Current Contributions of Organofluorine Compounds to the Agrochemical Industry

Photocatalyzed Aryl C-H Fluorocarbonylation with CF2Br2

The use of abundant and inexpensive fluorine feedstocks to synthesize fluorinated compounds is a promising strategy that has not been extensively investigated. Dibromodifluoromethane (CF2Br2) is an inexpensive fluorine source that has rarely been used for C-H fluoroalkylation. This study reveals an iridium-catalyzed, tunable strategy for synthesizing acyl fluorides and difluorobromomethylated products using CF2Br2. To achieve the desired products, this process only requires the change of solvent (from DMSO to 1,4-dioxane) under blue LED illumination. A variety of arenes and heteroarenes with electron-donating substituents were successfully used, yielding the corresponding products in moderate to good yields. Mechanistic experiments revealed that DMSO served a dual role, functioning as both solvent and nucleophilic reagent in C-H fluorocarbonylation.

Theoretical design of new ligands to boost reaction rate and selectivity in palladium-catalyzed aromatic fluorination

The development of palladium-catalyzed fluorination with biaryl monophosphine ligands has faced two important problems that limit its application for bromoarenes: the formation of regioisomers and insufficient catalysis for heteroaryl substrates as bromothiophene derivatives. Overcoming these problems requires more ligand design. In this work, reliable theoretical calculations were used to elucidate important ligand features necessary for achieving more rate acceleration and selectivity. These features include increasing the ligand-substrate repulsion and creating a negative charge in the space around the fluoride ion bonded to the palladium. The investigated L5 ligand presents these features, and the calculations predict that this ligand completely suppresses the regioisomer formation in the difficult case of 4-bromoanisole. In addition, the free energy barriers are decreased by 2-3 kcal mol-1 in comparison with the catalysis involving the AlPhos ligand. Thus, the present study points out a direction for new developments in palladium-catalyzed fluorination.

Mechanochemical Radical Transformations in Organic Synthesis

Organic synthesis has historically relied on solution-phase, polar transformations to forge new bonds. However, this paradigm is evolving, propelled by the rapid evolution of radical chemistry. Additionally, organic synthesis is witnessing a simultaneous resurgence in mechanochemistry, the formation of new bonds in the solid-state, further contributing to this shift in the status quo. The aforementioned advances in radical chemistry have predominantly occurred in the solution phase, while the majority of mechanochemical synthesis advances feature polar transformations. Herein, we discuss a rapidly advancing area of organic synthesis: mechanochemical radical reactions. Solid-state radical reactions offer improved green chemistry metrics, better reaction outcomes, and access to intermediates and products that are difficult or impossible to reach in solution. This review explores these reactions in the context of small molecule synthesis, from early findings to the current state-of-the-art, underscoring the pivotal role solid-state radical reactions are likely to play in advancing sustainable chemical synthesis.

Recent advances in the transformation of maleimides via annulation

Over the past five years, maleimide scaffolds have gained considerable attention in organic synthesis for their role in forming cyclized molecules through annulation and C-H activation. As versatile and reactive coupling agents, maleimides have enabled the efficient synthesis of various cyclized products, including annulation, benzannulation, cycloaddition, and spirocyclization, with applications in medicinal chemistry, drug discovery, and materials science. Despite the extensive study of maleimide chemistry, certain reactions-such as cycloaddition-based annulation, photoannulation, and electrochemical transformations-remain underexplored despite their promising potential in the pharmaceutical and chemical industries. Recent advancements, such as photocatalysis and electrochemical methods, have expanded the utility of maleimides, providing more sustainable and selective approaches for synthesizing complex molecules. This review compiles research published between 2019 and 2024, highlighting the substrate scope, reaction diversity, and industrial relevance of maleimide-based annulation strategies. Additionally, we discuss emerging trends and future directions in maleimide chemistry, exploring opportunities for novel reaction pathways and broader applications in synthetic biology and materials science.

Two fluorinases prioritized from protein families of fluorinase, SAM-dependent chlorinase and hydroxide adenosyltransferase

Fluorinases represent the only known biological catalysts capable of forming carbon-fluorine bonds, but their slow catalytic rate limits their broader application. In this study, two fluorinases, FlASbac and FlAPbac, were identified from a pool of 12 718 nonredundant proteins using a genome-mining approach, with FlASbac showing high catalytic activity. Both newly identified fluorinases contain a Phe50 residue in place of the Trp50 typically found in fluorinases. Structural and mutagenesis studies revealed that the Trp50 or Phe50 residue at this position is crucial for fluorinase activity. This work highlights the utility of genomic enzymology in expanding the repertoire of biocatalysts for fluorination chemistry.

Confronting PFAS persistence: enzymes catalyzing C-F bond cleavage

Studies of enzymes catalyzing carbon-fluorine (C-F) bond cleavage have focused largely on a limited number of native microbial hydrolases that are reactive with the natural product fluoroacetate. Driven by widespread interest in biodegrading commercial fluorinated compounds, many of which are known as per- and polyfluorinated alkyl substances (PFAS), it is necessary to identify and engineer new enzymes. For example, some hydrolases react with -CF2- moieties, a common functionality in PFAS. Additional enzymatic C-F cleaving mechanisms catalyzed by reductases, lyases, and oxygenases have been identified via screening. Screening and evolving PFAS defluorination in bacteria is inhibited by the obligate release of toxic fluoride from C-F cleavage. Engineering greater fluoride tolerance in bacteria is a problem that must be solved in tandem with enzyme improvement.

Mitigation of sodium fluoride-induced growth inhibition, immunosuppression, hepatorenal damage, and dysregulation of oxidative stress, apoptosis, and inflammation-related genes by dietary artichoke (Cynara scolymus) leaf extract in Oreochromis niloticus

This study evaluated the efficacy of integrating artichoke (Cynara scolymus) leaf extract (CSLE) into the Nile tilapia (Oreochromis niloticus) diet to mitigate fluoride (FLR) adverse effects on growth, immune components, renal and hepatic function, and the regulation of oxidative stress, inflammation, and apoptosis-related genes. A 60-day feeding experiment was conducted with 240 O. niloticus fish separated into four groups as follows: a control group (CON) fed on a basic diet, a CSLE group receiving 300 mg CSLE/kg via the diet, a FLR group exposed to 6.1 mg/L waterborne FLR, and a group receiving both CSLE and FLR. Fish exposed to FLR exhibited slower growth rates and poorer feed conversion compared to the control group. They also displayed signs of anemia, leukopenia, and elevated serum levels of renal injury indicators and liver enzymes. Consistent with a decrease in both non-enzymatic and enzymatic antioxidants, higher levels of hepatic lipid peroxidation products were observed. Exposure to FLR resulted in decreased serum lysozyme activity, nitric oxide, complement 3, IgM, total protein, globulin, and albumin levels. FLR induced multiple pathological perturbations in the spleen, liver, and kidneys, and increased the mRNA expression of splenic tumor necrosis factor-alpha, heat shock protein 70, interleukin-1 beta, tumor protein p53, and cysteine-aspartic acid protease 3 while reducing superoxide dismutase and catalase genes expressions. However, the majority of FLR adverse effects were significantly reduced by adding 300 mg CSLE/ kg diet. Adding CSLE to O. niloticus' diet may reduce FLR's negative effects, making it a beneficial aquafeed.

Exploring the therapeutic potential of acridines: Synthesis, structure, and biological applications

The objective of this review was to explore the trends and chemical characteristics of acridines and their derivatives, analyze their contribution to the scientific literature and international cooperation, identify the most influential authors and articles, and provide an overview of the knowledge produced in elucidating their mechanisms of action. To this end, a bibliometric analysis was performed using RStudio software, along with a systematic review focusing on articles indexed in the "Web of Science" and "Scopus" databases. The keywords used were "acridine$", "Synthesi$", "Structure$", and "Biologic* Application$" for the period from 2020 to 2024. Relevant articles were carefully selected from these databases, and a bibliometric analysis was carried out to comprehensively discuss the most relevant biological activities associated with acridines. The results showed that, during the analyzed period, China and India led in the number of publications, followed by Brazil in third place. However, a decline in the number of publications was observed in the last two years of the period. Keyword analysis revealed that antitumor activity remains the most extensively studied aspect of acridines and their derivatives.

Nonheme Mononuclear and Dinuclear Iron(II) and Iron(III) Fluoride Complexes and Their Fluorine Radical Transfer Reactivity

The nonheme iron(II) complexes containing a fluoride anion, FeII(BNPAPh2O)(F) (1) and [FeII(BNPAPh2OH)(F)(THF)](BF4) (2), were synthesized and structurally characterized. Addition of dioxygen to either 1 or 2 led to the formation of a fluoride-bridged, dinuclear iron(III) complex [Fe2III(BNPAPh2O)2(F)2(μ-F)]+ (4), which was characterized by single-crystal X-ray diffraction, 1H NMR, and elemental analysis. An iron(II)(iodide) complex, FeII(BNPAPh2O)(I) (3), was prepared and reacted with O2 to give the mononuclear complex cis-FeIII(BNPAPh2O)(OH)(I) (5). Addition of excess fluoride to 5 led to the formation of the oxo-bridged, dinuclear iron(III) complex [Fe2III(BNPAPh2O)2(F)2(μ-O)] (6), while the mononuclear iron(III)(fluoride) complex cis-FeIII(BNPAPh2O)(F)(Cl) (7) was prepared from the addition of excess F- to FeIII(BNPAPh2O)Cl2. The dinuclear complexes 4 and 6 were unreactive to fluorine radical transfer, but mononuclear 7 reacts with the radical substrate (p-MeO-C6H4)3C• to give the fluorine radical transfer products FeII(BNPAPh2O)(Cl) and (p-OMe-C6H4)3CF. These results show that a mononuclear FeIII(F) complex is capable of mediating fluorine radical transfer, even in the presence of second coordination sphere hydrogen bonds to the F- ligand. These findings are placed in context with what is known about the nonheme iron halogenases and related synthetic catalysts regarding their ability, or lack thereof, to mediate fluorine radical transfer reactions.

General access to furan-substituted gem-difluoroalkenes enabled by PFTB-promoted cross-coupling of ene-yne-ketones and difluorocarbene

Replacement of a carbonyl group with fluorinated bioisostere (e.g., CF2[double bond, length as m-dash]C) has been adopted as a key tactical strategy in drug design and development, which typically improves potency and modulates lipophilicity while maintaining biological activity. Consequently, new gem-difluoroalkenation reactions have undoubtedly accelerated this shift, and conceptually innovative practices would be of great benefit to medicinal chemists. Here we describe an expeditous protocol for the direct assembly of furan-substituted gem-difluoroalkenes via PFTB-promoted cross-coupling of ene-yne-ketones and difluorocarbene. In this multi-step tandem reaction process, the furan ring and the gem-difluorovinyl group are constructed simultaneously in an efficient manner. These products can serve as bioisosteres of the α-carbonyl furan core, which is an important scaffold present in natural products and drug candidates. The broad generality and practicality of this method for late-stage modification of bioactive molecules, gram-scale synthesis and versatile derivatisation of products has been described. Biological activity evaluation showed that the gem-difluoroalkene skeleton exhibited dramatic antitumor activity.

Rhodium-Catalyzed Synthesis of Trifluoromethyl-Containing Allylic Alcohols Via Z-Alkenyl Transfer with High Stereochemistry Retention

Herein, we report the rhodium-catalyzed Z-alkenyl transfer from tertiary allylic alcohols to aryl trifluoromethyl ketones, which provided an efficient way of preparation of trifluoromethyl-containing Z-allylic alcohols via β-Z-alkenyl elimination. The key Z-alkenyl-rhodium species were generated with a high degree of stereochemical retention. This reaction featured a broad substrate scope and good functional tolerance and would offer a fascinating approach for the synthesis of Z-alkenes.

Copper-Catalyzed Asymmetric Tertiary Radical Cyanation for the Synthesis of Chiral Tetrasubstituted Monofluoroacyl Nitriles

The construction of chiral tetrasubstituted α-fluoro-α-cyano carbonyl compounds remains a key challenge in synthetic organic chemistry because of their popularity in multiple disciplines. In this paper, we report the copper-catalyzed asymmetric fluorinated tertiary radical cyanation reaction of cyclic α-iodo-α-fluoroindanones with TMSCN to achieve chiral nitriles with carbon-fluorine quaternary stereogenic centers. Thus, an array of optically active tetrasubstituted monofluoroacyl nitriles were synthesized with high reaction efficiency and excellent enantioselectivities (up to 91% yield, 99% ee). Moreover, mechanistic investigations, including experiments, were conducted to clarify the reaction pathway and stereochemical outcomes.

Synthesis of Ngai Reagent and Longer Carbon Chain Variants for Perfluoroalkoxylations

We present a straightforward method for the synthesis of Ngai trifluoromethoxy reagent and longer carbon chain variants, thereby expanding the range of options for perfluoroalkoxylation reactions. Utilizing cost-effective sodium perfluoroalkane sulfinates (RfSO2Na) and N-hydroxylamines, we achieved efficient oxidative cross-coupling reactions facilitated by cerium(IV) ammonium nitrate (CAN) without the need for transition-metal catalysts. The methodology proved effective not only for the synthesis of Ngai-type radical perfluoroalkoxylation reagents but also Qing-type nucleophilic perfluoroalkoxylation reagents.

Beyond expectations: the development and biological activity of cytokinin oxidase/dehydrogenase inhibitors

Cytokinins are one of the main groups of plant hormones that regulate growth and development of plants. Cytokinin oxidase/dehydrogenase (CKX) is an enzyme that rapidly and irreversibly degrades cytokinins and thus directly affects their concentration and physiological effect. Genetically modified plants with reduced CKX activity in the shoot, i.e. with a higher concentration of cytokinins, showed e.g. increased tolerance to drought stress, formed larger inflorescences and had higher grain yield. For these reasons, chemical compounds capable of inhibiting the CKX activity (CKX inhibitors) were sought. First, they were identified among strong synthetic cytokinins, but their inhibitory activity was low. The trend has been to develop potent CKX inhibitors with minimal intrinsic cytokinin activity in the hope of avoiding the negative effect of cytokinins on root growth. Cloning CKX, production of key recombinant enzymes from Arabidopsis (AtCKX2) and maize (ZmCKX1 and ZmCKX4a), development of screening bioassays and progress in X-ray crystallography and synthetic organic chemistry led to extensive progress in the development of these compounds. Currently, the most suitable CKX inhibitors are seeking their application in research and the commercial sphere in two main areas - plant tissue cultures and agriculture. The key milestones that preceded it are summarized in this review.

Visible light-driven and substrate-promoted alkenyltrifluoromethylation of alkenes to synthesize CF3-functionalized 1,4-naphthoquinones

The first example of the visible light-driven and substrate-promoted three-component alkenyltrifluoromethylation of alkenes is developed. This approach uses easily available alkenes, 2-arylamino-1,4-naphthoquinones and Togni reagent as the reactants, and describes good functionality tolerance. The reaction offers a precise synthesis of valuable CF3-functionalized 1,4-naphthoquinones and can be applied in late-stage modification of natural products and pharmaceuticals. Experimental results imply that bifunctional 2-arylamino-1,4-naphthoquinones serve as both substrates and catalysts. In terms of this autocatalytic system, the protocol enables a straightforward intermolecular difunctionalization of alkenes under visible light irradiation without external catalysts.

Interaction of Difluorocarbene with the Thiocyanate Anion: Access to a Silicon Reagent Bearing the Isothiocyanate Group

The reaction between (bromodifluoromethyl)trimethylsilane (TMSCF2Br) and potassium thiocyanate providing TMSCF2NCS is described. The process involves the interaction of difluorocarbene with the nitrogen atom of the thiocyanate anion. The obtained silicon reagent served as a source of the fluorinated group and difluorocarbene in the reaction with N-alkyl imines, affording 2-(difluoromethylthio)-4-fluoroimidazoles.

Photoredox-Catalyzed Regioselective 1,3-Alkoxypyridylation of gem-Difluorocyclopropanes

Difluoromethylene and pyridine cores are very important structural units in medicinal chemistry. Herein, we report the development of photoredox-catalyzed ring-opening and 1,3-alkoxypyridylation of gem-difluorinated cyclopropanes using 4-cyanopyrines and alcohols, employing cyclopropane radical cations as the key intermediate. The reaction exhibits high regioselectivity under mild conditions and can also be practiced on gram-scale synthesis, telescoped reaction, and late-stage functionalization of biological molecules.

Physicochemical and Biological Evaluation of gem-Difluorinated Saturated Oxygen Heterocycles as Bioisosteres for Drug Discovery

A comprehensive study on the physicochemical properties of gem-fluorinated O-heterocyclic substituents is reported. Systematic additive effects of introducing O- and gem-CF2 group introduction on acidic properties (pKa) of the corresponding carboxylic acids/protonated primary amines were demonstrated. The impact of the O/CF2 moieties on lipophilicity (LogP) was found to be complex; significant mutual influence of the corresponding polar moieties governed the compound's overall properties in this case. Biological evaluation of MAPK kinase inhibitors incorporating the title substituents demonstrated their utility as promising fragments for bioisosteric replacements in drug discovery campaigns.

On the Performance of Second-Order Polarization Propagator Methods in the Calculation of 1JFC and nJFH NMR Spin-Spin Coupling Constants

This study evaluates the performance of doubles-corrected random phase approximation (RPA) and higher random phase approximation (HRPA) approaches in predicting nuclear magnetic resonance (NMR) coupling constants involving fluorine. Their performance is benchmarked against experimental data and compared with that of higher-level theoretical methods, specifically second-order polarization propagator (SOPPA) and SOPPA(CCSD). Additionally, we discuss their performance relative to density functional theory (DFT). We find that RPA(D) is severely constrained by (near) triplet instabilities, while HRPA(D) demonstrates markedly improved stability. Statistical analysis reveals stronger patterns for carbon-fluorine couplings across the methods and systems investigated compared with fluorine-hydrogen couplings. While SOPPA-based methodologies prove to be superior in accuracy, HRPA(D) shows promising performance in reducing the computational burden of these calculations, albeit with a tendency to underestimate the coupling strength. These findings highlight the potential of HRPA(D) as a practical alternative to SOPPA methods, even for such difficult properties as NMR spin-spin coupling constants involving fluorine, emphasizing its role in improving predictive accuracy and efficiency across diverse chemical environments.

Temporal and spatial distribution of inorganic fluoride, total adsorbable organofluorine, PFOA and PFOS concentrations in the Hungarian section of the Danube River

The existing technologies in municipal wastewater treatment plants are ineffective in eliminating persistent fluorine-containing contaminants. At the same time, there is an increasing demand for novel organofluorine compounds, particularly in the production of lithium-ion batteries, as well as in the agrochemical and pharmaceutical sectors for more efficient ingredients. This implies that we must account for ongoing changes in the fluorine levels within riverine environments. To determine the fluorine concentration in the water phase of rivers, it is essential to measure both inorganic fluoride and total organofluorine concentrations. These analytes were measured in water samples collected monthly from twelve locations along the Hungarian section of the Danube River during the period from July to December 2023, applying ion-chromatography and combustion ion-chromatography. The concentration of inorganic fluoride ranged from 28 to 76 µg/L, with a median of 45.3 µg/L. The total adsorbable organofluorine concentrations were between 0.22 and 12.5 µg/L, with a median of 2.43 µg/L. To assess the impact of restrictions on the use of PFOA and PFOS compounds, these substances were quantified using a UHPLC-Q-TOF-MS system. A comparison of our data with previously published concentrations in the Danube River reveals a decreasing tendency, justifying the restricted use of these chemicals.

Cobalt-Catalyzed Intramolecular Enantioselective Reductive Heck Reaction toward the Synthesis of Chiral 3-Trifluoromethylated Oxindoles

Herein, a cobalt-catalyzed intramolecular enantioselective reductive Heck reaction is disclosed. Starting from N-ortho-iodoaryl-2-(trifluoromethyl)acrylamides, a plethora of chiral oxindoles bearing trifluoromethylated quaternary stereogenic centers at the C3-position are achieved in moderate to good yields (up to 88% yield) and good to excellent enantioselectivities (up to 94% ee) by employing zinc/silane as reducing agent. Other than the trifluoromethyl group, a number of chiral oxindoles bearing alkyl, aryl, and ester groups at C3-position were also obtained albeit in relatively lower enantioselectivities (68-78% ee).

Site-Specific Dehydrogenative Hydroxyfluoroalkylation of Indoles with Hexafluoroisopropanol

An efficient and convenient method for the synthesis of C3-hydroxytrifluoroalkylated indoles and pyrroles was described in this paper. The copper-catalyst-free site-specific cross-dehydrogenative coupling reaction of various indoles and pyrroles with hexafluoroisopropanol proceeded smoothly by using MnO2 as oxidant to furnish a hydroxytrifluoroalkylated electron-rich N-heterocycle in satisfactory to excellent yields. Various groups, including the synthetically useful functional groups Cl, NO2, and CN, were tolerated well. The mechanistic study revealed that a radical pathway accommodated the formation of a hexafluoroacetone intermediate.

Mechanistic Investigations of Chiral Lithium Binaphtholate Catalysis for Asymmetric Aldol-Tishchenko Reaction of α-Fluoroarylketones

In this study, we analyzed the asymmetric aldol-Tishchenko reaction of α-fluoroarylketones with aldehydes in the presence of chiral lithium binaphtholate, which was readily prepared from a chiral BINOL derivative and lithium tert-butoxide. This tandem reaction afforded enantiomerically enriched 2-fluoro-1,3-diols with three contiguous stereogenic centers in high yield and with high diastereo- and enantioselectivities. Moreover, mechanistic investigations of the lithium binaphtholate-catalyzed enantioselective aldol-Tishchenko reaction were performed based on the kinetic isotope effect and computational analyses.

Rh(I)/Sulfoxide-Imine-Olefin Complex Catalyzed Enantioselective Allylic Alkylation of 2-Fluoromalonate: Synthesis of Chiral α-Fluorolactone Bearing Vicinal Stereogenic Centers

Highly enantioselective Rh-catalyzed allylic substitution of the racemic branched allylic substrates with 2-fluoromalonate was realized enabled by a novel chiral sulfoxide-imine-olefin ligand under mild reaction conditions. The utilization of CuSO4 is beneficial for improving the enantioselectivity. Notably, the chiral fluoro-containing allyl products can be employed in a selective cyclic esterification to form chiral α-fluorolactone bearing vicinal stereogenic centers.

Copper-Mediated -CF(OCF3)(CF2H) Transfer to Organic Electrophiles

The integration of fluorine into medicinal compounds has become a widely used strategy to improve the biochemical and therapeutic properties of drugs. Inclusion of -CF2H and -OCF3 fluoroalkyl groups has garnered attention due to their bioisosteric properties, enhanced lipophilicity, and potential hydrogen-bonding capability in bioactive substances. In this study, we prepared a series of stable Cu[CF(OCF3)(CF2H)]L n complexes by insertion of commercially available perfluoro(methyl vinyl ether), CF2=CF(OCF3), into Cu-H bonds derived from Stryker's reagent, [CuH(PPh3)]6, using ancillary ligands L. Notably, certain of these complexes effectively transfer the fluoroalkyl group to aroyl chlorides. Through reaction optimization and computational analysis, we identified dimethylsulfoxide as a pivotal coligand, playing a distinctive role in enabling the fluoroalkylation of a range of aroyl chlorides and aryl iodides. The latter also benefits from addition of CuBr to abstract PPh3, generating solvent-stabilized Cu[CF(OCF3)(CF2H)]. These methodologies allow for the introduction of geminal -OCF3 and -CF2H groups in a single transformation.

Mechanistic insight into the neurodevelopmental toxicity of the novel pesticide pyrifluquinazon (PFQ) and its major metabolite in early-life stage zebrafish

Pyrifluquinazon (PFQ), a novel insecticide containing a heptafluoroisopropyl moiety, has seen increasing use. However, limited research has been conducted on the toxicological effects and mechanisms of PFQ in aquatic organisms. To investigate the toxicity and underlying mechanisms of PFQ and its primary metabolite dPFQ in aquatic organisms, morphological, behavioral, hormonal, multi-omics analyses, and molecular docking studies were conducted on zebrafish larvae after exposure. The results showed that both PFQ and dPFQ induced developmental abnormalities, behavioral impairment, hormonal disruptions, and alterations in neurologically related metabolites and gene expression in early-stage zebrafish. Notably, delayed retinal vascular development was observed, which is also likely linked to the neurodevelopmental toxicity. Subsequently, identification and relative quantification of PFQ metabolites suggested that its toxicity might be primarily attributed to dPFQ. Finally, an Adverse Outcome Pathway (AOP) was proposed, initiating with the binding of dPFQ to the TRPV4 protein and ultimately leading to neurodevelopmental toxicity. This study delineated the neurodevelopmental toxicity of PFQ and its toxicological mechanisms in zebrafish, emphasizing the hazards posed by pesticide metabolites to non-target organisms and highlighting inherent limitations of extrapolating in vitro toxicity experiments.

Fluorinated Sulfonamides: Synthesis, Characterization, In Silico, Molecular Docking, ADME, DFT Predictions, and Structure-Activity Relationships, as Well as Assessments of Antimicrobial and Antioxidant Activities

The design and synthesis of unique two series of fluorinated sulfonamides 3a-f and 5a-g utilizing nucleophilic aromatic substitution reactions of tetrafluorophthalonitrile 1 with various sulfonamides 2 under a variety of different reactions conditions were the key goals of the current research. The chemical composition of the generated products has been investigated via mass spectroscopy, 1HNMR, 13CNMR, infrared, and elemental analyzes. Antimicrobial studies were conducted in vitro to evaluate the activity of all new synthesized compounds against resistant strains. The first series showed high potency in very low concentrations. All compounds were studied against DPPH Radical Scavenging Activity and the other series showed high activity even in low molar ratio. In silico molecular docking was used to investigate the potential binding pathways for different receptors: dihydroprotien synthase protein (ID Code: 1AJ0) as an antibacterial and EGFRWT co-crystallized with erlotinib [PDB ID code 1m17]. Furthermore, synthesized compounds with good ADME predictions to the Lipinski rule of five demonstrated that the recently synthesized compounds had high drug-likeness qualities when the physicochemical parameter for the most powerful novel candidates was determined. Moreover, the DFT/B3LYP method functionalized with a 6-31G (d, p) basis set was employed to calculate quantum parameters, MEP analysis, HUMO, and LUMO.

Phenotypic Plasticity During Organofluorine Degradation Revealed by Adaptive Evolution

A major factor limiting the biodegradation of organofluorine compounds has been highlighted as fluoride anion toxicity produced by defluorinating enzymes. Here, two highly active defluorinases with different activities were constitutively expressed in Pseudomonas putida ATCC 12633 to examine adaption to fluoride stress. Each strain was grown on α-fluorophenylacetic acid as the sole carbon source via defluorination to mandelic acid, and each showed immediate fluoride release and delayed growth. Adaptive evolution was performed for each recombinant strain by serial transfer. Both strains adapted to show a much shorter lag and a higher growth yield. The observed adaptation occurred rapidly and reproducibly, within 50 generations each time. After adaption, growth with 50-70 mM α-fluorophenylacetic acid was significantly faster with more fluoride release than a preadapted culture due to larger cell populations. Genomic sequencing of both pre- and postadapted strain pairs revealed decreases in the defluorinase gene content. With both defluorinases, adaption produced a 56%-57% decrease in the plasmid copy number. Additionally, during adaption of the strain expressing the faster defluorinase, two plasmids were present: the original and a derivative in which the defluorinase gene was deleted. An examination of the enzyme rates in the pathway suggested that the defluorinase rate was concurrently optimised for pathway flux and minimising fluoride toxicity. The rapid alteration of plasmid copy number and mutation was consistent with other studies on microbial responses to stresses such as antibiotics. The data presented here support the idea that fluoride stress is significant during the biodegradation of organofluorine compounds and suggest engineered strains will be under strong selective pressure to decrease fluoride stress.

Synthesis of 3,5-bis(fluoroalkyl)pyrazoles/pyrazolines via [3 + 2] cycloaddition of di/trifluoroacetohydrazonoyl bromides and trifluoromethyl-substituted alkenes

An efficient [3 + 2] cycloaddition reaction of difluoromethyl or trifluoromethyl hydrazonoyl bromides with trifluoromethyl-substituted alkenes was investigated to produce a variety of 3,5-bis(fluoroalkyl)pyrazoles/pyrazolines in moderate to good yields. This protocol features obvious advantages such as easily available and stable substrates, step economy, gram-scalability and simple operation, providing a novel and practical method for the preparation of 3,5-bis(fluoroalkyl)pyrazoles/pyrazolines.

Hypervalent iodine catalysis enabled iterative multi-fluorination: not just a simple alternative for the electrochemical approach

Unlike the well-established fluoroalkylation, the direct incorporation of multiple fluorine atoms into small molecules via iterative fluorinations has been much less investigated. Herein, we report a hypervalent iodine catalytically selective multi-fluorination in which the fluorination degree is controlled by the delicate balance between the HF/amine ratios. The pros and cons of hypervalent iodine catalysis and the previously established electrochemical approach in the iterative multi-fluorinations are also provided.

Formal meta-C-H-Fluorination of Pyridines and Isoquinolines through Dearomatized Oxazinopyridine Intermediates

Organofluorine compounds, including fluorinated pyridines and isoquinolines, play a crucial role in pharmaceuticals, agrochemicals, and materials science. However, step-economic selective C-H-functionalization to access these fluorinated azaarenes is still underexplored, with selective meta-C-H-fluorination proving to be especially elusive. Here we present a practical method for formal meta-C-H-fluorination of pyridines and isoquinolines. By applying an oxazinoazaarene-based temporary pyridine dearomatization strategy with Selectfluor as an electrophilic F-source, fluorination of pyridines was achieved with exclusive C3-selectivity in moderate to good yields. The same strategy can also be applied to the formal meta-C-H-fluorination of isoquinolines. Late-stage-functionalization of drugs, drug precursors, and ligands as well as a large-scale one-pot dearomatization-fluorination-rearomatization reaction further demonstrate the synthetic utility of this approach.

Photobiocatalytic Platform for the Efficient Enantio-Divergent Synthesis of β-Fluoromethylated Ketones

β-Fluoromethyl (CH2F, CHF2, and CF3)-substituted chiral ketones are essential moieties and are vital building blocks in pharmaceutical and agrochemistry. However, general and convenient methods for enantio-diverse access to diverse β-fluoromethylated ketones are lacking, hindering the further development of these functional moieties. In this study, we developed an ene-reductase-based photobiocatalytic platform for efficient synthesis of enantio-divergent β-fluoromethylated chiral ketones. Our method highlights substrate-type diversity, excellent enantioselectivity, enzymatic enantio-divergent synthesis, as well as a dicyanopyrazine (DPZ)-type photosensitizer for biocompatible olefin E/Z isomerization in enzymatic stereoconvergent olefin asymmetric reduction, thereby providing a general photobiocatalytic solution to diverse β-fluoromethylated chiral ketones.

Access to optically active tetrafluoroethylenated amines based on [1,3]-proton shift reaction

Treatment of various (R)-N-(2,2,3,3-tetrafluoropent-4-en-1-ylidene)-1-phenylethylamine derivatives with 2.4 equiv of DBU in toluene at room temperature to 50 °C for 24 h led to a smooth [1,3]-proton shift reaction with a high chirality transfer, affording the corresponding rearranged products in acceptable yields. Without purification, these products were subjected to acid hydrolysis and the subsequent N-Cbz protection, providing the optically active tetrafluoroethylenated amides in moderate three-step yields.

18F-Difluoromethyl(ene) Motifs via Oxidative Fluorodecarboxylation with [18F]Fluoride

Herein, we report that α-fluorocarboxylic acids undergo manganese-mediated oxidative 18F-fluorodecarboxylation with [18F]fluoride affording biologically relevant 18F-difluoromethyl(ene)-containing molecules. This no-carrier added process provides a solution to a known challenge in radiochemistry and expands the radiochemical space available for positron emission tomography (PET) ligand discovery. Scalability on a fully automated radiosynthetic platform is exemplified with the production of [18F]4,4-difluoropiperidine that, we demonstrate, is amenable to postlabeling functionalization including N-heteroarylation and amide as well as sulfonamide bond formation.

Identification of Plant Peroxidases Catalyzing the Degradation of Fluorinated Aromatics Using a Peroxidase Library Approach

In this work, the degradation of mono- and polyfluorinated phenolic compounds was demonstrated by a series of crude plant peroxidases, including horseradish root (HRP) and six members of the Cucurbita genus. Highly active samples were identified using a library screening approach in which more than 50 crude plant samples were initially evaluated for defluorination activity toward 4-fluorophenol. The highest concentrations were observed in the HRP, pumpkin skin (PKS), and butternut squash skin (BNS), which consistently gave the highest intrinsic rates of decomposition for all the substrates tested. Although HRP exhibited a significant decrease in activity with increased fluorination of the phenolic substrate, PKS showed only minor reductions. Furthermore, in silico studies indicated that the active site of HRP poorly accommodates the steric bulk of additional fluorines, causing the substrate to dock farther from the catalytic heme and thus slowing the catalysis rate. We propose that the PKS active site might be larger, allowing closer access to the perfluorinated substrate, and therefore maintaining higher activity compared to the HRP enzyme. However, detailed kinetic characterization studies of the peroxidases are recommended. Conclusively, the high catalytic activity of PKS and its high yield per gram of tissue make it an excellent candidate for developing environmentally friendly biocatalytic methods for degrading fluorinated aromatics. Finally, the success of the library approach in identifying highly active samples for polyfluorinated aromatic compound (PFAC) degradation suggests the method may find utility in the quest for other advanced catalysts for PFAS degradation.

Fluorspar to fluorochemicals upon low-temperature activation in water

The dangerous chemical hydrogen fluoride sits at the apex of the fluorochemical industry, but the substantial hazards linked to its production under harsh conditions (above 300 degrees Celsius) and transport are typically contracted to specialists. All fluorochemicals for applications, including refrigeration, electric transportation, agrochemicals and pharmaceuticals, are prepared from fluorspar (CaF2) through a procedure that generates highly dangerous hydrogen fluoride1-5. Here we report a mild method to obtain fluorochemicals directly from fluorspar, bypassing the necessity to manufacture hydrogen fluoride. Acid-grade fluorspar (more than 97 per cent CaF2) is treated with the fluorophilic Lewis acid boric acid (B(OH)3) or silicon dioxide (SiO2), in the presence of oxalic acid, a Brønsted acid that is highly effective for Ca2+ sequestration. This scalable process carried out in water at low temperature (below 50 degrees Celsius) enables access to widely used fluorochemicals, including tetrafluoroboric acid, alkali metal fluorides, tetraalkylammonium fluorides and fluoro(hetero)arenes. The replacement of oxalic acid with sulfuric acid gave comparable results for B(OH)3, but was not as effective when the fluorophilic Lewis acid was SiO2. A similar process also works with the lower-purity metspar. The production of fluorochemicals directly from fluorspar offers the possibility of decentralized manufacturing-an attractive model for the fluorochemical industry. With the renewed interest in innovative methods to synthesize oxalic acid via carbon dioxide capture and biomass6,7, and the challenges posed by our dependence on fossil fuels for sulfur and therefore sulfuric acid supply8,9, our technology may represent a departure towards a sustainable fluorochemical industry.

Pentafluorosulfanylation of Acrylamides: The Synthesis of SF5-Containing Isoquinolinediones with SF5Cl

We disclose herein an efficient and facile method for the synthesis of SF5-containing isoquinolinediones with an all-carbon quaternary stereocenter via intramolecular pentafluorosulfanylation of acrylamides using SF5Cl as a pentafluorosulfanylation reagent. The protocol proceeds under mild reaction conditions and enjoys a broad substrate scope, wide functional group compatibility, and high atom- and step-economy. A radical mechanism involving the SF5 radical cascade addition/cyclization of acrylamides is proposed.

Sequential One-Pot Transformation to R-CF2-Embedded 1,5-Diketones Enabled by Nickel: Access to 4-Perfluoroalkylpyridines

Herein, we have demonstrated the application of bench-stable polyfluorinated alcohols as fluoroalkylating reagents for a sequential one-pot transformation with ketones to R-CF2-embedded 1,5-diketones and pyridines enabled by a nickel catalyst. The protocol is tolerant to a range of functional groups (>31 examples and up to 85% yield) and perfluoro alcohols and releases H2 and H2O as byproducts. Preliminary mechanistic studies, EPR analyses, and deuterium scrambling experiments were performed, and observed PC-H/PC-D = 2.12.

Investigation of the ability of 3-((4-chloro-6-methyl pyrimidin-2-yl)amino) isobenzofuran-1(3H)-one to bind to double-stranded deoxyribonucleic acid

Phthalides represent a notable category of secondary metabolites that are prevalent in various plant species, certain fungi, and liverworts. The significant pharmacological properties of these compounds have led to the synthesis of a novel phthalide derivative. The current study focuses on investigating the binding interactions of a newly synthesized 3-substituted phthalide derivative, specifically 3-((4-chloro-6-methyl pyrimidine-2-yl)amino) isobenzofuran-1(3H)-one (Z11), with double-stranded deoxyribonucleic acid (dsDNA). Research in the pharmaceutical and biological fields aimed at developing more potent DNA-binding agents must take into account the mechanisms by which these newly synthesized compounds interact with DNA. This investigation seeks to explore the binding dynamics between dsDNA and our compound through a variety of analytical techniques, such as electrochemistry, UV spectroscopy, fluorescence spectroscopy, and thermal denaturation. The binding constant (Kb) of Z11 with DNA was determined using both spectroscopic and voltammetric approaches. The research revealed that Z11 employs a groove binding mechanism to associate with dsDNA. To further explore the interactions between Z11 and dsDNA, the study utilized density functional theory (DFT) calculations, molecular docking, and molecular dynamics simulations. These analyses aimed to ascertain the potential for a stable complex formation between Z11 and dsDNA. The results indicate that Z11 is situated within the minor groove of the dsDNA, demonstrating the ability to establish a stable complex. Furthermore, the findings imply that both π-alkyl interactions and hydrogen bonding play significant roles in the stabilization of this complex.

Pesticides can be a substantial source of trifluoroacetate (TFA) to water resources

Through the application of C-CF3-containing plant protection products (PPP) in agriculture, a substantial quantity of trifluoroacetate (TFA) can be formed and emitted. We here present estimations of TFA formation potentials from PPP across three important economical regions, namely Europe, the United States of America and China. PPP with TFA formation potential vary in type and use profile across those regions, but can be found throughout, with the estimated maximum TFA emissions ranging from 0 to 83 kg/km2 per year. Therein, some PPP are only used for specific crops in specific regions, while others are used more widely. The importance of PPP as a TFA source is supported by the field data from a region in Germany, which revealed a significant increase in TFA groundwater concentrations with agriculture compared to other land uses. Substance-specific TFA formation rates and field studies are necessary to characterize the formation of TFA from precursors under environmental conditions and to rank and prioritize PPP of concern for potential (regulatory) action.

Hydramethylnon induces mitochondria-mediated apoptosis in BEAS-2B human bronchial epithelial cells

Typically used household chemicals comprise numerous compounds. Determining mixture toxicity, as observed when using household chemicals containing multiple substances, is of considerable importance from a regulatory perspective. Upon examining the toxic effects of household chemical mixtures, we observed that hydramethylnon combined with tetramethrin resulted in synergistic toxicity. To determine the unknown toxicity mechanism of hydramethylnon, which carries the risk of inhalation exposure when using household chemicals, we conducted a further investigation using BEAS-2B cells, a human bronchial epithelial cell line. Hydramethylnon-induced cytotoxicity was determined following 24 and 48 h of exposure using the water-soluble tetrazolium 1 and lactate dehydrogenase assays. To elucidate the toxicity mechanism, we utilized flow cytometry and measured the levels of apoptosis-related proteins and caspase activities. Given that hydramethylnon, as an insecticide, disrupts the mitochondrial electron transfer chain, we analyzed the relevant mechanisms, including mitochondrial superoxide levels as well as the mitochondrial membrane potential (MMP). Hydramethylnon dose-dependently induced BEAS-2B cell apoptosis via the intrinsic pathway. Furthermore, it significantly increased mitochondrial superoxide levels and disrupted the MMP. Pre-treatment with a caspase inhibitor (Z-DEVD-FMK) confirmed that hydramethylnon induced caspase-dependent apoptosis. Apoptosis, a key event in the toxicological process of chemicals, can lead to lung diseases, including fibrosis and cancer. The results of the present study suggest a mechanism of toxicity of hydramethrylnon, an organofluorine biocide whose toxicity has been little studied, to the lung epithelium. Considering the potential risks associated with inhalation exposure, these results highlight the need for careful management and regulation of hydramethylnon.

Highly Enantioselective Decarboxylative Difluoromethylation

Organofluorine molecules that contain difluoromethyl groups (CF2H) at stereogenic centers have gained importance in pharmaceuticals due to the unique ability of CF2H groups to act as lipophilic hydrogen bond donors. Despite their potential, the enantioselective installation of CF2H groups into readily available starting materials remains a challenging and underdeveloped area. In this study, we report a nickel-catalyzed decarboxylative difluoromethylation reaction that converts alkyl carboxylic acids into difluoromethylated products with exceptional enantioselectivity. This Ni-catalyzed protocol exhibits broad functional group tolerance and is applicable for synthesizing fluorinated bioisosteres of biologically relevant molecules.

Characterizing the Areal Extent of PFAS Contamination in Fish Species Downgradient of AFFF Source Zones

Most monitoring programs next to large per- and polyfluoroalkyl substances (PFAS) sources focus on drinking water contamination near source zones. However, less is understood about how these sources affect downgradient hydrological systems and food webs. Here, we report paired PFAS measurements in water, sediment, and aquatic biota along a hydrological gradient away from source zones contaminated by the use of legacy aqueous film-forming foam (AFFF) manufactured using electrochemical fluorination. Clustering analysis indicates that the PFAS composition characteristic of AFFF is detectable in water and fishes >8 km from the source. Concentrations of 38 targeted PFAS and extractable organofluorine (EOF) decreased in fishes downgradient of the AFFF-contaminated source zones. However, PFAS concentrations remained above consumption limits at all locations within the affected watershed. Perfluoroalkyl sulfonamide precursors accounted for approximately half of targeted PFAS in fish tissues, which explain >90% of EOF across all sampling locations. Suspect screening analyses revealed the presence of a polyfluoroketone pharmaceutical in fish species, and a fluorinated agrochemical in water that likely does not accumulate in biological tissues, suggesting the presence of diffuse sources such as septic system and agrochemical inputs throughout the watershed in addition to AFFF contamination. Based on these results, monitoring programs that consider all hydrologically connected regions within watersheds affected by large PFAS sources would help ensure public health protection.

Recent advances in catalytic enantioselective construction of monofluoromethyl-substituted stereocenters

Chiral organofluorine compounds featuring a monofluoromethyl (CH2F)-substituted stereocenter are often encountered in a number of drugs and bioactive molecules. Consequently, the development of catalytic asymmetric methods for the enantioselective construction of CH2F-substituted stereocenters has made great progress over the past two decades, and a variety of enantioselective transformations have been accordingly established. According to the types of fluorinated reagents or substrates employed, these protocols can be divided into the following major categories: (i) enantioselective ring opening of epoxides or azetidinium salts by fluoride anions; (ii) asymmetric monofluoromethylation with 1-fluorobis(phenylsulfonyl)methane; (iii) asymmetric fluorocyclization of functionalized alkenes with Selectfluor; and (iv) asymmetric transformations involving α-CH2F ketones, α-CH2F alkenes, or other CH2F-containing substrates. This feature article aims to summarize these recent advances and discusses the possible reaction mechanisms, advantages and limitations of each protocol and their applications. Synthetic opportunities still open for further development are illustrated as well. This review article will be an inspiration for researchers engaged in asymmetric catalysis, organofluorine chemistry, and medicinal chemistry.

Synthesis of 2,3-Diperfluoroalkylated Quinoxalines via Selenium-Catalyzed Reductive C-C Coupling of Vicinal Perfluoroalkyl Formimidoyl Chlorides

A direct and efficient approach to access structurally interesting 2,3-diperfluoroalkylated quinoxalines via selenium-catalyzed reductive C-C construction of vicinal bis(perfluoroalkyl formimidoyl chloride)s has been disclosed. This protocol features the use of easily accessible starting materials, scalability, and a diverse functional group tolerance. Mechanism studies suggested that this reaction may involve an interesting selenium-containing seven-membered-ring intermediate and proceed through an electrocyclization/selenium reductive elimination pathway, which is significantly different from the traditional transition-metal-catalyzed reductive coupling strategies of alkyl halides.

Transition-Metal-Free Late-Stage Decarboxylative gem-Difluoroallylation of Primary Alkyl Acids

A transition-metal-free late-stage decarboxylative gem-difluoroallylation of carboxylic acids with α-trifluoromethyl alkenes has been described by the use of organo-photoredox catalysis. Both primary alkyl and heteroaryl acids were readily incorporated. This approach merits feedstock materials, mild reaction conditions, and wide functionality tolerance. The synthetic utility of this approach has been highlighted by the late-stage functionalization of a variety of acid-containing natural products and drug molecules.

Polar-Effect-Directed Control in Site-Selectivity of Radical Substitution Enables C-H Perfluoroalkylation of Coumarins

A novel Ru-catalyzed protocol for C-7 selective C-H trifluoromethylation of coumarins in the presence of light is presented. This reaction undergoes a radical type nucleophilic substitution instead of a radical type electrophilic substitution owing to the benzocore activation as a result of lowering the lowest unoccupied molecular orbital (LUMO).

Visible Light-Induced Organophotoredox-Catalyzed β-Hydroxytrifluoromethylation of Unactivated Alkenes

Herein, we report a mild transition metal-free organophotoredox-catalyzed approach for β-hydroxytrifluoromethylation of unactivated alkenes using CF3SO2Na and acridinium salt. The protocol is compatible with various mono-, di-, and trisubstituted aliphatic unactivated alkenes containing numerous functional groups and natural product derivatives. Further, the postsynthetic modifications of the synthesized trifluoromethylated products have been demonstrated through cross-coupling and functional group interconversion reactions. The method proved to be scalable and it works smoothly under the direct exposure of sunlight. A plausible mechanism has been proposed based on the fluorescence quenching experiment and cyclic voltammetry analysis.

A Continuous Flow Process for the Defluorosilylation of HFC-23 and HFO-1234yf

A continuous flow process has been developed for the defluorosilylation of trifluoromethane (HFC-23) and 2,3,3,3-tetrafluoropropene (HFO-1234yf) through reaction with lithium silanide reagents under inert conditions. Design of experiment optimization improved process conditions, including productivity, yields, reduction of solvent use, and gas destruction. The small chain fluorinated organosilane products R3SiCF2H and R3SiCH2C(F)═CF2 were competent nucleophiles in the fluoride-catalyzed difluoromethylation of aldehydes, and trifluoroallylation of aldehydes, ketones, and imines.

Advancing toxicity studies of per- and poly-fluoroalkyl substances (pfass) through machine learning: Models, mechanisms, and future directions

Perfluorinated and perfluoroalkyl substances (PFASs), encompassing a vast array of isomeric chemicals, are recognized as typical emerging contaminants with direct or potential impacts on human health and the ecological environment. With the complex and elusive toxicological profiles of PFASs, machine learning (ML) has been increasingly employed in their toxicity studies due to its proficiency in prediction and data analytics. This integration is poised to become a predominant trend in environmental toxicology, propelled by the swift advancements in computational technology. This review diligently examines the literature to encapsulate the varied objectives of employing ML in the toxicity studies of PFASs: (1) Utilizing ML to establish Quantitative Structure-Activity Relationship (QSAR) models for PFASs with diverse toxicity endpoints, facilitating the targeted toxicity prediction of unidentified PFASs; (2) Investigating and substantiating the Adverse Outcome Pathway (AOP) through the synergy of ML and traditional toxicological methods, with this refining the toxicity assessment framework for PFASs; (3) Dissecting and elucidating the features of established ML models to advance Open Research into the toxicity of PFASs, with a primary focus on determinants and mechanisms. The discourse extends to an in-depth examination of ML studies, segregating findings based on their distinct application trajectories. Given that ML represents a nascent paradigm within PFASs research, this review delineates the collective challenges encountered in the ML-mediated study of PFAS toxicity and proffers strategic guidance for ensuing investigations.