- Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
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In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
- Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
-
supporting information
p. 15396 - 15405
(2021/10/12)
-
- Cleavage of C(sp3)-F Bonds in Trifluoromethylarenes Using a Bis(NHC)nickel(0) Complex
-
The first example of the oxidative addition of a C(sp3)-F bond in trifluoromethylarenes to a nickel(0) complex is described. A nickel(0) complex that bears two N-heterocyclic carbene (NHC) ligands of low steric demand is able to cleave C(sp3)-F bonds of trifluoromethylarenes to afford the corresponding trans-difluorobenzyl nickel(II) fluoride complexes. Isolation and characterization studies suggested that the cleavage of the C(sp3)-F bond proceeds via an η2-arene nickel(0) complex. Taking advantage of the reactivity of these nickel(II) fluoride complexes, we developed a catalytic hydrodefluorination of trifluoromethylarenes using hydrosilanes. A computational study indicated that the electron-rich nickel(0) center supported by two relatively small NHC ligands cleaves the C(sp3)-F bond via a syn-SN2′ mechanism.
- Imiya, Hiroto,Iwamoto, Hiroaki,Ogoshi, Sensuke,Ohashi, Masato
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p. 19360 - 19367
(2020/11/13)
-
- Ligand-free trifluoromethylation of iodoarenes by use of 2-Aryl-2-trifluoromethylbenzimidazoline as new trifluoromethylating reagent
-
N-Methyl 2-aryl-2-trifluoromethylbenzimidazolines were synthesized and utilized in the trifluoromethylation reaction of iodoarenes in the presence of copper(I) salt and base. Iodoarenes bearing electron-donating and electron-withdrawing groups were tolerant to this reaction in the absence of a ligand and gave trifluorotoluene derivatives in good to high yields.
- Miyagawa, Masamichi,Ishikawa, Taisuke,Shinkai, Kota,Akiyama, Takahiko
-
supporting information
p. 29 - 31
(2019/01/04)
-
- Cathodic C-H Trifluoromethylation of Arenes and Heteroarenes Enabled by an in Situ-Generated Triflyltriethylammonium Complex
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While several trifluoromethylation reactions involving the electrochemical generation of CF3 radicals via anodic oxidation have been reported, the alternative cathodic, reductive radical generation has remained elusive. Herein, the first cathodic trifluoromethylation of arenes and heteroarenes is reported. The method is based on the electrochemical reduction of an unstable triflyltriethylammonium complex generated in situ from inexpensive triflyl chloride and triethylamine, which produces CF3 radicals that are trapped by the arenes on the cathode surface.
- Cantillo, David,Jud, Wolfgang,Kappe, C. Oliver,Maljuric, Snjezana
-
supporting information
(2019/10/08)
-
- Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents
-
The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [11C]-labeled PET tracer celecoxib.
- Heijnen, Dorus,Tosi, Filippo,Vila, Carlos,Stuart, Marc C. A.,Elsinga, Philip H.,Szymanski, Wiktor,Feringa, Ben L.
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supporting information
p. 3354 - 3359
(2017/03/17)
-
- Copper-Promoted Conversion of Aromatic Amines into Trifluoromethylated Arenes: One-Pot Sandmeyer Trifluoromethylation
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A simple copper-promoted one-pot Sandmeyer trifluoromethylation of aromatic amines with Langlois’ reagent has been demonstrated. The reaction is performed in mild reaction conditions under an air atmosphere with good substrate scope and functional group compatibility. It provides an alternative and straightforward synthetic approach to access a variety of trifluoromethylated arenes.
- Hong, Jianquan,Wang, Guifu,Huo, Lianguang,Zheng, Changge
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supporting information
p. 1761 - 1767
(2017/09/06)
-
- The first nucleophilic C-H perfluoroalkylation of aromatic compounds via (arene)tricarbonylchromium complexes
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The first nucleophilic perfluoroalkylation of arenes is based on the arene π-system activation via (η6-arene)tricarbonylchromium complexes. Perfluoroalkyl anions generated from Me3SiRF and a fluoride ion source [Me4N]F exclusively attack the arene ligand under mild conditions. The formed negatively charged analogs of Meisenheimer adducts readily undergo a one-pot oxidation to perfluoroalkyl arenes.
- Kirij, Natalia V.,Filatov, Andrey A.,Khrapach, Gleb Yu.,Yagupolskii, Yurii L.
-
supporting information
p. 2146 - 2149
(2017/02/19)
-
- Phosphovanadomolybdic acid catalyzed direct C-H trifluoromethylation of (hetero)arenes using NaSO2CF3 as the CF3 source and O2 as the terminal oxidant
-
A direct C-H trifluoromethylation of (hetero)arenes using NaSO2CF3 (Langlois' reagent) as the CF3 source and O2 as the terminal oxidant has been developed. In the presence of catalytic amounts of phosphovanadomolybdic acids, such as H6PV3Mo9O40, various kinds of substituted benzenes and heteroaromatic compounds could be converted into the corresponding trifluoromethylated products.
- Li, Chifeng,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
-
supporting information
p. 1417 - 1420
(2017/02/23)
-
- DBU-Promoted Trifluoromethylation of Aryl Iodides with Difluoromethyltriphenylphosphonium Bromide
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DBU-promoted trifluoromethylation of aryl iodides with difluoromethyltriphenylphosphonium bromide (DFPB) in the presence of copper source is described. In this transformation, DBU not only acts as base to deprotonate the difluoromethyl group in DFPB to generate difluoromethylene phosphonium ylide Ph3P+CF2-, but also converts the difluorocarbene generated from ylide Ph3P+CF2- into trifluoromethyl anion, finally resulting in the trifluoromethylation of aryl iodides. The reactions proceeded smoothly to afford expected products in moderate to good yields.
- Wei, Yun,Yu, Liuying,Lin, Jinhong,Zheng, Xing,Xiao, Jichang
-
p. 481 - 484
(2016/06/01)
-
- Trifluoromethylation of haloarenes with a new trifluoro-methylating reagent Cu(O2CCF2SO2F)2
-
A new trifluoromethylating reagent Cu(O2CCF2SO2F)2, which easily decomposes to generate active CuCF3 species in DMF at room temperature, has been conveniently prepared from inexpensive starting materials on a large scale. This new reagent can be applied to efficiently trifluoromethylate a variety of haloarenes under mild conditions, providing good-to-excellent yields of the desired products.
- Zhao, Gang,Wu, Hao,Xiao, Zhiwei,Chen, Qing-Yun,Liu, Chao
-
p. 50250 - 50254
(2016/06/15)
-
- Introducing a new radical trifluoromethylation reagent
-
Perfluoro-3-ethyl-2,4-dimethyl-3-pentyl radical (PPFR) is a persistent radical stable at room temperature, but easily decomposes at 90 °C to produce a CF3 radical which is able to react with a variety of aromatic compounds to afford the corresponding trifluoromethyl derivatives, usually as mixtures of regioisomers in good to excellent overall yields.
- Sato, Azusa,Han, Jianlin,Ono, Taizo,Wzorek, Alicja,Ace?a, José Luis,Soloshonok, Vadim A.
-
supporting information
p. 5967 - 5970
(2015/03/30)
-
- One-pot sandmeyer trifluoromethylation and trifluoromethylthiolation
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Practical one-pot procedures were developed for both Sandmeyer-type trifluoromethylations and trifluoromethylthiolations. Starting from broadly available (hetero)aromatic amines, various benzotrifluorides were synthesized in high yields via in situ diazotization and copper-mediated trifluoromethylation using the inexpensive Ruppert-Prakash trifluoromethylating reagent. In the presence of sodium thiocyanate as a sulfur source, aryl trifluoromethyl thioethers are exclusively formed.
- Bayarmagnai, Bilguun,Matheis, Christian,Risto, Eugen,Goossen, Lukas J.
-
supporting information
p. 2343 - 2348
(2014/07/21)
-
- Copper-mediated trifluoromethylation of aryl-, heteroaryl-, and vinyltrifluoroborates with Langlois' reagent
-
An effortless and realistic procedure for the copper-mediated trifluoromethylation of aryl-, heteroaryl- and vinyltrifluoroborates with CF3 radicals generated from NaSO2CF3 and tert-butyl hydroperoxide (TBHP) is presented. The developed method produces trifluoromethyl arenes and -alkenes in good to excellent yields and a wide range of electronically and structurally diverse substrates are tolerated.
- Dubbaka, Srinivas Reddy,Salla, Manohar,Bolisetti, Raghu,Nizalapur, Shashidhar
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p. 6496 - 6499
(2014/02/14)
-
- Mechanism of trifluoromethylation of aryl halides with CuCF3and the ortho effect
-
A combined experimental (radical clock, kinetic, Hammett) and computational (DFT, MM) study of the trifluoromethylation reaction of aryl halides with CuCF3 reveals a nonradical mechanism involving Ar-X oxidative addition to the Cu(I) center as the rate determining step. The reaction is second order, first order in each reactant with ΔG? ≈ 24 kcal/mol for PhI (computed ΔG? = 21.9 kcal/ mol). An abrupt change in the gradient on the Hammett plot of log(kR/ kH) versus σp for 11 p-RC6H4I substrates produces two correlations (ρ = +0.69 and +1.83), which is temptingly suggestive of two different reaction pathways. Only one mechanism is operational, however, as advocated by a single linear correlation with σp- (ρ = +0.91), analysis of the experimental ρ values, close similarity of the transition states varying in R and displaying clear signs of -M interactions, and excellent reproduction of the plot by DFT. The long-known yet previously uncomprehended ortho effect has been quantified, for the first time, using the reaction of CuCF3 with a series of o-RC6H4Br: R(kR/kH) = H (1) 2Me (850) 2 (4300) 2H (150 000). With minor contributions from electronic factors, the ortho effect is largely determined by (i) the stabilizing coordination of the o-substituent to Cu in the transition state with the Cu?O distance varying directly with the barrier and (ii) the steric bulk of the o-substituent that raises the ground state free energy of the haloarene (Go ortho - Go H or Go ortho - Go para) by inflicting molecular strain and consequently weakening the Ar-X bond.
- Konovalov, Andrey I.,Lishchynskyi, Anton,Grushin, Vladimir V.
-
supporting information
p. 13410 - 13425
(2015/03/30)
-
- Trifluoromethylation of aryl and heteroaryl halides with fluoroform-derived CuCF3: Scope, limitations, and mechanistic features
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Fluoroform-derived CuCF3 recently discovered in our group exhibits remarkably high reactivity toward aryl and heteroaryl halides, performing best in the absence of extra ligands. A broad variety of iodoarenes undergo smooth trifluoromethylation with the ligandless CuCF3 at 23-50 C to give the corresponding benzotrifluorides in nearly quantitative yield. A number of much less reactive aromatic bromides also have been trifluoromethylated, including pyridine, pyrimidine, pyrazine, and thiazole derivatives as well as aryl bromides bearing electron-withdrawing groups and/or ortho substituents. Only the most electrophilic chloroarenes can be trifluoromethylated, e.g., 2-chloronicotinic acid. Exceptionally high chemoselectivity of the reactions (no side-formation of arenes, biaryls, and C2F5 derivatives) has allowed for the isolation of a large number of trifluoromethylated products in high yield on a gram scale (up to 20 mmol). The CuCF3 reagent is destabilized by CuX coproduced in the reaction, the magnitude of the effect paralleling the Lewis acidity of CuX: CuCl > CuBr > CuI. While SNAr and SRN1 mechanisms are not operational, there is a well-pronounced ortho effect, i.e., the enhanced reactivity of ortho-substituted aryl halides 2-RC6H4X toward CuCF3. Intriguingly, this ortho-effect is observed for R = NO2, COOH, CHO, COOEt, COCH3, OCH3, and even CH3, but not for R = CN. The fluoroform-derived CuCF3 reagent and its reactions with haloarenes provide an unmatched combination of reactivity, selectivity, and low cost.
- Lishchynskyi, Anton,Novikov, Maxim A.,Martin, Eddy,Escudero-Adan, Eduardo C.,Novak, Petr,Grushin, Vladimir V.
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p. 11126 - 11146
(2013/12/04)
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- Sandmeyer trifluoromethylation of arenediazonium tetrafluoroborates
-
Copper capabilities: Diazonium salts are converted into the corresponding trifluoromethyl derivatives in the presence of a trifluoromethyl-copper complex generated in situ from CuSCN and the inexpensive, easy-to-use trifluoromethylating reagent Me3Si-CF3 (see scheme). This Sandmeyer-type reaction allows the straightforward synthesis of trifluoromethylated arenes and heteroarenes from the corresponding amines. Copyright
- Danoun, Grégory,Bayarmagnai, Bilguun,Grünberg, Matthias F.,Goo?en, Lukas J.
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p. 7972 - 7975
(2013/08/23)
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- Fluoroform-derived CuCF3 for low-cost, simple, efficient, and safe trifluoromethylation of aryl boronic acids in air
-
Easy does it: Aryl boronic acids undergo smooth and selective trifluoromethylation with low-cost fluoroform-derived CuCF3 in DMF in non-dried air. The reaction occurs under mild conditions (1 atm, room temperature), exhibits unprecedented funct
- Novak, Petr,Lishchynskyi, Anton,Grushin, Vladimir V.
-
supporting information; experimental part
p. 7767 - 7770
(2012/08/29)
-
- Silver-mediated trifluoromethylation of arenes using TMSCF3
-
The silver-mediated C-H trifluoromethylation of aromatic substrates using TMSCF3 is described. The development, optimization, and scope of these transformations are reported. AgCF3 intermediates are proposed.
- Ye, Yingda,Lee, Shin Hee,Sanford, Melanie S.
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supporting information; experimental part
p. 5464 - 5467
(2011/12/05)
-
- Mechanistic and computational studies of oxidatively-induced Aryl-CF 3 bond-formation at Pd: Rational design of room temperature aryl trifluoromethylation
-
This article describes the rational design of first generation systems for oxidatively induced Aryl-CF3 bond-forming reductive elimination from PdII. Treatment of (dtbpy)PdII(Aryl)(CF3) (dtbpy = di-tert-butylbipyridine) with NFTPT (N-fluoro-1,3,5-trimethylpyridinium triflate) afforded the isolable PdIV intermediate (dtbpy)Pd IV(Aryl)(CF3)(F)(OTf). Thermolysis of this complex at 80 °C resulted in Aryl-CF3 bond-formation. Detailed experimental and computational mechanistic studies have been conducted to gain insights into the key reductive elimination step. Reductive elimination from this PdIV species proceeds via pre-equilibrium dissociation of TfO- followed by Aryl-CF3 coupling. DFT calculations reveal that the transition state for Aryl-CF3 bond formation involves the CF3 acting as an electrophile with the Aryl ligand serving as a nucleophilic coupling partner. These mechanistic considerations along with DFT calculations have facilitated the design of a second generation system utilizing the tmeda (N,N,N′,N′-tetramethylethylenediamine) ligand in place of dtbpy. The tmeda complexes undergo oxidative trifluoromethylation at room temperature.
- Ball, Nicholas D.,Gary, J. Brannon,Ye, Yingda,Sanford, Melanie S.
-
supporting information; experimental part
p. 7577 - 7584
(2011/06/25)
-
- Copper-catalyzed trifluoromethylation of aryl iodides with potassium (trifluoromethyl)trimethoxyborate
-
Potassium (trifluoromethyl)trimethoxyborate is introduced as a new source of CF3 nucleophiles in copper-catalyzed trifluoromethylation reactions. The crystalline salt is stable on storage, easy to handle, and can be obtained in near-quantitative yields simply by mixing B(OMe)3, CF3SiMe3, and KF. The trifluoromethylation reagent allows the conversion of various aryl iodides into the corresponding benzotrifluorides in high yields under mild, base-free conditions in the presence of catalytic quantities of a CuI/1,10-phenanthroline complex.
- Knauber, Thomas,Arikan, Fatih,Roeschenthaler, Gerd-Volker,Goossen, Lukas J.
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experimental part
p. 2689 - 2697
(2011/04/15)
-
- Efficient access to 3-alkyl-trifluoromethylbenzenes using Kumada's coupling reaction
-
3-Alkyl-trifluoromethylbenzenes are obtained in good yields by Kumada's coupling reaction between methyl or ethyl magnesium halide and 3-bromo-trifluoromethylbenzene derivatives in the presence of Ni-Xantphos catalyst.
- Roques, Nicolas,Saint-Jalmes, Laurent
-
p. 3375 - 3378
(2007/10/03)
-
- Use of methyllithium in metal/halogen exchange; a mild and efficient method for the synthesis of ortho substituted toluenes
-
Methyllithium, in the presence of excess methyl iodide, can be used to convert suitably substituted aromatic bromides to the corresponding toluenes under mild conditions and in high yield.
- Andrews,Kitteringham,Voyle
-
p. 2323 - 2327
(2007/10/03)
-
- Process for the dechlorination and/or debromination of fluorine-and chlorine- and/or bromine-containing aromatic compounds
-
Fluorine- and chlorine- and/or bromine-containing aromatic compounds are dechlorinated and/or debrominated with hydrogen in an industrially advantageous and selective manner, if the palladium catalyst is present in stationary phase and the aromatic compound in gas phase.
- -
-
-
- Photocleavage of Benzyl-Sulfide Bonds
-
The nucleoside transport inhibitor 6--9-(β-D-ribofuranosyl)purine, NBMPR, has been used successfully in photoaffinity labeling.We have studied the mechanism for photocleavage of the benzyl-sulfur bond by using substituted benzyl phenyl sulfides as analogues of NBMPR.This has enabled us to enhance the photoreactivity of the benzyl-sulfur bond.We have also performed "radical clock" studies with a hexenyl side chain to trap reactive intermediates.The mechanistic interpretation from the substituent and side chain studies is that the benzyl-sulfur moiety is photocleaved via a homolytic pathway.
- Fleming, Steven A.,Jensen, Anton W.
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p. 7135 - 7137
(2007/10/02)
-
- Catalyst and process for the preparation of trifluoromethyltoluenes
-
A partially deactivated reduction catalyst is prepared by reacting palladium on alumina catalyst with benzotrifluoride in an amount of 0.1 to 10.0 millimoles of benzotrifluoride per gram of alumina and hydrogen in an amount ranging from 10 to 2000 moles of hydrogen per mole of benzotrifluoride at a temperature of 200° C. to 300° C. for 30 minutes to 2 hours. The catalyst is useful for the reduction of trifluoromethylbenzonitriles and trifluoromethylbenzylamines to produce the corresponding trifluoromethyltoluenes in high yields. The catalyst is also useful in other hydrogen reduction reactions, e.g., for conversion of o-chlorobenzonitrile, o-chlorobenzylamine and mandelonitrile to toluene and for conversion of phenethylamine to ethylbenzene.
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-
-
- A NOVEL AND CONVENIENT METHOD FOR TRIFLUOROMETHYLATION OF ORGANIC HALIDES USING CF3SiR'3/KF/Cu(I) SYSTEM
-
Fluoride ion induced cross-coupling reaction of organic halides with trifluoromethyltrialkylsilanes takes place in the presence of Cu(I) salts under mild reaction conditions to give the corresponding trifluoromethylated products in high yields.
- Urata, Hisao,Fuchikami, Takamasa
-
-
- Generation of trifluoromethylcopper from chlorodifluoroacetate
-
In the presence of fluoride ion, methyl chlorodifluoroacetate undergoes halide ion-promoted decarboxylation to give trifluoromethide which can be trapped with cuprous iodide.The resulting trifluoromethyl copper reagent has been observed spectroscopically and can be trapped with aryl iodides to give the corresponding trifluoromethylaromatic compound.
- MacNeil, James G.,Burton, Donald J.
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p. 225 - 228
(2007/10/02)
-
- TRIFLUORMETHYLIERUNGSREAKTIONEN VON Te(CF3)2 MIT HALOGENBENZOLEN UND METHYLBENZOLEN
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Substituent effects on yields and regioselectivity of photochemical and thermal trifluoromethylation reactions of Te(CF3)2 with halogen benzenes and methyl benzenes are investigated under comparable conditions.All reactions lead to trifluoromethylated products.The yields of the thermal are always higher than those of the corresponding photochemical reactions.The reactivity of the halobenzenes increases in the series C6H5-F a sidereaction, but H-substitution is the primary reaction pathway.During the reactions with iodobenzene tellurium containing compounds are also formed.The reactions with methyl benzenes show an increase in reactivity in the series hexamethylbenzene mesitylene toluene p-xylene.In all cases only ring substituted products are detected.Reactions with toluene and p-xylene yield tellurium containing compounds as well as addition products.The 19F-n.m.r spectra of the products are given.
- Naumann, Dieter,Kischkewitz, Jurgen
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p. 283 - 299
(2007/10/02)
-
- Reactions of Trifluoromethyl Bromide and Related Halides: Part 10. Perfluoroalkylation of Aromatic Compounds induced by Sulphur Dioxide Radical Anion Precursors
-
Perfluoroalkylation of electron-rich aromatic compounds with trifluoromethyl bromide, or long-chain perfluoroalkyl iodides, was performed in the presence of sodium dithionite or zinc-sulphur dioxide.This alkylation occurred at the ortho and para positions relative to the amino or hydroxy substitutent.Pyrroles were perfluoroalkylated regioselectively at the 2-position.This alkylation was interpreted as a radical aromatic substitution; the formation of the perfluoroalkyl radical can be induced by a single-electron transfer from sulphur dioxide radical anion to the perfluoroalkyl halide.
- Tordeux, Marc,Langlois, Bernard,Wakselman, Claude
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p. 2293 - 2299
(2007/10/02)
-
- Reactions of Perfluoroalkanesulfonyl Chlorides with Aromatic Compounds Catalyzed by a Ruthenium(II) Complex
-
The reactions of perfluoroalkanesulfonyl chlorides with aromatic compounds in the presence of a catalytic amount of dichlorotris(triphenylphosphine)ruthenium(II) were found to give perfluoroalkylated compounds in good yield.
- Kamigata, Nobumasa,Fukushima, Takamasa,Yoshida, Masato
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p. 649 - 650
(2007/10/02)
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- Sodium Perfluoroalkane Carboxylates as Sources of Perfluoroalkyl Groups
-
Sodium trifluoroacetate, in the presence of copper(I) iodide, is used as a source of trifluoromethyl to replace halogen by trifluoromethyl in benzenoid and heterocyclic aromatic systems, as well as in alkenyl and alkyl halogen compounds.The mechanism of this interesting copper-assisted process has been explored and an intermediate of the form - is proposed.Introduction of higher perfluoroalkyl groups from their respective sodium perfluoroalkane carboxylates has been demonstrated and the machanistic features are compared with those of the trifluoromethylation process.
- Carr, Gillian E.,Chambers, Richard D.,Holmes, Thomas F.,Parker, David G.
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p. 921 - 926
(2007/10/02)
-
- Le composes d'insertion du graphite comme precurseurs de metaux finement divises I. Couplage d'halogenures benzyliques
-
The reduction of a nickel salt by the intercalation compound KC8, results in highly dispersed nickel on graphite, which has been used as a coupling reagent for benzyl chloride.The yield and the selectivity of the reaction were slightly improved when nickel-copper bimetallic clusters were used.The properties of these mixtures are illustrated by the coupling of various substituted benzyl halides.Functional groups such as methoxy-, chloro-, bromo-, nitro-, cyano-, trifluoromethyl- and alkoxy-carbonyl groups, on the aromatic ring, were not affected by the conditions employed.
- Marceau, P.,Beguin, F.,Guillaumet, G.
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p. 137 - 142
(2007/10/02)
-
- Process for the preparation of compounds containing a difluoromethylene or trifluoromethyl group
-
A process for the preparation of compounds containing a difluoromethylene or trifluoromethyl group. A compound containing a carbonyl group, preferbly an acid, acid halide, amide, ketone or any compound containing a perhaloalkylcarbonyl moiety is placed, in anhydrous liquid hydrofluoric acid, in contact with boron trifluoride in a quantity such that the absolute pressure of boron trifluoride in the reaction system is at least one bar for a time sufficient to convert the carbonyl group to a difluormethylene or trifluoromethyl group. The compounds obtained are useful as synthesis intermediates in the pharmaceutical, plant-protection and dye industries, as anesthetics or as heat-transfer and lubricating fluids.
- -
-
-
- Flash Thermolysis of Aryl Trifluoroacetates: A New Approach to Trifluoromethylated Aromatic Compounds
-
Flash thermolysis of aryl trifluoroacetates yield trifluoromethyl aromatic compounds along with trifluoromethoxy compounds.
- Kobayashi, Y.,Nakazato, A.,Kumadaki, I.,Filler, R.
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p. 467 - 470
(2007/10/02)
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- Highly Reactive Metallic Nickel: Reductive Homocoupling Reagent for Benzylic Mono- and Polyhalides
-
Metallic nickel, prepared by the reduction of nickel halides with lithium in glyme using naphthalene as an electron carrier, was found to be a useful reagent for the homocoupling of benzylic mono- and polyhalides.Benzyl halides reacted with metallic nickel at room temperature to give the corresponding 1,2-diarylethanes in good to high yields and functional groups on the aromatic ring such as methoxy, chloro, bromo, nitro, cyano, and alkoxycarbonyl groups were not affected under the conditions employed.Benzylic monohalides (1-(chloromethyl)- or 2-(bromomethyl)naphthalene, chlorodiphenylmethane, and 9-bromofluorene) also underwent coupling reactions with metallic nickel at room temperature to give the corresponding ethane derivatives.On the other hand, benzylic di- and trihalides such as α,α-dibromotoluene and α,α,α-trichlorotoluene yielded mixtures of cis and trans isomers of substituted ethenes.The intermediate of the reaction, benzylnickel complex, was trapped with electron deficient olefins such as methyl acrylate and acrylonitrile.
- Inaba, Shin-ichi,Matsumoto, Hideyuki,Rieke, Reuben D.
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p. 2093 - 2098
(2007/10/02)
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- A CONVENIENT TRIFLUOROMETHYLATION OF AROMATIC HALIDES WITH SODIUM TRIFLUOROACETATE
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Regiospecific trifluoromethylation by substitution of the halogen in aromatic halides was achieved by the use of sodium trifluoroacetate and copper(I) iodide.The reaction proceeded smoothly in dipolar aprotic solvents in good to high yields.
- Matsui, Kiyohide,Tobita, Etsuko,Ando, Midori,Kondo, Kiyosi
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p. 1719 - 1720
(2007/10/02)
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- A New Method for the Trifluoromethylation of Aromatics
-
A new method is described for introducing a CF3-group, by a single-step synthesis, into aromatic compounds.This trifluoromethylation is done by means of a mixture consisting of HF/CCl4 and the aromatic compounds.The reaction is thought to be of a Friedel-Crafts type and limited to aromatics which are not substituted by electron withdrawing groups.
- Marhold, A.,Klauke, E.
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p. 281 - 292
(2007/10/02)
-