Synthesis and insecticidal activity of N-(5-phenylpyrazin-2-yl)-benzamide derivatives: Elucidation of mode of action on chitin biosynthesis through symptomology and genetic studies.

Among the six-membered heterocycles, the pyrazine ring is poorly explored in crop protection and does not feature in any product listed in the current IRAC MoA classification. In an effort to identify new leads for internal research, we synthesized a series of N-(5-phenylpyrazin-2-yl)-benzamide derivatives and evaluated them for their insecticidal activity. N-(5-phenylpyrazin-2-yl)-benzamide derivatives 3 were prepared using an automated two-step synthesis protocol. These compounds were tested for their initial biological activity against a wide range of sucking and chewing insect pests and found to be active against lepidopterans only. More detailed experiments, including symptomology studies on the diamondback moth, Plutella xylostella (L.) and the Egyptian cotton leafworm, Spodoptera littoralis (Boisduval) showed that analog 3q causes severe abnormalities in the lepidopteran cuticle leading to larval mortality. Compound 3q shows strong potency against both P. xylostella and S. littoralis, whereas analog 3i shows better potency against S. littoralis causing also impaired cuticular structure and death of the larvae. Additionally, P. xylostella genetic studies showed that compound 3q resistance is linked to Chitin Synthase 1. Our studies show that N-(5-phenylpyrazin-2-yl)-benzamide derivatives 3, and in particular analogs 3i and 3q, act as insect growth modulator insecticides. Conformational similarities with lufenuron are discussed.

The importance of trifluoromethyl pyridines in crop protection.

The pyridine ring, substituted by a trifluoromethyl substituent has been successfully incorporated into molecules with useful biological properties. During the period 1990 to September 2017, 14 crop protection products bearing a trifluoromethyl pyridine have been commercialized or proposed for an ISO common name, covering fungicides, herbicides, insecticides and nematicides. Chemical processes have been developed to provide trifluoromethyl pyridine intermediates, from non-fluorinated pyridine starting materials, at scale and with affordable costs of goods. These attractive starting materials were readily adopted by research chemists, and elaborated through simple chemical modifications into new active ingredients. In a second approach, substituted trifluoromethyl pyridine rings have been constructed from acyclic, trifluoromethyl starting materials, which again has served to identify new active ingredients. Molecular matched pair analysis reveals subtle, yet important differences in physicochemical and agronomic properties of trifluoromethyl pyridines compared with the phenyl analogues. This review focuses on the past 27 years, seeking to identify reasons behind the success of such research programmes, and inspire the search for new crop protection chemicals containing the trifluoromethyl pyridine ring. © 2017 Society of Chemical Industry.

Investigating the Structure-Activity Relationship of the Insecticidal Natural Product Rocaglamide.

The natural product Rocaglamide (1), isolated from the tree Aglaia elliptifolia, is a compelling but also challenging lead structure for crop protection. In laboratory assays, the natural product shows highly interesting insecticidal activity against chewing pests and beetles, but also phytotoxicity on some crop plants. Multi-step syntheses with control of stereochemistry were required to probe the structure-activity relationship (SAR), and seek simplified analogues. After a significant research effort, just two areas of the molecule were identified which allow modification whilst maintaining activity, as will be highlighted in this paper.

Bicyclic heterocyclic anthranilic diamides as ryanodine receptor modulators with insecticidal activity.

The diamide insecticides act on the ryanodine receptor (RyR). The synthesis of various bicyclic anthranilic derivatives is reported. Their activity against the insect ryanodine receptor (RyR) and their insecticidal activity in the greenhouse is presented, as well as structure activity relationship considerations.

Investigating the mode of action of sulfoxaflor: a fourth-generation neonicotinoid.

BACKGROUND: The precise mode of action of sulfoxaflor, a new nicotinic acetylcholine receptor-modulating insecticide, is unclear. A detailed understanding of the mode of action, especially in relation to the neonicotinoids, is essential for recommending effective pest management practices. RESULTS: Radiolabel binding experiments using a tritiated analogue of sulfoxaflor ([(3) H]-methyl-SFX) performed on membranes from Myzus persicae demonstrate that sulfoxaflor interacts specifically with the high-affinity imidacloprid binding site present in a subpopulation of the total nAChR pool. In competition studies, imidacloprid-like neonicotinoids displace [(3) H]-methyl-SFX at pM concentrations. The effects of sulfoxaflor on the exposed aphid nervous system in situ are analogous to those of imidacloprid and nitenpyram, and finally the high-affinity sulfoxaflor binding site is absent in a Myzus persicae strain (clone FRC) possessing a single amino acid point mutation (R81T) in the ß-nAChR, a region critical for neonicotinoid interaction. CONCLUSION: The nicotinic acetylcholine receptor pharmacological profile of sulfoxaflor in aphids is consistent with that of imidacloprid. Additionally, the insecticidal activity of sulfoxaflor and the current commercialised neonicotinoids is affected by the point mutation in FRC Myzus persicae. Therefore, it is suggested that sulfoxalfor be considered a neonicotinoid, and that this be taken into account when recommending insecticide rotation partnering for effective resistance management programmes.

Synthesis of CF3-substituted sulfoximines from sulfonimidoyl fluorides.

N-Protected trifluoromethyl-substituted sulfoximines have been prepared by treatment of sulfonimidoyl fluorides with a combination of the Ruppert-Prakash reagent (TMSCF(3)) and tetrabutyl ammonium fluoride (TBAF). The starting materials were accessed following two synthetic routes, and for each reaction sequence the substrate scope was evaluated. Accordingly, a wide variety of aryl-substituted products were obtained in moderate to good yield.

The design and synthesis of biologically active organophosphorus compounds--the role of a central research laboratory.

The properties and benefits offered by incorporating phosphorus into molecules are varied and numerous as shown by the many divisional research programs within Ciba-Geigy in the early eighties. This paper describes how a Central Research Group developed new materials in organophosphorous chemistry and identified new leads for life science applications.

An evaluation of the use of carbon dioxide angiography in endovascular aortic aneurysm repair.

INTRODUCTION: Renal dysfunction after endovascular aortic aneurysm repair is an increasingly recognised problem. Carbon dioxide (CO(2)) angiography has been used to limit the risk of contrast nephrotoxicity during endovascular procedures. This prospective study evaluates the performance of CO(2) angiography during EVAR. METHODS: Seventeen patients undergoing EVAR over a 12 month period were included. All were males with a median age of 74 (range 62-86) years. The median preoperative creatinine was 105 (range 77-165) micromol/L. CO(2) angiography was used routinely in all patients for graft positioning. Contrast was used for completion angiograms and whenever CO(2) did not satisfactorily demonstrate the anatomy. RESULTS: All patients had successful deployment of stent graft. The median contrast usage was 59 (range 20-250)ml. CO( 2) angiography successfully demonstrated the aortic and iliac bifurcation in all 17 cases and the renal artery anatomy in 9. 7 out of 17 patients had both CO(2) and contrast completion angiography. CO(2) correlated with contrast angiography in 6 of the 7 patients. There was no significant difference in pre and post-operative creatinine values (P >0.9; Wilcoxon test). CONCLUSION: CO(2) angiography is a useful adjunct to contrast during the performance of EVAR and helps reduce contrast load and the risk of contrast nephrotoxicity.

Herbicidal 4-hydroxyphenylpyruvate dioxygenase inhibitors--a review of the triketone chemistry story from a Syngenta perspective.

A review, outlining the origins and subsequent development of the triketone class of herbicidal 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors.

Substituted alpha-(phenylhydrazono)phenylacetonitrile derivatives. Part 2: Synthesis and biological activity of pro-pesticides.

Pro-pesticides of alpha-(2,6-dichloro-4-trifluoromethylphenylhydrazono)-4-nitrophenylacetonitrile have been prepared and tested against mite and insect pests. Variations in potency and spectrum were observed depending on the choice of cleavable pro-moiety. Cleavage of the pro-moiety was demonstrated in one case by measuring the rate of increase in the uncoupling activity using a mitochondrial preparation. Irradiation experiments have demonstrated a rapid isomerisation of the planar Z isomer to the E isomer, which is reversible.

Substituted alpha-(phenylhydrazono)phenylacetonitrile derivatives. Part 1: A new class of uncoupler of oxidative phosphorylation.

Substituted alpha-(phenylhydrazono)phenylacetonitrile derivatives have been discovered which constitute a series of potent uncouplers of oxidative phosphorylation. Systematic variation of substituents on both benzene rings has clearly demonstrated the importance of steric congestion around the ionisation site and delocalisation of negative charge in the anionic form. Replacement of the cyano group by other electron-withdrawing groups leads to a dramatic decrease in uncoupling activity. The sub-nanomolar levels of uncoupling activity found in certain members indicate that these compounds are the most potent uncouplers yet reported.