Synthetic approaches to the 2015-2018 new agrochemicals

Fungicidal Activity of New Pyrrolo[2,3-d]thiazoles and Their Potential Action on the Tryptophan Metabolic Pathway and Wax Biosynthesis

The main challenge in the development of agrochemicals is the lack of new leads and/or targets. It is critical to discover new molecular targets and their corresponding ligands. YZK-C22, which contains a 1,2,3-thiadiazol-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole skeleton, is a fungicide lead compound with broad-spectrum fungicidal activity. Previous studies suggested that the [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole scaffold exhibited good antifungal activity. Inspired by this, a series of pyrrolo[2,3-d]thiazole derivatives were designed and synthesized through a bioisosteric strategy. Compounds C1, C9, and C20 were found to be more active against Rhizoctonia solani than the positive control YZK-C22. More than half of the target compounds provided favorable activity against Botrytis cinerea, where the EC50 values of compounds C4, C6, C8, C10, and C20 varied from 1.17 to 1.77 μg/mL. Surface plasmon resonance and molecular docking suggested that in vitro potent compounds C9 and C20 have a new mode of action instead of acting as pyruvate kinase inhibitors. Transcriptome analysis revealed that compound C20 can impact the tryptophan metabolic pathway, cutin, suberin, and wax biosynthesis of B. cinerea. Overall, pyrrolo[2,3-d]thiazole is discovered as a new fungicidal lead structure with a potential new mode of action for further exploration.

Oxime chemistry in crop protection

An overview is given on the significance of the oxime moiety in crop protection chemistry. This review focuses on the two most important aspects of agrochemical oximes, which are the occurrence and role of oxime groups in compounds with herbicidal, fungicidal and insecticidal activity, as well as the application of oxime derivatives as intermediates in the synthesis of crop protection agents not bearing any oxime function. Especially noteworthy is the fact, that in the synthesis of agrochemicals, oximes can be cyclized to isooxazoline, isoxazole, oxadiazole, oxazine, pyrrole, isothiazole and imidazole rings. © 2024 Society of Chemical Industry.

Advances and Challenges in Development of Transition Metal Catalysts for Heterogeneous Hydrogenation of Organic Compounds

Actual problems of development of catalysts for hydrogenation of heterocyclic compounds by hydrogen are summarized and discussed. The scope of review covers composites of nanoparticles of platinum group metals and 3d metals for heterogeneous catalytic processes. Such problems include increase of catalyst activity, which is important for reduction of precious metals content; development of new catalytic systems which do not contain metals of platinum group or contain cheaper analogues of Pd; control of factors which make influence on the selectivity of the catalysts; achievement of high reproducibility of the catalyst's performance and quality control of the catalysts. Own results of the authors are also summarized and described. The catalysts were prepared by decomposition of Pd0 and Ni0 complexes, pyrolysis of Ni2+ and Co2+ complexes deposited on aerosil and reduction of Ni2+ in pores of porous support in situ. The developed catalysts were used for hydrogenation of multigram batches of heterocyclic compounds.

Isosteric Ring Exchange as a Useful Scaffold Hopping Tool in Agrochemistry

Replacing one ring in a molecule by a different carba- or heterocycle is an important scaffold hopping manipulation, because biologically active compounds and their analogues, which underwent such a transformation, are often similar in size, shape, and physicochemical properties and, therefore, likely in their potency as well. This review will demonstrate, how isosteric ring exchange led to the discovery of highly active agrochemicals and which ring interchanges have proven to be most successful.

Crystal structure of 3-((3,4-dichloroisothiazol-5-yl)methoxy)benzo[d] isothiazole 1,1-dioxide, C11H6Cl2N2O3S2

C11H6Cl2N2O3S2, triclinic, P1‾ (no. 2), a = 6.974(3) Å, b = 8.132(3) Å, c = 12.349(5) Å, α = 86.123(4)°, β = 78.299(4)°, γ = 85.715(4)°, V = 682.9(4) Å3, Z = 2, R gt(F) = 0.0410, wR ref(F 2) = 0.1058, T = 296(2) K.

A broadly applicable quantitative relative reactivity model for nucleophilic aromatic substitution (SNAr) using simple descriptors

We report a multivariate linear regression model able to make accurate predictions for the relative rate and regioselectivity of nucleophilic aromatic substitution (S_NAr) reactions based on the electrophile structure. This model uses a diverse training/test set from experimentally-determined relative S_NAr rates between benzyl alcohol and 74 unique electrophiles, including heterocycles with multiple substitution patterns. There is a robust linear relationship between the experimental S_NAr free energies of activation and three molecular descriptors that can be obtained computationally: the electron affinity (EA) of the electrophile; the average molecular electrostatic potential (ESP) at the carbon undergoing substitution; and the sum of average ESP values for the ortho and para atoms relative to the reactive center. Despite using only simple descriptors calculated from ground state wavefunctions, this model demonstrates excellent correlation with previously measured S_NAr reaction rates, and is able to accurately predict site selectivity for multihalogenated substrates: 91% prediction accuracy across 82 individual examples. The excellent agreement between predicted and experimental outcomes makes this easy-to-implement reactivity model a potentially powerful tool for synthetic planning.

Applications of Isosteres of Piperazine in the Design of Biologically Active Compounds: Part 2

Applications of piperazine and homopiperazine in drug design are well-established, and these heterocycles have found use as both scaffolding and terminal elements and also as a means of introducing a water-solubilizing element into a molecule. In the accompanying review (10.1021/acs.jafc.2c00726), we summarized applications of piperazine and homopiperazine and their fused ring homologues in bioactive compound design along with illustrations of the use of 4-substituted piperidines and a sulfoximine-based mimetic. In this review, we discuss applications of pyrrolidine- and fused-pyrrolidine-based mimetics of piperazine and homopiperazine and illustrate derivatives of azetidine that include stretched and spirocyclic motifs, along with applications of a series of diaminocycloalkanes.

Scaffold-Hopping Approach To Identify New Chemotypes of Dimpropyridaz

Dimpropyridaz is a pyrazole carboxamide insecticide with a novel mode of action, currently under worldwide development by BASF, providing excellent activity against sucking pests. A series of dimpropyridaz analogues were designed to investigate the impact of bioisosteric heterocyclic replacements on the biological activity and molecular properties. Focus was given to prepare analogues where the 4-pyridazinyl moiety was replaced by 5-pyrimidinyl, 2-pyrimidinyl, 3-pyridazinyl, and 2-pyrazinyl groups. Five different synthetic routes were developed for the preparation of these analogues, delivering the target compounds in moderate to good yields. We explained some aspects of the observed structure-activity relationship by a density functional theory (DFT) calculation and DFT-derived Multiwfn and VMD program models. These findings provide first insights into the important role of the 4-pyridazinyl heterocyclic moiety in the pyrazole carboxamide insecticide chemical class and the mechanism of action of dimpropyridaz.

Simultaneous enantioselective determination of two succinate- dehydrogenase-inhibitor fungicides in plant-origin foods by ultra-high performance liquid chromatography-tandem mass spectrometry

Fluindapyr and penthiopyrad are two new succinate-dehydrogenase-inhibitor fungicides both employed as racemic mixtures of enantiomers to control various fungal pathogens. In the present work, a robust and highly-sensitive method for simultaneous determination of fluindapyr and penthiopyrad enantiomers in plant-origin foods (cereals, fruits and vegetables) was developed using UPLC-MS/MS combined with a chiral stationary phase. Rapid baseline chiral separation of four stereoisomers of fluindapyr and penthiopyrad was obtained within 4.2 min on chiral MX(2)-RH column under reversed-phase conditions (with the eluent of acetonitrile/0.1% formic acid in water =70/30 (V:V) and column temperature maintained at 30 °C). The plant-origin samples were extracted quickly with acetonitrile and purified with multi-walled carbon nanotubes. Excellent linearity for the target analytes was observed in the concentration ranging from 1 to 250 µg/L with regression coefficient no less than 0.9967. The mean recoveries of fluindapyr and penthiopyrad enantiomers from six matrices were 77.1-107.2%, with all relative standard deviations values lower than 9.1%. The limit of quantification of four stereoisomers of two target chiral fungicides was 5 µg/kg. The analysis of real samples reveal that the developed method is suitable for the simultaneous chiral determination of fluindapyr and penthiopyrad residues in cereals, fruits and vegetables samples at enantiomeric level and can support their further investigation on enantioselective environmental behaviors and residue surveillance.

Organic Isocyanates and Isothiocyanates: Versatile Intermediates in Agrochemistry

In recent decades, organic isocyanates and isothiocyanates have been often applied as reactive intermediates in research syntheses or manufacturing routes of many agrochemicals. These heterocumulenes allowed the installation of crucial carboxylic functions, such as carbamates, ureas, and semicarbazones, but have also been used for the construction of five- and six-membered heterocycles, such as tetrazolones, thiazoles, and uracils.

1 Introduction

2 Preparation of Carboxylic Acid Functions

3 Preparation of Heterocyclic Rings

4 Conclusion

The inhibiting effects of biochar-derived organic materials on rice production

The effects of PBC and HBC on rice production, NUE and corresponding mechanisms were examined. Six treatments, P05, P30, H05, H30 (P: PBC; H: HBC; 05 and 30 represented the application rate of 0.5 and 3.0% w/w), CKU (urea application without char) and CK (no application of char and urea), were set up. Results showed that P05, P30 and H05 increased grain yield by 1.8-7.3% (P > 0.05), whereas H30 reduced grain yield by 60.4% (P < 0.05), compared to CKU. Meanwhile, HI under P05, P30 and H05 increased by 3.4-3.6%, while H30 decreased by 9.1% (P < 0.05). NUE and NAE showed similar trends with rice yield. By investigation, the excessive introduction of BDOM plays a crucial role in the reduction of rice production and NUE under higher HBC application. GC-MS/MS analysis showed that the soluble BDOM of HBC and PBC was quite different, and compounds such as 2,6-dimethoxyphenol might stress rice growth. ESI-FT-ICR-MS analysis showed that the BDOM of HBC contained a certain quantity of aromatic compounds, which may also stress rice growth. Overall, HBC pretreatment should be conducted, and the application rate should be strictly controlled before its agricultural application.