Design, synthesis, and insecticidal activities of phthalamides containing a hydrazone substructure

Article abstract of DOI:10.1021/jf1000919

Fluobendiamide is the first commercialized artificial synthetic insecticide acting on the ryanodine receptor. This new molecule possesses a combination of excellent insecticidal activity and eco-friendly characteristics with a skeleton structure of phthalamide. In this study, we incorporated hydrazone, present in many pesticidal compounds reported during the last two decades, into phthalamide derivatives via Schiff-base condensation and aminolysis to obtain 21 new compounds; these compounds were characterized by proton nuclear magnetic resonance (¹H NMR), infrared spectroscopy (IR), and high-resolution mass spectrometry (HRMS) or elemental analysis. A preliminary bioassay against peach aphids (Myzus persicae) revealed that the title compounds exhibited good stomach toxicity at 600 mg/L. Twelve new compounds were found to display higher activity than postive control flubendiamide (LC₅₀ = 184.099 mg/L), however, LC₅₀ was less than 100 mg/L only for compounds 4e, 4o, 4s, 4t (59-77 mg/L). That is, combinations of a p-fluorophenyl or (methyl)thienyl group at the Ar position with an isopropyl or cyclohexyl group at the R position might improve the lethality of the designed phthalamide derivative. Preliminary results of a bioassay at 600 mg/L against diamondback moth (Plutella xylostella, Linnaeus) showed that only the title compound 4e possessed good larvicidal activity. On comparison of the bioassay results of stomach toxicity and larvicidal activity, it is noteworthy that the compound incorporating phenylpyrazolyl exhibited good larvicidal activity and poor stomach activity.

Full text of DOI:10.1021/jf1000919

6858 J. Agric. Food Chem. 2010, 58, 6858–6863
DOI:10.1021/jf1000919
Design, Synthesis, and Insecticidal Activities of Phthalamides
Containing a Hydrazone Substructure
†
M
ING
L
IU,† Y
I
W
ANG,† WEI
-
ZI
W
ANGYANG,† FENG
L
IU, YONG
-
LIANG
C
R
UI
,
,‡
Y
OU
-
SHENG
D
UAN,† MIN
W
ANG,† SHANG
-
ZHONG
L
IU,*,† AND
C
HANG
-
HUI
UI
*
†Key Laboratory of Pesticide Chemistry and Application, Ministry of Agriculture,
Department of Applied Chemistry, China Agricultural University, Beijing 100193, People’s Republic of
China, and ‡Key Laboratory of Pesticide Chemistry and Application, Ministry of Agriculture,
Plant Protection Institute, China Academy of Agricultural Sciences, Beijing 100193,
People’s Republic of China
Fluobendiamide is the first commercialized artificial synthetic insecticide acting on the ryanodine
receptor. This new molecule possesses a combination of excellent insecticidal activity and eco-
friendly characteristics with a skeleton structure of phthalamide. In this study, we incorporated
hydrazone, present in many pesticidal compounds reported during the last two decades, into
phthalamide derivatives via Schiff-base condensation and aminolysis to obtain 21 new compounds;
these compounds were characterized by proton nuclear magnetic resonance (1H NMR), infrared
spectroscopy (IR), and high-resolution mass spectrometry (HRMS) or elemental analysis. A
preliminary bioassay against peach aphids (Myzus persicae) revealed that the title compounds
exhibited good stomach toxicity at 600 mg/L. Twelve new compounds were found to display higher
activity than postive control flubendiamide (LC50=184.099 mg/L), however, LC50 was less than 100 mg/
L only for compounds 4e, 4o, 4s, 4t (59-77 mg/L). That is, combinations of a p-fluorophenyl or
(methyl)thienyl group at the Ar position with an isopropyl or cyclohexyl group at the R position
might improve the lethality of the designed phthalamide derivative. Preliminary results of a bioassay
at 600 mg/L against diamondback moth (Plutella xylostella, Linnaeus) showed that only the title
compound 4e possessed good larvicidal activity. On comparison of the bioassay results of stomach
toxicity and larvicidal activity, it is noteworthy that the compound incorporating phenylpyrazolyl
exhibited good larvicidal activity and poor stomach activity.
KEYWORDS: Phthalamides; hydrazone; synthesis; insecticidal activity
INTRODUCTION
messenger, plays a special role in the nervous system and behavior
of insects (2,3). Thus, the ryanodine receptor has been regarded as
one of the potential targets for novel insecticide discovery ever
since it was found that natural ryanodine possessed insecticidal
activity. Although a large number of studies have been conducted
in the last several decades to reduce the mammalian toxicity of
ryanodine by modifying it to uncover new insecticides, all of these
attempts eventually failed (4-7). However, in 1989, when phtha-
lamide derivatives were designed and synthesized as candidate
herbicides (8,9), Tsuda et al. discovered not only that a compound
B found during the optimization of compound A possessed good
insecticidal activity but also that tested insects exhibited poisoning
symptoms remarkably similar to those caused by natural ryano-
dine. Subsequently in 1998, Tohnishi et al. further optimized the
structure of compound B and conducted numerous studies to find
the active molecule flubendiamide (C)-the first artificially synthe-
sized insecticide acting on the ryanodine receptor (10-15)-which
was commercialized in 2008. A brief summary of the discovery
process of flubendiamide is shown in Scheme 1.
The use of synthetic pesticides is one of the most effective
solutions for controlling pest organisms considered harmful to
crop growth in the current agricultural system. However, over
time, some pests become pesticide-resistant due to annual appli-
cations. That is, they adapt to the specific chemical and are no
longer affected by it. In addition, due to environmental concerns
associated with the accumulation of pesticides in food products
and water supplies, there is a great demand for environmentally
friendly products. Pesticide resistance and environmental con-
cerns compel us to choose alternative or new products; therefore,
we must discovernovel active molecules with new modes of action
and eco-friendly properties such as being easily degradable into
nontoxicresidues, being harmless tohuman beings, and beneficial
in meeting the demands of crop protection.
The ryanodine receptor (RyR), also known as the calcium ion
channel receptor, derives its name from the plant metabolite
ryanodine from Ryania speciosa (1). The calcium ion, a secondary
Phthalamide has the skeleton structure of flubendiamide and
is also a new active structure for insecticide discovery. The
*To whom correspondence should be addressed. E-mail: shangzho@
cau.edu.cn (S.L.); chrui@ippcaas.cn (C.R.).
pubs.acs.org/JAFC
Published on Web 05/07/2010
© 2010 American Chemical Society

Article
J. Agric. Food Chem., Vol. 58, No. 11, 2010 6859
Scheme 1. The Brief Discovery Process of Flubendiamide
Scheme 2. General Synthetic Route for Title Compounds 4a-u
Table 1. Types of Ar and R Groups in Title Compounds 4a-4u
compd
Ar
R
4a
4b
4c
4d
4e
4f
2-chlorophenyl
2-chlorophenyl
2-fluorophenyl
2-fluorophenyl
4-fluorophenyl
4-fluorophenyl
isopropyl
cyclohexyl
butyl
cyclohexyl
isopropyl
butyl
4g
4h
4i
4-(trifluoromethyl)phenyl
4-hydroxyphenyl
4-hydroxyphenyl
2-furanyl
butyl
isopropyl
cyclohexyl
isopropyl
butyl
4j
4k
4l
2-furanyl
2-furanyl
cyclohexyl
isopropyl
cyclohexyl
isopropyl
butyl
4m
4n
4o
4p
4q
4r
2-methyl-5-furanyl
2-methyl-5-furanyl
2-thienyl
2-thienyl
2-thienyl
cyclohexyl
isopropyl
cyclohexyl
isopropyl
cyclohexyl
3-methyl-2-thienyl
3-methyl-2-thienyl
5-methyl-2-thienyl
5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl
4s
4t
functional group hydrazone exists as an active substructure in
many biologically active compounds. For example, hydramethyl-
non, the first insecticide containing hydrazone, was launched
in 1980 to control ants and black beetles. Subsequently, many
active pesticidal molecules incorporating the functional group
hydrazone (16-20) were reported in the 1990s as follows: benzo-
phenone hydrazone derivatives were reported in 1993 by Syn-
genta to control Diabrotica balteata on corn and in 1996 by Bayer
to control Plutella xylostella on cabbage. In addition, some
heteroaryl hydrazone compounds as acaricides and insecticides
were introduced in 2000 by Sankyo Pharmaceuticals Co., Ltd.,
and Nippon Kayaku Co., Ltd. In order to discover new molecules
acting on the ryanodine receptor, we sought to incorporate the
active substructural unit hydrazone into the backbone structure
of flubendiamide. On the basis of molecular similarity and the
principle of combining active substructures, we designed and
synthesized the title compounds. This paper describes the synthe-
ses and bioactivities of the designed compounds.
4u
General Synthetic Procedure for Compound 2. A mixture of
5-chloroisoindoline-1,3-dione (1; 18.15 g, 100.0 mmol) in N,N-dimethyl-
formamide (DMF; 100 mL) was cooled to -15 °C and stirred for 2 h after
the addition of 99% hydrazine hydrate (5.50 g, 110.0 mmol). When the
reaction was completed, the mixture was poured into 300 mL of water, and
the resulting precipitate was filtered to obtain a yellow solid (2; 6.48 g,
33.0%); mp 178-179 °C. 1H NMR (300 MHz, DMSO-d6): δ 7.93-7.92
(m, 1H, Ph H), 7.90-7.86 (m, 2H, Ph H), 4.97 (s, 2H, NNH2).
General Synthetic Procedure for the Title Compounds 4a-u
(Scheme 2 and Table1). Synthesis of (E/Z)-2-(Cyclohexylcarbamoyl)-
5-chloro-N0-((5-methylfuran-2-yl)methylene)benzohydrazide (4n). To a
solution of 2 (1.97 g, 10 mmol) and 5-methyl-2-furanal (1.10 g, 10 mmol)
in 1,4-dixoane (100 mL) was added 12 N HCl (0.1 mL) at room tem-
perature. After the reaction mixture was stirred for 5-10 min, a solution of
cyclohexanamine (1.98 g, 20 mmol) in tetrahydrofuran (THF; 10 mL) was
added, and the reaction mixture was stirred overnight at room tempera-
ture. When the reaction was complete, the solvent was evaporated under
reduced pressure, and the resulting mixture was dissolved in ethyl acetate
(80 mL); this was followed by washing with H2O (3 ꢀ 30 mL) and drying
with anhydrous sodium sulfate. Ethyl acetate was evaporated under
reduced pressure to give a yellow solid as the crude product, which was
recrystallized with a mixture of THF and n-hexane (1:1, v/v) to obtain
the pure product 4n (2.40 g). Yield: 61.9%; light yellow solid. Mp:
MATERIALS AND METHODS
Instruments. Melting points were measured using a Fisher-Johns
melting point apparatus (Cole-Parmer Co.) without correcting the ther-
mometer. 1H nuclear magnetic resonance (1H NMR) spectra were
recorded on a Bruker Advance DPX 300 (Bruker Co.) spectrometer using
tetramethylsilane (TMS) as an internal reference. Chemical shift values
(δ) were given in parts per million (ppm). Infrared spectra were obtained
on Bruker IR-Tensor 27 spectrophotometer (Bruker Co.) using potas-
sium bromide pellets and were reported as wavenumbers (cm-1). Ele-
mental analysis was performed on a Yanaco Corder MT-3 (Yanaco Co.,
Ltd.) elemental analyzer. Mass spectra were recorded using a high-
resolution mass spectrometry (HRMS) spectrometer HPLC-1100/TOF
MS (Agilent Co.).
1
123-124 °C. H NMR (DMSO-d6): δ 11.65 (br s, 1H, CONHNdCH),
8.32-8.17 (m, 1H, Ph H), 8.05 (s, 0.7H, NdCH), 7.77 (s, 0.3H, NdCH),
7.64-7.40 (m, 3H, CONHCH þ Ph H), 6.80-6.16 (m, 2H, furanyl), 3.65
(br s, 0.7H, CONHCH), 3.62 (br s, 0.3H, CONHCH), 2.35 (s, 2H, CH3),
2.26 (s, 1H, CH3), 1.82-1.54 (m, 5H, cyclohexyl), 1.25-1.05 (m, 5H,
cyclohexyl). HRMS: m/z calcd for C20H23ClN3O3 (M þ H)þ 388.1428,
found 388.1976.
Reagents. All solvents and liquid reagents were of analytical reagent
grade and were dried in advance and redistilled before use. Flash column
chromatography with silica gel was used to purify the crude product.
The title compounds 4a-m,o-u were prepared by the same reaction
procedure as that described above. However, when R in the amine was an
n-butyl group, the crude products of compounds 4c, 4f, 4g, 4k, 4p were

6860 J. Agric. Food Chem., Vol. 58, No. 11, 2010
Liu et al.
purified by flash column chromatography with a mixture of ethyl acetate
and n-hexane (1:1 v/v) as the effluent.
Data for (E/Z)-2-(Cyclohexylcarbamoyl)-N0-(4-hydroxybenzylidene)-
5-chlorobenzohydrazide (4i). Yield: 58.5%; light yellow solid. Mp:
193-195 °C. H NMR (DMSO-d6): δ 11.64 (br s, 1H, CONHNdCH),
1
Data for (E/Z)-2-(Isopropylcarbamoyl)-N0-(2-chlorobenzylidene)-5-
chlorobenzohydrazide (4a). Yield: 64.6%; white solid. Mp: 199-202 °C.
1H NMR (DMSO-d6):δ12.04-11.83 (m, 1H, CONHNdCH), 8.67(s, 0.5H,
NdCH), 8.35 (s, 0.5H, NdCH), 8.39-8.35 (m, 1H, Ph H), 8.01-7.97 (m,
0.5H, Ph H), 7.69-7.26 (m, 6.5H, CONHCH þ Ph H), 4.00-3.77 (m, 1H,
CONHCH), 1.13 (d, J=6.57 Hz, 2.7H, CH(CH3)2), 0.92 (d, J=6.57 Hz,
9.81 (br s, 1H, OH), 8.29-8.25 (m, 1H, Ph H), 8.15 (s, 0.5H, NdCH), 7.83
(s, 0.5H, NdCH), 7.65-7.41 (m, 4H, CONHCH þ Ph H), 7.26 (d, J=
8.66 Hz, 1H, Ph H), 6.82 (d, J=8.58 Hz, 1H, Ph H), 6.72 (d, J=8.58 Hz,
1H, Ph H), 3.64 (br s, 0.5H, CONHCH), 3.50 (br s, 0.5H, CONHCH),
1.82-1.48 (m, 5H, cyclohexyl), 1.26-0.86 (m, 5H, cyclohexyl). HRMS:
m/z calcd for C21H23ClN3O3 (M þ H)þ 400.1428, found 400.2010.
Data for (E/Z)-2-(Isopropylcarbamoyl)-5-chloro-N0-((furan-2-yl)methylene)-
benzohydrazide (4j). Yield: 25.8%; yellow solid. Mp: 197-199 °C. 1H
NMR (DMSO-d6): δ 11.76 (s, 0.6H, CONHNdCH), 11.58 (0.4H, CON-
HNdCH), 8.35-8.24 (m, 1H, Ph H), 8.15 (s, 0.6H, NdCH), 7.85 (s, 0.4H,
NdCH), 7.85 (s, 0.6H, CONHCH), 7.68 (s, 0.4H, CONHCH), 7.64-7.40
(m, 3H, furanyl þ Ph H), 6.94-6.53 (m, 2H, furanyl), 4.00-3.82 (m, 1H,
CONHCH), 1.13 (d, J=6.57 Hz, 3H, CH(CH3)2), 0.96 (d, J=6.57 Hz, 3H,
CH(CH3)2). HRMS: m/z calcd for C16H17ClN3O3 (M þ H)þ 334.0958,
found 334.1331.
þ
3.3H, CH(CH3)2). HRMS: m/z calcd for C18H18Cl2N3O2 (M þ H)
378.0776, found 378.1127.
Data for (E/Z)-2-(Cyclohexylcarbamoyl)-N0-(2-chlorobenzylidene)-5-
chlorobenzohydrazide (4b). Yield: 33.5%; white solid. Mp: 206-209 °C.
1H NMR (DMSO-d6): δ 11.80 (br s, 1H, CONHNdCH), 8.68 (s, 0.45H,
NdCH), 8.36 (s, 0.55H, NdCH), 8.36-8.30 (m, 1H, Ph H), 8.02-7.99 (m,
1H, Ph H), 7.67-7.26 (m, 6H, CONHCH þ Ph H), 3.63, 3.48 (br s,
1H, CONHCH), 1.82-1.47 (m, 5H, cyclohexyl), 1.29-0.86 (m, 5H,
cyclohexyl). Anal. Calcd for C21H21Cl2N3O2: C, 60.30; H, 5.06; N,
10.05. Found: C, 60.27; H, 5.10; N, 10.06.
Data for (E/Z)-2-(Butylcarbamoyl)-5-chloro-N0-((furan-2-yl)methylene)-
benzohydrazide (4k). Yield: 25.9%; brown solid. Mp: 123-125 °C. 1H
NMR (DMSO-d6): δ 11.77-11.59 (m, 1H, CONHNdCH), 8.51-8.40
(m, 1H, Ph H), 8.13 (s, 0.5H, NdCH), 7.95-7.41 (m, 4.5H, CONHCH2þ
0.5NdCH þ furanyl þ Ph H), 6.94-6.54 (m, 2H, furanyl), 3.20-3.13 (m,
1.1H, CONHCH2), 3.03-3.00 (m, 0.9H, CONHCH2), 1.49-1.17 (m 4H,
CH2CH2CH2CH3), 0.88 (t, J=7.2 Hz, 2H, CH2CH3), 0.75 (t, J=7.2 Hz,
1H, CH2CH3). HRMS: m/z calcd for C17H19ClN3O3 (M þ H)þ 348.1115,
found 348.1455.
Data for (E/Z)-2-(Butylcarbamoyl)-N0-(2-fluorobenzylidene)-5-chloro-
benzohydrazide (4c). Yield: 5.3%; white solid. Mp: 84-86 °C. 1H NMR
(DMSO-d6): δ 11.75 (br s, 1H, CONHNdCH), 8.51 (s, 0.5H, NdCH),
8.51-8.46 (m, 1H, Ph H), 8.18 (s, 0.5H, NdCH), 7.94-7.87 (m, 0.5H,
Ph H), 7.69-7.13 (m, 6.5H, CONHCH2 þ Ph H), 3.21-3.15 (m, 1H,
CONHCH2), 3.00-2.96 (m, 1H, CONHCH2), 1.50-1.09 (m, 4H,
CH2CH2CH2CH3), 0.87 (t, J = 7.2 Hz, 1.5H, CH2CH3), 0.68 (t, J =
5.67 Hz, 1.5H, CH2CH3). Anal. Calcd for C19H19ClFN3O2: C, 60.72; H,
5.10; N, 11.18. Found: C, 60.48; H, 5.14; N, 11.07.
Data for (E/Z)-2-(Cyclohexylcarbamoyl)-N0-(2-fluorobenzylidene)-5-
chlorobenzohydrazide (4d). Yield: 45.1%; white solid. Mp: 157-160 °C.
1H NMR (DMSO-d6): δ 11.00 (br s, 1H, CONHNdCH), 8.53 (s, 0.5H,
NdCH), 8.38-8.32 (m, 1H, Ph H), 7.98-7.92 (m, 0.5H, Ph H), 8.18 (s,
0.5H, NdCH), 7.70-7.14 (m, 6.5H, CONHCH þ Ph H), 3.65 (br s, 0.5H,
CONHCH), 3.49 (br s, 0.5H, CONHCH), 1.83-1.47 (m, 5H, cyclohexyl),
1.30-0.96 (m, 5H, cyclohexyl). HRMS: m/z calcd for C21H22ClFN3O2
(M þ H) þ 402.1385, found 402.1744.
Data for (E/Z)-2-(Cyclohexylcarbamoyl)-5-chloro-N0-((furan-2-yl)-
methylene)benzohydrazide (4l). Yield: 18.7%; yellow solid. Mp: 137-
1
138 °C. H NMR (DMSO-d6): δ 11.77-11.56 (m, 1H, CONHNdCH),
8.35-8.18 (m, 1H, Ph H), 8.15 (s, 0.6H, NdCH), 7.85 (s, 0.4H, NdCH),
7.85 (s, 0.6H, CONHCH), 7.67 (s, 0.4H, CONHCH), 7.64-7.40 (m, 3H,
furanyl þ Ph H), 6.94-6.53 (m, 2H, furanyl), 3.63-3.49 (m, 1H,
CONHCH), 1.82-1.50 (m, 5H, cyclohexyl), 1.25-0.96 (m, 5H, cy-
clohexyl). HRMS: m/z calcd for C19H21ClN3O3 (M þ H)þ 374.1271,
found 374.1649.
Data for (E/Z)-2-(Isopropylcarbamoyl)-N0-(4-fluorobenzylidene)-5-
chlorobenzohydrazide (4e). Yield: 42.0%; white solid. Mp: 109-111 °C.
1H NMR (DMSO-d6): δ 11.85-11.65 (m, 1H, CONHNdCH), 8.36-8.27
(m, 1H, Ph H), 8.27 (s, 0.5H, NdCH), 7.94 (s, 0.5H, NdCH), 7.78-7.11
(m, 7H, CONHCH þ Ph H), 3.98-3.96 (m, 0.5H, CONHCH), 3.82-3.79
(m, 0.5H, CONHCH), 1.14 (d, J=6.45 Hz, 3H, CH(CH3)2), 0.92 (d, J=
6.45 Hz, 3H, CH(CH3)2). HRMS: m/z calcd for C18H18ClFN3O2
(M þ H)þ 362.1072, found 362.1198.
Data for (E/Z)-2-(Isopropylcarbamoyl)-5-chloro-N0-((5-methylfuran-
2-yl)methylene)benzohydrazide (4m). Yield: 61.5%; light yellow solid.
Mp: 168-170 °C. 1H NMR (DMSO-d6): δ 11.62 (br s, 1H, CON-
HNdCH), 8.33-8.25 (m, 1H, Ph H), 8.07 (s, 0.4H, NdCH), 7.77 (s,
0.4H, NdCH), 7.65-7.41 (m, 3H, CONHCH þ Ph H), 6.81-6.79 (m,
0.6H, furanyl), 6.65-6.64 (m, 0.4H, furanyl), 6.27-6.26 (m, 0.6H,
furanyl), 6.17-6.15 (m, 0.4H, furanyl), 3.99-3.80 (m, 1H, CONHCH),
2.35 (s, 2H, CH3), 2.26 (s, 1H, CH3), 1.13 (d, J=6.57 Hz, 4H, CH(CH3)2),
0.98 (d, J=6.57 Hz, 2H, CH(CH3)2). HRMS: m/z calcd for C17H19ClN3O3
(M þ H)þ 348.1115, found 348.1490.
Data for (E/Z)-2-(Butylcarbamoyl)-N0-(4-fluorobenzylidene)-5-chloro-
benzohydrazide (4f). Yield: 37.8%; light yellow solid. Mp: 131-133 °C. 1H
NMR (DMSO-d6): δ 11.79 (br s, 1H, CONHNdCH), 8.49-8.43 (m, 1H,
Ph H), 8.27 (s, 0.5H, NdCH), 7.94 (s, 0.5H, NdCH), 7.80-7.12 (m, 7H,
CONHCH2 þ Ph H), 3.19-3.15 (m, 1H, CONHCH2), 3.01-2.97 (m, 1H,
CONHCH2), 1.50-1.12 (m, 4H, CH2CH2CH2CH3), 0.87 (t, J=7.2 Hz,
1.5H, CH2CH3), 0.68 (t, J=7.2 Hz, 1.5H, CH2CH3). HRMS: m/z calcd for
C19H20ClFN3O2 (M þ H)þ 376.1228, found 376.1574.
Data for (E/Z)-2-(Isopropylcarbamoyl)-5-chloro-N0-((thiophen-2-yl)-
methylene)benzohydrazide (4o). Yield: 69.1%; white solid. Mp: 110-
111 °C. 1H NMR (DMSO-d6): δ 11.76 (s, 0.65H, CONHNdCH), 11.60
(s, 0.35H, CONHNdCH), 8.47 (s, 0.64H, NdCH), 8.36-8.23 (m, 1H, Ph
H), 8.12 (s, 0.36H, NdCH), 7.71-7.32 (m, 5H, CONHCH þ thienyl þ Ph
H), 7.16-7.13 (m, 0.65H, thienyl), 7.06-7.03 (m, 0.35H, thienyl),
3.97-3.81 (m, 1H, CONHCH), 1.13 (d, J=6.57 Hz, 4H, CH(CH3)2),
0.96 (d, J=6.54 Hz, 2H, CH(CH3)2). HRMS: m/z calcd for C16H17ClN3O2S
(MþH)þ 350.0730, found 350.0806.
Data for (E/Z)-2-(Butylcarbamoyl)-N0-(4-(trifluoromethyl)benzylidene)-
5-chlorobenzohydrazide (4g). Yield: 17.8%; white solid. Mp: 169-171 °C.
1H NMR (DMSO-d6): δ 11.99, 11.83 (s, 1H, CONHNdCH), 8.49-8.45
(m, 1H, Ph H), 8.33 (s, 0.5H, NdCH), 8.01 (s, 0.5H, NdCH), 8.00-7.46
(m, 7H, CONHCH2 þ Ph H), 2.97-2.91 (m, 1.2H, CONHCH2), 3.20-
3.14 (m, 0.8H, CONHCH2), 1.49-1.06 (m 4H, CH2CH2CH2CH3), 0.87
(t, J=7.24 Hz, 1.4H, CH2CH3), 0.63 (t, J=7.24 Hz, 1.6H, CH2CH3). Anal.
Calcd for C20H19ClF3N3O2: C, 56.41; H, 4.50; N, 9.87. Found: C, 56.37;
H, 4.49; N, 9.83.
Data for (E/Z)-2-(Butylcarbamoyl)-5-chloro-N0-((thiophen-2-yl)methylene)-
benzohydrazide (4p). Yield: 40.1%;light yellowsolid. Mp: 119-121 °C. 1H
NMR (DMSO-d6): δ 11.73 (br s, 1H, CONHNdCH), 8.47 (s, 0.7H,
NdCH), 8.47-8.39 (m, 1H, Ph H), 8.12 (s, 0.3H, NdCH), 7.69-7.31 (m,
5H, CONHCH2 þ thienyl þ Ph H), 7.16-7.13 (m, 0.65H, thienyl),
7.06-7.03 (m, 0.35H, thienyl), 3.2 (m, 1.3H, CONHCH2), 3.05-3.00
(m, 0.7H, CONHCH2), 1.49-1.14 (m 4H, CH2CH2CH2CH3), 0.88 (t, J=
7.17 Hz, 1H, CH2CH3), 0.75 (t, J=7.17 Hz, 1H, CH2CH3). Anal. Calcd
for C17H18ClN3O2S: C, 56.12; H, 4.99; N, 11.55. Found: C, 55.85; H, 4.94;
N, 11.41.
Data for (E/Z)-2-(Isopropylcarbamoyl)-N0-(4-hydroxybenzylidene)-5-
chlorobenzohydrazide (4h). Yield: 36.1%; white solid. Mp: 139-140 °C.
1H NMR (DMSO-d6): δ 11.59 (s, 0.5H, CONHNdCH), 11.41 (m, 0.5H,
CONHNdCH), 9.94 (s, 0.5H, OH), 9.78 (s, 0.5H, OH), 8.34-8.23 (m, 1H,
Ph H), 8.15 (s, 0.5H, NdCH), 7.83 (s, 0.5H, NdCH), 7.65-7.41 (m, 4H,
CONHCH þ Ph H), 7.29-7.26 (d, J=8.67 Hz, 1H, Ph H), 6.85-6.82 (d,
J=8.58 Hz, 1H, Ph H), 6.72-6.69 (d, J=8.58 Hz, 1H, Ph H), 3.99-3.93
(m, 0.5H, CONHCH), 3.83-3.76 (m, 0.5H, CONHCH), 1.13 (d, J=6.6
Hz, 3H, CH(CH3)2), 0.94 (d, J=6.6 Hz, 3H, CH(CH3)2). HRMS: m/z
calcd for C18H19ClN3O3 (M þ H)þ 360.1115, found 360.1588.
Data for (E/Z)-2-(Cyclohexylcarbamoyl)-5-chloro-N0-((thiophen-2-
yl)methylene)benzohydrazide (4q). Yield: 51.8%; yellow solid. Mp:
122-125 °C. 1H NMR (DMSO-d6): δ 11.77, 11.60 (br s, 1H, CON-
HNdCH), 8.47 (s, 0.7H, NdCH), 8.36 (d, J=7.86 Hz, 0.7H, Ph H), 8.19
(d, J=7.86 Hz, 0.3H, Ph H), 8.12 (s, 0.3H, NdCH), 7.71-7.32 (m, 5H,

Article
J. Agric. Food Chem., Vol. 58, No. 11, 2010 6861
CONHCH þ thienyl þ Ph H), 7.156-7.13 (m, 1H, thienyl), 7.06-7.03
(m, 1H, thienyl), 3.63-3.51 (m, 1H, CONHCH), 1.81-1.49 (m, 5H,
cyclohexyl), 1.26-0.98 (m, 5H, cyclohexyl). HRMS: m/z calcd for
C19H21ClN3O2S (M þ H)þ 390.1043, found 390.1494.
Table 2. Optimization of Reaction Conditions for Preparation of Compound 2
entry
solvent
time (min)
temp (°C)
yield (%)
1
EtOH
EtOH
EtOH
EtOH
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
2
40
78
30
0
Data for (E/Z)-2-(Isopropylcarbamoyl)-5-chloro-N0-((3-methylthiophen-
2-yl)methylene)benzohydrazide (4r). Yield: 40.7%; light yellow solid. Mp:
2
15.0
4.9
3
40
15
1
132-134 °C. H NMR (DMSO-d6): δ 11.61 (br s, 1H, CONHNdCH),
4
120
40
15
3.1
8.54 (s, 0.7H, NdCH), 8.26 (s, 0.3H, NdCH), 8.34-8.16 (m, 1H, Ph H),
8.18 (s, 0.3H, NdCH), 7.71-7.39 (m, 4H, CONHCH þ thienyl þ Ph H),
6.97 (d, J=5.03 Hz, 0.65H, thienyl), 6.87 (d, J=5.03 Hz, 0.35H, thienyl),
4.00-3.73 (m, 1H, CONHCH), 2.30 (s, 2H, CH3), 2.20 (s, 1H, CH3), 1.13
(d, J=6.57 Hz, 4H, CH(CH3)2), 0.98 (d, J=6.57 Hz, 2H, CH(CH3)2).
HRMS: m/z calcd for C17H19ClN3O2S (M þ H)þ 364.0887, found
364.1257.
5
15
19.0
15.4
25.2
24.8
9.9
6
120
40
15
7
5
8
120
40
5
9
-5
-5
-15
-15
-15
10
11
12
13
120
40
10.1
17.5
33.0
33.6
Data for (E/Z)-2-(Cyclohexylcarbamoyl)-5-chloro-N0-((3-methylthio-
phen-2-yl)methylene)benzohydrazide (4s). Yield: 11.4%; light yellow solid.
Mp: 121-124 °C. 1H NMR (DMSO-d6): δ 11.68 (br s, 1H, CON-
HNdCH), 8.54 (s, 0.7H, NdCH), 8.37-8.29 (m, 0.7H, Ph H), 8.18 (s,
0.3H, NdCH), 8.08-8.06 (m, 0.3H, Ph H), 7.86-7.39 (m, 4H, CONHCH þ
thienyl þ Ph H), 6.97 (d, J=5.03 Hz, 0.65H, thienyl), 6.88 (d, J=5.03 Hz,
0.35H, thienyl), 3.65-3.51 (m, 1H, CONHCH), 2.30 (s, 2H, CH3), 2.20 (s,
1H, CH3), 1.82-1.51 (m, 5H, cyclohexyl), 1.26-1.04 (m, 5H, cyclohexyl).
HRMS: m/z calcd for C20H23ClN3O2S (M þ H)þ 404.1200, found
404.1637.
120
150
RESULTS AND DISCUSSION
Synthesis. As shown in Scheme 2, 5-chloroisoindoline-1,3-
dione (1) reacted with 99% hydrazine hydrate in DMF to give
N-amino-5-chloroisoindoline-1,3-dione (2). Compound 2 con-
densed with aldehydes via a Schiff base condensation to give
compound 3, which was followed by a ring-opening reaction with
amines to afford the title compounds 4a-u.
Sanz et al. reported in 2002 that compound 2 was prepared
from compound 1 (R=H) and 99% hydrazine hydrate in ethanol
at reflux (24). We followed this method and found that the
obtained product was not the desired compound but the product
isomer 6-chloro-2,3-dihydrophthalazine-1,4-dione after struc-
tural characterization with 1H NMR (at 300 MHz in DMSO; δ
7.91-8.10 (m, 3H, Ph H), 11.71 (br s, 2H, NHNH)). When we
sought to conduct this reaction at a temperature of 30 °C, the
desired product was obtained with a yield of 15%. When the
reaction temperature was further decreased to 15 °C, the reaction
yield also decreased to 4.9%. However, when DMF was used as
the solvent instead of ethanol, the reaction yield could reach
33.6% by varying the reaction time and temperature. The detailed
yields under different conditions are listed in Table 2.
Data for (E/Z)-2-(Isopropylcarbamoyl)-5-chloro-N0-((5-methylthio-
phen-2-yl)methylene)benzohydrazide (4t). Yield: 58.8%; light yellow solid.
Mp: 166-169 °C. 1H NMR (DMSO-d6): δ 11.73 (br s, 1H, CON-
HNdCH), 8.37 (s, 0.7H, NdCH), 8.34-8.10 (m, 1H, Ph H), 8.01 (s, 0.3H,
NdCH), 7.90-7.38 (m, 3H, CONHCH þ Ph H), 7.27-6.58 (m, 2H,
thienyl), 4.38-4.30 (m, 0.3H, CONHCH), 4.02-3.81 (m, 0.7H, CON-
HCH), 2.49 (s, 2H, CH3), 2.38 (s, 1H, CH3), 1.13 (d, J=6.58 Hz, 3.3H,
CH(CH3)2), 0.98 (d, J=6.58 Hz, 1.7H, CH(CH3)2). HRMS: m/z calcd for
C17H19ClN3O2S (M þ H)þ 364.0887, found 364.0915.
Data for (E/Z)-2-(Cyclohexylcarbamoyl)-5-chloro-N0-((5-chloro-3-methyl-
1-phenyl-1H-pyrazol-4-yl)methylene)benzohydrazide (4u). Yield: 57.8%;
1
white solid. Mp: 207-208 °C. H NMR (DMSO-d6): δ 11.67 (br s, 1H,
CONHNdCH), 8.33-8.15 (m, 1H, Ph H), 8.28 (s, 0.5H, NdCH), 8.16
(s, 0.5H, NdCH), 7.74-7.41 (m, 8H, CONHCH þ Ph H), 3.57 (br s, 1H,
CONHCH), 2.50 (s, 1.5H, CH3), 1.92 (s, 1.5H, CH3), 1.83-1.53 (m, 5H,
cyclohexyl), 1.27-1.07 (m, 5H, cyclohexyl). HRMS: m/z calcd for
C25H26Cl2N5O2 (M þ H)þ 498.1464, found 498.2056.
The title compounds could be prepared via condensation of
compound 2 with different aldehydes and a ring-opening reaction
of the substituted amine in two separate steps (25, 26). In this
study, we attempted to combine the two reactions into a single pot
to obtain the desired products. When R in the amine was an
n-butyl group, the title compounds 4c, 4f, 4g, 4k, 4p were produced
as characterized by LC/MS. However, these compounds decom-
posed easily during removal of the solvent 1,4-dioxane (bp 101.5 °C)
via distillation. Subsequently, we attempted to use the low-boiling-
point solvent THF (bp 65.4 °C) as the reaction solvent and
obtained the corresponding products via purification of flash
column chromatography instead of recrystallization with lower
yields. Moreover, some title compounds such as 4j, 4l, 4s were also
obtained at lower yields (10-30%) after recrystallization because
of their good solubility in a mixture of THF and n-hexane.
In principle, the reaction of unsymmetric compound 2 with
aromatic aldehyde and amine could afford a pair of regioisomeric
products 4 and 5 (Scheme 2). In practice, only 4 was found after
the product was characterized using the heteronuclear multiple-
bond correlation (HMBC) and heteronuclear single-quantum
Biological Assay. The bioassay was performed ona representativetest
organism reared in the laboratory, and it 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, in which 0=no
activity and 100=total kill.
Stomach Toxicity against Peach Aphids (Myzus persicae). Adult
peach aphids were collected from vegetable fields of Haidian District,
Beijing, and bred indoors. The insecticidal activity of the title compounds
was tested against 3-day-old nymphs following foliar application. About
50 aphids were transferred to a shoot with cabbage leaves. The shoot with
aphids was cut and dipped in a solution of 600 mg/L of the test compound
for 5 s. After removing the extra solution on the leaves, the aphids were
raised in the shoot at 25 ( 1 °C and 85% relative humidity for 24 h. Each
treatment was carried out two times. Insecticidal activity was also tested
with concentrations of 200, 50, and 12.5 mg/L. For comparative purposes,
flubendiamide was tested as well. The corrected mortality rate was
calculated by Abbott’s formula.
Larvicidal Activity against Diamondback Moths (Plutella xylos-
tella Linnaeus). Adult diamondback moths were collected from vege-
table fields of Haidian District, Beijing, and bred indoors. The larvicidal
activity of the title compounds against second instar larvae was tested by
the leaf-dip method as follows, using a previously reported procedure
(22,23). Leaf disks (2.0 cm in diameter) cut from fresh cabbage leaves were
dipped in the test solution for 5 s. After air-drying, the treated leaf disks
were placed in a tube (6.0 cm inner diameter) lined with a piece of filter
paper, and then the instar diamondback moth larvae were transferred to
the tube within 10 s. Mortality rates as percentages were evaluated 3 days
after treatment, and two replications were carried out. For comparative
purposes, flubendiamide was also tested.
1
correlation (HSQC) techniques of NMR. However, H NMR
clearly showed that the product still constituted a pair of
geometric trans and cis isomers because of the CdN double bond
in hydrazone. Thus, there are two different chemical shifts for
some protons in the 1H NMR spectra of the product, particularly
for protons in the CdN double bond.
Bioassay. Stomach Toxicity against Peach Aphids (Myzus
persicae). The results of stomach toxicities of compounds 4a-u

6862 J. Agric. Food Chem., Vol. 58, No. 11, 2010
Liu et al.
Table 3. Insecticidal Activities of Title Compounds 4a-u Against Myzus
persicae
Table 4. Insecticidal Activities of Title Compounds 4a-u against Plutella
xylostella Linnaeus
mortality (%)
compd
mortality at a concn of 600 mg/L (%)
compd
600 mg/L 200 mg/L 50 mg/L 12.5 mg/L LC50 (mg/L)
4a
4b
4c
4d
4e
4f
33.3
66.7
22.2
33.3
100
4a
4b
4c
4d
4e
4f
92.9
100
28.2
41.3
39.6
23.8
57.8
20.0
49.3
55.6
24.6
29.3
20.0
15.7
50
12.5
28.0
34.0
8.3
16.3
26.2
9.7
170.644
148.396
121.941
276.113
68.055
94.6
90.2
91.3
97.7
96.6
5.9
33.3
33.3
55.6
55.6
44.4
44.4
33.3
44.4
33.3
0
52.8
18.6
22.9
16.9
19.4
25.4
11.7
20.0
16.9
7.3
21.9
19.0
12.5
5.4
4g
4h
4i
309.938
130.043
128.575
244.229
161.476
234.069
221.334
121.636
271.415
70.515
4g
4h
4i
100
92.6
100
4j
25.7
18.6
0
4k
4l
4j
4k
4l
100
100
4m
4n
4o
4p
4q
4r
8.2
4m
4n
4o
4p
4q
4r
96.4
13.8
0
93.0
98.7
98.6
98.8
90.6
90.6
16.0
45.5
35.7
37.8
56.1
45.2
52.3
9.5
44.4
33.3
44.4
11.1
55.6
66.7
30.3
23.3
13.5
25.5
41.7
32.7
9.1
24.0
9.4
124.039
113.217
124.447
58.903
19.6
16.3
22.4
29.3
16.7
4s
4t
4s
4t
4u
100
91.9
76.178
266.287
184.099
4u
flubendiamide
activity against diamondback moths compared to control
flubendiamide. The bioassay results indicated that the toxi-
cities of new compounds on the tested species did not exhibit
the expected excellent biological activities. Nonetheless, the
relationships between structure and activity obtained in this
study, such as the incorporation of (un)substituted thienyl,
(un)substituted phenyl and isopropyl, and cyclohexyl at different
positions of phthalamide could be beneficial in achieving the
further modification of designed structures for discovering new
insecticidal molecules.
against peach aphid (Myzus persicae) in Table 3 indicated that
most of the compounds had excellent stomach toxicity against
peach aphids at a concentration of 600 mg/mL, and 12 com-
pounds were found to display higher activity than the control,
flubendiamide (LC50=184.099 mg/L). However, the toxicities of
those 12 decreased significantly when the concentrations of test
compounds were reduced to 200 mg/mL or lower. Compounds
4e, 4o, 4s, 4t exhibited slightly higher activity (LC50<77 mg/L)
than other title compounds, suggesting that the introduction of
p-fluorophenyl or (methyl)thienyl groups at the Ar position and
isopropyl or cyclohexyl groups at the R position could have a
positive effect on stomach toxicity. Since substituted pyrazolyl
appears as a functional group in some commercial insecticidal
molecules such as fipronil and chlorantraniliprole, in this study,
we incorporated a substituted phenylpyrazolyl group into the
designed structure. However, compound 4u showed the lowest
activity among all compounds at a concentration of 200 mg/mL
and had a higher LC50 value (266 mg/L). This revealed that the
introduction of a 5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl
group could not improve stomach toxicity.
ACKNOWLEDGMENT
This work was supported by the National Natural Science
Foundation of China (NNSFC) (No. 20972186) and the National
Basic Research Program of China (No. 2010CB126105).
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Received for review August 6, 2009. Revised manuscript received April
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