%0 Journal Article %T Quantitative structure-activity relationship of 2,6-dimethoxy-N-(3-(4-substituted phenyl)isoxazol-5-yl)benzamide for the inhibition of chitin synthesis. %A Mori K %A Miyashita M %A Mori S %A Shibata N %A Nakagawa Y %J J Pestic Sci %V 49 %N 2 %D 2024 May 20 %M 38882705 %F 2.529 %R 10.1584/jpestics.D24-004 %X Previously, we found that 5-(2,6-dimethoxybenzoylamino)-3-phenylisoxazoles (IOXs) inhibit chitin synthesis in the cultured integument of Chilo suppressalis. In this study, IOXs with various substituents at the para-position of the 3-phenyl ring were synthesized, and the concentrations required to inhibit chitin synthesis to 50% (IC50) were determined for all compounds. The introduction of halogens-such as F, Cl, and Br-and small alkyls-such as Me, Et, Pr, and n-Bu-at the 3-phenyl ring slightly enhanced the activity. However, the activity decreased drastically with the introduction of NO2, CF3, and t-Bu. The quantitative analysis of the substituent effect at the 3-phenyl ring on chitin-synthesis inhibition using the Hansch-Fujita method showed that the hydrophobic substituent with the optimum value was favored for the activity, but the bulky substituent in terms of E s was detrimental to the activity.