacological and pesticidal importance,1–5 such as ketol-acid reductoisomerase
(KARI) inhibitors,6 fungicidal activity,7–9 anticancer activity,10 and antibacterial activity.11
Received 29 April 2013; accepted 25 June 2013.
Address correspondence to Xing-Hai Liu, College of Chemical Engineering and Materials Science, Zhejiang
University of Technology, Hangzhou 310014, Zhejiang, China. E-mail: xhliu@zjut.edu.cn
379

380
L.-J. MIN ET AL.
Figure 1 Commercial pesticides contain 1,2,3-thiadiazole group.
1,2,3-Thiadiazole derivatives as one type of sulfur nitrogen-linked heterocycles with a
wide spectrum of remarkable biological activities have been used as agrochemicals or
medicines such as fungicidals,12 anti-HBV,13 herbicidal activity,14 anti-TMV,15 necroptosis
inhibitory activities,16 and HIV-1 inhibitors.17 For example, some 1,2,3-thiadiazoles had
been developed as commercial agrochemicals such as the plant inducers tiadinal, BTH
(Figure 1). Furthermore, 1,2,4-triazoles displayed diverse bioactivities. For example, they
exhibited anti-HIV activity,18 antimicrobial activity,19 herbicidal activity,20 and antifungal21
activity. In the past years many triazole-containing drugs have been discovered.22–25 Some
compounds had been developed as commercial medicines and pesticides (Figure 2), such
as Flupoxam, Flusilazole, Fluconazole and Anastrozole. Owing to their diverse properties,
1,2,4-triazole fungicides may become one of the focuses in drug research.
In view of the above-mentioned facts, and also as a part of our work on the synthesis
of bioactive lead compounds,26,27 the title compounds were designed, synthesized, and
1
characterized by H NMR, MS, and elemental analysis. The crystal structure of the title
compound was determined. The biological activity of the title compound was tested in vivo
and in vitro.
RESULTS AND DISCUSSION
Chemistry
The synthesis procedure for the title compound is shown in Scheme 1. The thioether
intermediate 9 was synthesized by treating triazole sulfide intermediate 8 with 2-fluoro
benzyl chloride at room temperature for 24 h. Generally, the sulfone can be easily obtained
using a stronger oxidizing agent such as KMnO4, K2S2O8, or H2O2/HOAc system. Also,
the sulfone can be synthesized by using m-CPBA as an oxidizer with good control of the
reaction time. In this paper we use the m-CPBA as an oxidizer to yield the title compound.
Interestingly, during the m-CPBA oxidation process, two by-products were obtained: one
Figure 2 Some commercial medicines and pesticides about triazole.

SYNTHESIS, STRUCTURE, AND BIOLOGICAL ACTIVITY OF 1,2,3-THIADIAZOLE
381
Scheme 1 The synthetic route of the title compound.
was recognized as m-chloroperoxybenzoic acid, and the other as 3-chlorobenzoic peroxyan-
hydride, which was produced by radical coupling. The thioamide (–NH–C( = S)) structure,
1
triazole intermediates can exist either as thione or thiol tautomeric form. In H NMR
spectrum, the singlet at δ 10.86 ppm corresponds to SH proton, indicating that solution
exists in the thiol tautomeric form versus the thione form. The signals in the 3.0-ppm range
are methyl signals of 1,2,3-thiadiazole. Regarding the mass spectra, the title compounds
showed M–H signals.
Crystal Structure
The selected bond lengths, bond angles are shown in Table 1. The molecular structure
of the title compound is shown in Figure 3. The molecular packing of the molecule is shown
in Figure S1 (Supplemental Materials).
Generally, the average bond lengths and bond angles of a ring system (phenyl,
cyclopropane, triazole, and 1,2,3-thiadiazole) are within normal ranges.28–31 However, the
C2 N2 bond [1.369(2) Å] and C9 N2 [1.3182(19) Å] are longer than the general C N
double bond length of 1.27 Å.32 As shown in Figure 1, the 1,2,3-thiadiazole ring is nearly
planar with 1,2,4-triazole ring with a quite small dihedral angle (θ) of 8.5◦. The triazole
ring (N3, N4, C5, N5, C4) and thiadiazole ring (N1, N2, S1, C3, C2) are quite planar
with plane equation 6.844x + −7.126y + −1.607z = −5.3348 and 7.203x + −6.352y +
−3.729z = −5.0168 respectively, and the largest deviation from the least squares plane is
0.0030 nm and 0.0027 nm respectively. Meanwhile, the phenyl ring is vertical with both

382
L.-J. MIN ET AL.
Table 1 Selected bond lengths (Å) and bond angles (◦)
Bond
Dist.
Angle
(◦)
S(1)-N(1)
S(1)-C(3)
S(2)-O(1)
S(2)-O(2)
S(2)-C(5)
S(2)-C(9)
F(1)-C(15)
F(1’)-C(11)
N(1)-N(2)
N(2)-C(2)
N(3)-C(4)
N(3)-N(4)
N(4)-C(5)
N(5)-C(5)
N(5)-C(4)
N(5)-C(6)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(6)-C(8)
C(6)-C(7)
1.6657(15)
1.6981(16)
1.4286(12)
1.4395(12)
1.7789(15)
1.7837(16)
1.3471(18)
1.166(7)
N(1)-S(1)-C(3)
O(1)-S(2)-O(2)
O(1)-S(2)-C(5)
C(4)-N(5)-C(6)
F(1’)-C(11)-C(12)
C(5)-S(2)-C(9)
N(2)-N(1)-S(1)
N(1)-N(2)-C(2)
C(4)-N(3)-N(4)
C(5)-N(4)-N(3)
N(2)-C(2)-C(3)
N(2)-C(2)-C(1)
C(2)-C(3)-C(4)
C(2)-C(3)-S(1)
C(4)-C(3)-S(1)
N(3)-C(4)-N(5)
N(3)-C(4)-C(3)
N(5)-C(5)-S(2)
N(5)-C(6)-C(8)
N(5)-C(6)-C(7)
C(8)-C(6)-C(7)
93.25(8)
118.53(8)
107.99(7)
127.71(12)
122.4(4)
99.75(7)
111.53(12)
114.47(14)
107.46(12)
106.65(13)
112.82(15)
118.60(14)
125.53(14)
107.91(12)
126.50(11)
110.68(13)
122.77(13)
127.50(11)
118.54(13)
119.37(13)
59.70(10)
1.300(2)
1.369(2)
1.3182(19)
1.3815(18)
1.311(2)
1.3676(19)
1.3759(18)
1.4469(18)
1.488(2)
1.381(2)
1.458(2)
1.503(2)
1.503(2)
the 1,2,3-thiadiazole ring and the 1,2,4-triazole ring with the respective dihedral angles
of 108.1◦ and 99.8◦. Also, it is nearly that the cyclopropane ring is vertical with 1,2,3-
thiadiazole ring, 1,2,4-triazole ring, and phenyl ring with the dihedral angle of 64.9◦, 56.5◦,
43.6◦ respectively.
In the intermolecular face-to-face π-π stacking pattern of the title compound
(Figure 4), it is worth mentioning that the two molecules of each stacking unit are cet-
rosymmetric, which can be proved by the relative position of the two phenyl rings of the
two molecules: the centroid separation of them is 3.687 Å, and their dihedral angle is
Figure 3 The molecular structure of the title compound.

SYNTHESIS, STRUCTURE, AND BIOLOGICAL ACTIVITY OF 1,2,3-THIADIAZOLE
383
68.79◦. Another intermolecular face-to-face π-π stacking pattern of the title compound
can be proved by the relative position of the thiadiazole ring and triazole ring of the two
molecules: the centroid separation of them is 3.677 Å, and their dihedral angle is 72.99◦.
Herbicidal Activity
The biological activities were determined according to Kiriyama et al.,33 McKeage
et al.,34 Ravert et al.,35 and Mystakidou et al.36 To investigate the KARI inhibitory activity
and herbicidal activity of these synthesized title compounds, cyclopropane-1,1-dicarboxylic
acid (CPD), a potent inhibitor of KARI in vitro, was used as the control. We found that
title compounds 10 showed higher inhibition abilities of rape root than the control CPD
at 100 μg/mL (73%). It displayed weak activity against Echinochloa crusgalli (28%) and
KARI (35%) at 100 μg/mL (Table S1 in Supplemental Materials).
EXPERIMENTAL
Materials and Methods
1
Melting points were determined using an X-4 apparatus and uncorrected. H NMR
spectra were measured on a Bruker AV-400 instrument using TMS as an internal stan-
dard and CDCl3 as a solvent. Elemental analyses were performed on a Vario EL elemental
analyzer. Crystallographic data of the compound were collected on a Rigaku Saturn diffrac-
tometer. All the reagents are of analytical grade or freshly prepared before use.
Synthesis
The title compounds were synthesized according to the route shown in Scheme 1,
and the yields were not optimized.
Intermediate 4-methyl-1,2,3-thiadiazole-5-carboxylic acid hydrazide (5) was synthe-
sized according to the literature.23 A mixture of acylhydrazine (5) with isothiocyanatocy-
clopropane (6) (1.5 g, 11.1 mmol) was refluxed for 3 h in ethanol (10 mL). After cooling
down to room temperature, the products were obtained and recrystallized from methanol
to give 7. A mixture of compound (7) (2.57 g, 10 mmol) in aqueous NaOH solution (5 mL,
2N) was refluxed for 4 h. After cooling to room temperature, HCl aqueous solution (4N)
was added to afford a large amount of precipitate. The solid was filtered, dried, and recrys-
tallized from methanol to give intermediate (8). To a stirred solution of 8 (5.1 mmol) and
K2CO3 (0.2 g, 5.6 mmol) in dimethylformamide (DMF) (15 mL), 2-fluorobenzyl chloride
(5.6 mmol) was added dropwise. The resulting mixture was stirred at room temperature
overnight. The mixture was poured into water. The precipitate formed was filtered off
and recrystallized from petroleum ether/acetone to give (9) in good yields. To a stirred
solution of compound 9 (2 mmol) in CH2Cl2 (8 mL) was added m-CPBA (1.1 mmol).
The reaction was monitored by thin layer chromatography (TLC). When the reaction was
complete, the solvent was removed under reduced pressure vacuum. The crude product
was purified by chromatography over silica gel to give the title compound (PE:EA =
5:1) 5-(4-cyclopropyl-5-((2-fluorobenzyl)sulfonyl)-4H-1,2,4-triazol-3-yl)-4-methyl-1,2,3-
1
thiadiazole white crystal, yield, 80.5%; mp, 147–148◦C; H NMR (400 MHz, CDCl3),
0.99–1.02 (m, 2H, CH2), 1.22–1.28 (m, 2H, CH2), 3.00 (s, 3H, Het-CH3), 3.29–3.34 (m,
1H, CH), 5.00 (s, 2H, CH2), 7.09 (t, J = 8.58 Hz, 2H, Ph-H), 7.51 (t, J = 5.31 Hz, 2H,

384
L.-J. MIN ET AL.
Ph-H); ESI-MS: 378.70[M–H]−; Anal. Calcd for C15H14FN5O2S2 (%): C, 47.48; H, 3.72;
N, 18.46. Found: C, 47.21; H, 3.51; N, 18.29.
Crystal Structure Determination
The cube-shaped single crystal of the title compound was obtained by recrystallization
from EtOH. The crystal with dimensions of 0.18 × 0.16 × 0.12 mm was mounted on
a Rigaku Saturn diffractometer with a graphite-monochromated MoKα radiation (λ =
0.71073 Å) by using a Phi scan modes at 113(2) K in the range of 2.06◦ ≤ θ ≤ 27.49◦. A
total of 11,276 reflections were collected, of which 3720 were independent (Rint = 0.0342)
and 3012 were observed with I > 2σ(I). The calculations were performed with SHELXS-97
program37 and the empirical absorption corrections were applied to all intensity data. The
non-hydrogen atoms were refined anisotropically. The hydrogen atoms were determined
with theoretical calculations and refined isotropically. The final full-matrix least squares
refinement gave R = 0.0335 and wR = 0.0882 (w = 1/[σ2(Fo ) + (0.0542P)2 + 0.0747P],
2
2
2
where P = (Fo + 2Fc )/3), S = 1.08, (ꢀ/σ)max = 0.0010, ꢀρmax = 0.29 and ꢀρmin
=
−0.37 e Å−3. Atomic scattering factors and anomalous dispersion corrections were taken
from International Table for X-Ray Crystallography.38 A summary of the key crystallgraphic
information is given in Table 2.
Table 2 Crystal structure and data refinement parameters
Compound
10
Empirical formula
C15H14FN5O2S2
Formula weight
Crystal system/space group
a/Å
b/Å
379.43
Monoclinic/P2(1)/c
8.2371(16)
13.100(3)
c/Å
15.618(3)
90
105.11(3)
90
1627.0(6)
α/◦
β/◦
γ /◦
V/Å3
Z
4
Dcalc (g/cm3)
1.549
0.1800
μ (mm−1
)
Crystal size (mm)
Color/shape
Temp (K)
0.18 × 0.16 × 0.12
Colorless/cube
113(2)
Theta (θ) range for collection
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness of fit on F2
Final R indices [I > 2σ(I)]
R indices (all data)
2.06 to 27.49
11,276
3720
3720/0/237
1.077
R1 = 0.0335, wR2 = 0.0882
R1 = 0.0413, wR2 = 0.0924
0.294 and −0.369
Largest difference peak/hole

SYNTHESIS, STRUCTURE, AND BIOLOGICAL ACTIVITY OF 1,2,3-THIADIAZOLE
385
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