Synthesis, insecticidal, and acaricidal activities of novel 2-aryl-pyrrole derivatives containing ester groups

Article abstract of DOI:10.1021/jf802464d

A series of novel 2-aryl-pyrrole derivatives containing ester groups were synthesized, and their structures were characterized by ¹H NMR spectroscopy and elemental analysis. The insecticidal activities against oriental armyworm, mosquito, diamondback moth, green rice leafhopper, and bean aphids and acaricidal activities against spider mite of these new compounds were evaluated. The results of bioassays indicated that some of these title compounds exhibited excellent insecticidal and acaricidal activities. The insecticidal activities against oriental armyworm of compounds IVa, IVd, IVe, IVf, IVg, IVi, IVk, and IVp were equal to commercialized Chlorfenapyr, and the insecticidal activities of most of compounds IVb, IVc, IVd, IVf, IVg, IVj, IVk, IVI, IVs, IVt, IVu, IVw, IVx, IVz, and Chlorfenapyr against mosquito at 0.10 mg kg^-1 were 100%, and the acaricidal activities of compounds IVd, IVe, IVf, IVg, IVh, IVi, and IVk were equal or superior to Chlorfenapyr. Especially, the results indicated that the acaricidal activity of [4-bromo-2-(4- chlorophenyl)-3-cyano-5-(trifluoromethyl)pyrrol-1 -yl]methyl 3-methylbutanoate (IVg) against spider mite was 2.65-fold as high as that of Chlorfenapyr from the value of LC₅₀.

Full text of DOI:10.1021/jf802464d

10176 J. Agric. Food Chem. 2008, 56, 10176–10182
Synthesis, Insecticidal, and Acaricidal Activities of
Novel 2-Aryl-pyrrole Derivatives Containing Ester
Groups
YU ZHAO,† YONGQIANG LI,† XIAOMING OU,†,‡ PENGXIANG ZHANG,†
ZHIQIANG HUANG,† FUCHUN BI,† RUNQIU HUANG,† AND QINGMIN WANG*,†
State Key Laboratory of Elemento-Organic Chemistry, Institute of Elemento-Organic Chemistry, Nankai
University, Tianjin 300071, and Hunan Branch of National Pesticide R&D South Center, Hunan Research
Institute of Chemical Industry, Changsha 410007, Hunan Province, People’s Republic of China
A series of novel 2-aryl-pyrrole derivatives containing ester groups were synthesized, and their
structures were characterized by 1H NMR spectroscopy and elemental analysis. The insecticidal
activities against oriental armyworm, mosquito, diamondback moth, green rice leafhopper, and bean
aphids and acaricidal activities against spider mite of these new compounds were evaluated. The
results of bioassays indicated that some of these title compounds exhibited excellent insecticidal
and acaricidal activities. The insecticidal activities against oriental armyworm of compounds IVa, IVd,
IVe, IVf, IVg, IVi, IVk, and IVp were equal to commercialized Chlorfenapyr, and the insecticidal
activities of most of compounds IVb, IVc, IVd, IVf, IVg, IVj, IVk, IVl, IVs, IVt, IVu, IVw, IVx, IVz, and
Chlorfenapyr against mosquito at 0.10 mg kg-1 were 100%, and the acaricidal activities of compounds
IVd, IVe, IVf, IVg, IVh, IVi, and IVk were equal or superior to Chlorfenapyr. Especially, the results
indicated that the acaricidal activity of [4-bromo-2-(4-chlorophenyl)-3-cyano-5-(trifluoromethyl)pyrrol-
1-yl]methyl 3-methylbutanoate (IVg) against spider mite was 2.65-fold as high as that of Chlorfenapyr
from the value of LC50.
KEYWORDS: Aryl-pyrrole; Chlorfenapyr; ester group; insecticidal activity; acaricidal activity; oriental
armyworm; mosquito; diamondback moth; green rice leafhopper; bean aphids; spider mite
INTRODUCTION
first to be commercialized as an insecticide-miticide under the
trade name Chlorfenapyr (5, 6). It is a pro-insecticide activated
by the oxidative in vivo removal of its N-ethoxymethyl group
(7). Recently, its resistance has already been detected (8-11).
The activity spectrum of a pesticide is often determined by
physical properties of compound, and it is possible to develop
a compound of new style by attaching an appropriate functional
group to a present insecticide. Moreover, the physical properties
of an insecticidal compound may be manipulated to obtain
products with other selected types of activity by proper selection
of the derivative moiety (12). For example, it was reported that
N-ester derivatives of diacylhydrazine (D, Figure 1) displayed
an insecticidal activity comparable or superior to that of the
parent compound (13). In our previous work, it was found that
benzoylphenylureas derivatives containing an ester group (E,
Figure 1) exhibited excellent larvicidal activity (14).
Encouraged by these reports, we developed an idea that the
introduction of an ester group into 2-aryl-pyrrole B by
substituting the hydrogen on the nitrogen atom could improve
biological properties and decrease resistance. Therefore, in
a search for new aryl-pyrrole insecticides with improved
profiles, we designed and synthesized a series of novel 2-aryl-
pyrrole derivatives containing ester groups as shown in
Schemes 2 and 3.
In 1987, the American Cyanamid Company isolated and
identified dioxapyrrolomycin (A, Figure 1) from a Streptomyces
strain and found that dioxapyrrolomycin exhibited moderate
broad spectrum insecticidal and miticidal activities (1). At about
the same time, this pyrrole A was also reported by Meiji Seika
Kaisha and SS Pharmaceutical Company in Japan as an
antibiotic (2, 3). However, an oral LD50 of 14 mg kg1- to mice
showed it to be highly toxic. Then, the American Cyanamid
Company found that compound B (Figure 1) exhibited excellent
activities against tobacco budworm and two-spotted spider mite
and potato leafhopper. However, they once again found that
compound B had severe phytotoxicity. To circumvent this
problem, the American Cyanamid Company further prepared
its derivative C by introduction of an ethoxymethyl group into
compound B by substituting the hydrogen on the nitrogen atom
and found that compound C retained the high insecticidal
activity of the parent pyrrole B with none of the undesirable
phytotoxic properties (4). The compound C (Figure 1) was the
* To whom correspondence should be addressed. Tel: +86(0)22-
23499842. Fax: +86(0)22-23499842. E-mail: wang98h@263.net.
† Nankai University.
‡ Hunan Research Institute of Chemical Industry.
10.1021/jf802464d CCC: $40.75  2008 American Chemical Society
Published on Web 10/21/2008

Novel 2-Aryl-pyrrole Derivatives Containing Ester Groups
J. Agric. Food Chem., Vol. 56, No. 21, 2008 10177
Figure 1. Chemical structures of compounds A-E.
Scheme 1. Synthetic Route of Compound III
to afford compound II as a white crystal (8.00 g, 36%); mp 149-151
°C. Anal. calcd (%) for C15H10BrClF3N3O: C, 42.83; H, 2.40; N, 9.99.
Found (%): C, 42.86; H, 2.41; N, 9.82.
Scheme 2. General Synthetic Route of the Title Compounds IVa-IVy
A mixture of compound II (1.22 g, 2.90 mmol) and phosphoryl
tribromide (2.35 g, 8.2 mmol) was heated at refluxed temperature for
30 min, then diluted with water, and extracted with ethyl acetate (3 ×
20 mL). The combined organic extracts were washed successively with
water (20 mL) and brine (20 mL), dried over anhydrous magnesium
sulfate, and concentrated in vacuo to obtain a solid. Recrystallization
from a mixture of ethyl acetate and heptane gave the desired compound
III as a white solid (1.02 g, 80%); mp 136-138 °C. 1H NMR: δ 5.61
MATERIALS AND METHODS
1
Instruments. H NMR spectra were obtained at 300 MHz using a
Bruker AV300 spectrometer or at 400 MHz using a Varian Mercury
Plus400 spectrometer in CDCl3 solution with tetramethylsilane as the
internal standard. Chemical shift values (δ) were given in ppm.
Elemental analyses were determined on a Yanaca CHN Corder MT-3
elemental analyzer. The melting points were determined on an X-4
binocular microscope melting point apparatus (Beijing Tech Instruments
Co., Beijing, China) and were uncorrected. Yields were not optimized.
The reagents were all analytically or chemically pure. All solvents and
liquid reagents were dried by standard methods in advance and distilled
before use. 4-Bromo-2-(4-chlorophenyl)-5- (trifluoromethyl)pyrrole-
3-carbonitrile (B) was prepared according to the literature (15-19).
N-(Hydroxymethyl)acetamide acetate (I) was obtained according to the
reported procedure (20).
Synthetic Procedure for 4-Bromo-1-(bromomethyl)-2-(4-chlo-
rophenyl)-5- (trifluoromethyl)pyrrole-3-carbonitrile (III). A slurry
of 4-bromo-2-(4-chlorophenyl)-5- (trifluoromethyl)pyrrole-3-carbonitrile
(B) (17.47 g, 0.05 mol) and tetrahydrofuran (60 mL) was cooled to 10
°C and treated portionwise over 20 min with sodium hydride (2.2 g,
60% in oil, 0.055 mol). After it was stirred for 15 min, this solution
was added dropwise to a 50 °C solution of N-(hydroxymethyl)acetamide
acetate (I) (9.65 g, 0.074 mol) in tetrahydrofuran (40 mL). The reaction
mixture was refluxed for 4 h and cooled to room temperature, diluted
with water (30 mL), and extracted with ethyl acetate (3 × 60 mL).
The organic extract was washed with water (2 × 40 mL), dried over
anhydrous magnesium sulfate, and concentrated in vacuo to give a solid.
The solid was purified by column chromatography on a silica gel using
a mixture of petroleum ether (60-90 °C) and ethyl acetate as the eluent
3
(s, 2H); 7.49 (d, 2H, JHH ) 8.7 Hz), 7.54 (d, 2H,3JHH ) 8.7 Hz).
Anal. calcd (%) for C13H6Br2ClF3N2: C, 35.29; H, 1.37; N, 6.33. Found
(%): C, 35.32; H, 1.54; N, 6.57.
General Synthetic Procedure for the Title Compounds IVa-IVy.
The appropriate acid (4.50 mmol) was added to a stirred suspension of
sodium hydroxide (0.18 g, 4.50 mmol) in dimethylformamide (10 mL)
at 0 °C. After it was stirred for 1 h, the solution of compound III (4.50
mmol) in dimethylformamide (3 mL) was added dropwise. After it was
stirred for 6 h at room temperature, the reaction mixture was poured
into ice water (15 mL) and extracted with ethyl acetate (3 × 20 mL).
The organic layer was washed successively with saturated sodium
hydrogen carbonate solution (20 mL), water (3 × 20 mL), and brine
(20 mL) and then dried over anhydrous sodium sulfate. After the solvent
was removed, the residue was purified by recrystallization from a
mixture of ethyl acetate and petroleum ether (60-90 °C) to afford the
title compounds IVa-IVy.
Synthetic Procedure for the Title Compound IVz. Potassium
hydroxide (5.6 g, 0.1 mol) in alcohol (100 mL) was added to a stirred
solution of diethyl carbonate (17.7 g, 0.15 mol) in alcohol (100 mL).
After it was stirred for 2 h, the product was precipitated and filtered to
give potassium ethyl carbonate (10.8 g, 84.3%) as a white solid, which
was directly used for the next step without further purification.
Potassium ethyl carbonate (0.58 g, 4.50 mmol) was dissolved in
dimethylformamide (10 mL) at room temperature. Then, a solution of
compound III (4.50 mmol) in dimethylformamide (3 mL) was added
dropwise. After it was stirred for 6 h at room temperature, the reaction
Scheme 3. General Synthetic Route of the Title Compound IVz

10178 J. Agric. Food Chem., Vol. 56, No. 21, 2008
Zhao et al.
Table 1. Melting Points, Yields, and Elemental Analyses of the Compounds IVa-IVz

Novel 2-Aryl-pyrrole Derivatives Containing Ester Groups
J. Agric. Food Chem., Vol. 56, No. 21, 2008 10179
Table 1. Continued
mixture was poured into ice water (15 mL) and extracted with ethyl
acetate (3 × 20 mL). The organic layer was washed successively with
saturated sodium hydrogen carbonate solution (20 mL), water (3 × 20
mL), and brine (20 mL) and then dried over anhydrous sodium sulfate.
After the solvent was removed, the residue was purified by recrystal-
lization from a mixture of ethyl acetate and petroleum ether (60-90
°C) to afford the title compound IVz.
Biological Assay. All bioassays were performed on representative
test organisms reared 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 corrected using Abbott’s
formula (21). Evaluations were based on a percentage scale of 0-100,
where 0 equals no activity and 100 equals total kill. The error of the
experiments was 5%. For comparative purpose, Chlorfenapyr was tested
under the same conditions.
Insecticidal ActiVity against Oriental Armyworm (Mythimna sepa-
rata). The insecticidal activities against oriental armyworm of the title
compounds IVa-IVz and Chlorfenapyr were evaluated by foliar
application using the reported procedure (22, 23). 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 10 fourth-instar oriental armyworm larvae.
Percentage mortalities were evaluated 2 days after treatment. Each
treatment was performed three times. The insecticidal activities against
oriental armyworm of the title compounds IVa-IVz and Chlorfenapyr
are summarized in Table 3.
Insecticidal ActiVity against Mosquito (Culex pipiens pallens). The
toxicities of the title compounds IVa-IVz and Chlorfenapyr against
mosquito were evaluated by the reported procedure (24-26). One
milliliter of different concentrated dilution of each compound was added
to 99 mL of water to get different concentrations of tested solutions.
Then, 20 four-instar mosquito larva were put into 10 mL of the test
solution and raised for 2 days, and the results were expressed by death
percentage. The results of the insecticidal activity of the title compounds
IVa-IVz and Chlorfenapyr are shown in Table 3
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. This was done
about 2 h before treatment to allow the mites to move over to the test
plant and to lay eggs. The size of the piece was varied to obtain about
60-100 mites per leaf. At the time of the treatment, the piece of leaf
used to transfer the mites was removed and discarded. The mite-infested
plant were dipped in the test formulation for 3 s with agitation and set
in the hood to dry. Plants were kept for 2 days before the numbers of
live and dead adults were counted. The acaricidal activities against
spider mite of the title compounds IVa-IVz and Chlorfenapyr are
summarized in Table 3.
Acaricidal ActiVity against Two Spot Spider Mite (T. cinnabarinus
BoisduVal). The acaricidal activities of the title compound IVg and
Chlorfenapyr against two spot spider mites were evaluated using the
slide immersion method recommended by FAO (29). Thirty female
adult spider mites were fixed dorsally to a strip of double-sided tape
attached to the slide by using a small brush. The slide was immersed
and shaken for 10 s in the diluted solution of the test compound. After
the excessive solution was removed, the treated slides with the mites
were kept at 25 ( 2 °C in a Petri dish with moist filter paper. The
number of the dead mites was recorded 24 h after treatment. Each
treatment was replicated thrice, and each replicate involved 30 adult
mites. Chlorfenapyr was used as a standard. The data for the mort-
ality-regression lines of the compounds were subjected to probit
analysis by Finney’s method. The results of the median lethal con-
centrations (LC50) of the title compound IVg and Chlorfenapyr against
two spot spider mites are shown in Table 4.
Insecticidal ActiVity against Diamondback Moth (Plutella xylostella
L.). The insecticidal activities of the title compound IVg and Chlor-
fenapyr against diamondback moth were evaluated using the leaf disk
assay (29). The Leaf disks (1.8 cm diameter) were cut from fresh
cabbage leaves and then dipped into the test solution for 15 s. After
air drying, the treated leaf disks were placed in a Petri dish (9 cm
diameter) lined with a filter paper, and then, the second-instar
diamondback moth larvae were transferred to the Petri dish. Three
replicates (10 larvae per replicate) were carried out. Chlorfenapyr was
used as a standard. The data for the mortality-regression lines of the
compounds were subjected to probit analysis by Finney’s method. The
Acaricidal ActiVity against Spider Mite (Tetranychus cinnabarinus
BoisduVal). The acaricidal activities against spider mite of the title
compounds IVa-IVz and Chlorfenapyr were evaluated using the
reported procedure (27, 28). Sieva bean plants (Phaseolus Vulgaris L.)
with primary leaves expanded to 10 cm were selected and cut back to

10180 J. Agric. Food Chem., Vol. 56, No. 21, 2008
Table 2. 1H NMR of the Compounds IVa-IVz
Zhao et al.
and a bud were dipped in the test solution of the compounds for 15 s,
dried in air, and placed into a test tube (diameter 2.5 cm × height 30
cm). Fifteen third-instar green rice leafhoppers were introduced into
each test tube. The test tubes were capped with the white gauze and
maintained at a constant condition. Mortality was calculated 48 h after
treatment. At least five concentrations, a blank control, and a standard
Chlorfenapyr were included in each bioassay, and triplicates were done.
The data for the mortality-regression lines of the compounds were
subjected to probit analysis by Finney’s method. The results of the
median lethal concentrations (LC50) of the title compound IVg and
Chlorfenapyr against green rice leafhoppers are shown in Table 6.
Insecticidal ActiVity against Bean Aphids (Aphis fabae Scopoli). The
insecticidal activities of the title compound IVg and Chlorfenapyr
against bean aphids were evaluated (29). Bean aphids were dipped
according to a slightly modified FAO dip test. The tender shoots of
soybean with 40-60 healthy apterous adult aphids were dipped in the
diluted solutions of the compounds for 5 s, and the superfluous fluid
was removed and placed in the conditioned room. Mortality was
calculated 48 h after treatment. Each treatment was performed three
times. Chlorfenapyr was used as a standard. The data for the mort-
ality-regression lines of the compounds were subjected to probit
analysis by Finney’s method. The results of the median lethal con-
centrations (LC50) of the title compound IVg and Chlorfenapyr against
bean aphids are listed in Table 7.
compd
1H NMR (CDCl3) δ (ppm)
3
3
IVa
5.89 (s, 2H); 7.43 (d, 2H, JHH ) 8.6 Hz); 7.55 (d, 2H, JHH ) 8.6
Hz); 8.01 (s, 1H)
3
IVb
IVc
IVd
2.10 (s, 3H); 5.79 (s, 2H); 7.41 (d, 2H, JHH ) 8.6 Hz); 7.54 (d,
3
2H, JHH ) 8.6 Hz)
3
3
1.41 (t, 3H, JHH ) 7.5 Hz); 2.37 (q, 2H, JHH ) 7.5 Hz); 5.79 (s,
2H); 7.41 (d, 2H, JHH ) 8.6 Hz); 7.53 (d, 2H, JHH ) 8.6 Hz)
0.94 (t, 3H, JHH ) 7.4 Hz); 1.59-1.69 (m, 2H); 2.32 (t, 2H, JHH
3
3
3
3
3
) 7.4 Hz); 5.79 (s, 2H); 7.41 (d, 2H, JHH ) 8.6 Hz); 7.53 (d,
3
2H, JHH ) 8.6 Hz)
3
IVe
IVf
1.17 (d, 6H, JHH ) 7.0 Hz); 2.54-2.63 (m, 1H); 5.76 (s, 2H); 7.41
(d, 2H, JHH ) 8.3 Hz); 7.53 (d, 2H, JHH ) 8.3 Hz)
0.92 (t, 3H, JHH ) 7.3 Hz); 1.28-1.35 (m, 2H); 1.56-1.63 (m,
3
3
3
3
3
2H); 2.34 (t, 2H, JHH ) 7.4 Hz); 5.78 (s, 2H); 7.41 (d, 2H, JHH
3
) 8.4 Hz); 7.53 (d, 2H, JHH ) 8.4 Hz)
3
3
IVg
0.95 (d, 6H, JHH ) 6.6 Hz); 2.00-2..12 (m, 1H); 2.22 (d, 2H, JHH
3
) 7.2 Hz); 5.78 (s, 2H); 7.41 (d, 2H, JHH ) 8.4 Hz); 7.53 (d,
3
2H, JHH ) 8.4 Hz)
IVh
IVi
6.04 (s, 2H); 7.43-8.00 (m, 9H)
3
3
6.03 (s, 2H); 7.45 (d, 2H, JHH ) 8.5 Hz); 7.52 (d, 2H, JHH ) 8.5
3
3
Hz); 7.42 (d, 2H, JHH ) 8.6 Hz); 7.92 (d, 2H, JHH ) 8.6 Hz)
3
3
IVj
6.04 (s, 2H); 7.46 (d, 2H, JHH ) 8.6 Hz); 7.53 (d, 2H, JHH ) 8.6
Hz); 7.33-7.80 (m, 4H)
3
3
IVk
IVl
6.01 (s, 2H); 7.44 (d, 2H, JHH ) 8.5 Hz); 7.51 (d, 2H, JHH ) 8.5
3
3
RESULTS AND DISCUSSION
Hz); 7.26 (d, 2H, JHH ) 8.0 Hz); 7.87 (d, 2H, JHH ) 8.0 Hz)
3
5.69 (br, 2H); 5.99 (s, 2H); 7.44 (d, 2H, JHH ) 8.4 Hz); 7.51 (d,
Synthesis. 4-Bromo-1-(bromomethyl)-2-(4-chlorophenyl)-5-
(trifluoromethyl)pyrrole-3-carbonitrile (III) was synthesized as
shown in Scheme 1. 4-Bromo-2-(4-chlorophenyl)-5-(trifluo-
romethyl)pyrrole-3-carbonitrile (B) was prepared according to
the literature (14-18). N-(Hydroxymethyl)acetamide acetate (I)
was obtained according to reported procedure (19). The in-
termediate B was reacted with compound I in the presence of
sodium hydride to give compound II, and subsequent treatment
using phosphoryl tribromide as a bromination reagent provided
the key intermediate III.
The title compounds IVa-IVy were synthesized from
intermediate III and appropriate acid as shown in Scheme 2.
The key intermediate III was reacted with appropriate acid in
dimethylformamide using sodium hydroxide as alkali to yield
2-aryl-pyrrole derivatives containing ester groups IVa-IVy. The
title compound IVz was synthesized from intermediate III and
potassium ethyl carbonate as shown in Scheme 3.
The title compounds IVa-IVz could be purified by recrys-
tallization from a mixture of ethyl acetate and petroleum ether.
The melting points, yields, and elemental analyses of compounds
IVa-IVz are listed in Table 1. The 1H NMR data are listed in
Table 2.
Structure-Activity Relationship (SAR). Table 3 shows the
insecticidal activities against oriental armyworm and mosquito
and acaricidal activities against spider mite of the title com-
pounds IVa-IVz and contrast compound Chlorfenapyr.
Insecticidal ActiVities against Oriental Armyworm (M. sepa-
rata Walker). The results of insecticidal activities given in Table
3 indicate that some of the title compounds IVa-IVz exhibit
excellent activity against oriental armyworm, which are good
as compared to the commercialized Chlorfenapyr. For instance,
the insecticidal activities of compounds IVa, IVd, IVe, IVf,
IVg, IVi, IVk, and IVp were equal to Chlorfenapyr. Among
the R values of the title compounds IVa-IVz, saturated short
alkyl groups are most prominent in increasing activity. From
Table 3, we also found that aromatic-substituted compounds
exhibit lower insecticidal activities against oriental armyworm
than saturated short alkyl-substituted compounds.
3
2H, JHH ) 8.4 Hz); 6.63-7.55 (m, 4H)
4.19 (br, 2H); 5.97 (s, 2H); 7.44 (d, 2H, JHH ) 8.4 Hz); 7.51 (d,
2H, JHH ) 8.4 Hz); 6.63 (d, 2H, JHH ) 8.5 Hz); 7.79 (d, 2H,
3
IVm
3
3
3JHH ) 8.5 Hz)
3
IVn
IVo
3.85 (s, 3H); 6.02 (s, 2H); 7.43 (d, 2H, JHH ) 8.5 Hz); 7.52 (d,
2H, JHH ) 8.5 Hz); 7.15-7.59 (m,4H)
3.88 (s, 3H); 6.00 (s, 2H); 7.44 (d, 2H, JHH ) 8.5 Hz); 7.51 (d,
3
3
3
3
2H, JHH ) 8.5 Hz); 6.94 (d, 2H, JHH ) 8.9 Hz); 7.94 (d, 2H,
3JHH ) 8.9 Hz)
3
3
IVp
IVq
IVr
IVs
IVt
6.05 (s, 2H); 7.43 (d,2H, JHH ) 8.3 Hz); 7.59 (d, 2H, JHH ) 8.3
Hz); 7.64-8.05 (m, 4H)
3
3
6.10 (s, 2H); 7.44(d, 2H, JHH ) 8.5 Hz); 7.54 (d, 2H, JHH ) 8.5
Hz); 7.71-8.81 (m, 4H)
3
3
6.09 (s, 2H); 7.43 (d, 2H, JHH ) 8.5 Hz); 7.54 (d, 2H, JHH ) 8.5
3
3
Hz); 8.16 (d, 2H, JHH ) 8.9 Hz); 8.32 (d, 2H, JHH ) 8.9 Hz)
3
3
6.17 (s, 2H); 7.44 (d, 2H, JHH ) 8.4 Hz); 7.57 (d, 2H, JHH ) 8.4
Hz); 9.08-9.29 (m, 3H)
3
3
1.62 (d, 3H, JHH ) 6.8 Hz); 4.75 (q, 1H, JHH ) 6.7 Hz); 5.78 (q,
2
3
2H, JHH ) 11.4 Hz); 6.76 (d, 2H, JHH ) 8.8 Hz); 7.34 (d, 2H,
3JHH ) 8.8 Hz); 7.21 (d, 2H, JHH ) 8.0 Hz); 7.27 (d, 2H, JHH
3
3
) 8.0 Hz)
3
3
IVu
IVv
IVw
1.63 (d,3H, JHH ) 6.8 Hz); 4.77 (q,1H, JHH ) 6.8 Hz); 5.80
2 3
(q,2H, JHH ) 11.4 Hz); 6.71-7.06 (m,4H); 7.24 (d, 2H, JHH
)
3
8.4 Hz); 7.37 (d, 2H, JHH ) 8.4 Hz)
3
3
1.67 (d, 3H, JHH ) 6.8 Hz); 4.88 (q, 1H, JHH ) 6.8 Hz); 5.85 (q,
2
3
2H, JHH ) 11.4 Hz); 7.17-7.93 (m, 4H); 7.32 (d, 2H, JHH
)
3
8.5 Hz); 7.44 (d, 2H, JHH ) 8.5 Hz)
1.62 (d, 3H, JHH ) 6.8 Hz); 2.33 (s, 3H); 4.79 (q, 1H, JHH )6.8
3
3
2
Hz); 5.76 (q, 2H, JHH ) 11.4 Hz); 6.61-7.19 (m, 4H); 7.20 (d,
3
3
2H, JHH ) 8.6 Hz); 7.27 (d, 2H, JHH ) 8.6 Hz)
3
3
IVx
IVy
IVz
1.34 (s, 9H); 1.63 (d, 3H, JHH ) 6.8 Hz); 4.78 (q, 1H, JHH ) 6.8
2
Hz); 5.76 (q, 2H, JHH ) 11.4 Hz); 7.00-7.30 (m, 8H)
6.04 (s, 2H); 7.43 (d, 2H, JHH ) 8.3 Hz); 7.59 (d, 2H, JHH ) 8.3
Hz); 7.47-7.98 (m, 5H)
1.32 (t, 3H, JHH ) 7.1 Hz); 4.23 (q, 1H, JHH ) 7.1 Hz); 5.81
(s,2H); 7.44 (d, 2H, JHH ) 8.6 Hz); 7.54 (d, 2H, JHH ) 8.6 Hz)
3
3
3
3
3
3
results of the median lethal concentrations (LC50) of the title compound
IVg and Chlorfenapyr against diamondback moth larvae are shown in
Table 5.
Insecticidal ActiVity against Green Rice Leafhopper (Nephotettix
cincticeps Uhler). The insecticidal activities of the title compound IVg
and Chlorfenapyr against green rice leafhoppers were evaluated using
the seedling-dipping method (29). Fifteen rice seedlings with two leaves
Insecticidal ActiVities against Mosquito (C. pipiens pallens).
The insecticidal activities of the title compounds IVa-IVz

Novel 2-Aryl-pyrrole Derivatives Containing Ester Groups
J. Agric. Food Chem., Vol. 56, No. 21, 2008 10181
Table 3. Insecticidal and Acaricidal Activities of Compounds IVa-IVz against Oriental Armyworm, Mosquito, and Spider Mite
toxicities against oriental armyworm at concn (mg kg-1) toxicities against mosquito at concn (mg kg-1) toxicities against spider mite at concn (mg kg-1
)
compd
IVa
IVb
IVc
IVd
IVe
IVf
IVg
IVh
IVi
IVj
IVk
IVl
IVm
IVn
IVo
IVp
IVq
IVr
20
10
5
0.50
0.25
0.10
200
100
89
50
82
100
100
100
100
100
100
100
100
100
100
100
10
100
90
90
100
100
100
100
60
100
35
100
0
0
0
0
0
0
0
0
0
10
0
0
0
0
0
0
20
0
0
0
0
0
0
0
0
0
0
0
100
100
100
100
100
100
100
100
50
100
100
100
100
0
100
100
100
100
100
100
100
99
100
0
0
100
0
0
98
95
0
98
98
0
100
100
100
100
100
92
100
100
100
100
100
100
95
88
100
100
100
100
100
100
93
100
100
100
100
100
100
100
100
100
70
100
100
20
100
100
10
20
10
100
100
100
10
65
30
20
40
60
100
100
100
100
100
100
100
100
100
10
50
20
10
30
20
100
100
100
90
100
100
100
100
40
0
100
100
100
100
100
100
100
100
100
100
80
90
90
100
0
50
0
80
45
85
40
30
60
90
100
65
50
100
80
94
93
90
92
100
100
100
100
100
100
100
IVs
IVt
95
93
94
93
IVu
IVv
IVw
IVx
IVy
IVz
98
96
88
89
97
96
94
79
84
93
100
100
100
100
100
100
100
100
100
chlorfenapyr
Table 4. Acaricidal Activities of IVg and Chlorfenapyr against Two Spot
Spider Mite
shows that most of the title compounds IVa-IVz exhibit
excellent activities against spider mite. For example, the
acaricidal activities of compounds IVd, IVe, IVf, IVg, IVh,
IVi, and IVk were equal or superior to the commercialized
Chlorfenapyr at 50 mg kg-1. In particular, IVg was sent for
advanced testing of the acaricidal activities against two spot
spider mite and the insecticidal activities against diamondback
moth, green rice leafhopper, and bean aphids.
Acaricidal ActiVity against Two Spot Spider Mite (T. cinna-
barinus BoisduVal). The results of the median lethal concentra-
tions (LC50) and the toxicity regression equations of compound
IVg and Chlorfenapyr are shown in Table 4. The results indicate
that the acaricidal activity of IVg against two spot spider mite
was 2.65-fold as high as that of Chlorfenapyr from the value of
LC50.
compd
IVg
Chlorfenapyr
y ) a + bx
LC50 (mg/L)
toxic ratio
y ) 5.9227 + 2.5257x
y ) 4.8332 + 3.0078x
0.43
1.14
2.65
1.00
Table 5. Insecticidal Activities of IVg and Chlorfenapyr against
Diamondback Moth
compd
IVg
Chlorfenapyr
y ) a + bx
LC50 (mg/L)
toxic ratio
y ) 3.8885 + 4.0690x
y ) 4.1005 + 3.8385x
1.88
1.82
0.97
1.00
Table 6. Insecticidal Activities of IVg and Chlorfenapyr against Green Rice
Leafhopper
Insecticidal ActiVity against Diamondback Moth (P. xylostella
L.). The results of the median lethal concentrations (LC50) and
the toxicity regression equations of compound IVg and Chlo-
rfenapyr are shown in Table 5. The title compound IVg almost
exhibited equal activity as that of the commercialized Chlo-
rfenapyr.
compd
IVg
Chlorfenapyr
y ) a + bx
LC50 (mg/L)
toxic ratio
y ) -0.9351 + 3.8704x
y ) 0.9679 + 2.8227x
34.12
26.82
0.79
1.00
Insecticidal ActiVity against Green Rice Leafhopper (N.
cincticeps Uhler). The results of the median lethal concentrations
(LC50) and the toxicity regression equations of compound IVg
and Chlorfenapyr are shown in Table 6. The title compound
IVg showed a little lower insecticidal activity against green rice
leafhopper than the commercialized Chlorfenapyr.
Table 7. Insecticidal Activities of IVg and Chlorfenapyr against Bean
Aphids
compd
IVg
Chlorfenapyr
y ) a + bx
LC50 (mg/L)
toxic ratio
y ) 3.4188 + 1.2639x
y ) 4.1005 + 3.8385x
17.83
12.23
0.69
1.00
Insecticidal ActiVity against Bean Aphids (Aphis cracciVora).
The results of the median lethal concentrations (LC50) and the
toxicity regression equations of compound IVg and Chlor-
fenapyr are shown in Table 7. The title compound IVg exhibited
lower insecticidal activities against bean aphids than the com-
mercialized Chlorfenapyr.
In summary, a series of novel 2-aryl-pyrrole derivatives
containing ester groups were synthesized from 4-bromo-1-
(bromomethyl)-2-(4-chlorophenyl)-5-(trifluoromethyl)pyrrole-
against mosquito were evaluated. The results indicate that most
of the title compounds IVa-IVz exhibited excellent activities
against mosquito. For example, the insecticidal activities of
compounds IVb-IVd, IVf, IVg, IVj-IVl, IVs-IVu, IVw, IVx,
and IVz against mosquito at 0.10 mg kg-1 are 100%, which is
parallel to that of the commercialized Chlorfenapyr.
Acaricidal ActiVities against Spider Mite (T. cinnabarinus
BoisduVal). The result of acaricidal activities given in Table 3

10182 J. Agric. Food Chem., Vol. 56, No. 21, 2008
Zhao et al.
1
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3-carbonitrile, and their structures were characterized by H
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Received for review August 8, 2008. Revised manuscript received
September 16, 2008. Accepted September 16, 2008. This work was
supported by the National Natural Science Foundation of China
(20672064).
JF802464D