Figure 1. Chemical structures of several natural products and commercial drugs containing the quinazolinone backbone, hydrazide.
derivatives. Subsequently, these synthesized compounds were
tested against S. sclerotiorum, Rhizoctonia solani, Botrytis cinerea,
Fusarium graminearum, Pellicularia sasakii, and Fusarium
oxysporum. Afterward, a pot experiment was performed with
S. sclerotiorum to further evaluate the prospective application of
developing 4(3H)-quinazolinone derivatives as agricultural
fungicides. Furthermore, preliminary action mechanism
investigations were conducted for evaluating morphological
changes, relative electric conductivity, and cytoplasmic content
leakage.
product was washed with water and dried to obtain KZL-2−KZL-
30
16.
General Synthetic Procedure for Compounds KZL-17−KZL-34.
Hydrazine hydrate (0.0600 mL, 1.27 mmol) was added dropwise to a
stirred suspension of intermediate A (0.300 g, 1.06 mmol) in ethanol
(5 mL). The solution was refluxed and monitored by thin-layer
chromatography (TLC). After cooling and in vacuo concentration,
H O (20 mL) was added and ethyl acetate (EtOAc, 3 × 20 mL) was
2
extracted, which was dried under MgSO and concentrated in vacuo
4
to obtain a crude product. Purification by column chromatography
31
(with 9:1 petroleum ether/EtOAc) afforded KZL-17−KZL-34.
Synthesis of Key Intermediate 2. In a 50 mL flask, an appropriate
amount of triethylamine was added dropwise to a mixture solvent of
glycine methyl ester hydrochloride (0.310 g, 2.47 mmol) and
intermediate 1 in benzene (20 mL). After refluxing for 10 h, water
was added and extracted with EtOAc (3 × 20 mL), dried with
MATERIALS AND METHODS
■
Instruments and Chemicals. A WRS-2U melting point
apparatus (Shanghai Precision Instrument Co., Ltd., China) was
used to determine the uncorrected melting points (mp). A Bruker
AM-400 spectrometer (Bruker Company, Billerica, MA, US.) was
MgSO , and concentrated. Target compounds were harvested after
4
purification by flash chromatography (using 8:1 petroleum ether/
1
13
used to obtain the H and C NMR spectra of compounds (with
tetramethylsilane as the internal standard). Mass spectra were
recorded using a Bruker Daltonics APEXII49e spectrometer (Bruker
Daltonics Inc., Billerica, MA, USA) with an ESI or EI ionization
source. A scanning electron microscope (Hitachi, S-3400N, Japan)
and a transmission electron microscope (Hitachi, HT7700, Japan)
were used for morphological observation. Hypha relative conductivity
and cytoplasmic content leakage were obtained with a conductivity
meter (Leici DDS-307, China) and a UV−vis spectrophotometer
32
EtOAc).
Synthesis of Key Intermediate 3. In a 50 mL flask, a solution of
lithium hydroxide (0.190 g, 5.00 mmol) in H O was dropped into
2
intermediate 2 (0.700 g, 2.47 mmol) in tetrahydrofuran (THF) (20
mL). The solution was maintained at room temperature for 3 h and
monitored by TLC, followed by reduced pressure evaporation. The
residue was diluted with 2 N hydrochloric acid and extracted with
dichloromethane (DCM). Target compounds were finally harvested
after drying with MgSO4 and evaporated and purified by flash
chromatography (using 10:1 DCM /methanol).
(
UV1902 PC, China). Commercial solvents and reagents used were
of reagent grade, and the commercial fungicide azoxystrobin was used
as positive control in the assay.
Fungi. S. sclerotiorum, R. solani, B. cinerea, F. graminearum, and F.
oxysporum were provided by Gansu Academy of Agricultural Sciences
and P. sasakii was obtained from Huazhong Agricultural University.
These fungi were maintained in a potato dextrose agar medium at 4
General Methods for the Preparation of Compounds 1a−1g,
2
a. At 0 °C, to a suspension of intermediate 2 (5.00 g, 28.4 mmol) in
dry DCM, the corresponding amine (0.210 mL, 2.00 mmol),
hydroxybenzotriazole (0.270 g, 2.00 mmol), and 1-ethyl-3-(3-
dimethylaminopropyl)carbodiimide (0.380 g, 2.00 mmol) were
added successively. The reaction mixture was stirred for 24 h at
room temperature. After confirmation of the completion of the
reaction by TLC, the residue was washed with brine, dried over
°C.
Synthetic Procedures. The synthetic route of target compounds
KZL-1−KZL-34 and 1a−8i is outlined in Schemes 1−3 (Figure 1).
Synthesis of Key Intermediate 1(A). A stirred solution of
substituted aminobenzoic acid (0.500 g, 3.65 mmol) in trifluoroacetic
anhydride or acetic anhydride (6 mL) was refluxed for 4 h. The
anhydrous MgSO , and after removing the solvent was purified by
4
silica gel column chromatography (6:1 petroleum ether/EtOAc) to
33
give 1a−1g and 2a.
29
Synthesis of Key Intermediate 4. In a 50 mL flask, hydrazine
hydrate (0.360 mL, 7.41 mmol) was dropped into intermediate 2
reaction was concentrated under reduced pressure to a brown oil.
Synthesis of Quinazolinone KZL-1. In a 25 mL flask, the mixture
of 2-aminobenzoic acid (0.500 g, 3.65 mmol) and formamide (2.90
mL, 73.0 mmol) was refluxed at 150 °C for 7 h. Then, a white
precipitate was formed, filtered, washed with water, and dried to give
KZL-1.
General Methods for the Preparation of Compounds KZL-2−
KZL-16. In a 50 mL flask, ammonium acetate (1.90 g, 24.7 mmol) was
added to the corresponding intermediate A (0.700 g, 2.47 mmol) and
refluxed for 60 min. Then, the reaction mixture was transferred into
stirred ice-water, filtered, and the precipitate was obtained. The crude
(0.700 g, 2.47 mmol) solution in methanol (20 mL) at room
temperature while stirring and then refluxed for a short time; a white
34
solid was formed and that was collected by filteration.
General Synthetic Procedure for Compounds 3a−3g. In a 25 mL
flask, intermediate 4 (0.350 g, 1.00 mmol) was mixed with a
corresponding benzaldehyde (0.110 mL, 1.05 mmol) solution in
ethanol (10 mL) and was refluxed for 2 h. After cooling, the crude
product was collected by filtration, washed, and recrystallized from
35
hot ethanol to yield 3a−3g.
4
605
J. Agric. Food Chem. 2021, 69, 4604−4614
Peng, Jing-Wen
