This work reports halogenated 5-(2-hydroxyphenyl)pyrazoles as pseudilin analogues with the potential to target the enzyme IspD in the methylerythritol phosphate (MEP) pathway. Such analogues were designed using the bioisosteric replacement of the pseudilin core structure and synthesized via an efficient three-step route. With AtIspD-based screening and pre-and postemergence herbicidal tests, these compounds were demonstrated to have considerable activities against AtIspD, with IC 50 up to 3.27 μM, and against model plants rape and barnyard grass, with moderate to excellent activities. At a rate of 150 g/ha in the greenhouse test, three compounds exhibited higher or comparable herbicidal activities than pseudilin. Molecular docking of representative compounds into the allosteric site of AtIspD revealed a binding mode similar to that of pseudilin. The established bioisosterism and synthesis method in this work may serve as an important tool for the development of new herbicides and antimicrobials targeting IspD in the MEP pathway.
This work presents a strategy for fabricating low dielectric epoxy copolymers through copolymerizing bisphenol A diglycidyl ether with N,N′-disilyl bis(secondary amine)s, a series of difunctional silylamines synthesized by silylation of bis(secondary amine)s. A study on the model reaction of monoepoxy with monofunctional silylamines identified that the reaction proceeded smoothly in tetrahydrofuran with Mg(ClO 4 ) 2 catalysis and mechanistically through sequential silylamine-induced epoxy ringopening and silylotropic N → O migration, a process with favorable Gibbs free energy changes as confirmed by density functional theory calculations. The copolymers demonstrated remarkably low dielectric constants and dielectric losses due to the formation of the low-polarizable silyloxyl instead of the hydroxyl group in polymerization and the enlarged molecular free volume. In addition, the copolymers showed desirable toughness, hydrophobicity, and thermal stability. As a tool to achieve these desirable features, the strategy developed in this work may find promising application in designing low dielectric epoxy resin materials for use in the microelectronic field.
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