Journal of Fluorine Chemistry最新文献

Al₂O₃ exhibits high activity for the resource utilization of potent greenhouse gases, hydrofluorocarbons via dehydrofluorination or F/Cl exchange. However, it experiences completely fluorination under corrosive HF environment, leading to thorough fluorination of F-Al-O active site into F-Al-F, accompanied with serious carbon deposition. In this work, we successfully confined Al₂O₃ in SiC (Al₂O₃@SiC) via treating Al₂O₃/SiC under high temperatures (>800 °C). The results showed that different with simple loaded Al₂O₃(Al₂O₃/SiC), during high temperature treatment, reaction between Al₂O₃ and SiC occurred, leading to the confinement effect. Then, contributed by the interaction, desired F-Al-O species could be stabilized on the surface of SiC. While for Al₂O₃/SiC, it thoroughly turned into AlF₃ under identical reactive conditions, leading to inferior stability during CH₃CHF₂ dehydrofluorination. Furthermore, the reaction rate of 5 %Al₂O₃@SiC is nearly up to 4 folds higher than that of traditional AlF₃. Facilitated by the suitable Lewis acid intensity, less carbon deposition formed on Al₂O₃@SiC. Thus, constructing strong interaction between F-Al-O and stable SiC provides a potential strategy to stabilize unstable active centers.

Methyl 3-perfluoroethyl-pyropheophorbide-a exhibited a redmost visible (Qy) absorption maximum in solution at a longer wavelength than that of the non-fluorinated counterpart, while the former Qy band was sharper and more intense than the latter. In addition, the other visible bands of the fluorinated compound were red-shifted from those of the non-fluorinated. The perfluoroethylated molecule was more fluorescent at a longer wavelength with a longer lifetime, comparing with the ethylated analog. Similar results as in the above free bases were obtained for the corresponding nickel, copper, and zinc complexes. Additionally, the nickel and copper complexes exhibited similar absorption behaviors. This observation was due to the electron-withdrawing perfluoroethyl group bonding directly to the core chlorin π-system.

Positron emission tomography (PET) is a preclinical and clinical imaging technique that is extensively used in biomedical research and disease diagnosis to study and visualize biological and physiological processes. The positron emitter used most frequently for PET imaging is fluorine-18 (¹⁸F) due to its practical 109.8 min half-life, high yield production on fragile biomedical cyclotrons, and well-established ¹⁸F-radiochemistry. Fluorine atom(s) presented in many drugs and biomarkers that provides the opportunity for the development radioligand-labeled with ¹⁸F. Summarized in this paper are difluorocarbene (DFC)-enabled ¹⁸F-radiosynthesis to introduce [¹⁸F]CF₃, [¹⁸F]CF₂ and related motifs in organic molecules and to use them as bioactive radiotracers.

An efficient DBU-catalyzed β-addition of α-fluoro nitroalkane compounds to allenoates has been developed. Both γ-substituted and -unsubstituted allenoates participated in the reaction, giving a series of the β-addition products bearing a stereogenic carbon-fluorine structural unit in very good yields. The practicability of the method was also demonstrated.

The C₆F₁₂O gas mixture has good insulating properties and can replace the strong greenhouse gas sulfur hexafluoride (SF₆) in power equipment. To ensure the safe operation of the equipment, the compatibility between the C₆F₁₂O/N₂ gas mixture and commonly sealing rubber materials Ethylene-Propylene-Diene Monomer (EPDM), Nitrile Butadiene Rubber (NBR), and Fluororubber (FKM)) is an important factor. In this paper, the compatibility between the C₆F₁₂O/N₂ gas mixture and rubber materials at different temperatures is studied. Moreover, the free volume fraction, diffusion coefficient, and radial distribution function are calculated. It is found that there exists a chemical reaction between the C₆F₁₂O/N₂ gas mixture and rubbers, which leads to the appearance of folds or crystalline particles and the accumulation of a large number of F elements on the surface of NBR and EPDM. The simulation results show that the diffusion of the C₆F₁₂O/N₂ gas mixture in the rubber is enhanced with the increase of temperature, and the diffusion coefficient of C₆F₁₂O in NBR is the largest, reaching 33.439 × 10⁻¹¹m²/s. The experimental and theoretical results show that compatibility between the C₆F₁₂O/N₂ gas mixture and FKM is better. FKM will have a better application prospect in C₆F₁₂O/N₂-containing power equipment.

A convenient and efficient method for the synthesis of fluorinated phenanthridin-6(5H)-ones from the corresponding 2-isocyanato-1,1′-biphenyls mediated by trifluoromethanesulfonic acid in chlorobenzene is described. The reaction uses readily available starting materials, takes place under very mild reaction conditions (r. t.) and provides access to biologically promising fluorinated heterocycles in good to excellent yields. Synthesized compounds were tested in vitro for cytotoxicity in MDCK cell line and for antiviral activity against influenza virus A/Puerto Rico/8/34 (H1N1).

An asymmetric dearomative cyclopropanation of benzofuran has been accomplished by a novel catalytic method that relies on using trifluoromethyl N-triftosylhydrazones as carbene sources in the presence of a chiral rhodium catalyst. This reaction produces chiral trifluoromethyl-tethered 2,3-disubstituted benzofuran cyclopropane, which carries versatile pharmacophores 2,3-dihydrobenzofuran and trifluoromethyl-substituted quaternary carbon centers. Notably, this process offers distinct advantages over other existing approaches due to being step-economic and eliminating green-gas N₂ as a harmless coproduct. DFT calculations explain the reason behind the high enantioselectivity during this cyclopropanation reaction.

Fluorinated molecules often show superior bioactivity or ADME (absorption, distribution, metabolism, and excretion) properties compared to their non-fluorinated analogues. In fact, 20–30 % of newly approved drugs and the majority of recently approved agrochemicals are organofluorine compounds. Unsurprisingly, there is great interest in the development of new and/or improved processes for fluorine incorporation. Pd-catalyzed arylfluorination of alkenes is a novel, emerging fluorination method, which simultaneously introduces a fluorine atom and an aryl group into an alkene framework. The aim of the current work was studying, improving, and extending a literature arylfluorination protocol, which originally utilized N-allylated sulfonamide substrates.

The use of metal catalysts to modulate the generation and reactivity of carbenes has offered a powerful tool for construction of functional molecules. The design and synthesis of relevant transition-metal difluorocarbene complexes have benefited the development and interpretation of transition-metal catalyzed difluorocarbene transfer reactions. Although many achievements have been made in difluorocarbene chemistry, it is still a challenging task to make use of transition-metal difluorocarbenes in synthetic chemistry. To aid interested readers in better understanding the reactivity of transition-metal difluorocarbene species and designing catalytic methods for transfer of difluorocarbene intermediates, we summarize the advances of group VIII metal difluorocarbene complexes. Details include the preparation and properties of these complexes as well as their involvement in organic synthesis.

Novel simple approach was elaborated for the preparation of 3,3-difluoropyrrolidine hydrochloride starting from commercially available technical 2,2-dichlorotrifluoro-1-iodoethane. Its radical addition to ethylene afforded the corresponding iodide that was transformed into the primary amine. The last one was heated with sodium hydrosulfide to form previously unknown 3,3-difluoropyrrolidine-2-thione which was converted into the target product in high yield. The whole transformation does not require the use of toxic, flammable, explosive and hazardous reagents as well as column chromatography purification. Alternative syntheses have been proposed for the intermediate and target compounds.