Structural Optimization\nof Natural Plant Products:\nConstruction, Pesticidal Activities, and Toxicology Study of New 2‑Isopropanol-4-methoxy-7-alkyl/aryloxycarbonyl‑(<i>E</i>)‑vinyl-2,3-dihydrobenzofurans

Recently, the structural optimization of natural bioactive\nproducts\nhas been one of the important ways to discover new pesticide candidates.\nBased on osthole as a lead compound, herein, a series of new 2-isopropanol-4-methoxy-7-alkyl/aryloxycarbonyl-(<i>E</i>)-vinyl-2,3-dihydrobenzofuran derivatives were synthesized.\nSteric configurations of compounds <b>3</b>, <b>4</b>, <b>6</b>, <b>9</b>, <b>11</b>, <b>29</b>, and <b>31</b> were confirmed by X-ray monocrystallography. Notably, an\nefficient method for preparation of 2-isopropanol-2,3-dihydrobenzofurans\nfrom osthole by the epoxidation and rearrangement reactions was developed.\nAgainst Plutella xylostella Linnaeus,\ncompound <b>31</b> (<i>R</i> = CH<sub>2</sub>CH<sub>2</sub>Ph; LC<sub>50</sub>: 0.759 mg/mL) displayed a 1.9-fold insecticidal\nactivity compared to that of osthole; against Tetranychus\ncinnabarinus Boisduval, compound <b>34</b> (<i>R</i> = (CH<sub>2</sub>)<sub>9</sub>CH<sub>3</sub>; LC<sub>50</sub>: 0.401 mg/mL) exhibited a 3.3-fold acaricidal activity and good\ncontrol effects compared to those of osthole. By the scanning electron\nmicroscope (SEM) imaging method, it was demonstrated that the acaricidal\nactivity of compound <b>34</b> may be related to the damage\nof the cuticle layer crest of T. cinnabarinus. Compound <b>34</b> could be further studied as a potential\nacaricide.