Direct Electrophilic (Benzenesulfonyl)Difluoromethylthiolation with a Shelf‐Stable Reagent

The (benzenesulfonyl)difluoromethylsulfanyl (PhSO₂CF₂S) group is a valuable substituent with specific properties which can provide access to new applications of fluoroalkylthiolated compounds. Direct introduction of this moiety can be performed by in an electrophilic manner by using a new shelf‐stable reagent, namely a (benzenesulfonyl)difluoromethanesulfenamide. Furthermore, mild magnesium‐mediated reduction of the PhSO₂CF₂S group leads to a facile synthesis of difluoromethylthiolated molecules and their deuterated analogs.     

Ionic Liquids as Organocatalysts for Nucleophilic Fluorination: Concepts and Perspectives

Besides their extremely useful properties as solvent, ionic liquids (ILs) are now considered to be highly instructive tools for enhancing the rates of chemical reactions. The ionic nature of the IL anion and cation seems to be the origin of this fascinating function of ILs as organocatalyst/promoter through their strong Coulombic forces on other ionic species in the reaction and also through the formation of hydrogen bonds with various functional groups in substrates. It is now possible to tailor-make ILs for specific purposes as solvent/promoters in a variety of situations by carefully monitoring these interactions. Despite the enormous potentiality, it seems that the application of ILs as organocatalysts/promoters for chemical reactions have not been fully achieved so far. Herein, we review recent developments of ILs for promoting the nucleophilic reactions, focusing on fluorination. Various aspects of the processes, such as organocatalytic capability, reaction mechanisms and salt effects, are discussed.     

A Vicinal Electrophilic Diborylation Reaction Furnishes Doubly Boron‐Doped Polycyclic Aromatic Hydrocarbons

Ten examples of unsymmetrically benzannulated, boron‐doped polycyclic aromatic hydrocarbons (B‐PAHs) were prepared by a one‐pot protocol using 4,5‐dichloro‐1,2‐bis(trimethylsilyl)benzene ( 1 ), BBr₃, and selected PAHs—among them anthracene, benzo[a ]pyrene, biphenylene, and fluoranthene. After mesitylation at the boron centers, the resulting air‐ and water‐stable products were investigated by ¹H/¹¹B{¹H}/¹³C{¹H} NMR spectroscopy, X‐ray crystallography, cyclic voltammetry, and UV/Vis absorption/emission spectroscopy. The experiments were augmented by DFT calculations. Most of the B‐PAHs are brightly luminescent (Φ _PL up to 90 %) and undergo reversible reduction at moderate half‐wave potentials. The two chloro substituents of 1 are not only mandatory for accomplishing efficient diborylation, but can subsequently be used for Stille‐type coupling reactions to introduce 2‐thienyl moieties. Alternatively, Cl/H exchange is achievable with HSiEt₃ in a quantitative, Pd‐catalyzed transformation.     

Innovative Syntheses of Cyano(fluoro)borates: Catalytic Cyanation,Electrochemical and Electrophilic Fluorination

Different types of high-yield, easily scalable syntheses for cyano(fluoro)borates Kt[BF_n(CN)_4−n] (n=0–2) (Kt=cation), which are versatile building blocks for materials applications and chemical synthesis, have been developed. Tetrafluoroborates react with trimethylsilyl cyanide in the presence of metal-free Brønsted or Lewis acid catalysts under unprecedentedly mild conditions to give tricyanofluoroborates or tetracyanoborates. Analogously, pentafluoroethyltrifluoroborates are converted into pentafluoroethyltricyanoborates. Boron trifluoride etherate, alkali metal salts, and trimethylsilyl cyanide selectively yield dicyanodifluoroborates or tricyanofluoroborates. Fluorination of cyanohydridoborates is the third reaction type that includes direct fluorination with, for example, elemental fluorine, stepwise halogenation/fluorination reactions, and electrochemical fluorination (ECF) according to the Simons process. In addition, fluorination of [BH(CN)₂{OC(O)Et}]⁻ to result in [BF(CN)₂{OC(O)Et}]⁻ is described.     

N-Fluoro Ammonium Salts of Cinchona Alkaloids in Enantioselective Electrophilic Fluorination

From 2000, our two research groups independently and simultaneously designed and developed a novel family of electrophilic fluorinating reagents based on the use of Cinchona alkaloids. The chiral N-fluoro ammonium salts demonstrated the highest efficiency compared to prior art in enantioselective electrophilic fluorination for a wide range of substrates. In this account, we tell our respective stories, how the same idea germinated in our laboratories, the characterization of the chiral reagents, the use in stoichiometric quantity then the development of a catalytic version, the application to the synthesis of chiral fluorinated molecules of pharmaceutical interest, and finally the exploitation of our reagents by other teams and for other applications.     

N-硫二氟甲基膦酸二乙酯邻苯二甲酰亚胺:一种新的亲电氟烷硫基试剂

发展了一例新型亲电氟烷硫基试剂:N-硫二氟甲基膦酸二乙酯邻苯二甲酰亚胺,该试剂可以在溴化镁作用下,以温和的条件高效地实现富电子吲哚傅克类型的亲电氟烷硫基化反应,还可在碱促进下与sp³碳亲核试剂,包括β-酮酸酯、氧化吲哚、苯并呋喃酮等,发生亲电氟烷硫基化反应,简单高效地向分子一步引入硫二氟甲基膦酸二乙酯基团.     

Origin of the Regioselectivity in the Gas‐Phase Aniline+CH3+ Electrophilic Aromatic Substitution

Nonadiabatic ab initio molecular dynamics simulations are carried out to monitor the attack of CH₃⁺ on aniline in the gas phase to form the corresponding σ complexes. The reaction is ultrafast and is governed by a single electron transfer within 30 fs, which involves two sequential conical intersections and finally produces a radical pair. Positive‐charge allocation in the aromatic compound is found to govern the substitution pattern in ortho, meta, or para position. Although the major products in the first step of the electrophilic aromatic substitution are the ortho and para σ complexes, initially 26 % of the simulated trajectories also form meta complexes, which then undergo H shifts, mainly to the para position.     

Electrophilic Formylation of Arenes by Silylium Ion Mediated Activation of Carbon Monoxide

Arene‐stabilized silylium ions react with carbon monoxide rather than carbon monoxide adducts of silylium ions reacting with arenes. This mechanism is supported by quantum‐chemical calculations. Even sterically hindered mesitylene and electronically deactivated chlorobenzene engage in this electrophilic aromatic substitution. The silylium ion mediated formylation corresponds to Gattermann–Koch reactions promoted by strong Brønsted acids. The resulting silylcarboxonium ion of the arenecarbaldehyde was crystallographically characterized, for the first time revealing the molecular structure of this synthetically important intermediate.     

离子液体辅助水热法合成六方WO3纳米棒束

提出了利用简单的离子液体1-甲基-3-乙基-咪唑溴辅助水热法合成六方WO₃纳米棒束的方法,对其结构进行了表征,并讨论其形成机理。TEM照片表明：WO₃纳米棒束由长200~300 nm、直径25~30 nm的纳米棒组装而成。离子液体1-甲基-3-乙基-咪唑溴在纳米棒的形成过程中起到了结构导向剂的作用。     

离子液体中制备无机材料

离子液体作为潜在的“绿色”溶剂,具有许多传统溶剂无法比拟的优异性能,在有机合成、催化、液液分离和萃取等领域引起了广泛的研究。而在离子液体领域无机材料的制备是一个较新的发展分支,现已利用其合成出多种具有独特结构和性能的无机材料。本文就离子液体在无机材料制备方面的应用及发展趋势进行了综述。目前,对于制备无机材料,离子液体主要是作为电解液、表面活性剂或溶剂,本文介绍了其在应用中的优缺点,并指出该领域未来的发展趋势是离子热合成和集模板-溶剂-反应物于一身的离子液体反应。     

Eco-Friendly Methodology for the Formation of Aromatic Carbon–Heteroatom Bonds by Using Green Ionic Liquids

A new sustainable method is reported for the formation of aromatic carbon–heteroatom bonds under solvent-free and mild conditions (no co-oxidant, no strong acid and no toxic reagents) by using a new type of green ionic liquid. The bromination of methoxy arenes was chosen as a model reaction. The reaction methodology is based on only using natural sodium bromine, which is transformed into an electrophilic brominating reagent within an ionic liquid, easily prepared from the melted salt FeCl₃ hexahydrate. Bromination reactions with this in-situ-generated reagent gave good yields and excellent regioselectivity under simple and environmentally friendly conditions. To understand the unusual bromine polarity reversal of sodium bromine without any strong oxidant, the molecular structure of the reaction medium was characterised by Raman and direct infusion electrospray ionisation mass spectroscopy (ESI-MS). An extensive computational investigation using density functional theory methods was performed to describe a mechanism that suggests indirect oxidation of Br⁻ through new iron adducts. The versatility of the methodology was successively applied to nitration and thiocyanation of methoxy arenes using KNO₃ and KSCN in melted hexahydrated FeCl₃.     

离子液体辅助水热法合成六方WO3纳米棒束

提出了利用简单的离子液体1-甲基-3-乙基-咪唑溴辅助水热法合成六方WO₃纳米棒束的方法,对其结构进行了表征,并讨论其形成机理。TEM照片表明:WO₃纳米棒束由长200~300nm、直径25~30nm的纳米棒组装而成。离子液体1-甲基-3-乙基-咪唑溴在纳米棒的形成过程中起到了结构导向剂的作用。     

离子液体中的不对称合成研究进展

离子液体作为溶剂已广泛应用于许多有机化学反应.总结了离子液体中的不对称有机反应,如氢化反应、酰基化反应、环氧化反应、酶催化反应等.     

Sugar-Based Ionic Liquids: Multifaceted Challenges and Intriguing Potential

Carbohydrates represent a promising option in transitioning from oil-based chemical resources to renewable ones, with the goal of developing chemistries for a sustainable future. Cellulose, hemicellulose, and largely available monosaccharides already provide useful chemical building blocks, so-called platform chemicals, such as levulinic acid and hydroxymethyl furfural, as well as solvents like cyrene or gamma-valerolactone. Therefore, there is great anticipation for novel applications involving materials and chemicals derived from sugars. In the field of ionic liquids (ILs), sugar-based ILs have been overlooked for a long time, mainly on account of their multistep demanding preparation. However, exploring new strategies for accessing sugar-based ILs, their study, and their exploitation, are attracting increasing interest. This is due to the growing concerns about the negative (eco)toxicity profile of most ILs in conjunction with their non-sustainable nature. In the present review, a literature survey concerning the development of sugar-based ILs since 2011 is presented. Their preparation strategies and thermal behavior analyses, sorted by sugar type, make up the first two sections with the intention to provide the reader with a useful guide. A final overview of the potential applications of sugar-based ILs and their future perspectives complement the present analysis.     

Selectfluor: Mechanistic Insight and Applications

The replacement of hydrogen atoms with fluorine substituents in organic substrates is of great interest in synthetic chemistry because of the strong electronegativity of fluorine and relatively small steric footprint of fluorine atoms. Many sources of nucleophilic fluorine are available for the derivatization of organic molecules under acidic, basic, and neutral conditions. However, electrophilic fluorination has historically required molecular fluorine, whose notorious toxicity and explosive tendencies limit its application in research. The necessity for an electrophilic fluorination reagent that is safe, stable, highly reactive, and amenable to industrial production as an alternative to very hazardous molecular fluorine was the inspiration for the discovery of selectfluor. This reagent is not only one of the most reactive electrophilic fluorinating reagents available, but it is also safe, nontoxic, and easy to handle. In this Review we document the many applications of selectfluor and discuss possible mechanistic pathways for its reaction.