Discovery and SAR of Halauxifen Methyl: A Novel Auxin Herbicide

145

147

Herbicides classified as synthetic auxins have been most commonly used to control broadleaf weeds in a variety of crops and in non‐cropland areas since the first synthetic auxin herbicide (SAH), 2,4‐D, was introduced to the market in the mid‐1940s. The incidence of weed species resistant to SAHs is relatively low considering their long‐term global application with 30 broadleaf, 5 grass, and 1 grass‐like weed species confirmed resistant to date. An understanding of the context and mechanisms of SAH resistance evolution can inform management practices to sustain the longevity and utility of this important class of herbicides. A symposium was convened during the 2nd Global Herbicide Resistance Challenge (May 2017; Denver, CO, USA) to provide an overview of the current state of knowledge of SAH resistance mechanisms including case studies of weed species resistant to SAHs and perspectives on mitigating resistance development in SAH‐tolerant crops. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Section: Recent Innovations In Synthetic Auxin Herbicide Discoverymentioning

confidence: 99%

Weed resistance to synthetic auxin herbicides

Busi

Goggin

Heap³

et al. 2018

145

147

“…Enzymatic carboxylate methyl ester cleavage in planta of the pro‐herbicide halauxifen‐methyl (Fig. ) results in a pyridine type auxin having physiological and phenotypic effects similar to those induced by the natural plant hormone indole‐3‐acetic acid (IAA) .…”

Section: Herbicidesmentioning

confidence: 99%

Latest generation of halogen‐containing pesticides

Jeschke

2017

200

134

Agriculture is confronted with enormous challenges, from production of enough high-quality food to water use, environmental impacts and issues combined with a continually growing world population. Modern agricultural chemistry has to support farmers by providing innovative agrichemicals, used in applied agriculture. In this context, the introduction of halogen atoms into an active ingredient is still an important tool to modulate the properties of new crop protection compounds. Since 2010, around 96% of the launched products (herbicides, fungicides, insecticides/acaricides and nematicides) contain halogen atoms. The launched nematicides contain the largest number of halogen atoms, followed by insecticides/acaricides, herbicides and fungicides. In this context, fungicides and herbicides contain in most cases fluorine atoms, whereas nematicides and insecticides contain in most cases 'mixed' halogen atoms, for example chlorine and fluorine. This review gives an overview of the latest generation of halogen-containing pesticides launched over the past 6 years and describes current halogen-containing development candidates. © 2017 Society of Chemical Industry.

“…In the late 1950s it was discovered that some soil microbial metabolites of experimental nitrification inhibitors were herbicidal . This discovery led to the identification of the pyridine‐2‐carboxylic acid (also known as picolinic acid) herbicide class including the commercial synthetic auxin herbicides picloram ( 8 , Fig.…”

Section: Discovery Of Halauxifen‐methylmentioning

confidence: 99%

“…Accordingly, a new round of synthesis effort was initiated that was focused on analogs with a variety of substituents at the 3‐position of the 6‐arylpicolinate phenyl ring. Substituents that had previously been shown to impart susceptibility to plant and soil microbe metabolism in other herbicide families were specifically selected for incorporation at the 3‐position of the 6‐arylpicolinate phenyl ring.…”

Section: Discovery Of Halauxifen‐methylmentioning

confidence: 99%

Fifty years of herbicide research: comparing the discovery of trifluralin and halauxifen‐methyl

Epp¹,

Schmitzer²,

Crouse³

2017

Fifty years separate the commercialization of the herbicides trifluralin and halauxifen-methyl. Despite the vast degree of technological change that occurred over that time frame, some aspects of their discovery stories are remarkably similar. For example, both herbicides were prepared very early in the iterative discovery process and both were developed from known lead compound structures by hypothesis-driven research efforts without the use of in vitro assays or computer-aided molecular design. However, there are aspects of the halauxifen-methyl and trifluralin discovery stories that are substantially different. For example, the chemical technology required for the cost-effective production of halauxifen-methyl simply did not exist just two decades prior to its commercial launch. By contrast, the chemical technology required for the cost-effective production of trifluralin was reported in the chemical literature more than two decades prior to its commercial launch. In addition, changes in regulatory environment since the early 1960s ensured that their respective discovery to commercial launch stories would also differ in substantial ways. Ultimately, the time and cost required to develop and register halauxifen-methyl demanded a global initial business case while the lower registration hurdles that trifluralin cleared enabled a narrow initial business case mainly focused on the USA.