Semi-Preparation\nand X‑ray Single-Crystal Structures\nof Sophocarpine-Based Isoxazoline Derivatives and Their Pesticidal\nEffects and Toxicology Study

Recently,\nresearch and development of novel pesticides from natural\nplant products have received much attention. To accelerate the application\nof sophocarpine as the agrochemical candidate, a series of novel sophocarpine-based\nisoxazoline derivatives were prepared by the 1,3-dipolar [2 + 3] cycloaddition\nreaction of sophocarpine with different chloroximes. Their structures\nwere well characterized by high-resolution mass spectra, infrared\nspectra, and proton/carbon-13 nuclear magnetic resonance spectra.\nEight steric configurations of compounds <b>5a</b>, <b>5e’</b>, <b>5f</b>, <b>5g</b>, <b>5h</b>, <b>5i</b>, <b>5r</b>, and <b>5u’</b> were further determined\nby X-ray single-crystallography. Against Aphis citricola Van der Goot, compounds <b>5n</b> (LD<sub>50</sub>: 0.032\nμg/nymph) and <b>5o</b> (LD<sub>50</sub>: 0.024 μg/nymph)\nexhibited greater than 3.7- and 4.9-fold potent aphicidal activity\ncompared to sophocarpine (LD<sub>50</sub>: 0.118 μg/nymph).\nAgainst Tetranychus cinnabarinus Boisduval,\nderivative <b>5g</b> displayed the most promising acaricidal\nactivity with the LC<sub>50</sub> value of 0.247 mg/mL, which was\n14.2-fold that of sophocarpine. Compounds <b>5d</b> and <b>5g</b> also exhibited good control efficacy against T. cinnabarinus. Scanning electron microscopy images\nindicated that compound <b>5g</b> can destroy the mite cuticle\nlayer. These results will provide the foundation for the structural\nmodification and use of sophocarpine derivatives as agrochemicals\nin the future.