Synthesis and Fungicidal Activities of Novel 1,2,4-Triazole Thione Derivatives Containing 1,2,3-Triazole and Substituted Piperazine Moieties

Article abstract of DOI:10.1080/10426507.2015.1085040

A series of novel 1,2,4-triazole thione derivatives containing 1,2,3-triazole and substituted piperazine moieties were synthesized via the Mannich reaction of 1,2,3-triazole-containing 1,2,4-triazole thiol intermediates with various substituted piperazines and formaldehyde in high yields. The structures of 14 title compounds were confirmed by melting points, IR, ¹H NMR, ¹³C NMR, and elemental analysis. The bioassay results showed that some of the title compounds exhibit significant fungicidal activities against several plant fungi at 50 μg/mL, especially trifluoromethyl-containing triazole thione derivative 9g showed broad activities and could be made further structural optimization for novel fungicides innovation research.

Full text of DOI:10.1080/10426507.2015.1085040

Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: http://www.tandfonline.com/loi/gpss20
Synthesis and Fungicidal Activities of Novel 1,2,4-
Triazole Thione Derivatives Containing 1,2,3-
Triazole and Substituted Piperazine Moieties
Bao-Lei Wang, Yi-Zhou Zhan, Li-Yuan Zhang, Yan Zhang, Xiao Zhang & Zheng-
Ming Li
To cite this article: Bao-Lei Wang, Yi-Zhou Zhan, Li-Yuan Zhang, Yan Zhang, Xiao Zhang
& Zheng-Ming Li (2015): Synthesis and Fungicidal Activities of Novel 1,2,4-Triazole Thione
Derivatives Containing 1,2,3-Triazole and Substituted Piperazine Moieties, Phosphorus, Sulfur,
and Silicon and the Related Elements, DOI: 10.1080/10426507.2015.1085040
To link to this article: http://dx.doi.org/10.1080/10426507.2015.1085040
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Date: 07 November 2015, At: 22:54

ACCEPTED MANUSCRIPT
Synthesis and Fungicidal Activities of Novel 1,2,4-Triazole Thione Derivatives Containing
1,2,3-Triazole and Substituted Piperazine Moieties
Bao-Lei Wang*,
Zheng-Ming Li*
Yi-Zhou Zhan,
Li-Yuan Zhang,
Yan Zhang,
Xiao Zhang,
State-Key Laboratory of Elemento-Organic Chemistry, Collaborative Innovation Center of
Chemical Science and Engineering (Tianjin), Nankai University, Tianjin, China
Submitted to: Phosphorus, Sulfur, and Silicon and the Related Elements
Running head: Novel 1,2,4-Triazole Thione Derivatives
Address correspondence to Bao-Lei Wang and Zheng-Ming Li, State-Key Laboratory of
Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China
E-mails: wangbaolei@126.com, nkzml@vip.163.com
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Abstract A series of novel 1,2,4-triazole thione derivatives containing 1,2,3-triazole and
substituted piperazine moieties were synthesized via the Mannich reaction of
1,2,3-triazole-containing 1,2,4-triazole thiol intermediates with various substituted piperazines
and formaldehyde in high yields. The structures of 14 title compounds were confirmed by melting
points, IR, 1H NMR, 13C NMR and elemental analysis. The bioassay results showed that some of
the title compounds exhibit significant fungicidal activities against several plant fungi at 50
μg/mL, especially trifluoromethyl-containing triazole thione derivative 9g showed broad
activities and could be made further structural optimization for novel fungicides innovation
research.
Keywords: triazole, thione derivatives, piperazine, Mannich reaction, synthesis, fungicidal
activities
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INTRODUCTION
Sulfur- and nitrogen-containing organic compounds play very important roles in the research
areas of organic chemistry, medicinal chemistry, and pesticidal chemistry [1-7]. In recent times,
the chemistry of heterocyclic thione derivatives with substituted aminomethyl at α-carbon of
thiocarbonyl group, that is the sulfur-containing heterocyclic Mannich base, has attracted much
attention owing to their versatile pharmacological properties. Different heterocyclic Mannich
bases have been regarded as antifungal[8], antitumor[9], antimicrobial[10], anticancer[11] agents.
Furthermore, 1,2,3-triazoles possess various bioactivities, such as antibacterial[12], fungicidal[13]
,
and insect GABA receptors antagonists[14]. As a result, 1,2,3-triazole is often used as an
important pharmacophore to design novel bioactive molecules. In addition, piperazine is one of
important nitrogen-containing five-membered heterocycles. It has been found that N-substituted
piperazine compounds have a wide range of pharmaceutical activities[15,16], but only a few
reports about their herbicidal and insecticidal properties are available in the literature[17]
.
It is known that many reports have appeared in the literature for the synthesis and medicinal
activities of azole Mannich bases[10,11], however there is no research reported about the synthesis
and pesticidal activities of 1,2,4-trizole Mannich bases containing 1,2,3-triazole and piperazine
groups. In view of the above reasones mentioned and with our pursuit for the synthesis of novel
heterocyclic compounds with pesticidal potential in mind, in this paper series of novel
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1,2,4-triazole thione derivatives containing methyl/trifluoromethyl, 1,2,3-triazole and
substitutedbenzylpiperazine or arylpiperazine moieties were synthesized via Mannich reaction of
the intermediate Schiff bases based on our previous work[18]. The research ideas for this new
work were to replace the (substituted)benzylideneamino group on triazole ring of the lead
structure, (substituted)benzylpiperazine-containing 1,2,4-triazole Mannich bases[18], with
1,2,3-triazolylmethyleneamino group, introduce various substituted piperazine moieties ----
phenyl piperazine, (pyridin-2-yl)piperazine, and 4,6-disubstituted pyrimidyl piperazine in
addition to the substituted benzyl piperazine (involved in the lead structure) into the triazole ring,
maintain the trifluoromethyl group or change it to methyl group, and study the synthesis and the
pesticidal activities of the new triazole thione derivertives. Meanwhile, considering there are two
secondary amine structures (-NH-) in piperazine ring that can be both used for undergoing
Mannich reaction, a series of novel bis(1,2,4-triazole thione) derivatives containing
methyl/trifluoromethyl, 1,2,3-triazole and piperazine moieties were also successfully synthesized.
The fungicidal activities of these novel herterocyclic Mannich bases against six plant fungi were
also investigated.
( insert SCHEME 1 )
( insert SCHEME 2 )
( insert SCHEME 3 )
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RESULTS AND DISCUSSION
Synthesis
The intermediates and the title compounds were synthesized as shown in SCHEME 1,
SCHEME 2 and SCHEME 3. According to the method reported [19], the intermediate triazole
carbaldehyde 5 was successfully prepared by the oxidation of phenyl-D-glucosotriazole 4 at
room temperature using sodium periodate as an oxidant. In our experiment the crude product
could be recrystallized from light petroleum to give pure carbaldehyde 5. It was further
condensed with 4-amino-5-methyl/trifluoromethyl-4H-1,2,4-triazole-3-thiol 6 in ethanol with a
small amount acetic acid as catalyst at refluxing temperature to afford Schiff base 7. The triazole
thione derivatives 8 and 9 that containing different substituted piperazine moiety were
conveniently synthesized via Mannich reaction of Schiff base 7, formalin, and various
4-substituted piperazine intermediates. It was found that the yields for 8a-d and 9a-h were 58-67%
and 70-88% respectively. As the amine reactant of Mannich reaction, the arylpiperazines
(4-phenylpiperazine, 4-(pyridyl-2-yl)piperazine, 4-(4,6-disubstituted)piperazine) seemed have
higher reactivity than those of substituted benzylpiperazines. In a 2:1 molar ratio of triazole thiol
1 and anhydrous piperazine, novel bis(1,2,4-triazole thione) containing piperazine and
1,2,3-triazole moieties 10 was also conveniently prepared in about 90% yield using the same
procedure, because there are two secondary amine group (>NH) available in piperazine structure
that can both occur such Mannich reaction. It’s known that the intermediate Schiff base 7 can
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exist either as a thiol or the thione tautomeric forms or as an equilibrium mixture of both forms
owing to the thioamide structure (-NH-C(=S)). In some cases the mercapto group (-SH) took part
in nucleophilic reaction and the sulfoether products obtained[20,21]. The results in our experiment
indicate the thione isomer undertakes the Mannich reaction via the N-H at α-position of
thiocarbonyl (C=S), though Schiff bases 7a and 7b exist in thiol isomer themselves which was
proven by their –SH proton signals at very downfield δ 13.89 and 15.02, respectively in 1H NMR
spectra.
Spectroscopic Characterization
1
The title compounds were identified by melting point, IR, H NMR and 13C NMR spectra. The
measured elemental analyses were also consistent with the corresponding calculated ones. In 1H
NMR, the –N=CH- proton and the proton in 1,2,3-triazole ring appeared at δ 10.33-10.95 and δ
8.29-8.74 as a singlet, respectively. The resonance signals of CH2 protons neighboring to the
1,2,4-triazole ring were observed at δ 5.12-5.23 in Mannich bases 8, while at δ 5.17-5.29 in
Mannich bases 9 and δ 5.08-5.19 in Mannich bases 10 as a singlet. The chemical shift of these
CH2 proton in trifluoromethyl-containing compounds appeared at downfield position compared
with those in trimethyl-containing ones, e.g. 8c (δ 5.23) vs. 8a (δ 5.12); 9h (δ 5.29) vs. 9d (δ
5.17); 10b (δ 5.19) vs. 10a (δ 5.08), which could be owing to the strong deshielding effect of
trifluoromethyl group. The chemical shifts at δ 2.81-3.96 and δ 2.40-3.20 can be ascribed to
piperazine ring protons, which appeared as two multiplet or broad signals, respectively. However
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the signals of these piperazine protons were observed at δ ~ 2.88 as a singlet in compounds 10
because of the symmetric structure of bis (1,2,4-triazole thione). In the 13C NMR spectra of
compounds 8 and 9, the typical carbon resonance at δ 162.9–167.7 was indicative of a
thiocarbonyl group (C=S). The piperazine carbons appeared at δ 50.3–53.0 and δ 43.5–50.5 as
two singlets. The signals of C5 in 1,2,4-triazole ring and carbon adjacent to it were observed at δ
139.4-151.3 and δ 11.1 (CH3) as singlet respectively in 8a, 8b and 9a-9d, while at δ ~138.7 and δ
~116.8 (CF3) as quartet respectively in 8c, 8d and 9e-9h, which is due to the “F” splitting of the
latter. The chemical shifts of all carbons for compounds 8d and 9h were shown in SCHEME 4
corresponding to their structures.
In IR spectra, the characteristic stretching vibration ν(C=S) appeared at 1153-1167 cm-1. The
strong absorption peak at 1575-1600 cm-1 can be ascribed to the C=N stretching. In the spectra of
trifluoromethyl-containing compounds, it showed bands at 1316-1321 cm-1 and 1194-1207 cm-1
respectively for C-F stretching.
( insert SCHEME 4 )
Fungicidal Activities
As shown in Table S 1 (Supplemental Materials), most of the compounds synthesized showed
obvious fungicidal activities against six test fungi at 50 μg/mL. For Gibberella sanbinetti,
compounds 9e, 9f and 9g possessed an inhibitory rate 68.4%, 63.2% and 68.4%, respectively,
and were more effective than the control Triadimefon (52.9%). In particular, the activities of 9e
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and 9g were closed with that of the control Chlorothalonil. For Cercospora arachidicola,
compounds 9g and 9h whose inhibitory activity were 70.0% and 65.0%, were comparable with
Triadimefon (66.7%). Compounds 8c, 9d, 9g, 10a and 10b exhibited 65.1%-88.4% fungicidal
activities against Physalospora piricola, especially 9d (72.1%), 10a (72.1%) and 10b (88.4%)
were more effective than Triadimefon (71.4%). Some compounds also displayed good fungicidal
activities against Alternaria solani Sorauer and Fusarium omysporum at 50 μg/mL. It was
worthy to note that most of compounds showed favorable fungicidal activities against
Rhizoctonia cerealis, such as 8c, 9e, 9f and 9g had inhibitory rate 85.7%-89.8%. Although these
compounds were less effective than the control Triadimefon, their structural information could
still be useful for further optimization to find novel fungicides against Rhizoctonia cerealis.
In analyzing the structure-activity relationship (SAR) of these compounds, it was found that
trifluoromethyl-containing triazole thione derivatives showed favorable fungicidal activities in
most cases, which may be due to the excellent properties (such as hydrophobicity and
permeability) of the trifluoromethyl group introduced into the parent structure. The activity of
most compounds, when R4 was fixed as H, indicated the trend Ph > Py, and 4-methylpyrimidyl >
4,6-dimethylpyrimidyl in the aryl group of piperazine 4-position; when R4 was fixed as F,
indicated the trend benzyl > 2,4-dichlorobenzyl, Ph ≈ Py, and 4-methylpyrimidyl >
4,6-dimethylpyrimidyl in the group of piperazine 4-position.
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EXPERIMENTAL
The melting points were determined on a Taike X-4 apparatus and were uncorrected. Infrared
spectra were recorded on a Bruker Tensor 27 spectrophotometer as KBr tablets. 1H NMR and 13C
NMR spectra were measured on a Bruker AV-400 instrument (400MHz) using TMS as an
internal standard and DMSO-d6 or CDCl3 as solvent. Elemental analysis was performed on a
Vario EL CUBE element analyzer. Partial 4-substituted piperazine intermediates were purchased
from Aladin and Alfa Aesar reagent companies. Anhydrous piperazine and other materials were
purchased from Nanjing Duodian Reagent Co. Ltd. All solvents were dried by standard methods
1
in advance and distilled before use. The Supplemental Materials contains sample H and 13C
NMR spectra for 8c and 9d (Figures S 1 – S 4).
4-Amino-5-methyl/trifluoromethyl-4H-1,2,4-triazole-3-thiol 6a and 6b were prepared
according to the literature[22]
.
Synthesis of the Intermediates 4-(Substituted)benzylpiperazine 1
Referring to the literature [23] method, to a solution of anhydrous piperazine (50 mmol) in 95%
ethanol (20 mL) was added 36% hydrochloric acid (25 mmol). The mixture was stirred under
refluxing and substituted benzyl chlorine (25 mmol) added dropwise over 5 min. The mixture
was refluxed for 4–8 h with TLC monitoring, then left standing overnight at room temperature.
The solid precipitated was filtered and washed with ethanol, the filtrate was evaporated in
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vacuum and the residue was dissolved in saturated K2CO3 aq. (30 mL), extracted with
chloroform (5 × 8 mL). The chloroform solution was dried with anhydrous Na2SO4 and
evaporated in vacuum. The residue was then distilled under reduced pressure to give compound
1 as a colorless liquid.
1a: yield 58%, bp 131-134 oC/10mmHg; 1b: yield 36%, bp 147-150 oC/6 mmHg.
Synthesis of the Intermediates 4-(4,6-Disubstituted-pyrimidin-2-yl)piperazine 3
By reacting the diazonium salts of 4,6-disubstituted pyrimidin-2-amines with concentrated
HCl and ZnCl2[24], 2-chloro-4,6-disubstituted pyrimidines 2 were prepared. Referring to the
literature[23], compounds 3 were prepared and the method was improved. To a stirred solution of
piperazine (45 mmol) and K2CO3 (16.5 mmol) in water (20 mL), was added chloropyrimidine 2
(18 mmol) in small portions at 50–60 °C. The mixture was stirred for 1 h at 60-65 oC and cooled
to room temperature. The yellow solid, 1,4-bis(4,6-disubstituted pyrimidin-2-yl)piperazine, was
filtered off, and the filtrate was then extracted three times with chloroform, dried over Na2SO4,
evaporated in vacuum to give 3, which was used for the following reactions without further
purification.
3a: yellow solid, yield 81%, mp 45-48 oC; 3b: yellow solid, yield 79%, mp 82-84 oC.
Synthesis of the Intermediate 2-Phenyl-2H-1,2,3-triazole-4-carbaldehyde 5
To a solution of sodium periodate (9.63 g, 0.045 mol) in water (150 mL) was added
phenyl-D-glucosotriazole 4 (4.0 g, 0.015 mol) (prepared according the reported method[19]). The
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mixture was stirred at room temperature for 24 h and filtrated. The solid was washed with water,
dried and recrystallized with light petroleum (30~60oC) to give intermediate triazole
carbaldehyde 5 as light yellow crystals. Yield 68.2%, mp 66-67oC (Lit.[19] mp 68-69oC).
Synthesis of the Intermediates 4-(((2-Phenyl-2H-1,2,3-triazol-4-yl)methylene)amino)-
5-(methyl/trifluoromethyl)-4H-1,2,4-triazole-3-thiol 7
Compound 6a or 6b (10 mmol), triazole carbaldehyde 5 (10.5 mmol) and acetic acid (10 drop)
were mixed in absolute ethanol (25 mL). After having been stirred and refluxed for 4-5 h, the
reaction mixture was cooled to room temperature. The resulting solid were filtered and
recrystallized from ethanol to give Schiff base 7.
7a: colorless crystals, yield 79.4%, mp 257-259 oC; 1H NMR (400 MHz, DMSO), δ: 13.89 (s,
1H, SH), 10.59 (s, 1H, CH), 8.74 (s, 1H, Triazole-H), 8.10 (d, J = 8.2 Hz, 2H, Ph-H), 7.63 (t, J =
7.8 Hz, 2H, Ph-H), 7.51 (t, J = 7.3 Hz, 1H, Ph-H), 2.40 (s, 3H, CH3). Elemental anal. (%) calcd.
For C12H11N7S: C 50.51, H 3.89, N 34.36; found: C 50.14, H 4.25, N 34.03.
7b: yellow crystals, yield 72.3%, mp 210-212 oC; 1H NMR (400 MHz, DMSO), δ: 15.02 (s,
1H, SH), 10.43 (s, 1H, CH), 8.72 (s, 1H, Triazole-H), 8.11 (d, J = 8.1 Hz, 2H, Ph-H), 7.64 (t, J =
7.8 Hz, 2H, Ph-H), 7.53 (t, J = 7.3 Hz, 1H, Ph-H). Elemental anal. (%) calcd. for C12H8F3N7S: C
42.48, H 2.38, N 28.90; found: C 42.22, H 2.65, N 28.58.
Synthesis of 4-(((2-Phenyl-2H-1,2,3-triazol-4-yl)methylene)amino)-2-((4-(substitutedbenzyl)
piperazin-1-yl)methyl)-5-(methyl/trifluoromethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 8
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Schiff base 7 (1 mmmol), 37% formalin (1.5 mmol) were dissolved in ethanol (15 mL), and
the mixture was stirred at room temperature for
5
min.
A
solution of
4-(substituted)benzylpiperazine 1 (1 mmol) in ethanol (2 mL) was slowly added dropwise. Then
the reaction mixture was stirred for 2-3 h and placed at room temperature or in a refrigerator
overnight. The resulting precipitate was filtered and recrystallized from ethanol to give novel
1,2,4-triazole Mannich base 8.
2-((4-Benzylpiperazin-1-yl)methyl)-5-methyl-4-(((2-phenyl-2H-1,2,3-triazol-4-yl)methyle
ne)amino)-2,4-dihydro-3H-1,2,4-triazole-3-thione (8a): colorless crystals, yield 61.4%, mp
154-156 oC; 1H NMR (400 MHz, CDCl3), δ: 10.94 (s, 1H, CH=N), 8.29 (s, 1H, Triazole-H), 8.12
(d, J = 8.0 Hz, 2H, Ph-H), 7.52 (t, J = 7.8 Hz, 2H, Ph-H), 7.41 (t, J = 7.3 Hz, 1H, Ph-H), 7.33 –
7.20 (m, 5H, Ph-H), 5.12 (s, 2H, NCH2N), 3.50 (s, 2H, PhCH2), 2.87 (bs, 4H, Piperazine-H),
13
2.49 (bs, 4H, Piperazine-H), 2.46 (s, 3H, Triazole-CH3); C NMR (101 MHz, CDCl3), δ: 162.9
(s, 1C, C=S), 150.7 (s, 1C, 1,2,4-Triazole-C5), 147.7 (s, 1C, 1,2,3-Triazole-C4), 144.2 (s, 1C,
N=CH), 139.4 (s, 1C, Ph-C), 138.0 (s, 1C, Ph-C), 134.8 (s, 1C, 1,2,3-Triazole-C5), 129.5 (s, 2C,
Ph-C), 129.2 (s, 2C, Ph-C), 128.4 (s, 1C, Ph-C), 128.2 (s, 2C, Ph-C), 127.1 (s, 1C, Ph-C), 119.2
(s, 2C, Ph-C), 68.7 (s, 1C, CH2), 63.1 (s, 1C, CH2), 53.0 (s, 2C, Piperazine-C), 50.5 (s, 2C,
Piperazine-C), 11.1 (s, 1C, CH3); IR (KBr), ν (cm-1): 2932, 2813(C-H), 1595(C=N), 1494,
1455(Ar), 1167(C=S). Elemental anal. (%) calcd. for C24H27N9S: C 60.87, H 5.75, N 26.62;
found: C 60.58, H 5.91, N 26.29.
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2-((4-(2,4-Dichlorobenzyl)piperazin-1-yl)methyl)-5-methyl-4-(((2-phenyl-2H-1,2,3-triazol
-4-yl)methylene)amino)-2,4-dihydro-3H-1,2,4-triazole-3-thione (8b): white solid, yield 66.9%,
o
mp 109-110 C; 1H NMR (400 MHz, CDCl3), δ: 10.95 (s, 1H, CH=N), 8.30 (s, 1H, Triazole-H),
8.13 (d, J = 7.6 Hz, 2H, Ph-H), 7.53 (t, J = 7.9 Hz, 2H, Ph-H), 7.48 – 7.32 (m, 3H, Ph-H), 7.19
(dd, J = 8.3, 2.1 Hz, 1H, Ph-H), 5.13 (s, 2H, NCH2N), 3.56 (s, 2H, ArCH2), 2.87 (bs, 4H,
13
Piperazine-H), 2.54 (bs, 4H, Piperazine-H), 2.48 (s, 3H, CH3); C NMR (101 MHz, CDCl3), δ:
162.9 (s, 1C, C=S), 150.8 (s, 1C, 1,2,4-Triazole-C5), 147.8 (s, 1C, 1,2,3-Triazole-C4), 144.2 (s,
1C, N=CH), 139.4 (s, 1C, Ph-C), 134.8 (s, 1C, Ph-C), 134.7 (s, 1C, Ph-C), 134.6 (s, 1C, Ph-C),
133.1 (s, 1C, 1,2,3-Triazole-C5), 131.4 (s, 1C, Ph-C), 129.5 (s, 2C, Ph-C), 129.2 (s, 1C, Ph-C),
128.4 (s, 1C, Ph-C), 126.9 (s, 1C, Ph-C), 119.2 (s, 2C, Ph-C), 68.7 (s, 1C, CH2), 58.7 (s, 1C,
CH2), 53.0 (s, 2C, Piperazine-C), 50.5 (s, 2C, Piperazine-C), 11.1 (s, 1C, CH3); IR (KBr), ν
(cm-1): 2940, 2812(C-H), 1593(C=N), 1560, 1496, 1464(Ar), 1172(C=S). Elemental anal. (%)
calcd. for C24H25Cl2N9S: C 53.14, H 4.65, N 23.24; found: C 52.88, H 4.68, N 23.02.
2-((4-Benzylpiperazin-1-yl)methyl)-4-(((2-phenyl-2H-1,2,3-triazol-4-yl)methylene)amino)
-5-(trifluoromethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (8c): white solid, yield 58.2%,
o
mp 119-120 C; 1H NMR (400 MHz, CDCl3), δ: 10.83 (s, 1H, CH=N), 8.32 (s, 1H, Triazole-H),
8.15 – 8.10 (m, 2H, Ph-H), 7.55-7.50 (m, 2H, Ph-H), 7.42 (t, J = 7.4 Hz, 1H, Ph-H), 7.33 – 7.21
(m, 5H, Ph-H), 5.23 (s, 2H, NCH2N), 3.50 (s, 2H, PhCH2), 2.87 (bs, 4H, Piperazine-H), 2.48 (bs,
4H, Piperazine-H); 13C NMR (101 MHz, CDCl3), δ: 165.2 (s, 1C, C=S), 152.5 (s, 1C,
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1,2,3-Triazole-C4), 143.5 (s, 1C, N=CH), 139.4 (s, 1C, Ph-C), 138.7 (q, JC-F = 42.4 Hz, 1C,
1,2,4-Triazole-C5), 137.9 (s, 1C, Ph-C), 135.0 (s, 1C, 1,2,3-Triazole-C5), 129.5 (s, 2C, Ph-C),
129.2 (s, 2C, Ph-C), 128.5 (s, 1C, Ph-C), 128.3 (s, 2C, Ph-C), 127.1 (s, 1C, Ph-C), 119.3 (s, 2C,
Ph-C), 116.8 (q, JC-F = 272.7 Hz, 1C, CF3), 70.0 (s, 1C, CH2), 63.1 (s, 1C, CH2), 52.9 (s, 2C,
Piperazine-C), 50.4 (s, 2C, Piperazine-C); IR (KBr), ν (cm-1): 2955, 2809(C-H), 1598(C=N),
1497, 1456(Ar), 1319, 1200(C-F), 1167(C=S). Elemental anal. (%) calcd. for C24H24F3N9S: C
54.64, H 4.59, N 23.89; found: C 54.36, H 4.80, N 23.74.
2-((4-(2,4-Dichlorobenzyl)piperazin-1-yl)methyl)-4-(((2-phenyl-2H-1,2,3-triazol-4-yl)met
hylene)amino)-5-(trifluoromethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (8d): white solid,
yield 62.8%, mp 127-128 oC; 1H NMR (400 MHz, CDCl3), δ: 10.83 (s, 1H, CH=N), 8.33 (s, 1H,
Triazole-H), 8.12 (d, J = 7.7 Hz, 2H, Ph-H), 7.53 (t, J = 7.9 Hz, 2H, Ph-H), 7.46 – 7.33 (m, 3H,
Ph-H), 7.19 (dd, J = 8.3, 2.1 Hz, 1H, Ph-H), 5.22 (s, 2H, NCH2N), 3.56 (s, 2H, ArCH2), 2.88 (bs,
13
4H, Piperazine-H), 2.54 (bs, 4H, Piperazine-H); C NMR (101 MHz, CDCl3), δ: 165.2 (s, 1C,
C=S), 152.5 (s, 1C, 1,2,3-Triazole-C4), 143.5 (s, 1C, N=CH), 139.3 (s, 1C, Ph-C), 138.7 (q, JC-F
= 42.4 Hz, 1C, 1,2,4-Triazole-C5), 135.0 (s, 1C, Ph-C), 134.8 (s, 1C, Ph-C), 134.4 (s, 1C, Ph-C),
133.2 (s, 1C, 1,2,3-Triazole-C5), 131.4 (s, 1C, Ph-C), 129.5 (s, 2C, Ph-C), 129.2 (s, 1C, Ph-C),
128.5 (s, 1C, Ph-C), 127.0 (s, 1C, Ph-C), 119.2 (s, 2C, Ph-C), 116.8 (q, JC-F = 272.7 Hz, 1C, CF3),
70.0 (s, 1C, CH2), 58.6 (s, 1C, CH2), 52.9 (s, 2C, Piperazine-C), 50.4 (s, 2C, Piperazine-C); IR
(KBr), ν (cm-1): 2950, 2816(C-H), 1597(C=N), 1498, 1462(Ar), 1320, 1201(C-F), 1170(C=S).
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Elemental anal. (%) calcd. for C24H22Cl2F3N9S: C 48.33, H 3.72, N 21.14; found: C 48.21, H
3.79, N 20.78.
Synthesis of 4-(((2-Phenyl-2H-1,2,3-triazol-4-yl)methylene)amino)-2-((4-arylpiperazin-1-yl)
methyl)-5-(methyl/trifluoromethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 9
It was similar with that of 8, using 4-phenylpiperazine 3c, or 4-(pyridin-2-yl)piperazine 3d, or
4-(4,6-disubstituted-pyrimidin-2-yl)piperazine 3(a-b) as amine material to give corresponding
novel Mannich base 9.
5-Methyl-4-(((2-phenyl-2H-1,2,3-triazol-4-yl)methylene)amino)-2-((4-phenylpiperazin-1-
yl)methyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (9a): white solid, yield 70.4%, mp 151-153
1
oC; H NMR (400 MHz, CDCl3), δ: 10.95 (s, 1H, CH=N), 8.30 (s, 1H, Triazole-H), 8.17 – 8.09
(m, 2H, Ph-H), 7.53 (dd, J = 10.7, 5.1 Hz, 2H, Ph-H), 7.42 (t, J = 7.4 Hz, 1H, Ph-H), 7.29 – 7.22
(m, 2H, Ph-H), 6.92 (d, J = 7.9 Hz, 2H, Ph-H), 6.86 (t, J = 7.3 Hz, 1H, Ph-H), 5.19 (s, 2H,
NCH2N), 3.26 – 3.15 (m, 4H, Piperazine-H), 3.05 – 2.95 (m, 4H, Piperazine-H), 2.48 (s, 3H,
CH3); 13C NMR (101 MHz, CDCl3), δ: 163.0 (s, 1C, C=S), 151.3 (s, 1C, 1,2,4-Triazole-C5),
150.9 (s, 1C, Ph-C), 147.9 (s, 1C, 1,2,3-Triazole-C4), 144.2 (s, 1C, N=CH), 139.4 (s, 1C,
1,2,3-Triazole-C5), 134.8 (s, 1C, Ph-C), 129.5 (s, 2C, Ph-C), 129.1 (s, 2C, Ph-C), 128.4 (s, 1C,
Ph-C), 119.9 (s, 1C, Ph-C), 119.2 (s, 2C, Ph-C), 116.4 (s, 2C, Ph-C), 68.6 (s, 1C, CH2), 50.5 (s,
2C, Piperazine-C), 49.4 (s, 2C, Piperazine-C), 11.1 (s, 1C, CH3); IR (KBr), ν (cm-1): 2945,
2830(C-H), 1598(C=N), 1497, 1453(Ar), 1159(C=S). Elemental anal. (%) calcd. for C23H25N9S:
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C 60.11, H 5.48, N 27.43; found: C 59.78, H 5.57, N 27.18.
5-Methyl-4-(((2-phenyl-2H-1,2,3-triazol-4-yl)methylene)amino)-2-((4-(pyridin-2-yl)piper
azin-1-yl)methyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (9b): colorless crystals, yield 73.8%,
mp 155-156 oC; 1H NMR (400 MHz, CDCl3), δ: 10.94 (s, 1H, CH=N), 8.29 (s, 1H, Triazole-H),
8.19 – 8.03 (m, 3H, Pyridine-H + Ph-H), 7.59 – 7.35 (m, 4H, Pyridine-H + Ph-H), 6.76 – 6.45 (m,
2H, Pyridine-H), 5.18 (s, 2H, NCH2N), 3.64 – 3.49 (m, 4H, Piperazine-H), 3.00 – 2.88 (m, 4H,
Piperazine-H), 2.47 (s, 3H, CH3); 13C NMR (101 MHz, CDCl3), δ: 163.0 (s, 1C, C=S), 159.3 (s,
1C, Py-C), 150.8 (s, 1C, 1,2,4-Triazole-C5), 148.0 (s, 1C, Py-C), 147.9 (s, 1C, 1,2,3-Triazole-C4),
144.1 (s, 1C, N=CH), 139.4 (s, 1C, Ph-C), 137.5 (s, 1C, Py-C), 134.7 (s, 1C, 1,2,3-Triazole-C5),
129.5 (s, 2C, Ph-C), 128.4 (s, 1C, Ph-C), 119.2 (s, 2C, Ph-C), 113.3 (s, 1C, Py-C), 107.1 (s, 1C,
Py-C), 68.7 (s, 1C, CH2), 50.4 (s, 2C, Piperazine-C), 45.2 (s, 2C, Piperazine-C), 11.1 (s, 1C,
CH3); IR (KBr), ν (cm-1): 2949, 2831(C-H), 1594(C=N), 1566, 1483, 1440(Ar), 1161(C=S).
Elemental anal. (%) calcd. for C22H24N10S: C 57.37, H 5.25, N 30.41; found: C 59.29, H 5.36, N
30.09.
5-Methyl-2-((4-(4-methylpyrimidin-2-yl)piperazin-1-yl)methyl)-4-(((2-phenyl-2H-1,2,3-tr
iazol-4-yl)methylene)amino)-2,4-dihydro-3H-1,2,4-triazole-3-thione (9c): colorless crystals,
yield 78.5%, mp 179-180 oC; 1H NMR (400 MHz, CDCl3), δ: 10.94 (s, 1H, CH=N), 8.28 (s, 1H,
Triazole-H), 8.14-8.11 (m, 3H, Pyrimidine-H + Ph-H), 7.52 (t, J = 7.9 Hz, 2H, Ph-H), 7.41 (t, J =
7.4 Hz, 1H, Ph-H), 6.34 (d, J = 5.0 Hz, 1H, Pyrimidine-H), 5.17 (s, 2H, CH2), 3.94 – 3.77 (m, 4H,
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Piperazine-H), 2.94 – 2.82 (m, 4H, Piperazine-H), 2.45 (s, 3H, Triazole-H), 2.30 (s, 3H,
Pyrimidine-CH3); 13C NMR (101 MHz, CDCl3), δ: 167.6 (s, 1C, C=S), 162.9 (s, 1C,
Pyrimidine-C4), 161.5 (s, 1C, Pyrimidine-C2), 157.2 (s, 1C, Pyrimidine-C6), 150.7 (s, 1C,
1,2,3-Triazole-C4), 147.8 (s, 1C, N=CH), 144.2 (s, 1C, Ph-C), 139.4 (s, 1C, 1,2,4-Triazole-C5),
134.7 (s, 1C, 1,2,3-Triazole-C5), 129.4 (s, 2C, Ph-C), 128.4 (s, 1C, Ph-C), 119.2 (s, 2C, Ph-C),
109.4 (s, 1C, Pyrimidine-C5), 68.9 (s, 1C, CH2), 50.6 (s, 2C, Piperazine-C), 43.6 (s, 2C,
Piperazine-C), 24.3 (s, C, CH3), 11.1 (s, 1C, CH3); IR (KBr), ν (cm-1): 2936, 2830(C-H),
1580(C=N), 1558, 1496, 1443(Ar), 1166(C=S). Elemental anal. (%) calcd. for C22H25N11S: C
55.56, H 5.30, N 32.40; found: C 55.43, H 5.36, N 32.26.
2-((4-(4,6-Dimethylpyrimidin-2-yl)piperazin-1-yl)methyl)-5-methyl-4-(((2-phenyl-2H-1,2,
3-triazol-4-yl)methylene)amino)-2,4-dihydro-3H-1,2,4-triazole-3-thione (9d): white solid,
yield 83.3%, mp 178-179 oC; 1H NMR (400 MHz, CDCl3), δ: 10.94 (s, 1H, CH=N), 8.28 (s, 1H,
Triazole-H), 8.20 – 8.04 (m, 2H, Ph-H), 7.52 (dd, J = 10.7, 5.1 Hz, 2H, Ph-H), 7.41 (t, J = 7.4 Hz,
1H, Ph-H), 6.23 (s, 1H, Pyrimidine-H), 5.17 (s, 2H, NCH2N), 3.92 – 3.82 (m, 4H, Piperazine-H),
2.91 – 2.81 (m, 4H, Piperazine-H), 2.45 (s, 3H, Triazole-CH3), 2.26 (s, 6H, Pyrimidine-CH3); 13C
NMR (101 MHz, CDCl3), δ: 167.0 (s, 1C, C=S), 162.9 (s, 2C, Pyrimidine-C4,6), 161.6 (s, 1C,
Pyrimidine-C2), 150.7 (s, 1C, 1,2,3-Triazole-C4), 147.8 (s, 1C, N=CH), 144.2 (s, 1C, Ph-C),
139.4 (s, 1C, 1,2,4-Triazole-C5), 134.7 (s, 1C, 1,2,3-Triazole-C5), 129.5 (s, 2C, Ph-C), 128.4 (s,
1C, Ph-C), 119.2 (s, 2C, Ph-C), 108.9 (s, 1C, Pyrimidine-C5), 68.9 (s, 1C, CH2), 50.7 (s, 2C,
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Piperazine-C), 43.5 (s, 2C, Piperazine-C), 24.1 (s, 2C, CH3), 11.1 (s, 1C, CH3); IR (KBr), ν
(cm-1): 2935, 2822(C-H), 1575(C=N), 1497, 1444(Ar), 1167(C=S). Elemental anal. (%) calcd.
for C23H27N11S: C 56.42, H 5.56, N 31.47; found: C 56.34, H 5.56, N 31.36.
4-(((2-Phenyl-2H-1,2,3-triazol-4-yl)methylene)amino)-2-((4-phenylpiperazin-1-yl)methyl)
-5-(trifluoromethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (9e): white solid, yield 75.2%,
mp 160-162 oC; 1H NMR (400 MHz, DMSO), δ: 10.33 (s, 1H, CH=N), 8.74 (s, 1H, Triazole-H),
8.10 (d, J = 7.9 Hz, 2H, Ph-H), 7.63 (t, J = 7.8 Hz, 2H, Ph-H), 7.52 (t, J = 7.3 Hz, 1H, Ph-H),
7.19 (t, J = 7.8 Hz, 2H, Ph-H), 6.92 (d, J = 8.2 Hz, 2H, Ph-H), 6.77 (t, J = 7.2 Hz, 1H, Ph-H),
13
5.27 (s, 2H, NCH2N), 3.13 (bs, 4H, Piperazine-H), 2.92 (bs, 4H, Piperazine-H); C NMR (101
MHz, CDCl3), δ: 165.2 (s, 1C, C=S), 152.6 (s, 1C, Ph-C), 151.2 (s, 1C, 1,2,3-Triazole-C4), 143.5
(s, 1C, N=CH), 139.3 (s, 1C, Ph-C), 138.6 (q, JC-F = 42.4 Hz, 1C, 1,2,4-Triazole-C5), 135.1 (s,
1C, 1,2,3-Triazole-C5), 129.5 (s, 2C, Ph-C), 129.2 (s, 2C, Ph-C), 128.5 (s, 1C, Ph-C), 120.2 (s,
1C, Ph-C), 119.3 (s, 2C, Ph-C), 116.8 (q, JC-F = 272.7 Hz, 1C, CF3), 116.5 (s, 2C, Ph-C), 69.9 (s,
1C, CH2), 50.4 (s, 2C, Piperazine-C), 49.4 (s, 2C, Piperazine-C); IR (KBr), ν (cm-1): 2942,
2833(C-H), 1600(C=N), 1579, 1497, 1455(Ar), 1318, 1196 (C-F), 1165(C=S). Elemental anal.
(%) calcd. for C23H22F3N9S: C 53.79, H 4.32, N 24.55; found: C 53.65, H 4.38, N 24.23.
4-(((2-Phenyl-2H-1,2,3-triazol-4-yl)methylene)amino)-2-((4-(pyridin-2-yl)piperazin-1-yl)
methyl)-5-(trifluoromethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (9f): white solid, yield
o
1
80.6%, mp 134-136 C; H NMR (400 MHz, DMSO), δ: 10.33 (s, 1H, CH=N), 8.73 (s, 1H,
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Triazole-H), 8.11-8.08 (m, 3H, Pyridine-H + Ph-H), 7.63 (t, J = 7.8 Hz, 2H, Ph-H), 7.53-7.50 (m,
2H, Pyridine-H + Ph-H), 6.82 (d, J = 8.7 Hz, 1H, Pyridine-H), 6.61 (dd, J = 6.7, 5.1 Hz, 1H,
Pyridine-H), 5.26 (s, 2H, NCH2N), 3.51 (bs, 4H, Piperazine-H), 2.86 (bs, 4H, Piperazine-H); 13C
NMR (101 MHz, CDCl3), δ: 165.2 (s, 1C, C=S), 159.3 (s, 1C, Py-C), 152.5 (s, 1C, Py-C), 148.0
(s, 1C, 1,2,3-Triazole-C4), 143.5 (s, 1C, N=CH), 139.3 (s, 1C, Ph-C), 138.8 (q, JC-F = 42.4 Hz,
1C, 1,2,4-Triazole-C5), 137.5 (s, 1C, Py-C), 135.0 (s, 1C, 1,2,3-Triazole-C5), 129.5 (s, 2C, Ph-C),
128.5 (s, 1C, Ph-C), 119.2 (s, 2C, Ph-C), 116.8 (q, JC-F = 272.7 Hz, 1C, CF3), 113.5 (s, 1C, Py-C),
107.2 (s, 1C, Py-C), 70.0 (s, 1C, CH2), 50.3 (s, 2C, Piperazine-C), 45.2 (s, 2C, Piperazine-C); IR
(KBr), ν (cm-1): 2957, 2828(C-H), 1597(C=N), 1566, 1498, 1482, 1457(Ar), 1316, 1207(C-F),
1153(C=S). Elemental anal. (%) calcd. for C22H21F3N10S: C 51.36, H 4.11, N 27.22; found: C
51.18, H 4.28, N 27.10.
2-((4-(4-Methylpyrimidin-2-yl)piperazin-1-yl)methyl)-4-(((2-phenyl-2H-1,2,3-triazol-4-yl)
methylene)amino)-5-(trifluoromethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (9g): white
o
1
solid, yield 80.1%, mp 149-150 C; H NMR (400 MHz, CDCl3), δ: 10.82 (s, 1H, CH=N), 8.31
(s, 1H, Triazole-H), 8.13 (m, 3H, Ph-H + Pyrimidine-H), 7.52 (t, J = 7.9 Hz, 2H, Ph-H), 7.42 (t, J
= 7.4 Hz, 1H, Ph-H), 6.35 (d, J = 4.9 Hz, 1H, Pyrimidine-H), 5.28 (s, 2H, NCH2N), 3.94 – 3.82
(m, 4H, Piperazine-H), 2.95 – 2.82 (m, 4H, Piperazine-H), 2.31 (s, 3H, Pyrimidine-CH3); 13C
NMR (101 MHz, CDCl3), δ: 167.7 (s, 1C, C=S), 165.2 (s, 1C, Pyrimidine-C4), 161.5 (s, 1C,
Pyrimidine-C2), 157.2 (s, 1C, Pyrimidine-C6), 152.5 (s, 1C, 1,2,3-Triazole-C4), 143.5 (s, 1C,
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N=CH), 139.3 (s, 1C, Ph-C), 138.7 (q, JC-F = 42.4 Hz, 1C, 1,2,4-Triazole-C5), 135.0 (s, 1C,
1,2,3-Triazole-C5), 129.5 (s, 2C, Ph-C), 128.5 (s, 1C, Ph-C), 119.2 (s, 2C, Ph-C), 116.8 (q, JC-F
=
272.7 Hz, 1C, CF3), 109.6 (s, 1C, Pyrimidine-C5), 70.1 (s, 1C, CH2), 50.5 (s, 2C, Piperazine-C),
43.5 (s, 2C, Piperazine-C), 24.3 (s, 1C, CH3); IR (KBr), ν (cm-1): 2946, 2854(C-H), 1578(C=N),
1560, 1493, 1451(Ar), 1316, 1194(C-F), 1166(C=S). Elemental anal. (%) calcd. for
C22H22F3N11S: C 49.90, H 4.19, N 29.10; found: C 49.74, H 4.17, N 28.96.
2-((4-(4,6-Dimethylpyrimidin-2-yl)piperazin-1-yl)methyl)-4-(((2-phenyl-2H-1,2,3-triazol-
4-yl)methylene)amino)-5-(trifluoromethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione
(9h):
white solid, yield 87.6%, mp 182-183 oC; 1H NMR (400 MHz, CDCl3), δ: 10.83 (s, 1H, CH=N),
8.31 (s, 1H, Triazole-H), 8.12 (d, J = 7.9 Hz, 2H, Ph-H), 7.53 (t, J = 7.8 Hz, 2H, Ph-H), 7.42 (t, J
= 7.4 Hz, 1H, Ph-H), 6.25 (s, 1H, Pyrimidine-H), 5.29 (s, 2H, NCH2N), 3.94 – 3.83 (m, 4H,
Piperazine-H), 2.96 – 2.82 (m, 4H, Piperazine-H), 2.26 (s, 6H, Pyrimidine-CH3); 13C NMR (101
MHz, CDCl3), δ: 167.1 (s, 1C, C=S), 165.2 (s, 2C, Pyrimidine-C4,6), 161.6 (s, 1C,
Pyrimidine-C2), 152.4 (s, 1C, 1,2,3-Triazole-C4), 143.5 (s, 1C, N=CH), 139.3 (s, 1C, Ph-C),
138.7 (q, JC-F = 42.4 Hz, 1C, 1,2,4-Triazole-C5), 135.0 (s, 1C, 1,2,3-Triazole-C5), 129.5 (s, 2C,
Ph-C), 128.5 (s, 1C, Ph-C), 119.2 (s, 2C, Ph-C), 116.8 (q, JC-F = 272.7 Hz, 1C, CF3), 109.1 (s, 1C,
Pyrimidine-C5), 70.2 (s, 1C, CH2), 50.5 (s, 2C, Piperazine-C), 43.5 (s, 2C, Piperazine-C), 24.1 (s,
2C, CH3); IR (KBr), ν (cm-1): 2940, 2841(C-H), 1583(C=N), 1565, 1495, 1452(Ar), 1321,
1197(C-F), 1161(C=S). Elemental anal. (%) calcd. for C23H24F3N11S: C 50.82, H 4.45, N 28.35;
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found: C 50.69, H 4.53, N 28.32.
Synthesis of 1,1’-((Piperazin-1,4-diyl)bis(methylene))bis(4- ((2-phenyl-2H-1,2,3-triazol-4-yl)
methylene)amino-3-methyl/trifluoromethyl-1H-1,2,4-triazole-5(4H)-thione) 10
Schiff base 7 (1.8 mmmol), 37% formalin (2.5 mmol) were dissolved in ethanol (30 mL), and
the mixture was stirred at room temperature for 5 min. A solution of piperazine (0.9 mmol) in
ethanol (2 mL) was slowly added dropwise. Then the reaction mixture was stirred for 2-3 h at
room temperature. The resulting precipitate was filtered and recrystallized from ethanol to give
novel bis(1,2,4-triazole) Mannich base 10.
2,2'-(Piperazine-1,4-diylbis(methylene))bis(5-methyl-4-(((2-phenyl-2H-1,2,3-triazol-4-yl)
methylene)amino)-2,4-dihydro-3H-1,2,4-triazole-3-thione) (10a): white solid, yield 90.4%,
1
mp 226-228oC(Dec.); H NMR (400 MHz, CDCl3), δ: 10.93 (s, 2H, CH=N), 8.29 (s, 2H,
Triazole-H), 8.12 (d, J = 7.8 Hz, 4H, Ph-H), 7.52 (t, J = 7.8 Hz, 4H, Ph-H), 7.41 (t, J = 7.3 Hz,
2H, Ph-H), 5.08 (s, 4H, NCH2N), 2.87 (s, 8H, Piperazine-H), 2.46 (s, 6H, Triazole-CH3); IR
(KBr), ν (cm-1): 2944, 2822(C-H), 1617(C=N), 1594, 1496(Ar), 1172(C=S). Elemental anal. (%)
calcd. for C30H32N16S2: C 52.93, H 4.74, N 32.92; found: C 52.80, H 4.85, N 32.78.
2,2'-(Piperazine-1,4-diylbis(methylene))bis(4-(((2-phenyl-2H-1,2,3-triazol-4-yl)methylene
)amino)-5-(trifluoromethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione) (10b): white solid, yield
88.5%, mp 215-216oC(Dec.); 1H NMR (400 MHz, CDCl3), δ: 10.83 (s, 2H, CH=N), 8.33 (s, 2H,
Triazole-H), 8.13 (d, J = 7.8 Hz, 4H, Ph-H), 7.65 – 7.34 (m, 6H, Ph-H), 5.19 (s, 4H, NCH2N),
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2.89 (s, 8H, Piperazine-H); IR (KBr), ν (cm-1): 2952, 2832(C-H), 1616(C=N), 1598, 1520, 1498,
1457(Ar), 1320, 1200(C-F), 1153(C=S). Elemental anal. (%) calcd. for C30H26F6N16S2: C 45.68,
H 3.32, N 28.41; found: C 45.29, H 3.68, N 28.01.
Fungicidal Activity Tests
Fungicidal activities of compounds against six plant fungi (Table S 1) were evaluated using
the mycelium growth rate test[4,25]. The method was performed in an isolated culture. Under a
sterile condition, 1 mL of sample was added to the culture plates, followed by the addition of 9
mL of culture medium. The final mass concentration was 50 μg/mL. The blank assay was
performed with 1 mL of sterile water. Circle mycelium with a diameter of 4 mm was cut using a
o
drill. The culture plates were cultivated at 24 ± 1 C. The extended diameters of the circle
mycelium were measured after 72 h. The relative inhibition rate of the circle mycelium
compared to blank assay was calculated via the following equation:
Relative inhibition rate ( % ) = [(dex - dex') / dex] × 100%
Where dex is the extended diameter of the circle mycelium during the blank assay; and dex' is
the extended diameter of the circle mycelium during testing.
The blank test was made using acetone. Three replicates were performed.
CONCLUSION
A series of novel 1,2,3-triazole- and piperazine-containing 1,2,4-triazole thione derivatives
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have been conveniently synthesized by the Mannich reaction of 1,2,4-triazole thiol, various
substituted piperazines and formaldehyde under mild conditions in high yields. The preliminary
bioassays for 14 title compounds showed that some of them exhibit significant fungicidal
activities against Gibberella sanbinetti, Cercospora arachidicola, Physalospora piricola and
Rhizoctonia cerealis at 50 μg/mL. Among which, trifluoromethyl-containing triazole thione
derivative 9g showed broad activities and could be made further structural optimization for novel
fungicides innovation research.
ACKNOWLEDGEMENTS
This work was supported by the National Natural Science Foundation of China (No. 21372133)
and “111” Project of Ministry of Education of China (No. B06005).
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Scheme 1: The synthetic routes of the intermediates 1a-b and 3a-b.
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Scheme 2: The synthetic routes of the title compounds 8a-d and 9a-h.
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Scheme 3: The synthetic routes of the title compounds 10a-b.
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