Design, Synthesis, and Acaricidal/Insecticidal Activities of Oxazoline Derivatives Containing a Sulfur Ether Moiety

Article abstract of DOI:10.1021/acs.jafc.5b04126

On the basis of etoxazole, a series of novel 2-(2,6-difluorophenyl)-4-(4-substituted phenyl)-1,3-oxazolines containing a sulfur ether moiety were designed and synthesized via the key intermediate N-(1-(4-(bromomethyl)phenyl)-2-chloroethyl)-2,6-difluorobenzamide. The bioassay results showed that most of these designed target compounds exhibited excellent acaricidal activity against both the eggs and larvae of Tetranychus cinnabarinus, especially the eggs. Among compounds with high activity against the eggs of mites, the LC₅₀ values of 2, 11, 17, and 19 were 0.0003, 0.0002, 0.0005, and 0.0008 mg L^-1, respectively, much lower than that of etoxazole (0.0089 mg L^-1). Compound 2 was chosen to evaluate the acaricidal activity in the field, and the results displayed that at a concentration of 22 mg kg^-1, 2 had a much better control effect than etoxazole against both T. cinnabarinus and P. latus on eggplant. Some compounds also showed good insecticidal activities against oriental armyworm and mosquito. On the basis of our research, the newly found structure-activity relationship may guide the development of new acaricides/pesticides that are required in the agriculture market.

Full text of DOI:10.1021/acs.jafc.5b04126

Article
pubs.acs.org/JAFC
Design, Synthesis, and Acaricidal/Insecticidal Activities of Oxazoline
Derivatives Containing a Sulfur Ether Moiety
Xiuling Yu, Yuxiu Liu,* Yongqiang Li, and Qingmin Wang*
State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin 300071, People’s Republic of China
*
S Supporting Information
ABSTRACT: On the basis of etoxazole, a series of novel 2-(2,6-difluorophenyl)-4-(4-substituted phenyl)-1,3-oxazolines
containing a sulfur ether moiety were designed and synthesized via the key intermediate N-(1-(4-(bromomethyl)phenyl)-2-
chloroethyl)-2,6-difluorobenzamide. The bioassay results showed that most of these designed target compounds exhibited
excellent acaricidal activity against both the eggs and larvae of Tetranychus cinnabarinus, especially the eggs. Among compounds
−
1
with high activity against the eggs of mites, the LC values of 2, 11, 17, and 19 were 0.0003, 0.0002, 0.0005, and 0.0008 mg L ,
50
−1
respectively, much lower than that of etoxazole (0.0089 mg L ). Compound 2 was chosen to evaluate the acaricidal activity in
−1
the field, and the results displayed that at a concentration of 22 mg kg , 2 had a much better control effect than etoxazole against
both T. cinnabarinus and P. latus on eggplant. Some compounds also showed good insecticidal activities against oriental
armyworm and mosquito. On the basis of our research, the newly found structure−activity relationship may guide the
development of new acaricides/pesticides that are required in the agriculture market.
KEYWORDS: 2,4-diphenyl-1,3-oxazolines, acaricidal activity, insecticidal activity, thioether, structure−activity relationship
INTRODUCTION
phenyl moiety of 1,3-oxazolines had a great influence on the
10,11
■
acaricidal and insecticidal activities.
In 2014, we further
To overcome the global food shortage, the emergence of
pesticide resistance, pollution, and the accumulation of pesticides
in food products and water supplies, researchers are compelled to
develop novel pesticides with unique modes of actions coupled
with a high degree of activity on targeted pests and low toxicity to
reported a series of 1,3-oxazolines with an oxime ether
substituent at the para position of the 4-phenyl moiety. The
bioassay results indicated that all of the target compounds
exhibited considerable acaricidal activity against T. cinnabarinus.
The acaricidal mechanism of action of the target compounds and
etoxazole were studied with a fluorescence polarization method,
which showed that they could bind to the site of the sulfonylurea
1
,2
nontarget organisms (including many beneficial arthropods).
Etoxazole (Figure 1) is the only commercial acaricide/insecticide
belonging to the chemical class of 2,4-diphenyl-1,3-oxazolines,
discovered by Kyoyu Agri Co., Ltd. (formerly Yashima Chemical
12
receptor (SUR) and therefore inhibit chitin synthesis.
3
,4
Inspired by these reports, herein we report a series of oxazoline
derivatives containing a sulfur ether moiety at the para position of
Industry Co., Ltd.) and launched to the market in 1998. The
acaricidal and insecticidal mode of action of the 2,4-diphenyl-1,3-
oxazolines (such as the commercial acaricide etoxazole) is chitin
4
-phenyl group. The bioactivities of the target compounds were
evaluated, and the structure−activity relationship of these
compounds is shown in this paper. The preparation of key
intermediate N-(1-(4-(bromomethyl)phenyl)-2-chloroethyl)-
5
biosynthesis inhibition, which is similar to that of benzoylphe-
nylureas (BPUs) (Figure 1), the well-known class of insect chitin
6
,7
biosynthesis inhibitors. Chitin is an important component
only in insect cuticles and fungal cell walls but not in higher
plants and mammals, so insect chitin synthesis inhibitors show
high bioactivity on target pests and low toxicity to nontarget
organisms and are safe to humans, livestock, insects’ natural
2
,6-difluorobenzamide is also modified to be more suitable for
scale-up.
MATERIALS AND METHODS
Instruments and Chemicals. Reagents (analytically or chemically
pure) were purchased from commercial sources and used as received. All
anhydrous solvents were dried and distilled by standard techniques just
before use. Reaction progress was monitored by thin-layer chromatog-
raphy on silica gel GF254 with ultraviolet (UV) detection. Melting
points were obtained using an X-4 binocular microscope melting point
■
1
,8,9
enemies, and the ecological environment.
Oxazoline
derivatives have attracted considerable attention for decades
because of the above advantages and their unique mechanism of
action.
There are three parts (parts A, B, and C) to the 2,4-diphenyl-
,3-oxazoline structure (Figure 1). Recently, our research group
reported the synthesis and acaricidal/insecticidal activities of
oxazoline compounds in which a substituted phenoxy or a
different alkoxy group was fixed at the para position of the 4-
phenyl moiety (part C), optionally with Cl, methyl, or ethoxy at
the ortho position and/or meta position. Most of the designed
compounds showed excellent acaricidal activity, and the results
also showed that the positions and types of substituents on the 4-
1
1
(mp) apparatus and are uncorrected. Yields were not optimized. H
NMR spectra and 13C NMR spectra were recorded utilizing a Bruker
AV400 spectrometer with CDCl as solvent and tetramethylsilane as
3
Received: August 23, 2015
Revised: October 18, 2015
Accepted: October 25, 2015
Published: October 25, 2015
©
2015 American Chemical Society
9690
DOI: 10.1021/acs.jafc.5b04126
J. Agric. Food Chem. 2015, 63, 9690−9695

Journal of Agricultural and Food Chemistry
Article
Figure 1. Chemical structure and the design of the target compounds.
Figure 2. Synthetic procedure for the target compounds 1−23.
internal standard. Chemical shifts (δ) are given in parts per million
Procedure for the Synthesis of the Target Compounds 1−23
(Figure 2). Synthesis of N-(2-Chloro-1-methoxyethyl)-2,6-difluor-
obenzamide (B). To a solution of 2,6-difluorobenzamide A (7.15 g,
0.046 mol) in dimethylchloroacetal (22.68 g, 0.184 mol) under stirring
(
ppm). High-resolution mass spectra (HRMS) were obtained with a
Fourier transform ion cyclotron resonance mass spectrometry (FTICR-
MS) spectrometer (ionspec, 7.0T).
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Journal of Agricultural and Food Chemistry
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Table 1. Acaricidal Activity of the Target Compounds against T. cinnabarinus
activities(%) against eggs at concentration (mg L−1)
activities (%) against larvae at concentration (mg L−1
)
compd
100
50
25
2.5
1
100
50
25
2.5
1
1
2
3
4
5
6
7
8
9
100
100
100
80
100
100
100
67
79
20
100
100
18
−
100
100
−
90
80
78
100
100
36
62
100
100
−
−
38
20
−
41
21
0
100
100
50
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
50
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
97
100
100
100
100
100
100
100
100
91
86
50
100
100
100
82
83
70
100
100
35
100
95
90
87
92
91
−
30
75
39
0
66
100
100
100
100
80
80
72
0
10
11
12
13
14
15
16
17
18
19
20
21
22
23
100
100
34
100
100
−
100
100
82
100
100
30
27
17
−
53
10
10
−
93
−
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
89
77
100
100
100
100
92
100
100
100
77
15
15
30
22
26
30
0
89
81
100
100
76
100
100
85
100
100
78
83
75
100
100
100
100
100
100
97
100
100
100
100
100
100
92
81
100
100
100
100
100
100
87
98
85
57
45
0
90
70
100
100
86
etoxazole
85
30
below 0 °C was added dropwise concentrated sulfuric acid (3 mL), and
then the reaction mixture was stirred at room temperature until the
reaction was complete, indicated by TLC. Water was added, and then
the reaction mixture was extracted with dichloromethane. The
combined organic phase was washed with water and saturated brine
successively, dried with anhydrous sodium sulfate, filtered, and
concentrated under reduced pressure. To the residue was added n-
hexane (50 mL), and the mixture was stirred overnight at 0 °C and
filtered to give B (10.20 g, yield 90%).
Compounds 2−23 were synthesized according to a procedure similar
to that used for compound 1. The physical data in detail can be found in
the Supporting Information.
Biological Assay. All biological assays were performed on
representative test organiams prepared in the laboratory. The bioassay
was repeated at 25 ± 1 °C according to statistical requirements.
Assessments were made on a dead/alive basis, and mortality rates were
1
3
corrected using Abbott’s formula. Percentage mortalities were
evaluated based on a percentage scale of 0−100, in which 0 indicates
no activity and 100 indicates total kill. The standard deviations of the
tested biologocal values were ±5%. LC50 values were calculated by
Synthesis of N-(2-Chloro-1-p-tolylethyl)-2,6-difluorobenzamide
C). To a solution of amide acetal B (2.0 g, 0.008 mol) in anhydrous
(
1
4
probit analysis.
dichloromethane (25 mL) was added toluene (0.89 g, 0.0096 mol), and
Acaricidal Activity against Eggs of Spider Mites (T.
cinnabarinus). The acaricidal activities of all target compounds 1−23
and etoxazole as the standard compound against the eggs of spider mites
the mixture was cooled to 0 °C. AlCl was added to the mixture, and then
3
the reaction mixture was stirred at room temperature overnight until the
reaction was complete as indicated by TLC. The mixture was poured
into ice−water. After the organic phase was separated, the aqueous
phase was extracted with dichloromethane. The combined organic
phase was washed with saturated brine, dried with anhydrous sodium
sulfate, filtered, and concentrated in vacuo to give a crude product, which
was purified by recrystallization using petroleum ether and ethyl acetate
to give C (2.36 g, yield 95%).
15−18
(
T. cinnabarinus) were measured by the leaf-dip method.
Sieva
bean plants (Phaseolus vulgaris L.) with primary leaves expanded to 10
cm were selected and cut back to one plant per pot. A small piece was cut
from a leaf taken from the main colony and placed on each leaf of the test
plants to allow the female mites to move to the test leaves and lay eggs.
The size of the piece was tuned to obtain about 60−100 eggs per leaf.
The leaves were kept for no more than 24 h before treatment. The mite-
egg-infested leaves were dipped into the test solution for 3 s with
agitation and set in the hood to dry, and then they were placed in a tube
The synthetic procedure for N-(1-(4-(bromomethyl)phenyl)-2-
chloroethyl)-2,6-difluorobenzamide (D) was performed according to
12
published literature.
(
10 cm inner diameter) lined with a piece of filter paper. Three replicates
were carried out, and percentage mortalities were evaluated 4 days after
treatment.
Synthesis of 4-(4-((1H-benzo[d]imidazol-2-ylthio)methyl)phenyl)-
2-(2,6-difluorophenyl)-4,5-dihydrooxazole (1): A mixture of 1H-
benzo[d]imidazole-2-thiol (0.19 g, 1.3 mmol) in 10 mL of dry DMF
was cooled below 0 °C. To this solution was added sodium hydride
Acaricidal Activity against Larvae of Spider Mites (T.
cinnabarinus). The acaricidal activities against the larvae of spider
17−20
(
0.12 g, 5.2 mmol). The reaction mixture was stirred below 0 °C for 30
mites (T. cinnabarinus) were measured by the leaf-dip method.
min, and then compound D (0.5 g, 1.3 mmol) was added. The reaction
progress was monitored by TLC until the reaction was complete. The
mixture was extracted with ethyl acetate three times, and the combined
organic phase was washed with water three times, dried with anhydrous
sodium sulfate, and filtered. After the solvent was removed under
reduced pressure, the residue was purified by flash chromatography on
silica gel with petroleum ether and ethyl acetate (v/v = 2:1) to give the
target compound 1 (0.25 g, yield 46%).
Mite-egg-infested leaves (choose the leaves with the eggs layed on the
same day) were kept at 25 °C for 4 days, and then they were cut and put
on the test leaves as described above. After 1 day, the larvae were hatched
and moved to the fresh leaves. Each leaf had about 60−100 mites. The
leaf was cut and dipped into the test solution for 3 s with agitation, set in
the hood to dry, and then placed in a tube (10 cm inner diameter) lined
with a piece of filter paper. Three replicates were carried out, and
percentage mortalities were evaluated 4 days after treatment.
9
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Journal of Agricultural and Food Chemistry
Article
Larvicidal Activity against Oriental Armyworm. The larvicidal
activities of the target compounds 1−23 against oriental armyworm
displayed good activities. Compounds 15−21 bear a substituted
benzene ring. The acaricidal activities of compound 15 (bearing
an unsubstituted benzene ring) were near those of 14 which
bears a naphthalene ring. Compounds bearing halogen (16, 17,
2
1
were tested by foliar application using the reported produre. For the
foliar armyworm tests, individual corn leaves were placed on moistened
pieces of filter paper in Petri dishes. The leaves were then sprayed with
the test solution and allowed to dry. The dishes were infested with 10
fourth-instar oriental armyworm larvae. Percentage mortalities were
examined 4 days after treatment. Each treatment was carried out three
times. Etoxazole as the control compound was tested under the same
conditions.
1
9, and 20) or methoxy (21) on the benzene ring showed better
activities than those of the compound bearing a methyl
substituent (18) on the benzene ring; for 22 and 23 the para
position of the 4-phenyl moiety was alkyl-substituted and also
had excellent activity against eggs but had relatively poor activity
against larvae.
Larvicidal Activity against Mosquito. The larvicidal activities of
the target compounds 1−23 against mosquito were tested by using the
Gernerally, all compounds exhibited better ovicidal activity
22
reported procedure. Compounds 1−23 were prepared in different
concentrations by dissolving 1−23 in acetone and adding distilled water.
Then 20 fourth-instar mosquito larvae were put into 10 mL of the test
solutions and raised for 8 days. The results are expressed by death
percentage. Etoxazole as the control compound was tested under the
same conditions.
than larvicidal activity. Compounds 2, 3, 6, 7, 10, 11, 16, 17, and
−1
1
9−23 gave 100% mortality against eggs at 1 mg L , so these
compounds were further assayed at lower concentrations and
LC values were calculated (Table 2). LC values of the target
50
50
Evaluation of Acaricidal Activity in the Field. The field trials
were carried out between June and July in 2015. The trial against T.
cinnabarinus in an eggplant field was performed in the trial area of
Institute of Plant Protection, Tianjin Academy of Agricultural Science,
Tianjin City, China. Moreover, the trial against Polyphagotarsonemus
latus Banks (P. latus) also in an eggplant field was performed in the trial
area of Institute of Plant Protection, College of Agriculture, Yangtze
University, Jingzhou City. The treatment plots of eggplants were
designed in a random block array with four replicates. The untreated
plots served as a blank control. A formulation of compound 2 and
etoxazole (1% emulsifiable concentrates (ECs)) was prepared in our
Table 2. LC of Acaricidal Activity against Eggs of T.
cinnabarinus
5
0
activities (%) at concentration (mg L−1)
LC50 (mg L−1
compd
0.1
0.01
0.001
0.0001
)
2
3
97
97
95
72
80
89
83
100
74
83
85
82
82
79
90
92
51
48
45
82
66
79
64
70
72
71
66
51
53
49
30
30
0
45
0
0.0003 ± 0.0001
0.0037 ± 0.0009
0.0077 ± 0.0024
0.0223 ± 0.0048
0.0265 ± 0.0127
0.0002 ± 0.0001
0.0224 ± 0.0080
0.0005 ± 0.0001
0.0008 ± 0.0001
0.0051 ± 0.0010
0.0043 ± 0.0008
0.0013 ± 0.0009
0.0056 ± 0.0011
0.0089 ± 0.0028
6
0
7
0
10
11
16
0
−1
research group. They were diluted to 10, 15, or 22 mg L before use.
The control effects expressed as percentages were arcsine transformed
to homogenize variances before analysis, in which different spraying
68
0
40
0
17
19
20
55
50
50
55
47
49
34
33
42
0
2
3
treatments were examined using analysis of variance (ANOVA).
RESULT AND DISCUSSION
21
0
■
1
2
2
3
28
0
Synthesis. The synthetic procedure of the target compounds
−23 is shown in Figure 2. 2,6-Difluorobenzamide (A) reacted
with chloroacetaldehyde dimethyl acetal under catalysis from
2
etoxazole
0
H SO , giving B. Friedel−Crafts alkylation of B with toluene
2
4
afforded compound C. Compound D was prepared through
compounds 2 and 3, substituted at the para position of 4-phenyl
moiety with a (benzothiazole)thiomethyl group and
(benzooxazole)thiomethyl group, respectively, were 0.0003 mg
bromination of C using NaBr/NaBrO , in which the reaction
3
temperature was strictly controlled between 0 and 5 °C to reduce
the generation of byproducts. Different substituted thiophenols
or mercaptans were treated with sodium hydride in DMF and
then reacted with D to afford the target compounds 1−23 in
moderate yields (28−71%) via cyclization and substitution in
one pot. The whole route has only four steps, much shorter than
−
1
−1
L
and 0.0037 mg L , both lower than that of other
heterocyclic aryl sulfide compounds and etoxazole (0.0089 mg
−1
L ). 6, which bears a thiazole moiety, had better activity than 7,
which bears a thiophene. 11, which bears a pyrimidinethiomethyl
−1
group, exhibited excellent activity (LC 0.0002 mg L ). Among
50
10,12
the route for previously reported oxazoline derivatives.
the three compounds with a (para-substituted halogen)-
Biological Activity. Table 1 shows acaricidal activities of the
target compounds 1−23 and commercial etoxazole against eggs
and larvae of spider mites (T. Cinnabarinus). The results
indicated that all compounds exhibited good acaricidal activities.
When the substituent at the para position of the 4-phenyl moiety
was a benzo heterocyclic moiety (e.g., compounds 1, 2, and 3),
the activities of compounds 2 [bearing a (benzothiazol-2-
yl)thiomethyl group] and 3 [bearing a (benzooxazol-2-yl)-
thiomethyl group] against eggs and larvae of spider mites were
slightly higher than those of 1 [bearing a (benzoimidazolyl)-
thiomethyl group]. For compounds 4−9, 12, and 13, the para
position of the 4-phenyl group was substituted with a five-
membered heterocyclic moiety; for example, compounds 5−7
and 9 bear a thiodiazole, thiazole, thiophene, and furan moiety,
respectively, and showed better acaricidal activities than that of
the others. For compounds 10 and 11, the para position of the 4-
phenyl moiety was substituted with a pyridinethiomethyl group
and a pyrimidinethiomethyl group, respectively, and also
phenylthiomethyl group, compound 17 (with a bromine atom
−1
at the para position of the phenyl, LC 0.0005 mg L ) and 19
50
−1
(bearing a fluorine atom, LC 0.0008 mg L ) exhibited ovicidal
50
activities higher than those of compound 16, which bears a
−1
chloro atom (LC50 0.0224 mg L ). Compounds 20 and 21,
which bear a bromine group and a methoxy group, respectively,
at the ortho position of the phenyl, showed the same level of
−1
ovicidal activities (LC 0.0051 and 0.0043 mg L , respectively).
50
Moreover, LC values of compounds 22 and 23, para substituted
50
at 4-phenyl with a benzylthio methyl group and a tert-butylthio
−1
methyl group, respectively, were 0.0013 mg L and 0.0056 mg
−1
L , also lower than that of etoxazole.
The insecticidal activities of the target compounds 1−23, and
the control compound etoxazole, against oriental armyworm and
mosquito larvae are listed in Table 3. The structure−activity
relationship is different from that of acaricidal activity, and the
structure−activity relationships between mosquito larvae and
oriental armyworm are also different. It was found that
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Table 3. Insecticidal Activity of the Target Compounds
against Oriental Armyworm and Mosquito
than that of etoxazole against P. latus. The data of the field trial
against P. latus in Jingzhou showed that, 1 day after the spray, the
control efficiency of 1% 2 EC against P. latus at 22 mg kg− was
1
activities (%) against
8
3%, whereas etoxazole was 75% under the same condition; 3
oriental armyworm at
activities (%) against mosquito at
−1
concentration (mg L−
1
)
concentration (mg L
)
days after the spray, the control efficiency was 88% and 83%,
respectively. This meant that the speed of action of 2 was faster
than that of etoxazole. Seven days after the spray, the control
efficiency of 2 was 90%, obviously much better than that of
etoxazole (84%). The control efficiencies of 2 at 22 mg kg− were
all greater than 80% after 1 day, 3 days, and 7 days spray,
indicating that it had a certain control and persistent effect.
Similarly, for T. cinnabarinus in Tianjin, 2 at concentrations of 10,
compd
600
200
100
10
5
2
1
1
2
3
4
5
6
7
8
9
100
100
100
100
100
100
100
70
60
20
−
−
−
−
−
−
−
−
−
100
50
100
−
−
−
−
100
−
−
−
−
30
−
−
−
−
20
−
−
−
80
−
−
−
−
−
−
−
−
−
−
−
−
−
−
1
40
65
40
60
70
70
40
100
75
100
100
−1
1
5, and 22 mg kg , all showed an excellent control effect and
60
−
−
−
−
−
−
persistent effect. Fourteen days after the spray, the control
efficiency of 2 against T. cinnabarinus at 10 mg kg− still remained
at 92%. It should be mentioned that in both of the field trials, 2
had no adverse effect on the growth of eggplants under all
processing concentrations. Therefore, it was suggested that 2
showed a certain field application prospect.
−
−
50
1
65
75
1
1
1
1
1
1
1
1
1
1
2
2
2
2
0
1
2
3
4
5
6
7
8
9
0
1
2
3
100
100
50
100
40
100
100
100
100
40
100
20
0
100
60
−
−
−
−
−
20
−
60
100
100
100
100
100
100
100
100
100
60
100
−
−
In summary, a series of 2,4-diphenyl-1,3-oxazolines containing
a sulfur ether moiety at the para position of the 4-phenyl group
were designed and synthesized based on the SARs of etoxazole
derivatives. Their acaricidal activities against eggs and larvae of T.
cinnabarinus and insecticidal activities against oriental armyworm
and mosquito larvae were tested. The results of the bioassay
indicated that certain compounds displayed acaricidal activities
higher than that of commercial etoxazole, especially against eggs
of spider mites, and some compounds also showed insecticidal
activity. So the modification of the substituents at the para site of
the 4-phenyl moiety of 2,4-diphenyl-1,3-oxazolines influenced
the acaricidal and insecticidal activity but with different
structure−activity relationships. In the field trial, compound 2
exhibited acaricidal activity against both T. cinnabarinus and P.
latus better than that of etoxazole at the same or lower
concentrations, showing an excellent field application prospect.
100
100
100
60
40
70
60
−
60
70
60
−
−
−
−
−
−
−
−
−
30
100
70
40
−
−
60
60
−
100
100
100
60
40
100
100
60
−
100
−
60
30
−
0
−
−
−
100
100
100
100
etoxazole
100
60
0
compounds 1, 6, 10, 11, and 13, para substituted at 4-phenyl with
a heterocyclic alkyl sulfide moiety, had insecticidal activities
against mosquito much higher than that of etoxazole, whereas
their activities against oriental armyworm were lower than that of
etoxazole. By contrast, compounds 15, 16, 18, 19, 20, and 23,
para substituted with an aryl alkyl sulfide moiety, showed the
same level or slightly higher activities than that of etoxazole.
Combining the comprehensive analysis of bioactivity and LC50
values of the target compounds, compound 2, which gave
excellent acaricidal activity in the laboratory, was chosen to
evaluate the acaricidal activity in the field (Table 4). One percent
ECs of 2 and etoxazole were separately prepared and evaluated
for the control of P. latus on eggplants in Jingzhou City (Hubei
Province, South China), and T. cinnabarinus on eggplants in
Tianjin City (North China). They were diluted to 10, 15, or 22
mg kg− before use, and equivalent amounts of solution were
sprayed to each test field in the same site. It was shown that at a
ASSOCIATED CONTENT
Supporting Information
■
*
S
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.jafc.5b04126.
The physical data of compounds B, C, D, and target
compounds 1−23 (PDF)
AUTHOR INFORMATION
Corresponding Authors
■
1
*Tel: +86-(0)22-23503952. Fax: +86-(0)22-23503952. E-mail:
wangqm@nankai.edu.cn.
−1
concentration of 22 mg kg , 2 had a control effect much better
*E-mail: liuyuxiu@nankai.edu.cn.
Table 4. Effect of Acaricidal Program on Spider Mites in the Field in 2015
%
effect of 2
% effect of etoxazole
1
c
c
c
c
c
c
c
c
target and trial sites
dose mg kg−
10
1 day
3 days
7 days
14 days
1 day
3 days
7 days
14 days
a
P. latus on eggplant, Jingzhou, Hubei Province
69
71
83
67
72
75
73
80
88
84
87
90
82
85
90
94
97
97
−
−
−
92
95
96
−
−
75
−
−
83
−
−
84
−
−
−
−
−
88
1
2
5
2
b
T. cinnabarinus on eggplant, Tianjin City
10
−
−
77
−
−
91
−
−
91
1
2
5
2
a
−1
b
−1
c
The amount sprayed is about 500 g ha . The amount sprayed is about 750 g ha . The number of days between spraying insecticides and
investigating the effects.
9
694
DOI: 10.1021/acs.jafc.5b04126
J. Agric. Food Chem. 2015, 63, 9690−9695

Journal of Agricultural and Food Chemistry
Article
Funding
novel spriocyclic tetronic acid derivatives containing an oxaili moiety. J.
Agric. Food Chem. 2011, 59, 12543−12549.
This work was supported by the National Natural Science
Foundation of China (21132003, 21421062, 21372131), the
Specialized Research Fund for the Doctoral Program of Higher
Education (20120031110010), and the “111” Project of Ministry
of Education of China (B06005).
(
20) Song, H. J.; Liu, Y. X.; Xiong, L. X.; Li, Y. Q.; Yang, N.; Wang, Q.
M. Design, synthesis, and insecticidal activity of novel pyrazole
derivatives containing α-hydroxymethyl-N-benzyl carboxamide, α-
chloromethyl-N-benzyl carboxamide, and 4,5-dihydrooxazole moieties.
J. Agric. Food Chem. 2012, 60, 1470−1479.
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B. Insecticidal N′-substituted-N,N′-disubstituted hydrazines. U.S.
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Notes
The authors declare no competing financial interest.
(
22) Chen, L.; Huang, Z. Q.; Wang, Q. M.; Shang, J.; Huang, R. Q.; Bi,
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