Study on fluoroalkylation and fluoroalkoxylation: 19. Iridium(I)-catalyzed reaction of fluoroalkyl iodides with alkenes and alkynes

Fluoroalkyl iodides reacted with alkenes in the presence of hydridocarbonyltris(triphenylphosphine)iridium (I) to give the corresponding adducts in excellent yields under the mild conditions. Fluoroalkyl iodides reacted also with alkynes to afford E isomer of adducts predominantly. Addition of free radical inhibitor or single electron transfer scavenger to the reaction mixture partially suppressed the reaction. Diallyl ether could trap the fluoroalkyl radical to afford tetrahydrofuran derivative. XPS showed that the valence of Ir (I) rised at the end of the reaction. All findings seem to indicate that the reaction involves a free radical chain mechanism initiated by Ir (I).     

Radical Fluoroalkylation of Isocyanides with Fluorinated Sulfones by Visible‐Light Photoredox Catalysis

The radical fluoroalkylation of isocyanides with fluorinated sulfones is enabled by visible‐light photoredox catalysis. A wide range of readily available mono‐, di‐, and trifluoromethyl heteroaryl sulfones can thus be used as efficient radical fluoroalkylation reagents under mild conditions. This method not only describes a new synthetic application of fluorinated sulfones, but also provides a new route to fluoroalkyl radicals.     

Solubilization of fullerene into ionic liquids by the use of fluoroalkyl end‐capped oligomers

Fluoroalkyl end‐capped oligomers were solubilized into a variety of ionic liquids such as N‐methylpyrazolium tetrafluoroborate, 3‐methylpyrazolium tetrafluoroborate and 1‐butyl‐3‐methylimidazolium hexafluorophosphate, and these fluorinated oligomers were able to reduce the surface tension of these ionic liquids. Interestingly, these fluorinated oligomers were able to solubilize fullerene into ionic liquids effectively. Fluoroalkyl end‐capped fullerene co‐oligomers, which were prepared by the oligomerizations of fluoroalkanoyl peroxides with radical polymerizable monomers such as acryloylmorpholine in the presence of fullerene, were more effective in solubilizing fullerene into ionic liquids compared to the corresponding fluoroalkyl end‐capped homo‐oligomers possessing no fullerene units. Fluoroalkyl end‐capped fullerene co‐oligomers/fullerene/ionic liquid complexes thus obtained were applied to the arrangements of fullerenes above the poly(methyl methacrylate) (PMMA) surface, and the higher fluorescent intensity of fullerene was obtained in the modified PMMA surface, although the reverse side of this modified film surface afforded an extremely weak fluorescent intensity. Copyright © 2005 John Wiley & Sons, Ltd.     

Visible light induced C-H monofluoroalkylation to synthesize 1,4-unsaturated compound

We developed a method to synthesize fluorinated 1,4-unsaturated dicarbonyl compounds via photoredox catalyzed radical addition process. Commercially available ethyl bromodifluoroacetate (BrCF₂CO₂Et) as fluoroalkyl source, the corresponding fluoro-containing dicarbonyl compounds could be obtained in moderate to good yields.     

Metallaphotoredox Difluoromethylation of Aryl Bromides

Herein, we report a convenient and broadly applicable strategy for the difluoromethylation of aryl bromides by metallaphotoredox catalysis. Bromodifluoromethane, a simple and commercially available alkyl halide, is harnessed as an effective source of difluoromethyl radical by silyl‐radical‐mediated halogen abstraction. The merger of this fluoroalkyl electrophile activation pathway with a dual nickel/photoredox catalytic platform enables the difluoromethylation of a diverse array of aryl and heteroaryl bromides under mild conditions. The utility of this procedure is showcased in the late‐stage functionalization of several drug analogues.     

Fluoroalkyl N-sulfonyl hydrazones: An efficient reagent for the synthesis of fluoroalkylated compounds

Fluoroalkyl N-sulfonyl hydrazones are versatile reagents that can be used to synthesize a wide range of diverse fluoroalkylated organic molecules. Although it has been known since 1975, the chemistry of fluoroalkyl N-sulfonyl hydrazones has recently only received great attention from the scientific community. Generally, they are used as either safe and bench-stable diazo precursors in carbene transfer reactions or as 1,3-dipoles in cycloaddition and cyclization reactions. Notably, fluoroalkyl N-sulfonyl hydrazones to replace toxic fluoroalkyl diazo compounds in carbene transfer reactions reduce the risk of rapid accumulation of explosive diazo compounds and improve functional group compatibility and substrate scope. Given the growing importance of fluoroalkyl N-sulfonyl hydrazones in chemical synthesis, a comprehensive review of this topic in the literature is essential to demonstrate their synthetic potential. In this review, we critically summarize and comprehensively analyze the publications in various literatures on the chemistry of fluoroalkyl N-sulfonyl hydrazones starting from 1990 to date. The classification of the different reactivity profiles of fluoroalkyl N-sulfonyl hydrazones and the efficiencies of similar types of reactions or substrates with fluoroalkyl diazo compounds are compared.     

Preparation of magnetic nanoparticles by the use of self-assembled fluorinated oligomeric aggregates—A new approach to the dispersion of magnetic particles on poly(methyl methacrylate) film surface

Fluoroalkyl end-capped acrylic acid oligomer-encapsulated magnetic nanoparticles were prepared by the coprecipitation of aqueous ferric and ferrous ions in the presence of the corresponding oligomers under alkaline conditions. The dynamic light scattering measurements showed that these fluorinated oligomer magnetic nanoparticles were encapsulated in the self-assemblies of fluoroalkyl end-capped oligomers. Fluoroalkyl end-capped oligomer-encapsulated magnetic nanoparticles thus obtained were applied to the dispersion of magnetic particles on the poly(methyl methacrylate) film surface to exhibit not only the surface active property imparted by fluorine but also magnetic behavior toward a permanent magnet.     

Novel self-assembled molecular aggregates formed by fluoroalkyl end-capped oligomers and their application

A variety of fluoroalkyl end-capped oligomers were prepared under mild conditions by the use of fluoroalkanoyl peroxide as a key intermediate. These oligomers can form the self-assembled molecular aggregates with the aggregations of end-capped fluoroalkyl groups in aqueous and organic media. Fluorinated self-assembled molecular aggregates containing carboxyl and sulfo groups were suggested to interact with positively charged HIV-1 to exhibit a potent anti-HIV-1 activity in vitro. In contrast, fluoroalkyl end-capped oligomers containing cationic segments exhibited not only the unique surface active properties imparted by fluorine as well as the usual low-molecular fluorinated surfactants, but also high surface antibacterial activity. Fluoroalkyl end-capped oligomers containing betaine-type segments were found to cause a gelation where the strong aggregation of the end-capped fluoroalkyl groups is involved in establishing the physical gel network in water and polar organic solvents under non-crosslinked conditions. Similarly, fluoroalkyl end-capped oligomers containing hydroxyl groups could cause a gelation, where the aggregation of fluoroalkyl groups and hydrogen-bonding interaction is involved in establishing a physical gel network in water and polar organic solvents under non-crosslinked conditions. Fluoroalkanoyl peroxide is also a convenient tool for the preparation of new fluoroalkyl end-capped oligomers containing recognition moieties such as diacetone segments. These fluorinated oligomers containing recognition moieties could form the self-assembled molecular aggregates to recognize selectively the hydrophilic amino and N,N-dimethylamino compounds as guest molecules.     

Preparation of novel fluoroalkyl end-capped oligomers/silica hybrid nanoparticles-encapsulation of a variety of guest molecules into fluorinated nanoparticles

Fluoroalkyl end-capped oligomers reacted with tetraethoxysilane and silica/nanoparticles under alkaline conditions to afford fluoroalkyl end-capped oligomers/silica nanoparticles (mean diameters: 31–54 nm) with a good dispersibility and stability in organic media. Interestingly, the isolated fluorinated particle powders were found to afford nanometer size-controlled colloidal particles with a good redispersibility and stability in these media. In addition, fluoroalkyl end-capped oligomers/silica nanoparticles-encapsulated guest molecules such as stable organic radicals and ionic liquids were prepared under similar conditions. These fluorinated nanoparticles-encapsulated guest molecules were applied to a new type of surface-modification agent, and these particles were able to disperse well above the poly (methyl methacrylate) films.     

Studies on fluoroalkylation and fluoroalkoxylation: 8. Palladium(0)-catalyzed addition reaction of fluoroalkyl iodides with alkynes

Fluoroalkyl iodide R_fI [R_F=(CF₂)_nCl, n=2, 4, 6; CF₃(CF₂)_n, n=1, 3; H(CF₂)₄] reacted with alkyne (CH≡CC₄H₉; CH≡CSiMe₃; CH≡CC₆H₅) in the presence of catalytic amounts of tetrakis (triphenylphosphine) palladium (0) to give a mixture of E and Z-fluoroalkylated adduct. The reaction could not be catalyzed by dichloro-bis(triphenylphosphine)palladium (II) and fluoroalkyl complex of palladium (II). 2-Nitro-2-nitrosopropane partly suppressed the reaction. It is believed that the reaction proceeds through a free radical intermediate rather than fluoroalkyl complex of palladium (II).     

Preparation of fluoroalkyl end-capped oligomers/magnetite nanocomposites possessing a good dispersibility and stability

Fluoroalkyl end-capped vinylphosphonic acid cooligomers-encapsulated magnetite nanocomposites were prepared by the magnetization of aqueous ferric and ferrous ions in the presence of the corresponding fluorinated cooligomers and magnetic nanoparticles under alkaline conditions. These fluorinated cooligomers magnetic composites are nanometer size-controlled very fine particles and have a good dispersibility and stability in water and traditional organic solvents. These fluorinated nanocomposites were also applied to the surface modification of poly(methyl methacrylate) to exhibit a good oleophobicity imparted by fluorine on their surface. Fluoroalkyl end-capped 2-methacryloyloxyethanesulfonic acid oligomer-encapsulated magnetite nanocomposites and fluoroalkyl end-capped 2-acrylamide-2-methylpropanesulfonic acid oligomer-encapsulated magnetite nanocomposites were prepared in good isolated yields by the magnetization of iron chlorides in the presence of the corresponding oligomers and magnetic nanoparticles under similar conditions. Colloidal stability of these fluorinated nanocomposites thus obtained in water was demonstrated to become extremely higher than that of fluorinated vinylphosphonic acid cooligomers/magnetic nanocomposites.     

氟碳端基聚合物合成及其表面吸附性能

综述了近十年来氟端基聚合物的合成,表征及其在表面吸附行为的研究成果。通过含有氟烷基的引发剂或终止剂在活性阴离子聚合反应或自由基聚合反应中使聚合物接上氟端基。已经成功地利用活性阴离子聚合反应合成了氟端基聚苯乙烯,通过含氟自由基引发烯类单体（如丙烯酸,乙烯硅等）可在相应聚合物链上引入氟端基,另外,聚合物的化学改性方法也可将氟基团接在聚合物链端（如氟基聚氧乙烯,氟端基聚合物具有的表面活性,当水溶液中或聚     

Synthesis and applications of novel fluorinated dendrimer-type copolymers by the use of fluoroalkanoyl peroxide as a key intermediate

Fluoroalkanoyl peroxide reacted with 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (TTRV-Si) to afford fluoroalkyl end-capped oligomers containing some unreacted vinyl segments under very mild conditions. Fluoroalkyl end-capped cyclosiloxane oligomers containing some vinyl segments thus obtained reacted with N,N-dimethylacrylamide and fluoroalkanoyl peroxide to afford new fluorinated dendrimer-type block copolymers in good isolated yield. Similar reactions were also occurred by the use of 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane instead of TTRV-Si, and the corresponding fluorinated dendrimer-type block copolymer was obtained in good isolated yield. These fluorinated dendrimer-type block copolymers had an excellent solubility not only in water but also in traditional organic solvents including aliphatic fluorinated solvents. Interestingly, these fluorinated block copolymers were found to form the self-assembled dendrimer-type polymeric aggregates in aqueous solutions. More interestingly, these fluorinated block copolymers had an extremely higher dispersion ability of not only single-walled carbon nanotube and fullerenes but also magnetic nanoparticles into water, compared to that of the corresponding two fluoroalkyl end-capped oligomers.     

Preparation and applications of novel fluoroalkyl end‐capped oligomers/polyimide/silica nanocomposites

Fluoroalkyl end‐capped acrylic acid, N,N‐dimethylacrylamide, N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide and vinyltrimethoxysilane oligomers reacted with polyamic acid possessing trimethoxysilyl groups under alkaline conditions to yield the corresponding fluoroalkyl end‐capped oligomers/polyamic acid/silica nanocomposites. These isolated fluorinated composite powders were found to afford nanometer size‐controlled fine particles with a good dispersibility and stability in water and traditional organic solvents. We succeeded in preparing new fluoroalkyl end‐capped oligomers/polyimide/silica nanocomposites by the imidization of fluorinated polyamic acid silica nanocomposites through the stepwise heating at 110 and 270°C under air atmosphere conditions. These fluorinated polyimide/silica nanocomposites thus obtained were applied to the surface modification of glass and poly(methyl methacrylate) (PMMA) to exhibit good hydro‐ and oleo‐phobic characteristics imparted by fluoroalkyl groups in the composites on their surface. In addition, the surface morphology of the modified glass treated with these fluorinated nanocomposites were analyzed by using FE‐SEM and DFM. Copyright © 2011 John Wiley & Sons, Ltd.     

Photocatalytic Fluoro Sulfoximidations of Styrenes

Reactions of difluoroiodotoluene with NH‐sulfoximines provide new hypervalent iodine(III) reagents, which photocatalytically transfer a fluoro and a sulfoximidoyl group onto styrenes with high regioselectivity. The substrate scope is broad with respect to both sulfoximines and olefins. Following an operationally simple protocol, a large library of fluorine‐containing N‐functionalized sulfoximines can be accessed. Results from mechanistic investigations revealed the importance of radical intermediates.     

Leaving Group Assisted Strategy for Photoinduced Fluoroalkylations Using N‐Hydroxybenzimidoyl Chloride Esters

Redox‐active esters (RAEs) as alkyl radical precursors have been extensively developed for C?C bond formations. However, the analogous transformations of fluoroalkyl radicals from the corresponding acid or ester precursors remain challenging because of the high oxidation potential of the fluoroalkyl carboxylate anions. The newly developed N‐hydroxybenzimidoylchloride (NHBC) ester provides a general leaving group assisted strategy to generate a portfolio of fluoroalkyl radicals, and can be successfully applied in photoinduced decarboxylative hydrofluoroalkylation and heteroarylation of unactivated olefins. In addition, DFT calculations revealed that the NHBC ester proceeds by the fluorocarbon radical pathway, whereas other well‐known RAEs proceed by the nitrogen radical pathway.     

Studies on fluoroalkylation and fluoroalkoxylation. Part 26. Wilkinson's catalyst-induced addition of fluoroalkyl iodides to olefins

Addition of fluoroalkyl iodides to olefins in the presence of tris(triphenylphosphine)chlororhodium (I) in benzene or acetonitrile gives the corresponding 1:1 adducts in good yields. The reaction can be suppressed with p-dinitrobenzene (p-DNB) or di-t-butylnitroxide, and tetrahydrofuran derivatives are obtained from the reaction of fluoroalkyl iodides with diallyl ether. A radical chain-reaction mechanism induced by single electron transfer (SET) is proposed.     

(甲基)丙烯酸氟烷基酯的“活性”/可控聚合

带氟烷基侧链的(甲基)丙烯酸氟烷基酯聚合物是一类具有独特表面性能和光学特性的氟聚合物,传统的自由基共聚合由于无法调节聚合物的微细结构和氟原子的分布,限制了该类聚合物在更广领域的应用.活性聚合为聚合物分子设计和合成提供了一个有效方法,利用活性聚合方法可以获得预期结构和性能的含氟嵌段聚合物材料.由于引入了氟烷基侧链,(甲基)丙烯酸氟烷基酯的活性聚合又有其特殊性,本文针对它的活性阴离子聚合、基因转移聚合、活性自由基聚合等方面作一综述.     

Fluorous ionic liquids as solvents for the liquid-liquid extraction of metal ions by macrocyclic polyethers

The predominant mode of strontium ion transfer from aqueous nitrate media into a series of 1-fluoroalkyl-3-methylimidazolium bis[(trifluoromethylsulfonyl)]imides containing dicyclohexano-18-crown-6 (DCH18C6) is shown to shift from cation exchange to strontium nitrato-crown ether complex partitioning as the length of the fluoroalkyl substituent is increased. Fluoroalkyl substituents are shown to be only slightly more effective than their non-fluorous analogs at inducing this shift. At the same time, the fluorinated ionic liquids (ILs) yield strontium distribution ratios as much as an order of magnitude lower than the corresponding 1-alkyl-3-methylimidazolium (C_nmim⁺) salts. Fluorous ILs thus appear to offer no compelling advantages over C_nmim⁺ ionic liquids as extraction solvents.     

Reductive Amination by Photoredox Catalysis and Polarity‐Matched Hydrogen Atom Transfer

The excitation of a Ru^II photosensitizer in the presence of ascorbic acid leads to the reduction of iminium ions to electron‐rich α‐aminoalkyl radical intermediates, which are rapidly converted into reductive amination products by thiol‐mediated hydrogen atom transfer (HAT). As a result, the reductive amination of carbonyl compounds with amines by photoredox catalysis proceeds in good to excellent yields and with broad substrate scope and good functional group tolerance. The three key features of this work are 1) the rapid interception of electron‐rich α‐aminoalkyl radical intermediates by polarity‐matched HAT in a photoredox reaction, 2) the method of reductive amination by photoredox catalysis itself, and 3) the application of this new method for temporally and spatially controlled reactions on a solid support, as demonstrated by the attachment of a fluorescent dye on an activated cellulose support by photoredox‐catalyzed reductive amination.