The novel herbicide icafolin-methyl is a plant-specific inhibitor of tubulin polymerization.

BACKGROUND: Without controlling weeds, it is estimated that about one third of global crop yields would be lost. Herbicides remain the most effective solution for weed control, but they face multiple challenges, such as the emergence and growth of resistant weed populations. Consequently, there is an urgent need for either herbicides with new modes of action or at least novel chemistries within established modes of action, with outstanding efficacy but without showing cross-resistance to the herbicides present in the prospective markets. RESULTS: Icafolin-methyl is a novel herbicide with a unique biological profile. It is hydrolyzed in planta to the carboxylic acid icafolin. After post-emergence application icafolin-methyl and icafolin both show high efficacy against the most relevant competitive weeds in cold and warm season cropping systems at low application rates, including resistant black-grass and rye-grass biotypes. Biochemical and genetic evidence is provided that icafolin-methyl and icafolin inhibit plant tubulin polymerization probably by binding to ß-tubulins. CONCLUSION: Icafolin-methyl is a novel non-selective herbicide with an established mode of action, but with a superior potency and spectrum, specifically after foliar application. This makes icafolin-methyl fundamentally different from existing tubulin polymerization inhibiting herbicides. It complements the farmers weed control toolbox, particularly with respect to resistance management. © 2024 Society of Chemical Industry.

What makes a molecule a pre- or a post-herbicide - how valuable are physicochemical parameters for their design?

Pre-emergence herbicides are taken up by seeds before germination and by roots, hypocotyls, cotyledons, coleoptiles or leaves before emergence, whereas post-emergence herbicides are taken up primarily by foliage and stems. Most modern pre-emergence herbicides are lipophilic, but post-emergence herbicides may be lipophilic or hydrophilic. The metabolic conversion of herbicides to inactive or active metabolites after plant uptake is of major importance for some compound classes. Several herbicides are proherbicides as for example some acetyl-coenzyme A carboxylase (ACCase)-inhibitors. The physicochemical characteristics of proherbicides and herbicides are usually unrelated. A major role can be attributed to the site of action at a cellular level. A great number of herbicides such as photosystem II (PS II)-inhibitors, protoporphyrinogen oxidase (PPO)-inhibitors or carotenoid biosynthesis inhibitors require light for activity. Others, such as cellulose-biosynthesis and mitotic inhibitors seem to be primarily active in belowground organs. Several lipophilic barriers against the uptake of xenobiotics exist in aboveground and belowground plant parts. The relevance of these barriers needs, however, further clarification. Uptake and translocation models are valuable tools for the explanation of the potential movement of compounds. Many factors other than uptake and translocation have, however, to be considered for the design of herbicides. For post-emergence herbicides, ultraviolet (UV) light stability, stability in formulations, and mixability with other agrochemicals have to be kept in mind while, in addition to the aforementioned factors soil interaction plays a major role for pre-emergence herbicides. In our opinion, general physicochemical characteristics of pre- or post-emergence herbicides do, unfortunately not exist yet. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Solid supported synthesis of phosphinates via palladium (0) catalysed coupling reactions.

In order to gain a broad access to phosphinic acid derivatives, a palladium catalysed coupling reaction of aryl iodides with hypophosphorous acid derivatives has been developed on the solid phase. The resulting arylphosphorous acids (or esters) were derivatised using addition reactions with aldehydes, imines and isocyanates, to give phosphinic acids (or esters) with alpha-hydroxy, alpha-amino or aminoacyl groups attached to the aryl phosphorus moiety. This approach provided a broad chemical entry into a class of polar phosphinates compounds which were rather difficult to handle using normal solution phase synthesis. The synthetic potential of this solid phase based methodology was demonstrated by the synthesis of targeted libraries against the enzyme dihydrodipicolinate synthase (DHDPS).