- Siloxane based syntheses of fluorous ethenes and their tandem Heck reactions with aryl iodides
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Perfluoroalkyl-ethenes (RfnCHCH2, 6a-c; a, n = 4; b, n = 6; c, n = 8) were prepared in good isolated yields (67-89%) and high purity (GC assay > 98%) from various fluorinated organosilanes in fluoride-anion assisted protodesilylation reactions. The environmentally more benign 'KF/NEt3/H2O' reagent combination introduced here was found as an effective substitute for the commonly used tetrabutylammonium- fluoride trihydrate (TBAF·3H2O) as a fluoride source. Fluorous styrenes ((E)-RfnCHCHAr, 8) were then prepared in good isolated yields (58-93%/iodoarene) and purities (GC assay > 95%) with the Pd(0) catalyzed Heck coupling of iodoarenes (Ar-I, 7) and perfluoroalkyl-ethenes generated in situ by the fluoride assisted cleavage of (β-perfluoroalkyl- α-iodo-ethyl)-siloxane ([RfnCH2CH(I)SiMe 2]2O, 3) precursors in DMF solution at elevated temperatures. They are accessible by the one-pot reaction of dimethylvinylchlorosilane (CH2CHSiMe2Cl, 2) and perfluoroalkyl iodides (Rfn-I, 1) as we reported earlier. Similarly, the radical chain addition of C8F17I to CH 2CHSi(OMe)3 (9) gave (β-perfluorooctyl-α-iodo- ethyl)-trimethoxysilane ([C8F17CH2CH(I)]Si(OMe) 3, 10) in good yield, which then was reacted with silica gel in dry toluene to obtain an SiO2-bonded (perfluorooctyl)ethene surrogate [silica(O)3SiCH(I)CH2C8F17, 11]. The fluoride assisted cleavage of 11 and tandem Heck reaction with iodobenzene afforded the appropriate cross-coupled product (E)-C8F 17CHCHPh.
- Csapo, Agnes,Rabai, Jozsef
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p. 79 - 85,7
(2020/09/16)
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- A fluorous phosphate protecting group with applications to carbohydrate synthesis
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The first fluorous protecting group for phosphate is reported. This group can be used as a facile tag for purification and be removed under mild reducing conditions using zinc and ammonium formate. Synthesis of a disaccharide from Leishmania using this fluorous protecting group demonstrated the group's stability to the acidic conditions necessary for glycosylation as well as its orthogonality to several other common protecting groups.
- Liu, Lin,Pohl, Nicola L. B.
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p. 1824 - 1827
(2011/06/19)
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- PROCESS FOR PRODUCING FLUORINATED (METH)ACRYLIC ESTER
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A mixture of fluoroalkyl iodides of the formula C2F5(CF2CF2)nI ( n is an integer of ≥0) wherein the sum of such fluoroalkyl iodides of n=3 and n=4 contained is ≥85 mol% is provided. This mixture is subjected to an ethylene addition step and an esterification step, and C2F5(CF2CF2)nCH=CH2 and C2F5(CF2CF2)nCH2CH2OH are removed. Thus, there can be obtained a mixture of fluorine-containing (meth)acrylic esters of the formula C2F5(CF2CF2)nCH2CH2OCOCR1=CH2 (wherein R1 represents a hydrogen atom or a methyl group, and n is an integer of ≥0) wherein the content of impurities (namely, olefins of the formula C2F5(CF2CF2)nCH=CH2 and alcohols of the formula C2F5(CF2CF2)nCH2CH2OH) is low.
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Page/Page column 9
(2010/11/25)
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- Process for preparing fluorinated alkyl carboxylate esters
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A process for preparing fluorinated alkyl carboxylate esters comprises reaction of a silver carboxylate or silver carboxylate precursor, such as silver (I) iodide with a fluorinated alkyl iodide and a carboxylic acid. Preferably the fluorinated alkyl iodide has the general formula CF3(CF2)nCH2CH2I, wherein n is an integer in the range of from 1 to 29 and the carboxylic acid is acetic acid, acrylic acid or methacrylic acid.
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Page/Page column 5
(2008/06/13)
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- PROCESS FOR PRODUCING FLUORINATED ACRYLIC ESTER
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A mixture of fluorine-containing acrylic esters represented by CF3(CF2)nCH2CH2OCOCR1=CH2 wherein R1 is a hydrogen atom, a methyl group or a halogen atom and "n" is an integer of at least zero is subjected to distillation under such conditions that the esters are not polymerized, so as to give a mixture of the esters with a less content of impurities (that is, olefins represented by CF3(CF2)nCH=CH2 and alcohols represented by CF3(CF2)nCH2CH2OH) at a high yield.
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Page/Page column 8-9
(2008/06/13)
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- Coupling between a fluorinated olefin and a perfluorinated iodide: A model study on the reaction mechanism of perfluorinated polymer cross-linking
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In a model study, 1H, 19C, 13 C-1H and 1H-1H correlated NMR techniques confirm a Markovnikov type reaction intermediate for the major coupling products between a short, low MW perfluorinated iodide C2F5I (I) and a short, low MW fluorinated olefin CF3(CF2)7CH=CH2 (II). The reaction is peroxide induced (di-t-butyl peroxide, DTBP) and is conducted at 140 °C for a 3 h reaction time in a sealed glass ampoule. Side reaction products due to the reaction of DTBP with radical reaction intermediates were also observed and identified. The study aimed to mimic as closely as possible the peroxide-initiated coupling reaction between an iodine terminated fluoropolymer (model compound I) and its fluorinated di-olefin coupling agent (model compound II). A mono-olefin was chosen to simplify the model reaction.
- Wlassics, Ivan,Barchiesi,Sala
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p. 119 - 126
(2007/10/03)
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- Nucleophilic displacements of 2-perfluoroalkyl-1-iodoethanes: Improved synthesis of fluorine-containing malonic esters
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The replacement of iodide in 2-perfluoroalkyl-1-iodoethanes by anions derived from dialkyl malonate affords α-(2-perfluoroalkyl)ethyl malonic esters in high yields with negligible elimination and dialkylation, using bases such as K2CO3/su
- Trabelsi,Szoenyi,Geribaldi
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p. 177 - 181
(2007/10/03)
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- Application of trimethylvinylsilane as a convenient synthetic precursor of (perfluoroalkyl)ethenes: An unusual fluoride-induced elimination-desilylation coupled reaction
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(equation presented) A convenient and effective method for the preparation of perfluoroalkylated ethenes is described. First, the free radical addition of perfluoroalkyl iodides to trimethylvinylsilane in the presence of AIBN gave iodoethylsilane intermediates (F(CF2)nCH2CHISiMe3, n = 4 (1), 6 (2),8 (3), 10 (4); 94-99%). Then an unusual dehydrohalogenation-desilylation reaction was effected by tetrabutylammonium fluoride, and finally the product isolation (F(CF2)nCH=CH2 (5-8), 62-87%) was facilitated using a fluorous phase separation technique. This novel approach can also be applied to adjust short C2 hydrocarbon units to functionalized fluorinated segments (e.g., HOCH2(CF2)8CH=CH2 (11), 71%). All structures were verified by state-of-the-art multinuclear one- and two-dimensional NMR experiments involving both homo-(19F-19F) and heteronuclear (1H-13C, 19F-13C) correlations based on the GMQFCOPS and inverse 1H and/or 19F detected GHSQC, GHMQC sequences with broad-band adiabatic 13C decoupling.
- Szlávik, Zoltán,Tárkányi, Gábor,G?m?ry, ágnes,Rábai, József
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p. 2347 - 2349
(2007/10/03)
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- Synthesis and properties of fluorosilicon-containing polybutadienes by hydrosilylation of fluorinated hydrogenosilanes. Part 1. Preparation of the silylation agents
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The synthesis of new fluorinated hydrogenosilanes CnF(2n+1)(CH2)xC2H4Si(CH3)2H with n = 6 or 8 and x = 0 or 1 is presented.Such compounds were prepared in 85percent-90percent yield by the selective reduction of the corresponding fluorine-containing (dimethyl)chlorosilanes.These chlorinated derivatives were produced by the hydrosilylation of (dimethyl)chlorosilane with perfluoroalkylvinyl, CnF(2n+1)CH=CH2 (x = 0), or allyl, CnF(2n+1)CH2CH=CH2 (x = 1), olefins, both obtained from perfluoroalkyl iodides in two steps, the latter olefins being more reactive than the former.For all these steps, the influence of the spacer (C2H4 or C3H6) located between the fluorinated chain and the silicon atom with respect to the reactivity is discussed. - Keywords: Perfluoroalkyl iodide; Fluorinated olefin; Hydrosilylation; Reduction; Chlorofluorosilane; Polyfluoroalkyl(dimethyl)hydrogenosilanes
- Ameduri, B.,Boutevin, B.,Nouiri, M.,Talbi, M.
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p. 191 - 198
(2007/10/03)
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