Molecules 2020, 25, 3379
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reaction was complete; the mixture was then poured into water, and a 2 M HCl aqueous solution
was added to the flask until the reaction mixture was neutralized. The resultant solid was separated
by filtration, then washed with water (60 mL), and finally dried in a desiccator to form 25.0 g of
intermediate 2h as a white solid at a yield of 93%; melting point: 116.2–116.8 ◦C; 1H NMR (500 MHz,
DMSO-d6)
δ 13.36 (br, 1H, OH), 6.58 (s, 1H, pyrimidy1-H), 5.54 (s, 1H, CH2), 5.32 (s, 1H, CH2), 4.10 (s,
2H, CH2).
3.2.4. Synthesis of (E)-Methyl
3-methoxy-2-(2-((2-(3,4,4-trifluorobut-3-enylthio)-6-(trifluoromethyl)pyrimidin-4-yloxy)methyl)
phenyl)acrylate Compound 4b
Potassium carbonate (1.55 g, 98.0%, 0.011 mol) and 2-(3,4,4-trifluorobut-3-enylthio)-6-(trifluoromethyl)
pyrimidin-4-ol (2f) (2.5 g, 0.01 mol) were added to 50 mL of DMF and reacted for 1 h at 60 ◦C; then,
2.55 g (0.011 mol) of (E)-methyl 2-(2-(chloromethyl)phenyl)-3-methoxyacrylate 3a was introduced into
the batches. The reaction temperature was raised to 80 ◦C and maintained for 2 h; the reaction was
monitored by TLC. Afterward, the reaction mixture was poured into water and extracted with ethyl
acetate (50 mL). The organic phase was washed successively with water (20 mL) and saturated brine
(20 mL), then dried, filtered, and evaporated under reduced pressure. The residue was purified by
silica gel chromatography using ethyl acetate/petroleum ether (1:10, v/v) as the eluent in a temperature
1
range of 60–90 ◦C to obtain 4.4 g of the compound 4b as a yellow oil at a yield of 87%. H NMR (500
MHz, DMSO-d6)
1H, Ar-H), 7.11 (s, 1H, pyrimidy1-H), 5.35 (s, 2H, CH2), 3.78 (s, 3H, CH3), 3.57 (s, 3H, CH3), 3.33 (t,
J = 7.0 Hz, 2H, CH2), 2.73–2.81 (m, 2H, CH2); 13C NMR (125 MHz, DMSO-d6)
171.76, 169.42, 166.85,
δ 7.61 (s, 1H, CH), 7.48–7.50 (m, 1H, Ar-H), 7.22–7.36 (m, 2H, Ar-H), 7.13–7.15 (m,
δ
160.87, 160.81, 154.89 (q, J = 36.3 Hz), 153.24 (m), 134.29, 132.65, 131.30, 128.64, 128.14, 127.62, 127.81 (m),
120.24 (q, J = 272.5 Hz), 108.66, 101.43(q, J = 2.5 Hz), 67.12, 61.79, 51.16, 25.49, 25.35 (dd, J1 = 21.3 Hz,
J2 = 2.5 Hz); HRMS: m/z 531.0787 (M + Na)+(calcd. [M + Na]+ 531.0784.
3.3. Acaricidal Activities Assay
The detailed procedure of the acaricidal activity against adult T. cinnabarinus was measured
according to the related literature [51].
Each of the test compounds was first dissolved in a mixture of acetone and water (at a volume ratio
of 9 to 1) containing 0.1% TWEEN® 80 to furnish the stock solutions. A series of test solutions were
then prepared by diluting the stock solutions with water containing 0.1% TWEEN® 80. Afterward, the
kidney bean plants with one true leaf were infested with T. cinnabarinus (carmine spider mite) prior to
spraying. An airbrush was used to spray the plants with the test solutions, and each bioassay was
replicated three times at a temperature of 25
±
1 ◦C to meet the statistical requirements. After the
plants were dried, they were transferred to a maintenance room for observation. The mortality rate of
the spider mite was investigated after 72 h. The mites that did not either fly away or respond to the
touch of a fine brush were considered to be dead. The rate of mortality was evaluated according to
a percentage scale of 0–100, in which 0 indicates no activity of the test solutions against the spider
mites, and 100 indicates totally killing them. When the percentage of the mortality of the blank control
was less than 5%, the results of the treatment were directly used. However, if the percentage of the
mortality of the blank control ranged from 5 to 20%, the results were corrected by the means of the
following equation:
V = (X − Y)/Y × 100
(1)
where, V is the value of the corrected percentage of mortality, and X represents the viability of the blank
control; Y stands for the viability of the treatment. As a positive control, commercial fluacrypyrim was
also evaluated using exactly the same procedure.