The stereospecific preparation of two perfluoro-1,3-butadiene synthons; (E)-1-trimethylsilyl-1,2,3,4,4-pentafluoro-1,3-butadiene and (E)-1-tributylstannyl-1,2,3,4,4-pentafluoro-1,3-butadiene

(E)-1-Trimethylsilyl-1,2,3,4,4-pentafluoro-1,3-butadiene (1) can be stereospecifically prepared by Pd(0)/CuI catalyzed cross-coupling of (Z)-1-tributylstannyl-1,2-difluoro-2-trimethylsilylethene with iodotrifluoroethene. The corresponding (E)-1-tributylstannyl-1,2,3,4,4-pentafluoro-1,3-butadiene can be prepared via the stereospecific conversion of 1 with Bu₃SnOSnBu₃/KF (catalysis) to the corresponding vinylstannane.     

含氟聚酰亚胺及其在微电子工业中的研究进展I含氟单体及聚酰亚胺的合成

综述了近年来国内外在含氟聚酰亚胺(PI)研究及应用领域中的最新进展情况。主要从含氟二胺单体、二酐单体及含氟聚酰亚胺在合成方面的研究进展情况进行了详细的综述。重点阐述了中国科学院化学研究所305组近几年在这方面的研究进展情况，并指出为了推动含氟聚酰亚胺这类具有优良综合性能的功能材料在工业上的广泛应用，就必须首先解决含氟单体种类较少这个制约含氟聚酰亚胺发展的瓶颈问题。     

Fluorinated Vinyl Sulfonium Salts and Their Synthetic Utilization

The fluorinated building block strategy and the direct fluorination strategy are of great importance for the synthesis of new fluorinated molecules. These strategies complement each other and can be combined to develop a new methodology for the construction of a wide variety of fascinating organofluorine compounds. In our opinion, the versatile building blocks used in this method should satisfy the following conditions: 1) readily prepared from commercially available reagents; 2) easy to handle; 3) storage under ordinary conditions without noticeable decomposition; 4) wide applicability. Based on the aforementioned requirements, we focused on the use of vinyl sulfonium salts. This brief review describes the synthesis of five types of fluorinated vinyl sulfonium salts and their reactions. Especially, we featured typical fluorinated groups containing trifluoromethyl (CF₃), difluoromethyl (CF₂H), monofluoromethyl (CFH₂), monofluoro (F) or β-bromotetrafluoroethyl (BrCF₂CF₂) moieties in combination with vinyl sulfonium salts.     

Highly regio- and stereo-selective carbometallation reaction of fluorine-containing internal acetylenes with organocopper reagents

The carbometallation reactions of fluoroalkylated internal alkynes with various organocopper reagents derived from organolithium, Grignard, and organozinc reagents were examined. All carbocupration reactions proceeded smoothly in a highly regio- and stereo-selective manner to give the corresponding vinylcopper intermediates. The intermediates reacted with H⁺ smoothly, leading to the trisubstituted alkenes in high to excellent yields, whereas they reacted only with strictly limited carbon electrophiles such as allyl-, crotyl-, methallyl bromide, etc, probably due to the low reactivity exerted by an electron-withdrawing fluoroalkyl group. Treatment of vinylcopper with iodine resulted in a high yield of the corresponding vinyl iodide, which was employed successfully for Suzuki-Miyaura and Sonogashira cross-coupling reactions. In addition, two key reactions, the carbocupration and the Suzuki-Miyaura cross-coupling reaction realized the first highly stereoselective total synthesis of anti-estrogen drug, panomifene.     

Fluorinated molecules relevant to conducting polymer research

The synthesis of versatile fluorine compounds for conducting polymer research on fluorinated materials is presented. 1,2,4,5-Tetrafluorobenzene was converted to 1,2,4,5-tetrafluorobenzaldehyde (1) and protected as an acetal. This gave the acetals 1,2,4,5-tetrafluoro-3-(1,3-dioxol-2-yl)benzene (2a) and 1,2,4,5-tetrafluoro-3-(5,5-dimethyl-1,3-dioxan-2-yl)benzene (2b). Compounds 2a and 2b were converted into the semiprotected 2,3,5,6-tetrafluoroterephthaldehydes: 1,2,4,5-tetrafluoro-3-(1,3-dioxol-2-yl)-6-formylbenzene (3a) and 1,2,4,5-tetrafluoro-3-(5,5-dimethyl-1,3-dioxan-2-yl)-6-formylbenzene (3b). While 3a was easily deprotected to give 2,3,5,6-tetrafluoroterephthaldehyde (4) compound 3b proved very resilient to hydrolysis and gave a 1:1 mixture of 4 and 1,2,4,5-tetrafluoro-3,6-bis(5,5-dimethyl-1,3-dioxan-2-yl)benzene (5). Compound 4 was reduced to 1,2,4,5-tetrafluoro-3,6-dihydroxymethylbenzene (6) and converted into 1,2,4,5-tetrafluoro-3,6-dibromomethylbenzene (7). Compound 7 was finally converted into 1,2,4,5-tetrafluoro-3,6-bis(diethylphosponylmethyl)benzene (8). Compounds 4 and 8 are versatile fluorinated molecules that can be used to replace their hydrogen counterparts in many molecules and materials. To illustrate this compounds 4 and 8 were oligomerised to give partially fluorinated polyphenylenevinylene (9).     

One-pot synthesis of 2-trifluoromethyl and 2-difluoromethyl substituted benzo-1,3-diazoles

2-Trifluoromethyl and 2-difluoromethyl substituted benzimidazole, benzoxazole and benzothiazole derivatives were efficiently prepared through a one-pot reaction of trifluoroacetic acid and difluoroacetic acid, respectively, with commercially available o-phenylenediamines, 2-aminophenols, and 2-aminobenzenethiols in good to excellent yields. Subsequential bromination of 2-difluoromethyl groups by photolysis with NBS led to the formation of bromodifluoromethyl benzo-1,3-diazoles which may be utilized to prepare the new generation of gem-difluoromethylene linked identical or non-identical twin molecules for drug synthesis.     

Synthesis and characterization of fluorinated polyurethane with fluorine-containing pendent groups

A novel fluorinated polyurethane （FPU） with fluorine-containing pendent groups was prepared by using fluorinated polyether glycol （PTMG-g-HFP） as a soft segment, 1,6-hexamethylene diisocyanate （HDI） or toluene diisocyanate （TD1） as a hard segment and 1,4-butanodiol （BDO） as a chain extender. FTIR, ^1H NMR, ^13C NMR and GPC were used to characterize the structure of the fluorinated polyurethane. Thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by TGA. XPS analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU. The results showed the fluorine enrichment on the surface of FPU.     

含氟聚氨酯的研究进展

综述了溶剂性、水性含氟聚氨酯的合成及研究，并进行了讨论。     

Facile synthetic pathway to β-hydroxy-β-trifluoromethyl imines and their derivatives

Synthetic approach based on mediated addition of different trifluoromethylated building blocks to selected acyclic imines giving access to a variety of β-hydroxy-β-trifluoromethyl imines are elaborated. A reaction between fluorinated adducts and imines proceed easily giving the condensation products in good to excellent yields. β-Hydroxy-β-trifluoromethyl imines possessing trifluoromethyl group and exhibiting strong intramolecular hydrogen bonding are great precursors to different β-hydroxy-β-trifluoromethyl ketones and alcohols.     

p-TsOH promoted Fischer indole synthesis of multi-substituted 2-trifluoromethyl indole derivatives

A p-TsOH promoted one-pot synthesis of multi-substituted 2-trifluoromethyl indole derivatives, for instance, 2-trifluoromethyl-3-phenylindoles, 2-trifluoromethyl-indole-3-propanoates, and 2-trifluoromethyl-indole-3-butanoates from reactions of 1,1,1-trifluoro-3-phenylacetone and simply prepared ω-trifluoromethyl substituted δ and ?-ketoesters with arylhydrazines via Fischer indole synthesis has been developed.     

Fluorinated styrene-based monomers for cyclopolymerizations

The synthesis of versatile fluorine compounds and monomers for conducting polymer research and cyclopolymerizations is presented. Semiprotected 2,3,5,6-tetrafluoroterephthaldehyde 1 could be elaborated through Wittig olefination chemistry, deprotection and reduction to the previously unknown 4-vinyl-2,3,5,6-tetrafluorobenzylalcohol 8 in good yields. Compound 8 can be reacted to form the malonate ester, and then alkylation on the malonate moiety in mild conditions affords difunctional monomer 3. Through sequential esterifications on the malonate moiety, and subsequent alkylation, compound 4, a difunctional monomer for cyclopolymerization bearing one styrene and one perfluoroaryl styrene moiety, has been obtained. Preliminary experiments show that it is possible to cyclopolymerize 4 under free radical conditions.     

Fluoroaziridines as novel substrates in the modified Petasis reaction: synthesis of monofluorinated propargyl amines

Reaction of 2-fluoroaziridines with potassium alkynyltrifluoroborates in the presence of BF₃·OEt₂ leads to fluorinated propargyl amines in moderate to good yields. The reaction proceeds as an in situ isomerization of 2-fluoroaziridines to α-fluorinated imines, followed by the reaction of the imine with alkynyldifluoroborane, which is generated in situ from the potassium alkynyltrifluoroborates and BF₃·OEt₂.     

Cu(I)-catalyzed coupling reactions of fluorinated imidoyl halides with terminal alkynes: Convenient synthesis of fluorinated alkynyl imines

The first example of coupling reactions of fluorinated imidoyl halides with terminal alkynes catalyzed by CuI is presented. Each reaction needed no ligand, and fluorinated alkynyl imines were obtained with excellent yields.     

Fluorinated acrylates via alkoxycarbonylation of 1-alkynes with fluorinated alcohols

The system formed by combining in situ Pd(OAc)₂ with (2-pyridyl)diphenylphosphine (PyPPh₂) and CH₃SO₃H catalyzes efficiently the carbonylation of terminal alkynes (phenylacetylene or 1-hexyne) with alcohols having perfluorinated segments of the type CF₃(CF₂)_m(CH₂)_n–OH (m=1 or 3, n=1, 2 or 3) or with pentafluorophenol. Good carbonylation rates accompanied by high regioselectivity towards acrylate ester formation are obtained under mild reaction conditions (T=60–80 °C, P(CO)=30 atm). The influence of the CO pressure, the catalyst composition, the temperature and the number (n) of protonated methylene groups on the catalysis has been studied.     

Update on fluoroelastomers: from perfluoroelastomers to fluorosilicones and fluorophosphazenes

A survey of the synthesis, properties and applications of fluoroelastomers is reported falling into two main parts. After describing commercially available (per)fluorocarbon elastomers, fluoro-phosphazenes and silicones, recent data on hybrid fluorosilicones containing longer chains (often fluorinated) between silicon atoms are supplied. The second part deals with well-architectured fluoroelastomers. First, fluorinated thermoplastic elastomers obtained either by sequential iodine transfer polymerisation of fluoroalkenes (leading to triblock copolymers) or by a two-step procedure involving a monomer bearing peroxide that generated macroperoxides which thus produced graft copolymers. Then, multiblock copolymers were achieved either from telechelic perfluoropolyethers or from polyhydrosilylation of telechelic non-conjugated diene polyimides with fluorinated polyhybrid siloxane bearing Si-H end groups leading to exceptional materials.     

活性聚合法合成结构精确的含氟嵌段共聚物

结构精确的含氟嵌段共聚物具有优异而独特的化学和物理性能,有广阔的应用前景,因此受到广泛的关注.含氟嵌段共聚物可分为两类,一类是侧基含氟嵌段共聚物,另一类是主链含氟嵌段共聚物.活性聚合为嵌段共聚物的合成提供了最为重要的方法,利用它可以合成结构精确、分子量可控、分子量分布窄的嵌段共聚物.根据单体的反应特性选择不同的聚合方法,可以得到不同的含氟嵌段共聚物.本文主要综述了近几年利用各种活性聚合方法合成结构精确的含氟嵌段共聚物方面的进展.     

Synthesis of fluorinated allylic amines: Reaction of 2-(trimethylsilyl)ethyl sulfones and sulfoxides with fluorinated imines

A new synthesis of fluorinated allylamines through the reaction of 2-(trimethylsilyl)ethyl sulfones and sulfoxides (as vinyl anion equivalents) with imines and imino esters has been described. The process includes a TBAF-mediated fragmentation of 2-(trimethylsilyl)ethyl sulfones to afford the desired allylic amines. When the reaction is performed with the corresponding sulfoxides, the fragmentation takes place under the addition conditions, affording the final products in a single step.     

A new strategy for the synthesis of fluorinated 3,4-dihydropyrimidinones

A new family of 3,4-dihydropyrimidinones (DHPMs) bearing fluorinated substituents at C6 have been prepared from gem-difluorinated nitriles, alkyl 3-butenoates and iso(thio)cyanates. This novel Biginelli-type process relies on the γ-addition of the ester-derived enolate to fluorinated nitriles. A tandem nucleophilic addition aza-Michael reaction sequence completes the synthetic process.     

Synthesis, characterization and properties of a novel fluorinated polyurethane

A novel fluorinated polyurethane (FPU) was prepared by fluorinated polyether glycol (PTMG-g-HFP) as a soft segment, 1,6-hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) as a hard segment and 1,4-butanodiol (BDO) as a chain extender. Fourier transform infrared spectroscopy (FTIR), ¹H NMR, ¹³C NMR and gel permeation chromatography (GPC) were used to characterize the structure of the fluorinated polyurethane. The thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by thermogravimetric analysis (TGA). X-ray photoelectron spectroscopy (XPS) analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU. And the mechanical properties of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were also measured. Chemical resistance of polyurethane films was estimated through spot tests with different solvents. The results showed that FPU had high thermal stability, strain-hardening property and good chemical resistance. The XPS measurements showed the fluorine enrichment on the surface of FPU.     

Synthesis and monolayer properties of double-chained phosphatidylcholines containing perfluoroalkyl groups of different length

A series of double-chained phosphatidylcholines (PCs), 1,2-dioctadec-9′-ynoyl-sn-glycero-3-phosphocholine analogs containing perfluoroalkyl moieties (CF₃, C₂F₅, n-C₄F₉ or n-C₈F₁₇) as the terminal segment in two hydrophobic chains, 1a-d, were synthesized. Equilibrium spreading pressures of these fluorinated PCs at the air-water interface were measured as an indication of monolayer stability, in order to obtain the minimal fluorine content in PC molecule efficient to exhibit monolayer stabilizing effect. The monolayer stability sigmoidally increased with the fluorine content in PC molecule and subsequently leveled off above a certain fluorine content, i.e., n-C₄F₉ moiety, at 25 °C. Under this condition, the replacement of at least five hydrogen atoms at the terminal hydrophobic segment in double-chained PC molecule by fluorine atoms, i.e., CF₃CF₂ moiety, is required to exhibit the monolayer stabilizing effect, whereas further fluorination of double-chained PC (F(CF₂)_n; n > 4) has a minor effect on the monolayer stability.