- Metal-free hydrogen evolution cross-coupling enabled by synergistic photoredox and polarity reversal catalysis
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A synergistic combination of photoredox and polarity reversal catalysis enabled a hydrogen evolution cross-coupling of silanes with H2O, alcohols, phenols, and silanols, which afforded the corresponding silanols, monosilyl ethers, and disilyl ethers, respectively, in moderate to excellent yields. The dehydrogenative cross-coupling of Si-H and O-H proceeded smoothly with broad substrate scope and good functional group compatibility in the presence of only an organophotocatalyst 4-CzIPN and a thiol HAT catalyst, without the requirement of any metals, external oxidants and proton reductants, which is distinct from the previously reported photocatalytic hydrogen evolution cross-coupling reactions where a proton reduction cocatalyst such as a cobalt complex is generally required. Mechanistically, a silyl cation intermediate is generated to facilitate the cross-coupling reaction, which therefore represents an unprecedented approach for the generation of silyl cationviavisible-light photoredox catalysis.
- Cao, Jilei,Lu, Kanghui,Ma, Lishuang,Yang, Xiaona,Zhou, Rong
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supporting information
p. 8988 - 8994
(2021/11/23)
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- PROCESS FOR PRODUCING SULFONIC ACID GROUP-CONTAINING MONOMER
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The present disclosure is directed to provide a process capable of producing a sulfonic acid group-containing monomer in a good yield, which can be used as a raw material of fluorine-based polymer electrolytes, such as membranes for fuel cells, catalyst binder polymers for fuel cells, and membranes for chlor-alkali electrolysis. A process for producing a sulfonic acid group-containing monomer represented by the general formula (3) includes the step of mixing and stirring a cyclic compound represented by the general formula (1) and a silanol compound represented by the general formula (2).
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- C?H and C?F Bond Activation Reactions of Fluorinated Propenes at Rhodium: Distinctive Reactivity of the Refrigerant HFO-1234yf
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The reaction of [Rh(H)(PEt3)3] (1) with the refrigerant HFO-1234yf (2,3,3,3-tetrafluoropropene) affords an efficient route to obtain [Rh(F)(PEt3)3] (3) by C?F bond activation. Catalytic hydrodefluorinations were achieved in the presence of the silane HSiPh3. In the presence of a fluorosilane, 3 provides a C?H bond activation followed by a 1,2-fluorine shift to produce [Rh{(E)-C(CF3)=CHF}(PEt3)3] (4). Similar rearrangements of HFO-1234yf were observed at [Rh(E)(PEt3)3] [E=Bpin (6), C7D7 (8), Me (9)]. The ability to favor C?H bond activation using 3 and fluorosilane is also demonstrated with 3,3,3-trifluoropropene. Studies are supported by DFT calculations.
- Talavera, Maria,von Hahmann, Cortney N.,Müller, Robert,Ahrens, Mike,Kaupp, Martin,Braun, Thomas
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supporting information
p. 10688 - 10692
(2019/07/10)
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- Facile synthesis of cyclic fluorosiloxanes
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Novel 1,3,5,7-tetrafluorocyclotetrasiloxanes were synthesized from cyclotetrasiloxanetetraol by a facile synthetic method. By adjusting the amount of the fluorinating reagent, synthesis of a single isomer of 1,3,5,7-tetrafluorocyclotetrasiloxanes as well as the preparation of all four isomers were accomplished. The products are expected to serve as potential precursors to not only well-defined silsesquioxanes but also asymmetric cyclic siloxanes.
- Oguri, Naoki,Takeda, Nobuhiro,Unno, Masafumi
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supporting information
p. 1506 - 1508
(2015/11/24)
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- [B(C6F5)4]: An air stable, lewis acidic stibonium salt that activates strong element-fluorine bonds
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As part of our ongoing interest in main group Lewis acids for fluoride anion complexation and element-fluorine bond activation, we have synthesized the stibonium borate salt [Sb(C6F5)4][B(C 6F5)4] (3). The perfluorinated stibonium cation [Sb(C6F5)4]+ present in this salt is a potent Lewis acid which abstracts a fluoride anion from [SbF 6]- and [BF(C6F5)3] - indicating that it is a stronger Lewis acid than SbF5 and B(C6F5)3. The unusual Lewis acidic properties of 3 are further reflected by its ability to polymerize THF or to promote the hydrodefluorination of fluoroalkanes in the presence of Et 3SiH. While highly reactive in solution, 3 is a perfectly air stable salt, making it a convenient Lewis acidic reagent.
- Pan, Baofei,Gabba?, Fran?ois P.
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supporting information
p. 9564 - 9567
(2014/07/22)
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- Meerwein's reagent mediated, significantly enhanced nucleophilic fluorination on alkoxysilanes
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We developed a new facile method to fluorosilanes from alkoxysilanes using Meerwein's reagent. Our protocol afforded fluorosilanes in excellent yields in various organic solvents including acetonitrile under mild reaction conditions at room temperature. We also proposed a reaction mechanism with the probable silyloxonium intermediates. Georg Thieme Verlag Stuttgart · New York.
- Jorapur, Yogesh R.,Shimada, Toyoshi
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scheme or table
p. 1064 - 1068
(2012/06/17)
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- Synthesis, structure and reactivity of iridium hydrido fluorido complexes
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The oxidative addition of HF at trans-[Ir(ArF) (η2-C2H4)(PiPr3)2] (1a: ArF = 4-C5NF4; 1b: ArF = 2-C6H3F2) affords the fluorido complexes trans-[Ir(ArF)(F)(H)(PiPr3)2] (2a: Ar F = 4-C5NF4; 2b: ArF = 2-C 6H3F2). The hydrido fluorido complex 2a is also accessible by means of the reaction of the hydroxido complex trans-[Ir(4-C 5NF4)(H)(OH)(PiPr3)2] (3a) with Et3N·3HF. Both compounds 2a and 2b react with CO to give the carbonyl complexes trans-[Ir(4-C5NF4)(F)(H)(CO)(PiPr 3)2] (4a: ArF = 4-C5NF4; 4b: ArF = 2-C6H3F2). In the presence of traces of water, a slow reaction of 2a with CO2 yields the hydrogencarbonato complex trans-[Ir(4-C5NF4)(H)( 2-(O,O)-O2COH)(PiPr3)2] (5a). Upon using 2a or 2b as fluorinating agent, Ph3SiH could be converted into Ph3SiF and CH3C(O)Cl into CH3C(O)F. The oxidative addition of HF at trans-[Ir(4-C5NF4) (I·2-C2H4)(PiPr3) 2] affords the fluorido complex trans-[Ir(4-C5NF 4)(F)(H)(PiPr3)2], which exhibits a square-pyramidal configuration. The latter reacts with acetyl chloride to yield acetyl fluoride and trans-[Ir(4-C5NF4)(Cl)(H)(PiPr 3)2].
- Klaering, Paul,Jungton, Ann-Katrin,Braun, Thomas,Mueller, Carsten
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experimental part
p. 1430 - 1436
(2012/06/15)
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- Preparation of (Z)-1-fluoro-1-alkenyl carboxylates, carbonates and carbamates through chromium mediated transformation of dibromofluoromethylcarbinyl esters and the reactivity as double acyl group donors
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CrCl2/Mn-mediated transformation of various dibromofluoromethylcarbinyl esters including carboxylates, carbonates and carbamates provided 1-fluoro-1-alkenyl esters via [2,3]-sigmatropic rearrangement of ester group. Reaction proceeded by using CrCl2/Mn system under mild conditions (in THF at room temperature) to give 1-fluoro-1-alkenyl esters in good yield with an excellent Z selective manner. 1-Fluoro-1-alkenyl ester thus obtained acts as a double acyl donor in the reaction with necleophiles such as amine, thiol, alcohol as well as bifunctional necleophiles such as ethylene diamine derivative.
- Saito, Akio,Tojo, Manabu,Yanai, Hikaru,Wada, Fukiko,Nakagawa, Muga,Okada, Midori,Sato, Azusa,Okatani, Rieko,Taguchi, Takeo
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experimental part
p. 38 - 51
(2012/02/04)
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- Equilibrium shift in the rhodium-catalyzed acyl transfer reactions
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Rhodium/phosphine complexes catalyze equilibrium acyl transfer reactions between acid fluorides, aryl esters, acylphosphine sulfides, and thioesters. The use of appropriate co-substrates to accept heteroatom groups shifted the equilibrium to desired products. Acylphosphine sulfides and aryl esters were converted to acid fluorides using benzoylpentafluorobenzene as the fluoride donor, and the fluorination reaction of thioesters employed (4-tolylthio) pentafluorobenzene. Acid fluorides were converted into acylphosphine sulfides and thioesters using diphosphine disulfides and disulfides/triphenylphosphine, respectively. Aryl esters were obtained from acid fluorides and phenols in the presence of triphenylsilane. Aryl esters, acylphosphine sulfides, and thioesters were also interconverted in the presence of rhodium complexes. These rhodium-catalyzed acyl transfer reactions proceeded under neutral conditions without using acid or base. The involvement of acyl rhodium intermediates in these reactions was suggested by the carbothiolation reaction of thioesters and alkynes.
- Arisawa, Mieko,Igarashi, Yui,Kobayashi, Haruki,Yamada, Toru,Bando, Kentaro,Ichikawa, Takuya,Yamaguchi, Masahiko
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supporting information; experimental part
p. 7846 - 7859
(2011/10/12)
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- Sequential C-F activation and borylation of fluoropyridines via intermediate Rh(i) fluoropyridyl complexes: A multinuclear NMR investigation
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The C-F bond activation of fluoropyridines by [Rh(SiPh3) (PMe3)3] afforded Rh(i) fluoropyridyl complexes of the type [Rh(ArF)(PMe3)3] with concomitant formation of fluorotriphenylsilane; subsequent treatment with bis-catecholatodiboron yielded fac-[Rh(Bcat)3(PMe3) 3] and the free fluoropyridyl boronate esters (ArFBcat). The Royal Society of Chemistry.
- Lindup, Richard J.,Marder, Todd B.,Perutz, Robin N.,Whitwood, Adrian C.
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p. 3664 - 3666
(2008/03/14)
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- Nucleophilic fluorination of alkoxysilane with alkali metal salts of perfluorinated complex anions. Part 2
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Alkali metal salts of perfluorinated complex anions have been used to effect nucleophilic fluorination of alkyl-, arylalkyl- and arylalkoxy-silanes both in the presence and absence of solvent. Near-quantitative yields of fluorinated silanes are obtained using equimolar quantities of fluoride ion equivalents and alkoxysilanes. In certain cases, intermediate organoboron and organophosphorus compounds derived from the corresponding complex anions and alkoxysilanes are identified in the reaction mixtures, and based on these intermediates a mechanism of reaction has been proposed.
- Farooq, Omar
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p. 661 - 665
(2007/10/03)
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- Rate increases in the fluorination of bulky chlorosilanes caused by ultrasound or by water
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The conversion of bulky chlorosilanes to fluorosilanes under anhydrous conditions with hexafluorosilicate salts is accelerated by ultrasound. The fluorination of sterically hindered chlorosilanes such as tBuPh2SiCl, in the absence of ultrasound, is greatly accelerated by the addition of water to the reaction mixture.
- Lickiss, Paul D.,Lucas, Ronan
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p. 167 - 172
(2007/10/03)
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- Alkali Metal Salts of Perfluorinated Complex Anions. Effective Reagents for Nucleophilic Fluorination
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Alkali metal salts of perfluorinated complex anions were used to effect halogen-exchange fluorination in organohalosilanes both in the presence and absence of solvent.By the use of salts of perfluorinated "non-nucleophilic" anions in a high-boiling multifunctional etheral solvent, organofluorosilanes have been conveniently prepared in high yields.
- Farooq, Omar,Tiers, George V. D.
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p. 2122 - 2124
(2007/10/02)
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- The effect of heteroatoms on the reactions of organic molecules with caesium fluoroxysulphate
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CsSO4F reacted at room temperature, or at 35°C in acetonitrile with various heteroatom-containing organic molecules, and three types of transformations have been observed. Fluoro substitution process took place with triphenylmethane, triphenylsilane, triphenylchlorosilane, 4-tert-butylphenol, benzaldehyde, and octanol, thus forming fluorotriphenylmethane, fluorotriphenylsilane, 2-fluoro-4-tert-butylphenol, benzoyl fluoride, or octanoyl fluoride in high yields. Substitution reaction was accompanied by fluoroaddition process in the case of 2-fluoro-4-tert-butylphenol, where 2,2-difluoro-4-tert-butylcyclohexadienon-4,6- was isolated. CsSO4F easily oxidised secondary alcohols to ketones, and 1,2-dihydro-4-tert-butylbenzene to quinone derivate. Oxygenation process was observed in the case of triphenylphosphine, and dibenzothiophene, while ethyl iodide was transformed to ethyliodo(III) difluoride. Solvent plays an important role in these reactions, being successfully performed in CH3CN, and completely inhibited in CH2Cl2, while different shapes of the effect on fluorination of various organic molecules were observed by altering solvent nature by successive mixing of CH3CN with CH2Cl2.
- Stavber,Zupan
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p. 5875 - 5882
(2007/10/02)
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- Electrochemical Halogenation of Trisubstituted Germanes and Silanes
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Electrochemical halogenation of trisubstituted germanes and silanes in acetonitrile occured in the cathode compartment in contrast to the well-known electrochemical halogenations which always occur in the anode compartment.
- Okano, Mitsutoshi,Mochida, Kunio
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p. 1381 - 1382
(2007/10/02)
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- The interaction of fluoride ion with organosilicons: facile isomerizations and new reactions of silicon hydrides
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Cesium fluoride isomerization of several derivatives of 3-silabicyclooctane and 2-silabicycloheptane as well as chiral α-NpPhMeSiH are described.The effect of solvent, 18-crown-6 ether, and other salts is discussed.Associated side reactions prompted study of the conversion of Ph3SiH to Ph3SiF by CsF and the identification of the products formed from the reaction of Ph3SiH with DMF, N-methylformanilide, and benzamide in the presence of metal fluorides.
- Blankenship, Craig,Cremer, Sheldon E.
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- USE OF SbF5 INTERCALATED IN GRAPHITE AS FLUORINATING REAGENT IN ORGANO-SILICON AND -GERMANIUM CHEMISTRY
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The use of SbF5 intercalated in graphite as fluorinating reagent of organo-silicon and -germanium derivatives is described.While Si-O and Si-Cl bonds are readily cleaved, Si-H and Si-S bonds are only reactive in bifunctional silanes.Ge-X bonds (X=Br, Cl, OR, H) are unreactive.Allyl-silicon and allyl-germanium bonds are broken under mild conditions and in high yields, leading to the corresponding fluorosilane or fluorogermane.With bifunctional silanes, it is always possible to obtain the difluorinated derivatives.
- Corriu, R.J.P.,Fernandez, J.M.,Guerin, C.
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p. 347 - 352
(2007/10/02)
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