Design, synthesis, and analysis of the quantitative structure-activity relationships of 4-phenyl-acyl-substituted 3-(2,5-dimethylphenyl)-4-hydroxy-1- azaspiro[4.5]dec-3-ene-2,8-dione derivatives

Article abstract of DOI:10.1021/jf3002069

A series of 4-phenyl-acyl-substituted 3-(2,5-dimethylphenyl)-4-hydroxy-1- azaspiro[4.5]dec-3-ene-2,8-dione derivatives were designed and synthesized, and their structures were characterized using ¹H NMR (or ¹³C NMR), mass spectrometry, and elemental analysis. The bioactivities of the new compounds were evaluated. These compounds exhibited good inhibition activities against bean aphids (Aphis fabae) and carmine spider mite (Tetranychus cinnabarinus), and 4-phenyl acyl esters showed stronger bioactivity than 4-arylesterases and alkyl esters. The results showed that compound 8-I-e, which contains a para-methoxy group on the phenyl acyl, and compound 8-I-m, which contains a para-trifluoromethyl group on the phenyl acyl, displayed potent insecticidal activity against A. fabae and T. cinnabarinus respectively. The insecticidal activity showed a clear structure-activity relationship, confirming the importance of the flexible bridge. The DFT/B3LYP/6-31(d) level method was used to calculate molecular geometries and electronic descriptors. These factors included total energy, charge distribution, and the linear orbital level of the title compounds. Quantitative structure-activity relationship studies were performed on these compounds using quantum-chemical and physicochemical parameters as independent variables and insecticidal activity as a dependent variable. Insecticidal activity was most closely correlated (r > 0.8) with quantum chemical and physicochemical parameters.

Full text of DOI:10.1021/jf3002069

Article
pubs.acs.org/JAFC
Design, Synthesis, and Analysis of the Quantitative
Structure−Activity Relationships of 4-Phenyl-acyl-substituted
3-(2,5-Dimethylphenyl)-4-hydroxy-1-azaspiro[4.5]dec-3-ene-2,8-
dione Derivatives
Jinhao Zhao,*,†,‡ Jiangong Zhang,† Bingrong Xu,†,‡ Zongcheng Wang,§ Jingli Cheng,† and Guonian Zhu†
†Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Pesticide and Environment
Toxicology, Zhejiang University, Hangzhou 310029, China
‡Key Laboratory of Pharmaceutical Engineering of Ministry of Education, College of Pharmaceutical Sciences,
Zhejiang University of Technology, Hangzhou 310032, China
§Department of Biology and Chemistry, Hunan University of Science and Engineering, Yongzhou 425100, China
ABSTRACT: A series of 4-phenyl-acyl-substituted 3-(2,5-dimethylphenyl)-4-hydroxy-1-azaspiro[4.5]dec-3-ene-2,8-dione
1
derivatives were designed and synthesized, and their structures were characterized using H NMR (or 13C NMR), mass spec-
trometry, and elemental analysis. The bioactivities of the new compounds were evaluated. These compounds exhibited good
inhibition activities against bean aphids (Aphis fabae) and carmine spider mite (Tetranychus cinnabarinus), and 4-phenyl acyl
esters showed stronger bioactivity than 4-arylesterases and alkyl esters. The results showed that compound 8-I-e, which contains
a para-methoxy group on the phenyl acyl, and compound 8-I-m, which contains a para-trifluoromethyl group on the phenyl acyl,
displayed potent insecticidal activity against A. fabae and T. cinnabarinus respectively. The insecticidal activity showed a clear
structure−activity relationship, confirming the importance of the flexible bridge. The DFT/B3LYP/6-31(d) level method was
used to calculate molecular geometries and electronic descriptors. These factors included total energy, charge distribution, and
the linear orbital level of the title compounds. Quantitative structure−activity relationship studies were performed on these com-
pounds using quantum-chemical and physicochemical parameters as independent variables and insecticidal activity as a dependent
variable. Insecticidal activity was most closely correlated (r > 0.8) with quantum chemical and physicochemical parameters.
KEYWORDS: spirocyclic tetronic acids, 3-(2,5-dimethylphenyl)-4-hydroxy-1-azaspiro[4.5]dec-3-ene-2,8-dione, insecticidal activities,
QSAR
its cis-configuration displays the best bioactivity, and it is very
costly to prepare.9−13 To the best of our knowledge, little atten-
tion has been paid to structural modification of these com-
pounds, especially arylesterase in their C4 positions. In con-
tinuation of our program aimed at the discovery and development
of more effective, broad-spectrum, bioactive, low-cost novel
compounds, we modified the methoxy group into a keto
moiety. Through careful observation of the side chain substit-
uents of the three commercial compounds, we found a flexible
bridge and large volume to promote bioactivity (Figure 2). To
validate the hypothesis, a series of phenyl-acyl-substituted deriv-
atives were prepared and tested for their insecticidal activity.
Some unsubstituted derivatives were also designed. Most of the
phenyl-acyl-substituted derivatives exhibited better bioactivity
than the unsubstituted derivatives.
INTRODUCTION
■
Spirocyclic tetronic acid compounds have been attracting the
interest of scientists continuously due to their original struc-
tures, novel mode of action, and excellent biological activity
levels.1−3 In recent years, some spirocyclic tetronic acid com-
pounds have been developed by Bayer CropScience AG. They
include such highly effective acaricides and insecticides as
Spirodiclofen, Spiromesifen, and Spirotetramat4−8 (Figure 1).
At present, quantitative structure−activity relationships (QSAR)
are widely used to study the relationships between chemical struc-
tures and biological or other functional activities.14 In this study
QSAR models were built using precise density functional theory
Figure 1. Commercial spirocyclic tetronic acid pesticides.
Spirotetramat has a special mechanism by which it inhibits lipid
biosynthesis, and it has no cross-resistance with any other
insecticide. Spirotetramat is considered a novel two-way ambi-
mobile systemic insecticide, and it has shown outstanding
performance against many species of insects in crops. However,
Received: January 20, 2012
Revised: April 23, 2012
Accepted: April 24, 2012
Published: April 24, 2012
© 2012 American Chemical Society
4779
dx.doi.org/10.1021/jf3002069 | J. Agric. Food Chem. 2012, 60, 4779−4787

Journal of Agricultural and Food Chemistry
Article
Figure 2. Design of target molecules.
solid, which was recrystallized from water to afford 15.4 g of 9,12-
dioxa-1,3-diazadispiro[4.2.4.2]tetradecane-2,4-dione 2 in 68% yield
as a colorless solid. H NMR (500 MHz, DMSO-d6): 10.61 (br s,
1H, (CO)NH(CO)), 8.46 (s, 1H, CONH−C), 3.87 (s, 4H,
−O(CH2)2O−), 1.89−1.57 (m, 8H, cyclohexane-H8). ESI-MS (m/z,
%): 249 (M + Na+, 100).
Synthesis of 8-Amino-1,4-dioxaspiro[4.5]decane-8-carboxylic
Acid (3).18 After 2 (15 g, 66 mmol) was suspended in 3 N sodium
hydroxide (154 mL, 462 mmol) under N2, the resulting mixture was
stirred under reflux conditions under N2 for 4 days and then cooled to
0 °C. The reaction mixture was adjusted to pH 6 by addition of
concentrated hydrochloric acid at 0 °C. The solution was filtered and
reduced in vacuo to one-third of its original volume. A white crystalline
material was precipitated and collected by filtration to give 6.4 g of
8-amino-1,4-dioxaspiro[4.5]decane-8-carboxylic acid 3 in 48% yield
as a white powder. 1H NMR (500 MHz, D2O): 4.03(s, 4H,
−O(CH2)2O−), 2.25−2.20 (m, 2H, cyclohexane-H2), 1.97−1.87 (m,
4H, cyclohexane-H4), 1.75−1.73 (m, 2H, cyclohexane-H2). ESI-MS
(m/z, %): 202 (M + H+, 100).
(DFT)-based calculation to determine quantum chemical
descriptors, and QSAR studies were performed on 8-I-a−8-
II-g using quantum chemical and physicochemical character-
istics as independent parameters and insecticidal activity as the
dependent parameter. The derived models showed better per-
formance than the semiempirical models and showed potential
predictive capability. This is because DFT is a very precise method,
capable of producing compounds in the optimal lowest-energy
conformation.15 The objective of this study was to further
understand the QSARs of substituted groups.
1
MATERIALS AND METHODS
■
1
Instruments. H NMR and 13C NMR spectra were obtained at
500 MHz using a Bruker AVANCE III spectrometer in CDCl3, D2O,
CD3OD, or DMSO-d6 solution with tetramethylsilane as the internal
standard. Chemical shift values (δ) were given in parts per million
(ppm). MS were recorded with a Finnigan Trace Mass 2000 spec-
trometer using the electrospray ionization (ESI) method. 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 are uncorrected. Yields were not optimized.
Column chromatographic purification was carried out using silica gel.
General Synthesis. The reagents were all analytically or chem-
ically pure. All anhydrous solvents were dried and purified by standard
techniques prior to use. All acyl chlorides were prepared according to
the method described in the literature.16
Synthesis of Methyl 8-Amino-1,4-dioxaspiro[4.5]decane-8-car-
boxylate (4).18 After 3 (6 g, 30 mmol) was dissolved in dry methanol
(150 mL) at room temperature, the resulting solution was cooled to
0 °C. Dry hydrogen chloride gas was bubbled into the solution at 0 °C
until there was no further increase in weight in the resulting mixture.
Then the hydrogen chloride gas-saturated reaction mixture was stirred
under reflux conditions for 7 h, cooled to room temperature, and
concentrated in vacuo. The residue was partitioned between saturated
aqueous sodium bicarbonate (300 mL) and diethyl ether (300 mL)
at 0 °C. After the organic layer was separated, the aqueous layer was
extracted with diethyl ether (300 mL). The organic layers were com-
bined, dried over anhydrous magnesium sulfate, filtered, and concen-
trated in vacuo to give 5.16 g of methyl 8-amino-1,4-dioxaspiro[4.5]-
Synthesis of 9,12-Dioxa-1,3-diazadispiro[4.2.4.2]tetradecane-2,4-
dione (2).17 1,4-Dioxaspiro[4.5]decan-8-one 1 (15.6 g, 100 mmol)
was dissolved in 250 mL of 50% aqueous ethanol, and the solution was
neutralized by the addition of ammonium solution. Potassium cyanide
(8.1 g, 125 mmol) and ammonium carbonate (37.4 g, 390 mmol) were
added, and the mixture was maintained at 55−60 °C for 8 h. The
product was isolated by acidification of the reaction mixture with
hydrochloric acid. Acidification caused the precipitation of a white
1
decane-8-carboxylate 4 in 80% yield as a slight yellow oil. H NMR
(500 MHz, CDCl3): 3.89−3.86 (m, 4H, −O(CH2)2O−), 3.65 (s, 3H,
−OCH3), 2.07−2.01 (m, 2H, cyclohexane-H2), 1.85−1.79 (m, 2H,
4780
dx.doi.org/10.1021/jf3002069 | J. Agric. Food Chem. 2012, 60, 4779−4787

Journal of Agricultural and Food Chemistry
Article
cyclohexane-H2), 1.58−1.52 (m, 4H, cyclohexane-H4). ESI-MS (m/z, %):
216 (M + H+, 100).
Ar−CH3), 2.29−1.58 (m, 8H, cyclohexane-H8). ESI-MS (m/z, %): 352
(M + Na+, 100).
Synthesis of 3-(2,5-Dimethylphenyl)-4-hydroxy-1-azaspiro[4.5]-
dec-3-ene-2,8-dione (7).19 3-(2,5-Dimethylphenyl)-9,12-dioxa-4-hy-
droxy-1-azadispiro[4.2.4.2]tetradec-3-en-2-one 6 (1.2 g, 4.2 mmol)
was stirred in 4 N hydrochloric acid at 60 °C for two hours. The
aqueous layer was extracted with ethyl acetate, dried over anhydrous
magnesium sulfate, and concentrated in vacuo. The mixture was
purified by column chromatography on silica gel (dichloromethane/
ethyl acetate = 1:1) to give 0.78 g of 3-(2,5-dimethylphenyl)-4-hydroxy-
1-azaspiro[4.5]dec-3-ene-2,8-dione 7 in 65% yield as a white solid, mp
Synthesis of Methyl 8-(2-(2,5-Dimethylphenyl)acetamido)-1,4-
dioxaspiro[4.5]decane-8-carboxylate (5).19 Methyl 8-amino-1,4-
dioxaspiro[4.5]decane-8-carboxylate 4 (4.5 g, 21 mmol) was initially
charged in 60 mL of anhydrous acetonitrile, and ground potassium
carbonate (6.9 g, 50 mmol) was added. Then 2,5-dimethylphenylacetyl
chloride (5.46 g, 30 mmol) in 30 mL of anhydrous acetonitrile was
added dropwise over a period of 20 min. The mixture was stirred at
room temperature for 3 h. The reaction solution was poured into
500 mL of ice water, and the precipitate was filtered off with suction. The
precipitate was washed with water and taken up in dichloromethane,
the mixture was dried, and the solvent was distilled off. The product
was purified by column chromatography on silica gel (dichloromethane/
ethyl acetate = 3:1) to afford 8-(2-(2,5-dimethylphenyl)acetamido)-1,4-
dioxaspiro[4.5]decane-8-carboxylate 5. Yield: 3.9 g (51% of theory), mp
1
190−192 °C. H NMR (500 MHz, DMSO-d6): 8.46 (s, 1H, NH-C
O), 7.10 (d, J = 7.5 Hz, 1H, Ar−H), 7.02 (dd, J1 = 7.5 Hz, J2 = 1 Hz,
1H, Ar−H), 6.93 (s, 1H, Ar−H), 2.35 (s, 3H, Ar−CH3), 2.12 (s, 3H,
Ar−CH3), 2.79−1.74 (m, 8H, cyclohexane-H8). ESI-MS (m/z, %): 286
(M + H+, 100).
Synthesis of 3-(2,5-Dimethylphenyl)-2,8-dioxo-1-azaspiro[4.5]-
dec-3-en-4-yl 2-Phenylacetate (8-I-a). A solution of phenethyl
chloride (62 mg, 0.40 mmol) in anhydrous dichloromethane (15 mL)
at 0 °C was added dropwise to a solution of compound 7 (100 mg,
0.35 mmol), triethylamine (0.076 g, 0.75 mmol), and N,N-dimethylpyr-
idin-4-amine (1 mg, 0.01 mmol) in dichloromethane (8 mL). The mixture
was stirred at room temperature for 1 h. The reaction mixture was poured
into water and extracted with dichloromethane (3 × 10 mL). The organic
layer was washed with 5% dilute hydrochloric acid (3 × 10 mL), 5%
aqueous sodium bicarbonate (3 × 10 mL), and saturated brine (3 × 10
mL), dried over anhydrous sodium sulfate, filtered, and concentrated
under reduced pressure. The residue was purified by flash chromato-
graphy on silica gel using a mixture of petroleum ether (60−90 °C)
and ethyl acetate (2:1 by volume) as the eluent to afford 107 mg of
3-(2,5-dimethylphenyl)-2,8-dioxo-1-azaspiro[4.5]dec-3-en-4-yl 2-phe-
nylacetate 8-I-a as a white solid. The spectroscopic data is listed in
Table 2.
1
138−139 °C. H NMR (500 MHz, CDCl3): 7.12 (d, 1H, J = 7.6 Hz,
Ar−H), 7.05 (d, J = 8 Hz, 1H, Ar−H), 7.03 (s, 1H, Ar−H), 5.46 (s, 1H,
NH−CO), 3.92 (s, 4H, −O(CH2)2O−), 3.72 (s, 3H, −OCH3), 3.55
(s, 2H, −CH2−Ar), 2.33 (s, 3H, Ar−CH3), 2.28 (s, 3H, Ar−CH3),
2.16−1.39 (m, 8H, cyclohexane-H8). 13C NMR (125 MHz, CDCl3):
173.7, 171.0, 136.2, 134.0, 133.0, 131.1, 130.8, 128.7, 107.4, 64.4, 64.3,
57.8, 52.4, 41.9, 30.4, 30.2, 20.9, 18.9. ESI-MS (m/z, %): 384 (M + Na+,
100).
Synthesis of 3-(2,5-Dimethylphenyl)-9,12-dioxa-4-hydroxy-1-
azadispiro[4.2.4.2]tetradec-3-en-2-one (6).19 Potassium tert-butoxide
(1.2 g, 12 mmol) was initially charged in 25 mL of dimethylforma-
mide, cooled on ice, a solution of the compound 5 (2.0 g, 5.5 mmol)
in 55 mL of dimethyl formamide was added dropwise at 0 to 10 °C,
and the mixture was stirred at 90 °C overnight. Most of the dimethyl
formamide was distilled off using a rotary evaporator. The residue was
acidified with hydrochloric acid and partitioned between water and
ethyl acetate. The ethyl acetate phase was dried and distilled off.
The mixture was purified by column chromatography on silica gel
(dichloromethane/ethyl acetate = 1:1) to give 3-(2,5-dimethylphenyl)-
9,12-dioxa-4-hydroxy-1-azadispiro[4.2.4.2]tetradec-3-en-2-one 6. Yield:
The target compounds 8-I-b−8-II-g were prepared by following the
same procedure as that used for 8-I-a. The properties and elemental
1
analyses of compounds are listed in Table 1, and their H NMR and
13C NMR data are listed in Table 2.
1
1.46 g (82% of theoretical yield). H NMR (500 MHz, CD3OD): 7.14
Biological Assay. All bioassays were performed on representative
test organisms reared in the laboratory. The bioassay was repeated at
(d, 1H, J = 8 Hz, Ar−H), 7.04 (d, 1H, J = 8 Hz, Ar−H), 6.97 (s, 1H, Ar−
H), 3.99 (s, 4H, −O(CH2)2O−), 2.31 (s, 3H, Ar−CH3), 2.18 (s, 3H,
25
1 °C according to statistical requirements. Assessments were
a
Table 1. Physical Properties and Elemental Analyses of the Synthetic Compounds
elemental anal. (%, calcd)
H
compd
R1/R2
yield (%)
mp (°C)
C
N
8-I-a
8-I-b
8-I-c
8-I-d
8-I-e
8-I-f
H
76
84
54
65
43
36
57
60
63
46
42
42
27
15
55
73
75
69
80
82
86
199−200
223−225
215−217
247−249
196−198
223−225
214−216
189−191
234−236
234−236
214−216
239−241
218−219
207−209
203−205
192−193
230−232
210−212
198−200
204−206
229−230
74.36 (74.42)
74.91 (74.80)
75.19 (75.15)
75.63 (75.48)
72.12 (72.04)
71.22 (71.24)
68.66 (68.57)
68.77 (68.57)
68.45 (68.57)
63.47 (63.57)
63.32 (63.57)
62.34 (62.25)
66.34 (66.24)
67.02 (66.95)
67.11 (67.21)
70.88 (70.96)
72.02 (72.04)
71.27 (71.37)
74.11 (74.02)
74.32 (74.42)
67.91 (68.00)
6.52 (6.25)
6.42 (6.52)
6.92 (6.77)
7.20 (7.01)
6.22 (6.28)
5.84 (5.74)
5.29 (5.52)
5.34 (5.52)
5.35 (5.52)
4.78 (4.91)
4.96 (4.91)
5.12 (5.01)
5.12 (5.13)
5.45 (5.39)
6.48 (6.49)
7.02 (7.09)
7.62 (7.62)
6.50 (6.56)
6.01 (5.95)
6.25 (6.25)
5.18 (5.23)
3.48 (3.47)
3.66 (3.35)
3.47 (3.25)
3.11 (3.14)
3.13 (3.23)
4.72 (4.51)
3.24 (3.20)
3.21 (3.20)
3.33 (3.20)
2.86 (2.97)
2.87 (2.97)
2.89 (2.90)
3.02 (2.97)
6.13 (6.25)
3.88 (3.92)
3.88 (3.94)
3.67 (3.65)
3.87 (3.96)
3.66 (3.60)
3.44 (3.47)
3.27 (3.30)
4-CH3
2,5-(CH3)2
2,4,6-(CH3)3
4-OCH3
4-F
8-I-g
8-I-h
8-I-i
2-Cl
3-Cl
4-Cl
8-I-j
2,4-(Cl)2
3,4-(Cl)2
4-Br
8-I-k
8-I-l
8-I-m
8-I-n
8-II-a
8-II-b
8-II-c
8-II-d
8-II-e
8-II-f
8-II-g
4-CF3
4-NO2
CH3CH2O−
CH3(CH2)2−
CH3C(CH3)2CH2−
CH3CHCH−
C6H5−
2-CH3−C6H4−
4-Cl−C6H4−
a
All compounds had the appearance of a white solid.
4781
dx.doi.org/10.1021/jf3002069 | J. Agric. Food Chem. 2012, 60, 4779−4787

Journal of Agricultural and Food Chemistry
Article
Table 2. Spectroscopic Data (1H NMR or 13C NMR) for Synthesized Compounds
compd
1H or 13C NMR δ (ppm)
ESI-MS (m/z %)
8-I-a
1H NMR (500 MHz, CDCl3) 9.11 (1H, s, −NH−), 7.27−7.25 (3H, m, Ar−H), 7.07−7.01 (4H, m, Ar−H), 6.86 (1H, s, Ar−
H), 3.62 (2H, s, CO−CH2−), 2.26, 2.14 (6H, s, Me2−Ar), 2.72−2.00 (8H, m, cyclohexane-H8); 13C NMR (125 MHz, CDCl3)
208.8, 171.8, 166.5, 164.3, 134.9, 134.2, 133.8, 132.1, 130.2, 129.8, 128.8, 128.5, 127.8, 123.6, 60.8, 40.8, 37.9, 33.8, 20.8, 19.1
404 (M + H+, 100)
8-I-b
8-I-c
1H NMR (500 MHz, CDCl3) 9.18 (1H, s, −NH−), 7.09−7.05 (4H, m, Ar−H), 6.92 (1H, s, Ar−H), 6.90 (1H, s, Ar−H), 6.85
418 (M + H+, 100)
432 (M + H+, 100)
(1H, s, Ar−H), 3.58 (2H, s, CO−CH2−), 2.34 (3H, s, Me−Ar), 2.26, 2.15 (6H, s, Me2−Ar), 2.70−1.98 (8H, m, cyclohexane-
H8)
1H NMR (500 MHz, CDCl3) 9.39 (1H, s, −NH−), 7.06−7.05 (2H, m, Ar−H), 6.99 (2H, m, Ar−H), 6.87 (1H, s, Ar−H),
6.82 (1H, s, Ar−H), 3.60 (2H, s, CO−CH2−), 2.26, 2.11 (6H, s, Me2−Ar), 2.24, 1.92 (6H, s, Me2−Ar), 2.76−2.00 (8H, m,
cyclohexane-H8)
8-I-d
8-I-e
1H NMR (500 MHz, CDCl3) 9.06 (1H, s, −NH−), 7.05 (2H, s, Ar−H), 6.84 (1H, s, Ar−H), 6.80 (2H, s, Ar−H), 3.64 (2H, s,
CO−CH2−), 2.26, 2.12 (6H, s, Me2−Ar), 2.25, 1.99 (9H, s, Me3−Ar), 2.74−2.00 (8H, m, cyclohexane-H8)
446 (M + H+, 100)
434 (M + H+, 100)
1H NMR (500 MHz, CDCl3) 9.39 (1H, s, −NH−), 7.06−7.05 (2H, m, Ar−H), 6.99 (2H, m, Ar−H), 6.87 (1H, s, Ar−H),
6.82 (1H, s, Ar−H), 3.60 (2H, s, CO−CH2−), 2.26, 2.11 (6H, s, Me2−Ar), 2.24, 1.92 (6H, s, Me2−Ar), 2.76−2.00 (8H, m,
cyclohexane-H8)
8-I-f
8-I-g
8-I-h
1H NMR (500 MHz, CDCl3) 8.71 (1H, s, −NH−), 7.08−7.02 (2H, m, Ar−H), 6.95−6.93 (4H, m, Ar−H), 6.82 (1H, s, Ar−
H), 3.60 (2H, s, CO−CH2−), 2.25, 2.14 (6H, s, Me2−Ar), 2.68−2.04 (8H, m, cyclohexane-H8); 13C NMR (125 MHz, CDCl3)
208.7, 171.4, 166.5, 164.3, 163.2, 161.2, 135.0, 134.0, 130.5, 130.4, 130.2, 129.8, 129.6, 127.8, 127.7, 123.9, 115.8, 115.6, 60.7,
39.9, 37.9, 33.9, 20.8, 19.1
422 (M + H+, 100)
438 (M + H+, 100)
438 (M + H+, 100)
1H NMR (500 MHz, CDCl3) 8.91 (1H, s, −NH−), 7.36−7.34 (1H, t, J = 8 Hz, Ar−H), 7.26−7.01 (5H, m, Ar−H), 6.90 (1H,
s, Ar−H), 3.77 (2H, s, CO−CH2−), 2.30, 2.19 (6H, s, Me2−Ar), 2.73−2.02 (8H, m, cyclohexane-H8); 13C NMR (125 MHz,
CDCl3) 208.9, 171.5, 166.6, 164.2, 135.0, 134.4, 134.0, 131.1, 130.6, 130.3, 129.9, 129.6, 127.7, 127.1, 123.9 60.8, 38.6, 37.9,
33.9, 20.9, 19.2
1H NMR (500 MHz, CDCl3) 8.79 (1H, s, −NH−), 7.27−7.05 (4H, m, Ar−H), 7.02 (1H, s, Ar−H), 6.88 (1H, d, J = 8 Hz,
Ar−H), 6.84 (1H, s, Ar−H), 3.60 (2H, s, CO−CH2−), 2.26, 2.17 (6H, s, Me2−Ar), 2.72−2.03 (8H, m, cyclohexane-H8); 13
C
NMR (125 MHz, CDCl3) 208.6, 172.1, 168.6, 166.7, 163.5, 137.4, 135.4, 134.1, 133.5, 132.9, 130.1, 129.7, 129.1, 128.9, 127.1,
126.5, 122.7, 59.8, 39.0, 37.3, 32.9, 20.4, 18.7
8-I-i
8-I-j
1H NMR (500 MHz, CDCl3) 8.62 (1H, s, −NH−), 7.22 (2H, dd, J = 1.5 Hz, J = 6.5 Hz, Ar−H), 7.08 (1H, s, Ar−H), 7.07
(1H, d, J = 8 Hz, Ar−H), 6.90 (2H, d, J = 8.5 Hz, Ar−H), 6.80 (1H, s, Ar−H), 3.59 (2H, s, CO−CH2−), 2.25, 2.13 (6H, s,
Me2−Ar), 2.71−2.05 (8H, m, cyclohexane-H8)
438 (M + H+, 100)
472 (M + H+, 100)
1H NMR (500 MHz, CDCl3) 8.18 (1H, s, −NH−), 7.37 (1H, d, J = 2 Hz, Ar−H), 7.15−7.13 (1H, m, Ar−H), 7.11−7.06 (2H,
m, Ar−H), 6.92 (1H, d, J = 8 Hz, Ar−H), 6.88 (1H, s, Ar−H), 3.74 (2H, s, CO−CH2−), 2.29, 2.16 (6H, s, Me2−Ar),
2.69−2.06 (8H, m, cyclohexane-H8)
8-I-k
8-I-l
1H NMR (500 MHz, CDCl3) 8.74 (1H, s, −NH−), 7.29 (1H, d, J = 8 Hz, Ar−H), 7.08−7.06 (3H, m, Ar−H), 6.79−6.76 (2H,
m, Ar−H), 3.57 (2H, s, CO−CH2−), 2.26, 2.14 (6H, s, Me2−Ar), 2.74−2.07 (8H, m, cyclohexane-H8)
472 (M + H+, 100)
482 (M + H+, 100)
472 (M + H+, 100)
449 (M + H+, 100)
1H NMR (500 MHz, CDCl3) 8.45 (1H, s, −NH−), 7.37 (2H, d, J = 8.5 Hz, Ar−H), 7.07 (2H, s, Ar−H), 6.84−6.80 (3H, m,
Ar−H), 3.58 (2H, s, CO−CH2−), 2.25, 2.14 (6H, s, Me2−Ar), 2.70−2.04 (8H, m, cyclohexane-H8)
8-I-m
8-I-n
1H NMR (500 MHz, CDCl3) 8.95 (1H, s, −NH−), 7.50 (2H, d, J = 8 Hz, Ar−H), 7.07 (2H, s, Ar−H), 7.06 (2H, s, Ar−H),
6.80 (1H, s, Ar−H), 3.69 (2H, s, CO−CH2−), 2.24, 2.13 (6H, s, Me2−Ar), 2.75−2.06 (8H, m, cyclohexane-H8)
1H NMR (500 MHz, CDCl3) 8.48 (1H, s, −NH−), 8.28 (2H, d, J = 8.5 Hz, Ar−H), 7.69 (2H, d, J = 8 Hz Ar−H), 7.15 (1H, d,
J = 8 Hz, Ar−H), 7.10 (1H, s, Ar−H), 7.07 (1H, d, J = 7.5 Hz, Ar−H), 3.64 (2H, s, CO−CH2−), 2.26, 2.15 (6H, s, Me2−Ar),
2.73−2.05 (8H, m, cyclohexane-H8)
8-II-a
8-II-b
1H NMR (500 MHz, CDCl3) 8.97 (1H, s, −NH−), 7.14 (1H, d, J = 8 Hz, Ar−H), 7.08 (1H, m, Ar−H), 6.99 (1H, s, Ar−H),
4.06 (2H, q, J = 7 Hz, CH3−CH2−), 2.31, 2.24 (6H, s, Me2−Ar), 2.78−2.06 (8H, m, cyclohexane-H8), 1.13 (3H, t, J = 7 Hz,
CH3−CH2−); 13C NMR (125 MHz, CDCl3) 208.7, 171.5, 164.2, 149.9, 135.0, 134.1, 130.3, 129.9, 129.7, 127.6, 122.1, 65.8,
60.5, 37.9, 33.8, 20.8, 19.2, 13.7
358 (M + H+, 100)
356 (M + H+, 100)
1H NMR (500 MHz, CDCl3) 9.67 (1H, s, −NH−), 7.12 (1H, d, J = 8 Hz, Ar−H), 7.06 (1H, d, J = 8 Hz, Ar−H), 6.92 (1H, s,
Ar−H), 2.27,2.22 (6H, s, Me2−Ar), 2.26−2.25 (2H, m, CH3−CH2−CH2−), 2.84−2.05 (8H, m, cyclohexane-H8), 1.55−1.47
(2H, m, CH3−CH2−), 0.77 (3H, t, J = 7 Hz, CH3−CH2−); 13C NMR (125 MHz, CDCl3) 209.0, 171.5, 168.5, 164.5, 134.9,
134.0, 130.2, 129.9, 129.5, 128.0, 123.5, 60.7, 38.0, 35.6, 20.8, 19.2, 18.2, 13.1
8-II-c
8-II-d
8-II-e
8-II-f
8-II-g
1H NMR (500 MHz, CDCl3) 9.53 (1H, s, −NH−), 7.11 (1H, d, J = 8 Hz, Ar−H), 7.05 (1H, d, J = 8 Hz, Ar−H), 6.91 (1H, s,
Ar−H), 2.28, 2.25 (6H, s, Me2−Ar), 2.24−2.21 (2H, m, Me3C−CH2−), 2.82−2.07 (8H, m, cyclohexane-H8), 0.84 (9H, s,
Me3C−CH2−)
384 (M + H+, 100),
354 (M + H+, 100)
390 (M + H+, 100)
404 (M + H+, 100)
424 (M + H+, 100)
1H NMR (500 MHz, CDCl3) 9.29 (1H, s, −NH−), 7.11 (1H, d, J = 8 Hz, Ar−H), 7.09−7.01 (2H, m, Ar−H+ CH3−CH
CH−), 6.97 (1H, s, Ar−H), 5.84 (1H, dd, J = 16.0 Hz, J = 1.5 Hz, CH3−CHCH−), 2.29, 2.23 (6H, s, Me2−Ar), 2.81−2.06
(8H, m, cyclohexane-H8), 1.91 (3H, dd, J = 1.5 Hz, J = 7 Hz, CH3−CH)
1H NMR (500 MHz, CDCl3) 9.76 (1H, s, −NH−), 7.98 (2H, d, J = 8 Hz, Ar−H), 7.62 (1H, m, Ar−H), 7.46 (2H, t, J = 6 Hz,
Ar−H), 7.07 (1H, d, J = 7.5 Hz, Ar−H), 7.02−6.99 (2H, m, Ar−H), 2.27, 2.23 (6H, s, Me2−Ar), 2.87−2.16 (8H, m,
cyclohexane-H8)
1H NMR (500 MHz, CDCl3) 9.94 (1H, s, −NH−), 7.86 (1H, d, J = 7.5 Hz, Ar−H), 7.47−7.44 (1H, m, Ar−H), 7.28−7.23
(2H, m, Ar−H), 7.09−7.01 (3H, m, Ar−H), 2.36 (3H, s, Me−Ar), 2.28,2.24 (6H, s, Me2−Ar), 2.91−2.17 (8H, m,
cyclohexane-H8)
1H NMR (500 MHz, CDCl3) 9.49 (1H, s, −NH−), 7.91 (2H, d, J = 8.5 Hz, Ar−H), 7.45 (2H, d, J = 8.5 Hz, Ar−H),
7.08−7.00 (3H, m, Ar−H), 2.26, 2.23 (6H, s, Me2−Ar), 2.84−2.15 (8H, m, cyclohexane-H8)
made on a dead/alive basis, and mortality rates were corrected using
Abbott’s formula.20 Evaluations were based on a percentage scale of
0−100, in which 0 = no activity and 100 = total mortality. The devia-
tion of values was 5%. Each test sample was prepared in N,N-
dimethylformamide at a concentration of 0.5 mg L−1 and diluted to
the required concentration with distilled water containing TW-80
(0.1 mL L−1).
Inhibition Activity against Bean Aphids (Aphis fabae). The inhibi-
tion activities of derivative compounds against bean aphids were evalu-
ated according to the reported procedure.21,22 Bean aphids were dipped
according to a slightly modified FAO dip test. Tender soybean shoots with
fifty healthy apterous third-instar nymphae were dipped into the diluted
solutions of the compounds for 5 s, superfluous fluid was removed, and the
nymphae were placed in an air-conditioned room. Mortality was calculated
4782
dx.doi.org/10.1021/jf3002069 | J. Agric. Food Chem. 2012, 60, 4779−4787

Journal of Agricultural and Food Chemistry
Article
72 h after treatment. Each treatment was performed three times.
Control groups were tested with water only.
A stepwise regression procedure was used to identify key de-
scriptors. To achieve an accurate model for inhibition activity, descrip-
tors were analyzed for evidence of intercorrelation, using Pearson and
Spearman rank correlation procedures. Parameters that were highly
correlated were noted. The multiparameter linear regression analysis
was carried out using SPSS 16.0.
Inhibition Activity against Carmine Spider Mite (Tetranychus
cinnabarinus). The larvicidal activities of derivative compounds
against carmine spider mites were tested according to the reported
procedure.23,24 Fifty third-instar mite larvae were dipped in the diluted
solutions of related chemicals for 5 s, the superfluous liquor was
removed, and the larvae were kept in an air-conditioned room.
Mortality was evaluated 72 h after treatment. Controls were treated
under the same conditions. Each test was performed in triplicate.
Control groups were treated with water only.
The key descriptors correlating with the final equations are sum-
marized in Table 4.
RESULTS AND DISCUSSION
■
Synthesis. Compound 7 was synthesized in a series of
steps as shown in Figure 3. First, compound 2 was prepared by
Bucherer−Bergs synthesis from 1 using ammonium carbonate
and potassium cyanide. It was then hydrolyzed with aqueous
sodium hydroxide into the corresponding 8-amino-1,4-
dioxaspiro[4.5]decane-8-carboxylic acid 3, followed by methyl
esterification in acidic conditions. The obtained methyl 8-
amino-1,4-dioxaspiro[4.5]decane-8-carboxylate 4 was treated
with 2,5-dimethylphenylacetyl chloride to produce compound
5. Compound 5 was treated with potassium tert-butoxide via
Dieckmann condensation to convert it to 6, followed by 4 N
hydrochloric acid in reflux to generate primary 7. Phenyl-acyl-
substituted and other groups reacted with 7, generating the
corresponding compounds 8-I-a−8-II-g. The derivatives of
compounds 8 were prepared with DMAP as catalyst giving the
best yield and short reaction time. In comparison to the phenyl-
acyl-substituted compounds, some non-phenyl-acyl-substituted
group compounds were designed and prepared. It was found
that the chemical shift of NH ranged from 8.18 to 9.94 in
different compounds (Table 2). In addition, it was observed
that the substituted groups on the phenyl acyl had a great effect
on the yield of compounds 8, where electron withdrawing group
substituted phenyl acyl gave a low yield, while the electron
donating group substituted phenyl acyl afforded the best yield
(Table 1).
Commercial insecticides Spirodiclofen, Spiromesifen, and Spirote-
tramat were tested and compared under the same conditions. The
insecticidal activity levels are summarized in Table 3.
Table 3. Inhibitive Activity of the Synthetic Compounds
% inhibition
against
against A. fabae
T. cinnabarinus
100
10
100
10
compd
8-I-a
R1/R2
mg/L
mg/L
mg/L
mg/L
H
95.59
73.45
76.16
69.17
92.11
93.65
96.53
44.60
89.82
85.59
97.32
47.83
98.56
92.15
93.55
98.69
62.15
85.56
91.78
25.47
68.25
60.27
62.45
100
62.76
48.36
37.29
25.22
87.34
69.27
59.22
13.55
47.32
26.88
49.31
9.78
66.79
70.82
61.57
39.44
80.48
49.05
53.53
24.70
58.03
75.91
71.67
32.47
85.27
73.79
62.3
38.86
21.75
24.55
12.11
24.38
29.86
28.33
3.23
8-I-b
4-CH3
8-I-c
2,5-(CH3)2
2,4,6-(CH3)3
4-OCH3
4-F
8-I-d
8-I-e
8-I-f
8-I-g
2-Cl
8-I-h
3-Cl
8-I-i
4-Cl
17.82
31.22
28.90
5.25
8-I-j
2,4-(Cl)2
3,4-(Cl)2
4-Br
8-I-k
8-I-l
8-I-m
8-I-n
4-CF3
59.96
32.29
45.89
37.28
21.57
34.85
29.33
6.27
48.97
16.33
30.35
19.66
8.76
4-NO2
8-II-a
8-II-b
8-II-c
8-II-d
8-II-e
8-II-f
CH3CH2O−
CH3(CH2)2−
(CH3)3CCH2−
CH3CHCH−
C6H5−
Bioassay. Inhibition Activity against Bean Aphids (A. fabae).
The inhibition activities of compounds 8-I-a−8-II-g against A.
fabae are shown in Table 3. The commercial insecti-
cides Spirodiclofen, Spiromesifen, and Spirotetramat were
used as standards. Two levels of concentration inhibition
were observed. As expected, the activity levels of compounds
substituted with phenyl acyl groups were predominantly higher
than those of other compounds, suggesting that the flexible
bridge maybe important. Fortunately, when a methoxy group
existed at the para-position in the benzene ring, compound 8-I-
e showed the most activity. Moderate activity was observed for
compounds 8-I-a, 8-I-f, 8-I-g, and 8-I-m. It was also observed
that introduction of a multisubstituted benzene ring decreased
the bioactivity and replacement of the nitro group (8-I-n) with
a bromine atom (8-I-l) caused an obvious decrease in activity.
According to the result of 8-II-b and 8-II-c, it may be deduced
that the side chain must be of suitable volume. The hypothesis
that introducing huge volume moieties favors activity may not
be accurate.
Inhibition Activity against Carmine Spider Mite
(T. cinnabarinus). As shown in Table 3, most of the
compounds were found to display promising insecticidal activity
against T. cinnabarinus. The most promising one was compound
8-I-m bearing the para-trifluoromethyl group, whose inhibition
activity at 10 mg L−1 was 48.97%, higher than that of the
commercial compounds Spirodiclofen, Spiromesifen, and Spirote-
tramat. However, compounds 8-I-a, 8-I-e, 8-I-f, 8-I-m, and 8-II-a
only showed moderate insecticidal activity at the same
54.72
26.15
58.22
49.80
59.38
42.87
70.62
80.21
74.96
23.45
18.22
17.28
9.23
2-CH3−C6H4−
4−Cl−C6H4−
8-II-g
Spirodiclofen
Spiromesifen
Spirotetramat
10.85
19.36
14.35
96.78
36.70
42.10
26.34
Quantum Chemical and Physicochemical Parameters. To
determine the structural requirements of phenyl-acyl-substituted 3-
(2,5-dimethylphenyl)-4-hydroxy-1-azaspiro[4.5]dec-3-ene-2,8-dione
derivatives for bioactivity, activity values were quantitatively analyzed
using quantum-chemical and physicochemical parameters.
In the present study, quantum-chemical parameters included highest
occupied molecular orbital (HOMO), lowest unoccupied molecular
orbital (LUMO), HOMO−LUMO energy gap, Mulliken population,
dipole moment (DM), total energy (ET), and rms force. Each molecular
structure was first preoptimized with a molecular mechanics force field
(MM) procedure, and the resulting geometric conclusions were further
refined by means of semiempirical method AM1. All molecules were
then subjected to density functional theory (DFT)-based B3LYP/6-31G
calculation using Gaussian 03W (version 6.0).25,26
Physicochemical parameters were calculated using ChemBio3D
Ultra 12.0 software,27 including ClogP (octanol−water partition co-
efficient), molar refractivity (MR), van der Waals volume (Vw),
parachor (Pc), the index of refraction (η), surface tension (ST),
density (D), and polarizability (Pol).
4783
dx.doi.org/10.1021/jf3002069 | J. Agric. Food Chem. 2012, 60, 4779−4787

Journal of Agricultural and Food Chemistry
Article
a
Table 4. Quantum-Chemical and Physicochemical Parameters
HOMO
LUMO
QN
QO
ClogP
MR
Vw
DM
ET
8-I-a
8-I-b
8-I-c
8-I-d
8-I-e
8-I-f
−0.22700
−0.22624
−0.22344
−0.22725
−0.22626
−0.22916
−0.22812
−0.22882
−0.23159
−0.23166
−0.23009
−0.22926
−0.23214
−0.23392
−0.22914
−0.22894
−0.22743
−0.22531
−0.22662
−0.22639
−0.22837
−0.04499
−0.04377
−0.05014
−0.04507
−0.04420
−0.04847
−0.04832
−0.04875
−0.05067
−0.05269
−0.05305
−0.04920
−0.06014
−0.09926
−0.04786
−0.04719
−0.04841
−0.07048
−0.07691
−0.07021
−0.08369
−0.628053
−0.628054
−0.677501
−0.628593
−0.627780
−0.628298
−0.629739
−0.628729
−0.631186
−0.630178
−0.631545
−0.628665
−0.628962
−0.629124
−0.680131
−0.680322
−0.679789
−0.680361
−0.666019
−0.679893
−0.649780
−0.429435
−0.429793
−0.444494
−0.429829
−0.429695
−0.428548
−0.42991
−0.428903
−0.429249
−0.429197
−0.402639
−0.428612
−0.427224
−0.426360
−0.440759
−0.406776
−0.406419
−0.407804
−0.418992
−0.444377
−0.443196
3.139
3.626
4.113
4.600
3.013
3.297
3.697
3.697
3.697
4.256
4.256
3.968
4.060
2.725
2.221
2.368
3.169
2.348
3.195
3.682
3.752
115.042
120.083
125.124
130.165
121.505
115.258
119.847
119.847
119.847
124.651
124.651
122.665
121.016
121.654
96.642
321.563
334.275
311.735
371.943
394.280
312.222
294.103
343.995
274.821
353.848
324.508
389.395
337.164
344.650
278.293
281.710
310.630
256.594
266.629
280.323
352.880
4.4341
4.6277
4.4189
4.1550
4.0321
3.9249
4.1645
4.9283
3.5041
4.1319
3.7193
3.8303
4.2311
5.0256
3.9901
3.8564
3.8306
5.1295
4.0102
4.7993
2.5413
−86.74
−94.54
−98.51
−108.42
−124.98
−131.53
−92.27
−93.25
−93.21
−98.51
−98.08
−81.33
−241.85
−81.60
−159.87
−126.90
−134.33
−98.28
−73.80
−84.34
−85.27
8-I-g
8-I-h
8-I-i
8-I-j
8-I-k
8-I-l
8-I-m
8-I-n
8-II-a
8-II-b
8-II-c
8-II-d
8-II-e
8-II-f
8-II-g
99.548
108.572
100.641
110.493
115.534
115.297
a
HOMO (highest occupied molecular orbital), LUMO (lowest unoccupied molecular orbital), QN,QO (Mulliken charge of N atom on the amide
bonds, O atom on cyclohexane respectively), ClogP (octanol−water partition coefficient), MR (molar refractivity), Vw (van der Waals volume), DM
(dipole moment), ET (total energy).
concentrations. Compound 8-I-h, containing meta-chlorine,
and compound 8-I-l, containing para-bromine, showed much
lower levels of activity. Compounds 8-I-a and 8-I-i had more
insecticidal activity than the corresponding compounds 8-II-e
and 8-II-g, indicating that the flexible bridge in the substituent
group improved activity.
QSAR. To further explore the structural requirements for the
activity of the compounds, the data were analyzed using a
physicochemical-based QSAR (Hansch) approach involving
quantum-chemical and physicochemical factors as independent
parameters (Table 4). Insecticide activity data (% I) was
converted to log{I/[(100 − I) × MW]}and used as a depen-
dent parameter. MW is molecular weight.28
The resulting best models for each concentration are given in
Table 5, where N is the number of compounds included in the
model, r is the correlation coefficient, SE is the standard devia-
tion of the regression, F is the Fisher ratio, and P is the sig-
nificance of the model. Variations in the insecticide activities
against A. fabae and T. cinnabarinus were analyzed at con-
centrations of 100 mg L−1 and 10 mg L−1, respectively, using
the corresponding eqs 1, 2, 3, and 4.
It is worth noting that all equations were found to be suitable
for the prediction of insecticidal activities according to the
statistical parameters, especially taking into account that all the
models showed an r > 0.8 and the P < 0.05, and the eq 2 was
the best because the r = 0.937 with P = 0.0002. However, eqs 3
and 4 described the worst statistical significance, especially
when predictive capability was higher than the critical value of
0.01 (P value). For eq 3, improvement of the correlation (r
value) was achieved by removing compounds 8-I-i, 8-I-j, and 8-
I-n. Compounds 8-I-a and 8-I-j were excluded from the regres-
sion analysis for eq 4 to improve the correlation (r value).
The entire correlation matrix of the regression variables in
eq 2 is shown in Table 6. The activities calculated using eq 2
are listed in Table 7. The correlation relationship between
observed values and predicted values for eq 2 of the insecticidal
activity is shown in Figure 4.
The four equations show that the bioactivity of each com-
pound is highly correlated with HOMO, LUMO, QN, QO,
ClogP, MR, Vw, DM, and ET.
HOMO and LUMO energies, measures of nucleophilicity
and electrophilicity, respectively, are used for description of
electron donating and accepting power. In most cases, the
HOMO−LUMO energy gap is widely used as a measure of
chemical reactivity with bigger gaps implying larger excitation
energies and higher stability. The Pearson and Spearman rank
correlation demonstrates the high correlation between HOMO
and HOMO−LUMO (R2 = 0.97), so the HOMO−LUMO
energy gap was not involved in the final equations, similar to
the conclusion of Wang et al.29 This may suggest that a com-
pound with higher EHOMO has higher electron-donating ability
in agreement with its higher inhibition activity.
It has been shown that the Mulliken population of the mole-
cule may be important to the inhibition activity.30 The stepwise
regression shows that Mulliken population most related with
biological activity was the electric charges at QN and QO, which
reflects the overall effect of the electron withdrawing/donating
substituents to the charge distribution. Equations 1 and 2
indicate that an increase in the Mulliken population at the QN
and QO increases the biological activity. Results from these
models highlight the importance of electronic properties. It also
suggests that electronic properties of the molecule can help
explain the relationship between structure and inhibition
activity.
ClogP (hydrophobic constant) is used to rationalize interac-
tions of small ligands with various macromolecules in the fields
of biochemistry, medicinal chemistry, and environmental
sciences. ClogP is also considered to be one of the principal
parameters for the evaluation of the lipophilicity of a chemical
compound, and it significantly influences the bioactivity in
4784
dx.doi.org/10.1021/jf3002069 | J. Agric. Food Chem. 2012, 60, 4779−4787

Journal of Agricultural and Food Chemistry
Article
Figure 3. Synthetic route for compounds 8-I-a−8-I-n and 8-II-a−8-II-g. Reagents and conditions: (a) (NH4)2CO3, KCN, EtOH/H2O, 60 °C; then
concentrated HCl, 0 °C; (b) 3 N NaOH, reflux; adjusted to pH 6, 0 °C; (c) dry HCl (gas)/MeOH, 0 °C to reflux; (d) CH3CN, K2CO3, rt; (e)
DMF, t-BuOK; (f) 4 N HCl, reflux; (g) DCM, TEA, 4-DMAP, rt.
Table 5. Comparisons of Different Regression Equations and Statistical Parameters
regression eq
X1 = 11.438 + 10.371QN + 15.194Q O − 0.869 ClogP + 0.061 MR
− 0.011 Vw − 0.421DM − 0.009ET
removing compds
N
r
SE
F
P
21
0.829
0.444
4.087
0.014
(1)
21
18
19
0.937
0.805
0.807
0.218
0.243
0.243
10.734
3.385
4.861
0.0002
0.038
0.010
X2 = 23.619 + 89.081 HOMO + 8.125 LUMO + 12.218QN − 1.136
ClogP + 0.081 MR − 0.009 Vw − 0.326 DM − 0.008ET
(2)
8-I-i, 8-I-j, 8-I-n
8-I-a, 8-I-j
X3 = −1.779 + 26.824 HOMO − 9.587 LUMO − 0.888 ClogP + 0.072
MR − 0.004 Vw − 0.006ET
(3)
X4 = 2.129 + 32.666 HOMO − 0.386 ClogP + 0.041 MR − 0.007 Vw
− 0.007ET
(4)
heterogeneous systems.31 The four equation models indicate
that ClogP is negatively correlated with insecticidal inhibition; a
decrease in value may increase the bioactivity.
These equations indicate that inhibition activity of the deriv-
atives may be increased with the increase in MR (molar refrac-
tivity), which is a very important physicochemical parameter
to the understanding of bonding electrons in organic
molecules.32
The prediction models in each of these descriptors differ in
terms of either one or two parameters, but all maintain a nega-
tive relationship between inhibition activity and Vw (van der
Waals volume). It has been reported that molecular size is an
4785
dx.doi.org/10.1021/jf3002069 | J. Agric. Food Chem. 2012, 60, 4779−4787

Journal of Agricultural and Food Chemistry
Article
Table 6. Correlation Matrix of the Parameters Used in Equation 2
ET
Vw
DM
LUMO
HOMO
ClogP
QN
MR
ET
1.000
Vw
0.245
1.000
DM
0.157
0.339
1.000
LUMO
HOMO
ClogP
QN
0.340
−0.017
−0.159
0.331
0.002
1.000
−0.430
0.183
−0.181
0.504
−0.523
−0.259
−0.451
0.272
1.000
0.002
0.577
−0.083
1.000
−0.156
−0.229
−0.193
−0.460
0.058
0.325
1.000
MR
−0.474
−0.881
−0.506
1.000
Table 7. Values of Percentage of Inhibition (I%) Observed
and Predicted by Equation 2 and the Standard Residuals for
Each Compound
models. The Vw can reflect both the steric influence and the
recognition effects.
The DM (dipole moment) gives a measure of bond polarity
and charge separation throughout the molecule.34 In the pre-
sent study, all models show that the magnitude of DM inversely
correlates to the inhibition activity.
compd
obsd
predicted
residual
std residual
8-I-a
8-I-b
8-I-c
8-I-d
8-I-e
8-I-f
−2.38
−2.65
−2.86
−3.12
−1.80
−2.27
−2.48
−3.45
−2.69
−3.11
−2.69
−3.65
−2.50
−2.97
−2.62
−2.78
−3.14
−2.82
−2.97
−3.78
−3.54
−2.44
−2.62
−2.89
−3.08
−1.89
−2.23
−2.47
−3.19
−2.43
−3.53
−3.03
−3.44
−2.45
−2.94
−2.65
−2.80
−3.04
−2.98
−3.06
−3.59
−3.48
0.07
−0.02
0.03
0.30
−0.11
0.12
ET, total energy, has been interpreted in other QSAR studies
to measure stability.35 The significance of total energy might
relate to the difference in stability of the derivatives. All models
highlight the importance of total energy, as it relates to
inhibition activity, might include further examination of steric
energy, rotational energy barriers, as well as other structural and
physicochemical parameters.36
In summary, a series of novel 3-(2,5-dimethylphenyl)-4-
hydroxy-1-azaspiro[4.5]dec-3-ene-2,8-dione derivatives were
designed and synthesized. Their insecticidal activities against
A. fabae and T. cinnabarinus were evaluated. The results showed
that most of the derivatives containing phenyl-acyl-substituted
groups maintained more powerful insecticidal activity than
others, potentially at lower cost. QSAR demonstrated that
ClogP, HOMO, LUMO, Vw, MR, DM, and ET were the critical
parameters for the inhibition of target compounds. Although
only a small set of derivatives was used to develop these QSAR
models, the models still provided insight useful for the design
of derivatives and improvement of insecticidal activity.
−0.04
0.10
−0.17
0.44
−0.04
−0.01
−0.25
−0.25
0.42
−0.17
−0.02
−1.16
−1.17
1.92
8-I-g
8-I-h
8-I-i
8-I-j
8-I-k
8-I-l
0.34
1.56
−0.21
−0.04
−0.03
0.02
−0.95
−0.21
−0.15
0.10
8-I-m
8-I-n
8-II-a
8-II-b
8-II-c
8-II-d
8-II-e
8-II-f
8-II-g
0.03
0.12
−0.11
0.16
−0.50
0.75
0.09
0.40
−0.19
−0.06
−0.86
−0.26
AUTHOR INFORMATION
Corresponding Author
■
*No. 268 Kaixuan Road, Hangzhou, Zhejiang, P. R. China. Tel:
+86-571-86971220. Fax: +86-571-86971220. E-mail:
jinhaozhao@zju.edu.cn.
Funding
This project was supported by the National Natural Science
Foundation of China (No. 31101470).
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We would like to thank the National Engineering Research
Center for Agrochemicals for helping us to test biological
activity.
REFERENCES
Figure 4. Relationship between observed and predicted activity
by eq 2.
■
(1) Campbell, A. C.; Maidment, M. S.; Pick, J. H.; Stevenson, D. F.
M. Synthesis of (E)-and (Z)-pulvinones. J. Chem. Soc., Perkin. Trans. 1
1985, 8, 1567−1576.
(2) Effenberger, F.; Syed, J. Stereoselective synthesis of biologically
active tetronic acids. Tetrahedron: Asymmetry 1998, 9, 817−825.
(3) Schobert, R.; Schlenk, A. Tetramic and tetronic acids: an update
on new derivatives and biological aspects. Bioorg. Med. Chem. 2008, 16,
4203−4221.
important factor how to reach active sites and affect biological
activities.33 As explained by the lock−key model and induced-fit
model hypothesis, molecular recognition of chemical com-
pounds by receptors determines the biological activity. In this
study, Vw is one of the statistically significant descriptors in all
4786
dx.doi.org/10.1021/jf3002069 | J. Agric. Food Chem. 2012, 60, 4779−4787

Journal of Agricultural and Food Chemistry
Article
(4) Rauch, N.; Nauen, R. Spirodiclofen resistance risk assessment in
Tetranychus urticae (Acari: Tetranychidae): a biochemical approach.
Pestic. Biochem. Physiol. 2003, 74, 91−101.
(24) Dai, H.; Li, Y. Q.; Du, D.; Qin, X.; Zhang, X.; Yu, H. B.; Fang, J.
X. Synthesis and biological activities of novel pyrazole oxime
derivatives containing a 2-chloro-5-thiazolyl moiety. J. Agric. Food
Chem. 2008, 56, 10805−10810.
(25) Becke, A. D. Density-functional thermochemistry. III. The role
of exact exchange. J. Chem. Phys. 1993, 98, 1372−1377.
(26) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; et al. Gaussian 03,
Revision D.01; Gaussian, Inc.: Wallingford, CT, 2004. http://www.
gaussian.com/.
(27) Cao, S.; Wei, N.; Zhao, C. M.; Li, L.; Huang, Q. C.; Qian, X. H.
Syntheses, antifeedant activity, and QSAR analysis of new oxa(thia)-
diazolyl 3(2H)-pyridazinones. J. Agric. Food Chem. 2005, 53, 3120−
3125.
(28) Cai, M. Y.; Li, Z.; Fan, F.; Huang, Q. C.; Shao, X. S.; Song, G. H.
Design and Synthesis of novel insecticides based on the serotonergic
ligand 1-[(4-aminophenyl)ethyl]-4-[3-(trifluoromethyl)phenyl]-
piperazine (PAPP). J. Agric. Food Chem. 2010, 58, 2624−2629.
(29) Wang, Z. D.; Song, J.; Han, Z. J.; Jiang, Z. K.; Zheng, W. Q.;
Chen, J. Z.; Song, Z. Q.; Shang, S. B. Quantitative structure-activity
relationship of terpenoid aphid antifeedants. J. Agric. Food Chem. 2008,
56, 11361−11366.
(30) Thakur, M.; Thakur, A.; Balasubramanian, K. QSAR and SAR
studies on the reduction of some aromatic nitro compounds by
xanthine oxidase. J. Chem. Inf. Model. 2006, 46, 103−110.
(31) Han, R. M.; Tian, Y. X.; Liu, Y.; Chen, C. H.; Ai, X. C.; Zhang, J.
P.; Skibsted, L. H. Comparison of flavonoids and isoflavonoids as
antioxidants. J. Agric. Food Chem. 2009, 57, 3780−3785.
(32) Roy., K.; Saha, A. QSPR with TAU indices: molar refractivity of
diverse functional acyclic compounds. Indian J. Chem. 2005, 44B,
1693−1707.
(33) Sodano, G.; Caprioli, V.; Cimino, G.; Colle, R.; Gavagnin, M.;
Spinella, A. Insect antifeedant activity and hot taste for humans of
selected natural and synthetic 1,4-dialdehydes. J. Nat. Prod. 1987, 50,
146−151.
(34) Spillane, W. J.; Coyle, C. M.; Feeney, B. G.; Thompson, E. F.
Development of structure-taste relationships for thiazolyl-, benzothia-
zolyl-, and thiadiazolylsulfamates. J. Agric. Food Chem. 2009, 57, 5486−
5493.
(35) Bello-Ramirez, A. M.; Buendia-Orozco, J.; Nava-Ocampo, A. A.
A QSAR analysis to explain the analgesic properties of aconitum
alkaloids. Fundam. Clin. Pharmacol. 2003, 17, 575−580.
(36) Paluch, G.; Grodnitzky, J.; Bartholomay, L.; Coats, J.
Quantitative structure-activity relationship of botanical sesquiterpenes:
spatial and contact repellency to the yellow fever mosquito, Aedes
aegypti. J. Agric. Food Chem. 2009, 57, 7618−7625.
(5) Ke, S. Y.; Sun, T. T.; Zhang, Z. G.; Zhang, Y. N.; Liang, Y.
Spirodiclofen analogues as potential lipid biosynthesis inhibitors: a
convenient synthesis, biological evaluation, and structure-activity
relationship. Bull. Korean Chem. Soc. 2010, 31, 2315−2321.
(6) Liu, T. X. Toxicity and efficacy of spiromesifen, a tetronic acid
insecticide, against sweetpotato whitefly (homoptera: aleyrodidae) on
melons and collards. Crop Prot. 2004, 23, 505−513.
(7) Zhao, J. H.; Ji, M. H.; Xu, X. H.; Cheng, J. L.; Zhu, G. N.
Synthetic derivatives of spiromesifen and their bioactivity research.
Chin. Chem. Lett. 2009, 20, 1307−1310.
(8) Fischer, R.; Wei, H. C. Spirotetramat (Movento®) − discovery,
synthesis and physicochemical properties. Bayer CropSci. J. 2008, 61
(2), 127−140.
(9) Bruck, E.; Elbert, A.; Fischer, R.; Krueger, S.; Kuhnhold, J.
̈
̈
Movento®, an innovative ambimobile insecticide for sucking insect
pest control in agriculture: biological profile and field performance.
Crop Prot. 2009, 28, 838−844.
(10) Nauen, R.; Reckmann, U.; Thomzik, J.; Thielert, W. Biological
profile of spirotetramat (Movento®) − a new two-way systemic
(ambimobile) insecticide against sucking pest species. Bayer CropSci. J.
2008, 61 (2), 245−278.
(11) Maus, Ch. Ecotoxicological profile of the insecticide
spirotetramat. Bayer CropSci. J. 2008, 61 (2), 159−180.
(12) Casida, J. E. Pest toxicology: the primary mechanisms of
pesticide action. Chem. Res. Toxicol. 2009, 22, 609−619.
(13) Himmler, T.; Fischer, R.; Gallenkamp, B.; Knops, H. J.; Mulder,
L. Cis-alkoxy-substituted spirocyclic 1H-pyrrolidine-2,4-dione deriva-
tives serving as pesticides. DE 10231333, 2004.
(14) Zhu, Y. Q.; Liu, P.; Si, X. K.; Zou, X. M.; Liu, B.; Song, H. B.;
Yang, H. Z. A quantitative structure-activity relationship study of
herbicidal analogues of α-hydroxy-substituted 3-benzylidenepyrroli-
dene-2, 4-diones. J. Agric. Food Chem. 2006, 54, 9593−9598.
(15) Lei, B. L.; Li, J. Z.; Lu, J.; Du, J.; Liu, H. X.; Yao, X. J. Rational
prediction of the herbicidal activities of novel protoporphyrinogen
oxidase inhibitors by quantitative structure-activity relationship model
based on docking-guided active conformation. J. Agric. Food Chem.
2009, 57, 9593−9598.
(16) Coutrot, P.; Ghribi, A. A Facile and General, One-pot synthesis
of 2-oxoalkane phosphonates from diethylphosphonocarboxylic acid
chlorides and organometallic reagents. Synthesis 1986, 661−664.
(17) Chu, Y. J.; Lynch, V; Iverson, B. L. Synthesis and DNA binding
studies of bis-intercalators with a novel spiro-cyclic linker. Tetrahedron
2006, 62, 5536−5548.
(18) Hayashi, S.; Nakata, E.; Morita, A.; Mizuno, K.; Yamamura, K;
Kato, A.; Ohashi, K. Discovery of {1-[4-(2-{hexahydropyrrolo[3,4-c]-
pyrrol-2(1H)-yl}-1H-ben-zimidazol-1-yl)piperidin-1-yl]cyclooctyl}-
methanol, systemically potent novel non-peptide agonist of
nociceptin/orphanin FQ receptor as analgesic for the treatment of
neuropathic pain: design, synthesis, and structure-activity relationships.
Bioorg. Med. Chem. 2010, 18, 7675−7699.
(19) Bretschneider, T.; Lohmar; Fischer, R.; Manheim;et al.
Spiroketal-substituted cyclic ketoenols. US 20080305955A1, 2008.
(20) Abbott, W. S. A method of computing the effectiveness of an
insecticide. J. Econ. Entomol. 1925, 18, 265−267.
(21) Zhao, Q. Q.; Li, Y. Q.; Xiong, L. X.; Wang, Q. M. Design,
synthesis and insecticidal activity of novel phenylpyrazoles containing
a 2,2,2-trichloro-1-alkoxyethyl moiety. J. Agric. Food Chem. 2010, 58,
4992−4998.
(22) Zhao, Y.; Li, Y. Q.; Ou, X. M.; Zhang, P. X.; Huang, Z. Q.; Bi, F.
C.; Huang, R. Q.; Wang, Q. M. Synthesis, insecticidal, and acaricidal
activities of novel 2-aryl-pyrrole derivatives containing ester groups. J.
Agric. Food Chem. 2008, 56, 10176−10182.
(23) Luo, Y. P.; Yang, G. Fu. Discovery of a new insecticide lead by
optimizing a target-diverse scaffold: tetrazolinone derivatives. Bioorg.
Med. Chem. 2007, 15, 1716−1724.
4787
dx.doi.org/10.1021/jf3002069 | J. Agric. Food Chem. 2012, 60, 4779−4787