Developments in the Catalytic Asymmetric Synthesis of Agrochemicals and Their Synthetic Importance

Evaluation of the Safety of Fenbuconazole Monomers via Enantioselective Toxicokinetics, Molecular Docking and Enantiomer Conversion Analyses

Fenbuconazole, a chiral triazole fungicide, is produced and used as a racemate. Previous toxicological research on fenbuconazole in nontarget organisms primarily used the racemate, necessitating an investigation into each enantiomer's distribution and elimination for safety assessment. In this study, the absolute configurations of fenbuconazole enantiomers were first confirmed by ECD, designating them as S-(+)-fenbuconazole and R-(-)-fenbuconazole based on their optical activity. The UHPLC-QQQ/MS method was selected to systematically study the toxicokinetics and enantiomer conversion of fenbuconazole enantiomers in mice. The results revealed significant enantioselectivity, with S-(+)-fenbuconazole exhibiting 15.11 times higher AUC0-∞ than R-(-)-fenbuconazole, indicating greater blood absorption. In the distribution experiment involving the 14 examined tissues, S-(+)-fenbuconazole consistently exceeded R-(-)-fenbuconazole levels, except in the stomach. Notably, S-(+)-fenbuconazole concentration in the liver was second only to the stomach and was 4.35 times higher than R-(-)-fenbuconazole, suggesting a greater propensity for hepatic accumulation. Molecular docking studies further demonstrated a stronger interaction between S-(+)-fenbuconazole and the CYP2B enzyme in the liver, implying higher hepatotoxic potential. Both enantiomers were rarely excreted in urine or feces, with a cumulative excretion rate below 2.5‰. Enantiomer conversion occurred unidirectionally (R → S) in mice, and the rates were generally low in most tissue. Thus, enantiomeric conversion was not the primary factor driving the enantioselectivity. In summary, R-(-)-fenbuconazole exhibited poor absorption, limited distribution, and a weak interaction with the CYP2B enzyme, which may be considered a low-risk product that could guide monomer development and promote the reduction of pesticide usage.

Dye Sensitized Solar Cells Based on 2-Amino-[(Coumarin-3-yl)-4-(4-(Diphenylamino)Phenyl]nicotinonitrile Fluorescent Dyes

By introducing novel sensitizer dyes such as ACT, BCT, and SCT, this study seeks to significantly contribute to the field of dye-sensitized solar cells (DSSCs). Modern microwave irradiation has been used to carefully design these dyes. These reaction's outcomes clearly demonstrate how superior this technique is to conventional synthetic approaches. It not only reduces reaction time but also yields better results. A detailed analysis of these novel dyes has demonstrated their superior optical and electrochemical characteristics, which have been validated with the help of Cyclic Voltammetry and UV-Vis spectroscopy. The thorough investigation into solar cell domain involved creation of DSSC devices, where these dyes were used as sensitizers along with Cadmium sulphide Nanowires, as semiconductor material. The results demonstrated a notable increase in the device performance, boosting to 3.67 times the efficiency of bare CdS NW devices. Accompanying these results were Density Functional Theory (DFT) calculations and external quantum efficiency data, pleasantly validating the photovoltaic experiments. This research reveals the fascinating potential of these novel compounds as efficient sensitizers for DSSCs. Furthermore, it confers vital insights into their photovoltaic performance, thereby opening a way to researcher in advancements in solar cell technology.

The stereoselective bioactivity and mechanism of indoxacarb against Spodoptera frugiperda

BACKGROUND

Indoxacarb, a type of chiral pesticide, is used to control Lepidoptera insects. Most studies had focused on the environmental behavior and selective toxicity of indoxacarb enantiomers, and the mechanism behind its selective biological activity against target organisms is not well understood.

RESULTS

Spodoptera frugiperda was selected as the target insect. The lethal concentrations (96 h) of indoxacarb enantiomers on S. frugiperda were 2.61 mg/kg (S-indoxacarb) and 463.52 mg/kg (R-indoxacarb). S-Indoxacarb resulted in stronger oxidative damage to S. frugiperda than R-indoxacarb, and catalase and malondialdehyde were upregulated by 40.46% and 68.64% respectively after treatment with S-indoxacarb. Furthermore, cytochrome P450 and carboxylesterase were activated by S-indoxacarb, increasing by 39.62% and 63.68% respectively. Decarbomethoxyllated JW062 (DCJW), a metabolite of indoxacarb, has insecticidal activity. The concentration of DCJW in the S-indoxacarb treatment group was 2.73 times that in the R-indoxacarb treatment group. Molecular docking results demonstrated that S-indoxacarb could spontaneously bind to metabolic enzymes and be metabolized.

CONCLUSIONS

Enantiomeric bioactivity of indoxacarb enantiomers against on S. frugiperda was observed. S-Indoxacarb demonstrated remarkable insecticidal efficacy. Upon ingestion by S. frugiperda, it induced oxidative damage. Furthermore, S-indoxacarb was metabolized to DCJW, which has a significant role in its insecticidal properties. The selective bioactivity of indoxacarb enantiomers in S. frugiperda might be attributed to the enantiomeric metabolites. These findings offer a new perspective on the selective mechanisms of chiral pesticides. © 2025 Society of Chemical Industry.

Development of chiral ferrocenyl P,P,N,N,O-ligands for ruthenium-catalyzed asymmetric hydrogenation of ketones

A new type of ferrocenyl P,P,N,N,O-ligand has been developed through a one-step transformation. This represents a rare example of a ligand containing both chiral bisphosphine and diamine groups suitable for ruthenium-catalyzed asymmetric hydrogenation. Its ruthenium complex can be directly prepared by stirring the ligand and [Ru(benzene)Cl2]2 at 90 °C in DMF for 4 hours. The catalyst showed high reactivity and enantioselectivity in the hydrogenation (AH) of simple ketones and α,β-unsaturated ketones, providing the corresponding chiral aryl alkyl alcohols and chiral allyl alcohols with up to 99% yield and 96% ee.

Discovery of Enantiopure (S)-Methoprene Derivatives as Potent Biochemical Pesticide Candidates

(S)-Methoprene has been widely applied as a powerful biochemical pesticide to control disease vectors and other pestiferous arthropods of economic importance. As a juvenile hormone analogue, many products based on (S)-methoprene are developed and commercialized in the USA, Europe, and elsewhere. However, the agricultural use of (S)-methoprene and its analogues remains underexplored. Here, based on an intermediate derivatization strategy and structural modification, a series of enantiopure (S)-methoprene derivatives were designed for their expected bioactivity against two crop-threatening pests. Six compounds showed more than 2-fold stronger inhibition of emergence against Plutella xylostella than (S)-methoprene, among which one that was designated as B2 showed even superior activity to the conventional chemical pesticide and biopesticide with IE50 of 0.02 mg/L. Nine compounds exhibited over 2-fold higher bioactivity against Aphis craccivora growth than (S)-methoprene. The physicochemical property evaluation and toxicological test showed that the potent (S)-methoprene derivatives were low toxic to the nontarget organism and the environment. Molecular docking studies further demonstrated that the high bioactivity of B2 may be partially attributed to its great affinity for binding to juvenile hormone receptors of P. xylostella. The current study suggests that B2 is a biochemical pesticide candidate with potency to be developed as a new agrochemical for lepidopteran control.

Application of Asymmetric Catalysis in Chiral Pesticide Active Molecule Synthesis

The different configurations of chiral pesticides generally have significant influence on their biological activities. Chiral agrochemicals with high optical purities have become a prominent topic in the research field of new pesticides due to their advantages including lower toxicity, higher efficiency, and reduced residue levels. However, most commercially available pesticides that possess chiral elements are still used in their racemic forms. To date, asymmetric catalysis has emerged as a versatile tool for the enantioselective synthesis of various chiral agrochemicals and novel chiral pesticide active molecules. This perspective provides a comprehensive overview of the applications of diverse asymmetric catalytic approaches in the facile preparation of numerous novel pesticide active molecules, and our own outlook on the future development of this highly active research direction is also presented at the end of this review.

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.

Stereoselective analysis of chiral pesticides: a review

Chiral organic pollutants, including pesticides, herbicides, medicines, flame retardants, and polycyclic musk, represent a significant threat to both the environment and human health. The presence of asymmetric centers in the structure of chiral pesticides introduces stereoisomers with distinct distributions, fates, biomagnification capacities, and cytotoxicities. In aquatic environments, pesticides, as persistent/pseudo-persistent compounds, have been detected in substantial quantities, posing severe risks to non-target species and, ultimately, public health through water supply and food exposures. In response to this environmental challenge, stereoselective analytical methods have gained prominence for the identification of pesticide/drug enantiomers in recent years. This review examines the environmental impact of chiral pesticides, emphasizing the distinct biological activities and distribution patterns of their stereoisomers. By highlighting the advancements in liquid chromatography for enantiomeric analysis, the review aims to underscore the urgent need for a comprehensive understanding of these pollutants to facilitate informed remediation strategies and ensure the safer dispersal of chiral organic pollutants in the environment, thereby addressing the potential risks they pose to ecosystems and human health. Future research should focus on developing sustainable and efficient methodologies for the precise analysis of stereoisomers in complex matrices, particularly in sewage water, emphasizing the importance of sewage processing plants in ensuring water quality.

Bisphospholane Josiphos-type Ligands in Rhodium Asymmetric Catalysis

Asymmetric catalysis has become a universal and powerful method for constructing chiral compounds. In rhodium asymmetric catalysis, bisphospholane Josiphos-type ligands and their rhodium complexes are receiving increasing attention. This review provides comprehensive information on the bisphospholane Josiphos-type ligands in rhodium asymmetric catalysis. The scope of the literature covers from 2013 to now. The application of bisphospholane Josiphos-type ligands in rhodium asymmetric catalysis is summarized as follows: (i) asymmetric addition to C(sp2 )-C(sp2 ) bonds, (ii) asymmetric addition to C(sp2 )-C(sp) bonds of allenes, (iii) asymmetric hydrogenation of C(sp2 )-N bonds, C(sp2 )-O bonds and pyridinium salts, and (iv) asymmetric silanization of C-H and O-H bonds.

IPTG-induced high protein expression for whole-cell biosynthesis of L-phosphinothricin

BACKGROUND

Biocatalytic production of L-phosphinothricin (L-PPT) is currently the most promising method. In this work, we use an Escherichia coli strain coexpressing of D-amino acid oxidase and catalase (E. coli DAAO-CAT) to oxidation biocatalytic D-PPT to PPO, then use the second E. coli strain coexpressing glutamate dehydrogenase and formate dehydrogenase (E. coli GluDH-FDH) to reduce biocatalytic PPO to L-PPT.

MAIN METHODS AND MAJOR RESULTS

We compared the effects of different concentrations of IPTG or lactose on protein expression and enzyme activity in 5 L fermenter. The best induction conditions for E. coli DAAO-CAT were 0.05 mM IPTG, induction for 18 h at 28°C. The specific enzyme activities of DAAO and CAT were 153.20 U g-1 and 896.23 U g-1 , respectively. The optimal induction conditions for E. coli GluDH-FDH were 0.2 mM IPTG, induction for 19 h at 28°C. The specific enzyme activities of GluDH and FDH were 41.72 U g-1 and 109.70 U g-1 , respectively. The 200 mM D-PPT was biocatalyzed by E. coli DAAO-CAT for 4 h with space-time yield of 9.0 g·L-1 ·h-1 and conversion rate of over 99.0%. Then 220 mM PPO was converted to L-PPT by E. coli GluDH-FDH for 3 h with space-time yield of 14.5 g·L-1 ·h-1 and conversion rate of over 99.0%. To our knowledge, this is the most efficient biocatalytic reaction for L-PPT production.

CONCLUSIONS AND IMPLICATIONS

We found that IPTG has advantages compared with lactose in the enzyme activity and biomass of E. coli DAAO-CAT and E. coli GluDH-FDH, and IPTG is more environmentally friendly. Our data implicated that IPTG can replace lactose in terms of economic feasibility and effectiveness for scaled-up industrial fermentations.

Epoxides: Small Rings to Play with under Asymmetric Organocatalysis

Optically pure epoxides are recognized as highly valuable products and key intermediates, useful in different areas from pharmaceutical and agrochemical industries to natural product synthesis and materials science. The predictable fate of the ring-opening process, in terms of stereoselectivity and often of regioselectivity, enables useful functional groups to be installed at vicinal carbon atoms in a desired manner. In this way, products of widespread utility either for synthetic applications or as final products can be obtained. The advent of asymmetric organocatalysis provided a new convenient tool, not only for their preparation but also for the elaboration of this class of heterocycles. In this review, we focus on recent developments of stereoselective organocatalytic ring-opening reactions of meso-epoxides, kinetic resolution of racemic epoxides, and Meinwald-type rearrangement. Examples of asymmetric organocatalytic processes toward specific synthetic targets, which include ring opening of an epoxide intermediate, are also illustrated.

Mechanistic Details of the Sharpless Epoxidation of Allylic Alcohols—A Combined URVA and Local Mode Study

In this work, we investigated the catalytic effects of a Sharpless dimeric titanium (IV)–tartrate–diester catalyst on the epoxidation of allylalcohol with methyl–hydroperoxide considering four different orientations of the reacting species coordinated at the titanium atom (reactions R1–R4) as well as a model for the non-catalyzed reaction (reaction R0). As major analysis tools, we applied the URVA (Unified Reaction Valley Approach) and LMA (Local Mode Analysis), both being based on vibrational spectroscopy and complemented by a QTAIM analysis of the electron density calculated at the DFT level of theory. The energetics of each reaction were recalculated at the DLPNO-CCSD(T) level of theory. The URVA curvature profiles identified the important chemical events of all five reactions as peroxide OO bond cleavage taking place before the TS (i.e., accounting for the energy barrier) and epoxide CO bond formation together with rehybridization of the carbon atoms of the targeted CC double bond after the TS. The energy decomposition into reaction phase contribution phases showed that the major effect of the catalyst is the weakening of the OO bond to be broken and replacement of OH bond breakage in the non-catalyzed reaction by an energetically more favorable TiO bond breakage. LMA performed at all stationary points rounded up the investigation (i) quantifying OO bond weakening of the oxidizing peroxide upon coordination at the metal atom, (ii) showing that a more synchronous formation of the new CO epoxide bonds correlates with smaller bond strength differences between these bonds, and (iii) elucidating the different roles of the three TiO bonds formed between catalyst and reactants and their interplay as orchestrated by the Sharpless catalyst. We hope that this article will inspire the computational community to use URVA complemented with LMA in the future as an efficient mechanistic tool for the optimization and fine-tuning of current Sharpless catalysts and for the design new of catalysts for epoxidation reactions.