Synthesis and insecticidal activities of novel 1,3,4-thiadiazole 5-fluorouracil acetamides derivatives: An RNA interference insecticide

Article abstract of DOI:10.1080/15257770.2011.580811

A series of novel 1,3,4-thiadiazole 5-fluorouracil acetamides derivatives were designed and synthesized. Their structures were confirmed by infrared, 1H NMR spectroscopy, and elemental analysis. The insecticidal activities against Tetranychus cinnabarinus

Full text of DOI:10.1080/15257770.2011.580811

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Synthesis and Insecticidal Activities of
Novel 1,3,4-Thiadiazole 5-Fluorouracil
Acetamides Derivatives: An RNA
Interference Insecticide
Rong Wan a , Jian-Qiang Zhang a , Fen Han a , Peng Wang a , Peng Yu
a & Qiu He a
a College of Science , Nanjing University of Technology , Nanjing, P.
R. China
Published online: 27 May 2011.
To cite this article: Rong Wan , Jian-Qiang Zhang , Fen Han , Peng Wang , Peng Yu & Qiu He (2011)
Synthesis and Insecticidal Activities of Novel 1,3,4-Thiadiazole 5-Fluorouracil Acetamides Derivatives:
An RNA Interference Insecticide, Nucleosides, Nucleotides and Nucleic Acids, 30:4, 280-292, DOI:
10.1080/15257770.2011.580811
To link to this article: http://dx.doi.org/10.1080/15257770.2011.580811
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Nucleosides, Nucleotides and Nucleic Acids, 30:280–292, 2011
Copyright ꢀC Taylor and Francis Group, LLC
ISSN: 1525-7770 print / 1532-2335 online
DOI: 10.1080/15257770.2011.580811
SYNTHESIS AND INSECTICIDAL ACTIVITIES OF NOVEL
1,3,4-THIADIAZOLE 5-FLUOROURACIL ACETAMIDES DERIVATIVES:
AN RNA INTERFERENCE INSECTICIDE
Rong Wan, Jian-Qiang Zhang, Fen Han, Peng Wang, Peng Yu, and Qiu He
College of Science, Nanjing University of Technology, Nanjing, P. R. China
A series of novel 1,3,4-thiadiazole 5-fluorouracil acetamides derivatives were designed and syn-
2
thesized. Their structures were confirmed by infrared, 1H NMR spectroscopy, and elemental analysis.
The insecticidal activities against Tetranychus cinnabarinus and Aphis craccivora of these new
compounds were evaluated. The bioassay tests showed that most of these title compounds possessed a
good combination of stomach toxicity as well as contact toxicity against Tetranychus cinnabari-
nus and Aphis craccivora. In particular, the insecticidal activity of the title compound IVe against
Aphis craccivora was better than the commercialized thiacloprid and was also comparable to an-
other commercialized product, imidacloprid. The introduction of fluorines to meta and para-position
of the benzene ring was essential for high bioactivity.
Keywords 1,3,4-Thiadiazole; 5-fluorouracil; synthesis; insecticidal activities; RNA
interference
INTRODUCTION
Due to the rapidly developing resistance of insects to pesticides and the
desire to have compounds with less mammalian and environmental toxicity,
the discovery of new leading structures with ideal properties has been one
of the most important topics of research in pesticide chemistry for decades
and continues to be an active area of research today.
In a variety of biological heterocyclic compounds, 1,3,4-thiadiazole
derivatives have attracted considerable attention in chemical and medici-
nal research because of their diverse biological activities. It is reported that
1,3,4-thiadiazole derivatives possess wide spectrum insecticidal[1] and her-
bicidal[2] activities. Some of these compounds with broad spectrum have
Received 4 October 2010; accepted 11 April 2011.
We are thankful to Jue-ping Ni, Director of Bioassay Deptartment, Jiangsu Branch of National
Pesticide Research and Development South Center, for support with bioassays. This work was supported
by the Jiangsu High-Tech Research Project (Agriculture) (BG2007329) from the Science and Technology
Department of Jiangsu Province.
Address correspondence to Rong Wan, College of Science, Nanjing University of Technology,
Nanjing 210009, P. R. China. E-mail: rwan@njut.edu.cn
280

1,3,4-Thiadiazole 5-Fluorouracil Acetamides Derivatives
281
FIGURE 1 Chemical structures of compounds A and B.
already been commercialized, for instance, L 1215 (Figure 1A),[3] which is
highly effective against mosquito larvae,[4] spodoptera eridania larvae,[5] and
Western spruce budworm.[6] In addition, Liu et al. synthesized and tested a
series of 1,3,4-thiadiazole amide derivatives (Figure 1B) and found that these
compounds showed good fungicidal activities.[7] Furthermore, other 1,3,4-
thiadiazole derivatives also have anti-inflammatory,[8] antiproliferative[9] and
antibacterial[10–12] activities.
As a fluoropyrimidine, the mechanism of cytotoxicity of 5-fluorouracil
has been ascribed to the misincorporation of fluoronucleotides into RNA
and DNA and to the inhibition of the nucleotide synthetic enzyme thymidy-
late synthase. 5-Fluorouracil can be converted intracellularly to several
active metabolites: fluorodeoxyuridine monophosphate (FdUMP), fluo-
rodeoxyuridine triphosphate (FdUTP), and fluorouridine triphosphate
(FUTP)—these active metabolites restrain the action of thymidylate synthase
and disrupt RNA and DNA synthesis and repair.[13] Due to these satisfying
advantages, 5-fluorouracil and its derivatives have been widely used as an-
titumor agents in the treatment of colon cancer,[14,15] gastric cancer,[16]
esophageal cancer,[17] and so on.
Enlightened by the aforementioned findings and our desire to develop
new insecticides with higher potency and better biological activity, we de-
signed and synthesized a series of novel 1,3,4-thiadiazole acetamides deriva-
tives containing 5-fluorouracil as shown in Scheme 1, and their biological
activities were also evaluated.
RESULTS AND DISCUSSION
Synthesis
2-(5-fluoro-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-N-(5-aryl-
1,3,4-
thiadiazol-2-yl)acetamides IVa–r were synthesized as shown in Scheme 1.
It is reported that 2-amino-5-alkyl-1,3,4-thiadiazole can be prepared by

282
R. Wan et al.
SCHEME 1 General synthetic route for compounds IVa-p.
the reaction of aliphatic acid and thiosemicarbazide under the mineral
acid such as sulfuric acid, hydrochloric acid or polyphosphoric acid.
However, attempts to synthesize 2-amino-5-aryl-1,3,4-thiadiazoles using
these acids were unsuccessful, yielding only acyl thiosemicarbazides. In
this article, we obtained 2-amino-5-aryl-1,3,4-thiadiazole II in good yields
under phosphorus oxychloride by amidation, nucleophilic addition and
dehydration in one step. 5-Fluorouracil was reacted with chloroacetic
acid using potassium hydroxide as alkali to yield compound III. The title
compounds, IVa–r, were synthesized with the intermediate II and III in
N,N-dimethylformamide (DMF) under 1-hydroxybenzotriazole (HOBT)
and ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)
catalysis. Different akyl groups of the title compounds IVa–r are listed in
Table 1.
Bioassay
Contact Toxicity Against Tetranychus cinnabarinus (Spider Mite)
Table 2 and Table 3 show the contact toxicities of the title compounds
IVa–r and contrast compound avermectins against Tetranychus cinnabarinus
(spider mite). The results indicate that some of the title compounds ex-
hibit good acaricidal activities against Tetranychus cinnabarinus. The title com-
pounds IVa, IVc, IVe, IVk, IVm, IVn, and IVp exhibit >80% mortalities at
400 mg/L. In particular, the acaricidal activities of compounds IVe and IVm
against Tetranychus cinnabarinus are 100% at 400 mg/L, which are equal to
the commercialized avermectins. Encouragingly, when the concentration

1,3,4-Thiadiazole 5-Fluorouracil Acetamides Derivatives
283
TABLE 1 Different akyl groups of the title compounds IVa–r
Ar
Compd.
R1
R2
H
4-Cl
5-CH3
H
4-F
H
5-F
R3
IVa
IVb
IVc
IVd
IVe
IVf
IVg
IVh
IVi
3-OCH3
2-Cl
3-CH3
4-NO2
3-F
4-(n-C5H11
3-F
2-NO2
3-OCH3
2-F
H
H
H
H
H
H
H
H
)
4-Br
4-OCH3
6-F
H
H
IVj
IVk
IVl
IVm
IVn
IVo
IVp
4-CH3
3-OCH3
4-OPh
4-(n-C12H25
4-(n-C8H17
H
H
H
4-OCH3
H
5-OCH3
H
H
H
H
)
)
H
H
H
IVq
IVr
drops to 100 mg/L, IVe and IVm still had 95.65% and 97.67% acaricidal
activities, respectively.
Contact Toxicity Against Aphis craccivora (Pea Aphids)
Table 4 and Table 5 show the contact toxicities of the title compounds
IVa–r and contrast compound imidacloprid against Aphis craccivora (pea
aphids). The results indicated that most of the title compounds exhibit
good insecticidal activities against Aphis craccivora. The title compounds IVc,
IVe, IVg, IVj, IVk, IVm, IVn, IVo, IVp, and IVq had >80% mortalities at
400 mg/L. Moreover, the insecticidal activities of compounds IVe, IVg and
IVm are 100% at 40 mg/L against Aphis craccivora, which were equal to that
of the commercialized imidacloprid. Particularly, the insecticidal activity of
compound IVe is 91.03% at 2 mg/L against Aphis craccivora, which is com-
parable to that of the commercialized imidacloprid. Therefore, IVe stands
out as the best and could be served as a promising candidate compound for
further optimization.
The results of the contact toxicities of the title compounds IVa–r against
Tetranychus cinnabarinus and Aphis craccivora imply that the bioactivity is

284
R. Wan et al.
TABLE 2 Contact toxicities of compounds IVa–r and avermectins against Tetranychus cinnabarinus
(spider mite) at 400 mg/L
Mortality (%) at concn (mg/L)
Compd.
400
IVa
IVb
IVc
IVd
IVe
IVf
IVg
IVh
IVi
IVj
IVk
86.67
62.79
87.23
56.52
100.00
23.40
70.45
76.09
68.89
60.98
91.11
53.33
100.00
84.78
67.74
86.05
75.56
72.73
100.00
IVl
IVm
IVn
IVo
IVp
IVq
IVr
Avermectins
higher when the substituent on the benzene ring is a lower alkyl group
such as CH3, whereas it decreases as the groups are extended. Compared to
the polyalkoxy substituted compounds IVi and IVl, the monoalkoxy substi-
tuted compound IVa exhibits a better bioactivity. But the bioactivity of the
phenoxy substituted compound IVm is higher than these alkoxy substituted
compounds IVa, IVi and IVl. In those electron-withdrawing groups, the flu-
orines substituted on meta and para position of the benzene ring exhibit
better bioactivities than the ortho-substituted compounds. But the introduc-
tion of Cl, Br and nitro groups into the benzene ring results in decreased
biological activity.
TABLE 3 Contact toxicities of compounds IVc, IVe, IVk, IVm, and avermectins against Tetranychus
cinnabarinus (spider mite) at 100 mg/L
Mortality (%) at concn (mg/L)
Compd.
100
IVc
IVe
IVk
IVm
28.89
95.65
23.40
97.67
100.00
Avermectins

1,3,4-Thiadiazole 5-Fluorouracil Acetamides Derivatives
285
TABLE 4 Contact toxicities of compounds IVa–r and imidacloprid against Aphis craccivora (pea aphids)
at 400 mg/L
Mortality (%) at concn (mg/L)
Compd.
400
IVa
IVb
IVc
IVd
IVe
IVf
IVg
IVh
IVi
IVj
IVk
77.89
76.09
88.51
45.45
100.00
56.00
100.00
41.18
53.85
81.82
93.62
75.82
100.00
86.51
81.82
89.88
80.95
70.00
100.00
IVl
IVm
IVn
IVo
IVp
IVq
IVr
Imidacloprid
Table 6 shows the contact toxicities of IVe, IVg, IVm, and the contrast
compounds imidacloprid and thiacloprid against Aphis craccivora. The results
of the median lethal concentrations (LC50) and the toxicity regression equa-
tions of compounds IVe, IVg, IVm, imidacloprid, and thiacloprid are listed
in Table 6. The results show that the insecticidal activities of compounds
IVe and IVg against Aphis craccivora are 3.14- and 1.60-fold as high as that
of thiacloprid on the basis of the LC50 values. The LC50 value of compound
IVm is 2.40 mg/L, which is comparable to that of thiacloprid. Moreover, the
LC50 value of the title compound IVe is 0.63 mg/L compared to 0.41 mg/L
of the imidacloprid, which indicates that IVe possesses the same activity level
as the commercialized imidacloprid.
TABLE 5 Contact toxicities of compounds IVe, IVg, IVm, and imidacloprid against Aphis craccivora (pea
aphids) at 100–1 mg/L
Mortality (%) at concn (mg/L)
Compd.
100
40
10
4
2
1
IVe
IVg
IVm
Imidacloprid
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
92.70
87.21
100.00
74.14
58.18
91.03
58.66
31.96
53.06
46.24
27.88
100.00
100.00
100.00
100.00

286
R. Wan et al.
TABLE 6 Contact toxicities of compounds IVe, IVg, IVm, imidacloprid, and thiacloprid against Aphis
craccivora (pea aphids)
Compd.
y = a + bx
LC50 (mg/L)
Toxic ratio
IVe
IVg
IVm
Imidacloprid
Thiacloprid
y = 5.4151 + 2.1162x
y = 4.8559 + 1.5227x
y = 4.4537 + 1.4332x
y = 5.5238 + 1.3595x
y = 4.5241 + 1.6090x
0.63
1.24
2.40
0.41
1.98
3.14
1.60
0.83
4.83
1.00
Stomach Toxicity Against Aphis craccivora (Pea Aphids)
Table 7 shows the stomach toxicities of IVe and the contrast compounds
imidacloprid and thiacloprid against Aphis craccivora. The results of the me-
dian lethal concentrations (LC50) and the toxicity regression equations of
compounds IVe, imidacloprid and thiacloprid are shown in Table 7. The
LC50 value of the title compound IVe is 1.88 mg/L, compared to 2.04 mg/L
of thiacloprid and 0.50 mg/L of imidacloprid. The results indicate that
the insecticidal activity of the title compound IVe against Aphis craccivora is
higher than the commercialized thiacloprid.
In summary, a series of novel propesticides 2-(5-fluoro-2,4-dioxo-3,4-
dihydropyrimidin-1(2H)-yl)-N-(5-aryl-1,3,4-thiadiazol-2-yl)acetamides were
designed and synthesized by the reaction of 5-aryl-1,3,4-thiadiazol-2-amines
with 5-fluorouracil-1-yl acetic acid. The contact and stomach toxicities of
the title compounds IVa–r were evaluated. The results of bioassays show
that most of these title compounds possess a combination of good stomach
toxicities as well as contact toxicities. The title compound IVe stand out as
the best, which exhibits not only a higher insecticidal activity against Aphis
craccivora than the thiacloprid but also a comparable insecticidal activity to
imidacloprid.
EXPERIMENTAL
Melting points were recorded on an X-4 binocular microscope melting
point apparatus (Beijing Tech Instruments Co., Beijing, China) and were
corrected. Elemental analyses were performed with a Elementer Vario EL
III elemental analyzer. 1H NMR spectra were recorded on a Bruker DRX500
TABLE 7 Stomach toxicities of compounds IVe, imidacloprid, and thiacloprid against Aphis craccivora
(pea aphids)
Compd.
y = a + bx
LC50 (mg/L)
Toxic ratio
IVe
Imidacloprid
Thiacloprid
y = 4.3914 + 2.2080x
y = 5.3248 + 1.1097x
y = 4.4693 + 1.7103x
1.88
0.50
2.04
1.09
4.08
1.00

1,3,4-Thiadiazole 5-Fluorouracil Acetamides Derivatives
287
spectrometer with DMSO-d6 as solvent and TMS as internal standard. Chem-
ical shifts were reported in ppm (δ) values. Infrared (IR) spectra in KBr were
recorded on a Perkin-Elmer PE-683 infrared spectrometer. Reactions were
monitored by thin layer chromatography (TLC) with visualization by ultra-
violet light. Unless otherwise noted, all reagents and solvents were used as
received. Yields were not optimized.
General Synthetic Procedure for 5-Aryl-1,3,4-thiadiazol-2-amine II
To a mixture of compound I (0.1 mol) and thiosemicarbazide (0.1 mol)
was added POCl3 (0.3 mol) dropwise at 0–5◦C and maintained for 30 min-
utes. The reaction mixture was allowed to raise temperature until it was
refluxed and stirred for 4 hours. After cooling to room temperature, 50
mL water was added to the reaction mixture. The pH of the reaction so-
lution was adjusted to the range of 8 to 9 with a solution of 50% NaOH.
The crude product was precipitated, filtered, washed with water, dried, and
recrystallized from ethanol to afford compound II.
Synthetic Procedure for 5-Fluorouracil-1-yl Acetic Acid III
To a stirred solution of potassiumhydroxide (0.7 g, 0.012 mol) in water
(5 mL) was added 5-fluorouracil (1.3 g, 0.01 mol) and then heated at 60◦C
for 30 minutes. After that, the solution of chloroacetic acid (0.85 g, 0.009
mol) in water (2 mL) was added dropwise. The reaction mixture was then
allowed to raise temperature to 90◦C and stirred for 5 hours. The pH of the
reaction solution was maintained at the range of 9 to 10 with a solution of
50% KOH. After it was cooled to room temperature, the pH of the reaction
solution was adjusted to 2 with concentrated hydrochloric acid. The crude
product was then precipitated, filtered, washed with water, recrystallized
from ethanol, and dried to afford compound III as a white solid (1.50 g,
◦
1
81%); m.p. 275–277 C. H NMR: δ 4.37 (s, 2H, CH2CO); 8.08 (d, J =
11.0 Hz, 1H, FC CH), 11.88 (s, 1H, (CO)2NH), 13.18 (s, 1H, COOH).
Anal. calcd. (%) for C6H5FN2O4: C, 38.31; H, 2.68; F, 10.10; N, 14.89; O,
34.02. Found (%): C, 38.27; H, 2.63; F, 10.06; N, 14.82; O, 33.95.
General Synthetic Procedure for the Title Compounds IVa-r
To a stirred solution of compound II (0.01 mol) in DMF (15 ml) was
added compound III (0.0105 mol), HOBT (0.012 mol), and EDC (0.012
mol). The resulting mixture was further stirred at room temperature for 24
hours. After completion of the reaction, the mixed solution was poured into
water to precipitate. The precipitate was filtered, washed successively with
alkali, acid, water, dried, and recrystallized from ethanol to afford the title
compounds IVa-r.

288
R. Wan et al.
IVa: m.p. 221–223◦C; 1H NMR (DMSO-d6) δ(ppm): 3.93 (s, 3H, OCH3),
4.03 (s, 2H, CH2CO), 7.24–7.73 (m, 4H, Ar-H), 8.28 (d, J = 10.5 Hz, 1H,
FC CH), 12.23 (s, 1H, CONH); IR (cm−1): 3305 (νN-H); 3080 (νAr C-H);
2956, 2865 (νCH3 C-H, νCH2 C-H); 1721, 1697, 1665 (νC O); 1597 (νC N);
1581 (νC C); 1290 (νC-N); 1253 (νC-F); 1014 (νC-O); 659 (νC-S); Anal. calcd.
(%) for C15H12FN5O4S: C, 47.74; H, 3.21; N, 18.56; S, 8.50. Found (%): C,
48.80; H, 3.02; N, 18.90; S, 8.31.
IVb: m.p. 219–220◦C; 1H NMR (DMSO-d6) δ(ppm): 4.73 (s, 2H,
CH2CO), 7.52–8.13 (m, 3H, Ar-H), 8.18 (d, J = 14.1 Hz, 1H, FC CH),
12.00 (s, 1H, CONH), 13.19 (s, 1H, (CO)2NH); IR (cm−1): 3213 (νN-H);
3019 (νAr C-H); 2962 (νCH2 C-H); 1720, 1693, 1662 (νC O); 1640 (νC N);
1585 (νC C); 1315 (νC-N); 1273 (νC-F); 1250 (νC-Cl); 673 (νC-S); Anal. calcd.
(%) for C14H8Cl2FN5O3S: C, 40.40; H, 1.94; N, 16.83; S, 7.70. Found (%):
C, 40.32; H, 1.99; N, 16.91; S, 7.94.
IVc: m.p. 237–239◦C; 1H NMR (DMSO-d6) δ(ppm): 2.34 (s, 6H, 2CH3),
4.67 (s, 2H, CH2CO), 7.16–7.54 (m, 4H, Ar-H), 8.09 (d, J = 11.0 Hz, 1H,
FC CH), 11.98 (s, 1H, CONH), 13.03 (s, 1H, (CO)2NH); IR (cm−1): 3200
(νN-H); 3036 (νAr C-H); 2946, 2839 (νCH3 C-H,νCH2 C-H); 1727, 1694, 1666
(νC O); 1584 (νC N); 1561 (νC C); 1315 (νC-N); 1247 (νC-F); 691 (νC-S);
Anal. calcd. (%) for C16H14FN5O3S: C, 51.19; H, 3.76; N, 18.66; S, 8.54.
Found (%): C, 51.02; H, 3.87; N, 18.60; S, 8.32.
IVd: m.p. 213–215◦C; 1H NMR (DMSO-d6) δ(ppm): 4.71 (s, 2H,
CH2CO), 8.24 (m, 4H, Ar-H), 8.36 (d, J = 13.7 Hz, 1H, FC CH), 11.97
(s, 1H, CONH), 13.24 (s, 1H, (CO)2NH); IR (cm−1): 3253 (νN-H); 3089
(νAr C-H); 2975 (νCH2 C-H); 1728, 1697, 1673 (νC O); 1581 (νC N); 1560
(νN = O); 1517 (νC C); 1340 (νC-N); 1245 (νC-F); 692 (νC-S); Anal. calcd. (%)
for C14H9FN6O5S: C, 42.80; H, 2.31; N, 21.42; S, 8.17. Found (%): C, 42.80;
H, 2.34; N, 21.53; S, 8.43.
IVe: m.p. 211–212◦C; 1H NMR (DMSO-d6) δ(ppm): 4.71 (s, 2H, CH2CO),
7.56–8.07 (m, 3H, Ar-H), 8.11 (d, J = 11.5 Hz, 1H, FC CH), 11.99 (s, 1H,
CONH), 13.13 (s, 1H, (CO)2NH); IR (cm−1): 3178 (νN-H); 3024 (νAr C-H);
2842 (νCH2 C-H); 1732, 1697, 1662 (νC O); 1620 (νC N); 1576 (νC C); 1318
(νC-N); 1249 (νC-F); 659 (νC-S); Anal. calcd. (%) for C14H8F3N5O3S: C, 43.87;
H, 2.10; N, 18.27; S, 8.37. Found (%): C, 43.94; H, 2.23; N, 18.29; S, 8.54.
In order to further confirm the structure, 13C NMR, HSQC, and HMBC
of compound IVe were recorded as a representative. 13C NMR (300 MHz,
DMSO-d6) δ(ppm): 49.91, 115.90, 118.64, 124.34, 127.50, 130.57, 140.90,
149.78, 151.42, 152.45, 153.14, 157.50, 160.13, 166.51. HSQC (δH to δC)
δ(ppm): 4.71–49.91, 7.64–118.64, 7.80–124.34, 8.04–115.90, 8.11–130.57.
HMBC (δH to δC) δ(ppm): 4.71–130.57, 149.78, 166.51; 7.64–127.50, 151.42;
7.80–115.90, 152.45, 160.13; 8.04–124.34, 151.42, 160.13; 8.11–49.91, 140.90,
157.50.
IVf: m.p. 246–248◦C; 1H NMR (DMSO-d6) δ(ppm): 0.85 (t, J = 7.5 Hz,
3H, CH3), 1.29–1.58 (m, 6H, 3CH2), 2.55 (t, J = 10.6 Hz, 2H, CH2), 4.67 (s,

1,3,4-Thiadiazole 5-Fluorouracil Acetamides Derivatives
289
2H, CH2CO), 7.33–7.84 (m, 4H, Ar-H), 8.09 (d, J = 11.0 Hz, 1H, FC CH),
11.98 (s, 1H, CONH), 13.02 (s, 1H, (CO)2NH); IR (cm−1): 3195 (νN-H); 3029
(νAr C-H); 2927, 2842 (νCH3 C-H,νCH2 C-H); 1731, 1699, 1662 (νC O); 1582
(νC N); 1550(νC C); 1351 (νC-N); 1227 (νC-F); 685 (νC-S); Anal. calcd. (%)
for C19H20FN5O3S: C, 54.67; H, 4.83; N, 16.78; S, 7.72. Found (%): C, 54.78;
H, 4.80; N, 16.66; S, 7.84.
IVg: m.p. 218–219◦C; 1H NMR (DMSO-d6) δ(ppm): 4.68 (s, 2H,
CH2CO), 7.41–7.70 (m, 3H, Ar-H), 8.09 (d, J = 11.0 Hz, 1H, FC CH),
12.00 (s, 1H, CONH), 13.19 (s, 1H, (CO)2NH); IR (cm−1): 3250(νN-H);
3050 (νAr C-H); 2980 (νCH2 C-H); 1716, 1698, 1661 (νC O); 1660 (νC N);
1558 (νC C); 1321 (νC-N); 1200 (νC-F); 675 (νC-S); Anal. calcd. (%) for
C14H8F3N5O3S: C, 43.87; H, 2.10; N, 18.27; S, 8.37. Found (%): C, 43.98; H,
2.20; N, 18.39; S, 8.12.
IVh: m.p. 220–222◦C; 1H NMR (DMSO-d6) δ(ppm): 4.69 (s, 2H,
CH2CO), 7. 65–8.10 (m, 3H, Ar-H), 8.38 (d, J = 3.0 Hz, 1H, FC CH),
11.99 (s, 1H, CONH), 13.25 (s, 1H, (CO)2NH); IR (cm−1): 3255 (νN-H);
3095 (νAr C-H); 2950 (νCH2 C-H); 1704, 1683, 1653 (νC O); 1617 (νC N);
1564 (νN O); 1526 (νC C); 1348 (νC-N); 1292 (νC-F); 1090 (νC-Br); 668 (νC-S);
Anal. calcd. (%) for C14H8BrFN6O5S: C, 35.86; H, 1.71; N, 17.83; S, 6.08.
Found (%): C, 35.80; H, 1.65; N, 17.77; S, 6.32.
IVi: m.p. 229–230◦C; 1H NMR (DMSO-d6) δ(ppm): 3.84 (s, 6H, 2OCH3),
4.66 (s, 2H, CH2CO), 7.06–7.50 (m, 3H, Ar-H), 8.09 (d, J = 11.5 Hz, 1H,
FC CH), 11.98 (s, 1H, CONH), 13.00 (s, 1H, (CO)2NH); IR (cm−1): 3198
(νN-H); 3055 (νAr C-H); 2950, 2841 (νCH3 C-H,νCH2 C-H); 1717, 1690, 1653
(νC O); 1584 (νC N); 1526 (νC C); 1273 (νC-N); 1247 (νC-F); 1022 (νC-O);
662 (νC-S); Anal. calcd. (%) for C16H14FN5O5S: C, 47.17; H, 3.46; N, 17.19;
S, 7.87. Found (%): C, 47.09; H, 3.38; N, 17.07; S, 7.95.
IVj: m.p. 215–216◦C; 1H NMR (DMSO-d6) δ(ppm): 4.62 (s, 2H, CH2CO),
7.14–7.58 (m, 3H, Ar-H), 8.01 (d, J = 11.5 Hz, 1H, FC CH), 11.92 (s, 1H,
CONH), 13.15 (s, 1H, (CO)2NH); IR (cm−1): 3182 (νN-H); 3031 (νAr C-H);
2850 (νCH2 C-H); 1720, 1708, 1653 (νC O); 1569 (νC N); 1554 (νC C); 1319
(νC-N); 1242 (νC-F); 694 (νC-S); Anal. calcd. (%) for C14H8F3N5O3S: C, 43.87;
H, 2.10; N, 18.27; S, 8.37. Found (%): C, 43.84; H, 2.03; N, 18.11; S, 8.45.
1
IVk: m.p. 230–232◦C; H NMR (DMSO-d6) δ(ppm): 2.37 (s, 3H, CH3),
4.68 (s, 2H, CH2CO), 7.32–7.82 (m, 4H, Ar-H), 8.05 (d, J = 10.5 Hz, 1H,
FC CH), 11.82 (s, 1H, CONH), 12.89 (s, 1H, (CO)2NH); IR (cm−1): 3190
(νN-H); 3068 (νAr C-H); 2910, 2805 (νCH3 C-H,νCH2 C-H); 1716, 1696, 1635
(νC O); 1589 (νC N); 1550 (νC C); 1311 (νC-N); 1244 (νC-F); 657 (νC-S);
Anal. calcd. (%) for C15H12FN5O3S: C, 49.86; H, 3.35; N, 19.38; S, 8.87.
Found (%): C, 49.98; H, 3.50; N, 19.00; S, 8.35.
1
IVl: m.p. 235–237◦C; H NMR (DMSO-d6) δ(ppm): 2.37 (s, 3H, CH3),
4.68 (s, 2H, CH2CO), 7.32–7.82 (m, 4H, Ar-H), 8.05 (d, J = 10.5 Hz, 1H,
FC CH), 11.82 (s, 1H, CONH), 12.89 (s, 1H, (CO)2NH); IR (cm−1): 3300
(νN-H); 3060 (νAr C-H); 2946, 2837 (νCH3 C-H,νCH2 C-H); 1716, 1687, 1652

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(νC O); 1578 (νC N); 1510 (νC C); 1307 (νC-N); 1249 (νC-F); 1126 (νC-O);
693 (νC-S); Anal. calcd. (%) for C17H16FN5O6S: C, 46.68; H, 3.69; N, 16.01;
S, 7.33. Found (%): C, 46.70; H, 3.73; N, 16.00; S, 7.56.
IVm: m.p. 246–248◦C; 1H NMR (DMSO-d6) δ(ppm): 4.67 (s, 2H,
CH2CO), 7.13–7.95 (m, 9H, Ar-H), 8.08 (d, J = 11.5 Hz, 1H, FC CH),
11.98 (s, 1H, CONH), 13.08 (s, 1H, (CO)2NH); IR (cm−1): 3164 (νN-H);
3090 (νAr C-H); 2850 (νCH2 C-H); 1734, 1697, 1662 (νC O); 1590 (νC N);
1561 (νC C); 1313 (νC-N); 1247 (νC-F); 1080 (νC-O); 684 (νC-S); Anal. calcd.
(%) for C20H14FN5O4S: C, 54.67; H, 3.21; N, 15.94; S, 7.30. Found (%): C,
54.78; H, 3.34; N, 16.12; S, 7.86.
IVn: m.p. 261–263◦C; 1H NMR (DMSO-d6) δ(ppm): 0.83 (t, J = 7.5 Hz,
3H, CH3), 1.19–1.22 (m, 20H, 10CH2), 2.56 (t, J = 10.3 Hz, 2H, CH2),
4.67 (s, 2H, CH2CO), 7.32–7.84 (m, 4H, Ar-H), 8.09 (d, J = 11.0 Hz, 1H,
FC CH), 11.98 (s, 1H, CONH), 12.98 (s, 1H, (CO)2NH); IR (cm−1): 3200
(νN-H); 3030 (νAr C-H); 2930, 2860 (νCH3 C-H,νCH2 C-H); 1734, 1691, 1662
(νC O); 1586 (νC N); 1540(νC C); 1344 (νC-N); 1226 (νC-F); 690 (νC-S); Anal.
calcd. (%) for C26H34FN5O3S: C, 60.56; H, 6.65; N, 13.58; S, 6.22. Found
(%): C, 60.60; H, 6.72; N, 13.28; S, 6.55.
IVo: m.p. 252–254◦C; 1H NMR (DMSO-d6) δ(ppm): 0.83 (t, J = 7.1 Hz,
3H, CH3), 1.23–1.59 (m, 12H, 6CH2), 2.58 (t, J = 10.7 Hz, 2H, CH2), 4.67 (s,
2H, CH2CO), 7.32–7.83 (m, 4H, Ar-H), 8.09 (d, J = 10.0 Hz, 1H, FC CH),
11.97 (s, 1H, CONH), 13.02 (s, 1H, (CO)2NH); IR (cm−1): 3195 (νN-H);
3045 (νAr C-H); 2923, 2862 (νCH3 C-H,νCH2 C-H); 1735, 1687, 1660(νC O);
1580 (νC N); 1556(νC C); 1360 (νC-N); 1225 (νC-F); 693 (νC-S); Anal. calcd.
(%) for C22H26FN5O3S: C, 57.50; H, 5.70; N, 15.24; S, 6.98. Found (%): C,
57.56; H, 5.80; N, 15.33; S, 6.78.
IVp: m.p. 226–228◦C; 1H NMR (DMSO-d6) δ(ppm): 4.69 (s, 2H,
CH2CO), 7.41–7.54 (m, 5H, Ar-H), 7.78 (d, J = 12.5 Hz, 1H, FC CH),
13.22 (s, 1H, (CO)2NH); IR (cm−1): 3198 (νN-H); 3083 (νAr C-H); 2860 (νCH2
C-H); 1724, 1670, 1631 (νC O); 1570 (νC N); 1543 (νC C); 1312 (νC-N); 1242
(νC-F); 692 (νC-S); Anal. calcd. (%) for C14H10FN5O3S: C, 48.41; H, 2.90; N,
20.16; S, 9.23. Found (%): C, 48.45; H, 2.87; N, 20.13; S, 9.11.
IVq: m.p. 249–251◦C; 1H NMR (DMSO-d6) δ(ppm): 4.69 (s, 2H,
CH2CO), 7.55–7.59 (m, 1H, Ar-H), 8.10 (d, J = 11.5 Hz, 1H, FC CH),
8.31–9.12 (m, 3H, Ar-H), 11.99 (s, 1H, CONH), 13.17 (s, 1H, (CO)2NH);
IR (cm−1): 3225 (νN-H); 3012 (νAr C-H); 2986 (νCH2 C-H); 1733, 1700, 1657
(νC O); 1593 (νC N); 1550 (νC C); 1316 (νC-N); 1251 (νC-F); 702 (νC-S); Anal.
calcd. (%) for C13H9FN6O3S: C, 44.83; H, 2.60; N, 24.13; S, 9.21. Found (%):
C, 44.80; H, 2.60; N, 24.11; S, 9.46.
IVr: m.p. 245–247◦C; 1H NMR (DMSO-d6) δ(ppm): 4.70 (s, 2H, CH2CO),
7.89–7.92 (m, 2H, Ar-H), 8.09 (d, J = 11.5 Hz, 1H, FC CH), 8.72–8.74
(m, 2H, Ar-H), 11.99 (s, 1H, CONH), 13.26 (s, 1H, (CO)2NH); IR (cm−1):
3260 (νN-H); 3072 (νAr C-H); 2980 (νCH2 C-H); 1731, 1698, 1663 (νC ); 1589
(νC N); 1562 (νC C); 1305 (νC-N); 1250 (νC-F); 704 (νC-S); Anal. calcd. (%)

1,3,4-Thiadiazole 5-Fluorouracil Acetamides Derivatives
291
for C13H9FN6O3S: C, 44.83; H, 2.60; N, 24.13; S, 9.21. Found (%): C, 44.89;
H, 2.55; N, 24.09; S, 9.46.
Biological Assay
All bioassays were performed on representative test organisms reared in
the laboratory. The bioassay was repeated at 25 1◦C, according to statisti-
cal requirements. All compounds were dissolved in acetone and diluted with
water containing Tween80 (500 mg L−1) to obtain a series of concentrations
of 400.0, 100.0, 4.0 mg L−1, and others for bioassays. Assessments were made
on a dead/alive basis and the data were subjected to probit analysis. Evalua-
tions were based on a percentage scale of 0 to 100 in which 0 = no activity
and 100 = total kill.
Contact Toxicity Against Tetranychus cinnabarinus (Spider Mite)
The horsebean plant leaves with adult mites were dipped in diluted so-
lutions of the chemicals containing Tween80 (500 mg L−1) for 10 seconds.
After that, the leaves were transferred to penicillin vials within clean water for
cultivation. Water containing Tween80 (500 mg L−1) was used for contrast.
The number of live and dead insects were counted after 72 hours. Each treat-
ment was performed three times. For comparative purposes, avermectins was
tested under the same condition. The results were listed in Table 2.
Contact Toxicity Against Aphis Craccivora (Pea Aphids)
The horsebean seedlings with insects (third instar Aphis craccivora) were
dipped in diluted solutions of the chemicals containing Tween80 (500 mg
L−1) for 10 seconds. After that, the seedlings were transferred to penicillin
vials within clean water for cultivation. Water containing Tween80 (500 mg
L−1) was used for contrast. Mortality was assessed after 72 hours. Each treat-
ment was performed three times. For comparative purposes, imidacloprid
was tested under the same condition. The results of the contact toxicities
of the title compounds IVa–r and imidacloprid against Aphis craccivora (pea
aphids) were listed in Table 4 and Table 5. The data for the mortality-
regression lines of the compounds were subjected to probit analysis. The
LC50 values of the title compounds IVe, IVg, IVm, imidacloprid, and thiaclo-
prid against Aphis craccivora are listed in Table 6.
Stomach Toxicity Against Aphis craccivora (Pea Aphids)
The horsebean seedlings with insects (third instar Aphis craccivora)
were dipped in diluted solutions with different concentrations of the title
compounds IVa–r for cultivation. Mortality was calculated 72 hours after

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treatment, and LC50 values were established. The data for the mortality-
regression lines of the compounds were subjected to probit analysis. Each
treatment was performed three times. Water containing Tween80 (500 mg
L−1) served as a contrast, and imidacloprid and thiacloprid were used as pos-
itive control samples. The LC50 values of the title compound IVe, thiacloprid,
and imidacloprid against Aphis craccivora are shown in Table 7.
REFERENCES
1. Luo, Y.P.; Yang, G.F. Discovery of a new insecticide lead by optimizing a target-diverse scaffold:
Tetrazolinone derivatives. Bioorg. Med. Chem. 2007, 15, 1716–1724.
2. Hiroshi, K.; Rokuro, S.; Isao, H.; Takuo, O. Herbicidal activity of 1,3,4-thiadiazole derivatives. J. Agric.
Food Chem. 1970, 18, 60–65.
3. Ward, J.S. N-(1,3,4-thiadiazol-2-yl)benzamides. US Pat. No. 4141984, 1979.
4. Schaefer, C.H.; Miura, T.; Wilder, W.H. Biological activities of two new substituted benzamides
against mosquitoes and nontarget organisms. J. Econ. Entomol. 1981, 74, 658–661.
5. Gabrieli, S. N-(1,3,4-thiadiazol-2-yl)benzamides, their preparation and insecticidal compositions con-
taining them. Israel Patent. IL 55355, 1982, 1–26.
6. Robertson, J.L. Toxicity of experimental molt inhibitors to western spruce budworm. J. Ga. Entomol.
Soc. 1982, 17, 413–416.
7. Liu, X.H.; Shi, Y.X.; Ma, Y.; Zhang, C.Y.; Dong, W.L.; Pan, L.; Wang, B.L.; Li, B.J.; Li,
Z.M. Synthesis, antifungal activities and 3D-QSAR study of N-(5-substituted-1,3,4-thiadiazol-2-
yl)cyclopropanecarboxamides. Eur. J. Med. Chem. 2009, 44, 2782–2786.
8. Silvia, S.; Chiara, B.; Olga, B.; Francesco, B.; Angelo, R.; Walter, F.; Barbara, R.; Annalisa, C.; Giuseppe,
F. New 1,3,4-thiadiazole derivatives endowed with analgesic and antiinflammatory activities. Bioorg.
Med. Chem. 2006, 14, 1698–1705.
9. Matysiak, J.; Opolski, A. Synthesis and antiproliferative activity of N-substituted 2-amino-5-(2,4-
dihydroxyphenyl)-1,3,4-thiadiazoles. Bioorg. Med. Chem. 2006, 14, 4483–4489.
10. Alireza, F.; Saeed, E.; Abdolreza, H.; Majid, R.; Kazem, S.; Mohammad, H.M.; Abbas, S. Synthesis and
antibacterial activity of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-
2-yl)piperazinyl quinolone derivatives. Bioorg. Med. Chem. Lett. 2005, 15, 4488–4492.
11. Sara, T.; Tahmineh, A.; Mohammad, R.F.; Hossein, J.; Abbas, S. Synthesis and antibacterial ac-
tivity of 1-[1,2,4-triazol-3-yl] and 1-[1,3,4-thiadiazol-2-yl]-3-methylthio-6,7-dihydrobenzo[c]thiophen-
4(5H)ones. Bioorg. Med. Chem. Lett. 2005, 15, 1023–1025.
12. Thomasco, L.M.; Gadwood, R.C.; Weaver, E.A.; Ochoada, J.M.; Ford, C.W.; Zurenko, G.E.; Hamel,
J.C.; Stapert, D.; Moerman, J.K.; Schaadt, R.D.; Yagi, B.H. The synthesis and antibacterial activity of
1,3,4-Thiadiazole phenyl oxazolidinone analogues. Bioorg. Med. Chem. Lett. 2003, 13, 4193–4196.
13. Longley, D.B.; Harkin, D.P.; Johnston, P.G. 5-Fluorouracil: Mechanisms of action and clinical strate-
gies. Nat. Rev. Cancer. 2003, 3, 330–338.
14. Cheng, C.Y.; Lin, Y.H.; Su, C.C. Anti-tumor activity of Sann-Joong-Kuey-Jian-Tang alone and in
combination with 5-fluorouracil in a human colon cancer colo 205 cell xenograft model. Mol. Med.
Rep. 2010, 3, 227–231.
15. Lee, S.C.; Chan, J.Y.; Pervaiz, S. Spontaneous and 5-fluorouracil-induced centrosome amplification
lowers the threshold to resveratrol-evoked apoptosis in colon cancer cells. Cancer. Lett. 2010, 288,
36–41.
16. Won, H.J.; Ha, T.K.; Sung, C.H.; Hur, S.J.; Baik, H.H.; Suh, S.I.; Ha, E.; Kim, Y. Differential effects of
5-fluorouracil on glucose transport and expressions of glucose transporter proteins in gastric cancer
cells. Anti-Cancer Drugs. 2010, 21, 270–276.
17. Zemanova, M.; Petruzelka, L.; Pazdro, A.; Kralova, D.; Smejkal, M.; Pazdrova, G.; Honova, H. Prospec-
tive non-randomized study of preoperative concurrent platinum plus 5-fluorouracil-based chemora-
diotherapy with or without paclitaxel in esophageal cancer patients: long-term follow-up. Dis. Esoph-
agus. 2010, 23, 160–167.