- Reaction of Acetyl Hypofluorite with Aromatic Mercury Compounds: a New Selective Fluorination Method
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Aromatic fluorine compounds are prepared in acetic acid from the corresponding mercury compounds and acetyl hypofluorite.
- Visser, Gerard W. M.,Halteren, Bert W. v.,Herscheid, Jacobus D. M.,Brinkman, Gerard A.,Hoekstra, Arend
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- The regioselectivity in the fluorination of dibenzofuran, diphenylether and biphenyl with N-F type of reagents
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Dibenzofuran, diphenylether and biphenyl were used as target molecules in an investigation of the effect of N-F type of reagent structure and reaction conditions on the fluorination process. The yields of fluorinated products formed and the regioselectivity depend on the reagent used, and in the reactions with dibenzofuran three products were formed. The ratios of 2-fluorodibenzofuran (4) and 3-fluorodibenzofuran (5) formed were: 1.3 for 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (NFTh, 1b), 1.4 for 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (F-TEDA, 1a), and 1.8 for N-fluoro-2,6-dichloropyridinium tetrafluoroborate (FPD-B, 1c). Ortho regioselectivity predominated for all reagents in the fluorination of biphenyl (ortho: para ratio varied from 4.8 to 1.2), while para attack prevailed for diphenylether (ortho: para = 0.9-0.7); however substitution of a phenyl ring by a methyl group enhanced the amount of 2-fluoroanisole. Second order rate constants for the fluorination of aromatic molecules with F-TEDA in acetonitrile at 65°C were established: anisole 4.8 x 10-3 Lmol-1s-1, dibenzofuran 2.5 x 10-4 Lmol-1s-1 an biphenyl 1.0 x 10-4 Lmol-1s-1.
- Zupan, Marko,Iskra, Jernej,Stavber, Stojan
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- N,N′-Difluoro-1,4-diazoniabicyclo[2.2.2]octane Salts, Highly Reactive and Easy-to-Handle Electrophilic Fluorinating Agents
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A series of N,N′-difluoro-1,4-diazoniabicyclo[2.2.2]octane salts were synthesized in a pure form by the fluorination of 1,4-diazabicyclo[2.2.2]octane with F2 diluted with N2 in the presence of a Bronsted acid in fluoro alcohol or acetonitrile or by fluorination followed by a treatment with a different Bronsted or Lewis acid. Their complete structural assignment was made based on spectral and elemental analyses of the isolated crystals. A great through-bond interaction between the two N-F's of the salt was observed on 19FNMR. An assessment was made of the usefulness of N,N′-difluoro-1,4-diazoniabicyclo[2.2.2]octane bis(triflate), bis(HSO2), bis(BF4), and bis(SbF6) salts for electrophilic fluorination; the bis-(BF4) salt was demonstrated to be widely applicable as a highly reactive and easy-to-handle fluorinating agent. Thus, the bis(BF4) salt readily fluorinated activated aromatics, active methylene compounds or their salts, substituted styrenes, and vinyl acetates under mild conditions. It was shown that one N-F of the salt was effective for fluorination and that the other N-F played a role to activate fluorination through the bonds. Thus, the reaction mechanism was discussed, and fluorination followed by an immediate intramolecular one-electron transfer was suggested.
- Umemoto, Teruo,Nagayoshi, Masayuki
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- Radical Carbofluorination of Alkenes with Arylhydrazines and Selectfluor: Additives, Mechanistic Pathways, and Polar Effects
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Radical carbofluorination reactions starting from arylhydrazines and nonactivated alkenes, in which the C?F bond is formed through the use of Selectfluor, can be improved through the addition of anisole. Because direct trapping products could be detected only in trace amounts, anisole does primarily act as a reversible scavenger for the highly reactive ammonium radical dication released from Selectfluor in the C?F bond-forming step. As shown for three diverse substitution patterns, the main role of anisole is to prevent, or at least reduce, the undesired addition of the ammonium radical dication to the alkene, which in turn leads to an unfavorable consumption of the arylhydrazine-derived precursors required for carbofluorination. Moreover, besides the remarkable polar effects in radical trapping, this study shows that the Selectfluor-derived nitrogen-centered radical dication may add directly to alkenes, which has not been described so far.
- Pirzer, Anna S.,Alvarez, Eva-Maria,Friedrich, Heike,Heinrich, Markus R.
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- Electrophilic fluorination of aromatics with selectfluor and trifluoromethanesulfonic acid 1
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1-(chloromethyl)-4-fluoro-1,4-diazabicyclo[2.2.2]octane bis (tetrafluoroborate) [Selectfluor F-TEDA-BF4 (TEDA = triethylenediamine)] in the presence of trifluoromethanesulfonic acid has been found to be a very effective reagent system for the direct electrophilic fluorination of a wide variety of aromatic compounds under mild reaction conditions to the corresponding fluoroaromatics in good to excellent yields.
- Shamma, Tatyana,Buchholz, Herwig,Prakash, G. K. Surya,Olah, George A.
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- DIRECT FLUORINATION OF PHENOL AND CRESOLS
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A study has been made of the reaction of phenol with elemental fluorine using a variety of solvents and reaction temperatures.Yields of o- and p-fluorophenol were obtained as high as 85percent.The isomer ratio changed drastically between phenol conversions of 10percent and 56percent.The o-isomer changed to unidentified polymeric substances at higher conversion, but it might also be assumed that interconversion of some isomers is occuring.The three cresols have also been succesfully fluorinated with elemental fluorine. p-Cresol gave some expected 2-fluoroderivative but also formed a fluorocyclohexadienyl ketone.
- Misaki, Susumu
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- Facile Preparation of Aromatic Fluorides by the Fluoro-Dediazoniation of Aromatic Diazonium Tetrafluoroborates Using HF-Pyridine Solution
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The fluoro-dediazoniation of ArN2BF4 using HF-pyridine solution has been successfully carried out either thermaly or photochemically to afford the corresponding ArF in good yields.Particularly, the photochemically induced reaction in HF-pyridine was a useful tool for the preparation of ArF having polar substituents such as halogens, OH, OMe, CF3, etc.
- Fukuhara, Tsuyoshi,Sekiguchi, Manabu,Yoneda, Norihiko
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- Photochemical (Hetero-)Arylation of Aryl Sulfonium Salts
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The construction of (hetero)biaryls, which are ubiquitous scaffolds among medical substances, functional materials, and agrochemicals, constitutes a key application of cross-coupling methods. However, these usually require multiple synthetic steps. Herein, we report a simple photoinduced and catalyst-free C-H/C-H (hetero)arylation cross-coupling through aryl thianthrenium salts, which are formed site-selectively by direct C-H functionalization. The key to this approach is the UV-light, which can disrupt the C-S bond to form thianthrene radical cations and aryl radicals.
- Zhao, Yue,Yu, Congjun,Liang, Wenjing,Patureau, Frederic W.
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supporting information
p. 6232 - 6236
(2021/08/23)
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- Transition metal free, late-stage, regiospecific, aromatic fluorination on a preparative scale using a KF/crypt-222 complex
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We herein report the development of a convenient, regioselective, aromatic fluorination method of hypervalent iodonium ylides for synthesising fluoro-arenes on a preparative scale. This transition metal free, nucleophilic methodology provides good yields for sterically hindered substrates, irrespective of activation. The methodology simplifies reference synthesis for PET imaging.
- Jakobsson, Jimmy Erik,Riss, Patrick Johannes
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p. 21288 - 21291
(2018/06/26)
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- List fluoro Radicamine compounds and their use and preparation method
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The invention discloses a mono-fluorinated Radicamine compound which has a structure as shown in a formula (1), and further provides a preparation method for the mono-fluorinated Radicamine compound with the structure as shown in the formula (1) and an application of the mono-fluorinated Radicamine compound or the mono-fluorinated Radicamine compound prepared with the method to preparation of drugs for preventing and/or treating diabetes, drugs for preventing and/or treating Gaucher's diseases, drugs for preventing and/or treating tumors or antiviral drugs. The mono-fluorinated Radicamine compound provided by the invention is good in glycosidase inhibition activity.
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Paragraph 0082-0084
(2017/12/02)
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- Fluorinated Radicamine A and B: Synthesis and Glycosidase Inhibition
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Fluorinated derivatives of radicamine A and radicamine B have been synthesized from D-arabinose-derived cyclic nitrone. Structure-activity relationship studies showed that glycosidase inhibition of these fluorinated derivatives was significantly influenced by the position of the fluorine atom. C-7 or C-11 fluorination of the aromatic ring decreased α-glucosidase inhibition of the derivatives, whereas C-8 or C-10 fluorination preserved glycosidase inhibitory activities. Fluorinated derivatives of radicamine A and B have been synthesized from D-arabinose-derived cyclic nitrone. Structure-activity relationship studies revealed that glycosidase inhibition of these fluorinated derivatives was significantly influenced by the position of the fluorine atom.
- Li, Yi-Xian,Iwaki, Ren,Kato, Atsushi,Jia, Yue-Mei,Fleet, George W. J.,Zhao, Xuan,Xiao, Min,Yu, Chu-Yi
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p. 1429 - 1438
(2016/03/16)
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- Synthesis and characterization of a novel N-F reagent derived from the ethano-Tr?ger's base: 1JFN coupling constants as a signature for the N-F bond
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Methylation of 2,8-dimethyl-6H,12H-5,11-ethanodibenzo[b,f][1,5]-diazocine (ethano-Tr?ger's base) with methyl iodide followed by ion metathesis and fluorination with N-fluoro-2,3,4,5,6-pentachloropyridinium triflate affords a new electrophilic N-F reagent, that is more reactive than Selectfluor. 2D 19F-15N HMQC experiments provide 1JNF coupling constants which are diagnostic for the N-F functional group.
- Pereira, Raul,Wolstenhulme, Jamie,Sandford, Graham,Claridge, Timothy D. W.,Gouverneur, Véronique,Cvengro?, Ján
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supporting information
p. 1606 - 1609
(2016/01/30)
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- Synthesis of aryl fluorides from potassium aryltrifluoroborates and selectfluor mediated by iron(III) chloride
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The synthesis of fluorinated arenes by the iron-mediated fluorination of potassium aryltrifluoroborates with Selectfluor and potassium fluoride is described. The fluorination reaction uses commercially available reagents and without requiring the addition
- Dubbaka, Srinivas Reddy,Gadde, Satyanarayana,Narreddula, Venkateswara Reddy
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p. 854 - 860
(2015/03/14)
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- PhenoFluorMix: Practical chemoselective deoxyfluorination of phenols
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A practical deoxyfluorination with novel deoxyfluorinating reagent PhenoFluorMix, a mixture of N,N'-1,3-bis(2,6-diisopropylphenyl)chloroimidazolium chloride and CsF, is presented. PhenoFluorMix overcomes the challenges associated with hydrolysis of PhenoFluor. PhenoFluorMix does not hydrolyze, is readily available on decagram scale, and is storable in air. In this paper, we demonstrate the practicality of the reagent and exhibit the deoxyfluorination of a variety of phenols and heterocycles.
- Fujimoto, Teppei,Ritter, Tobias
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supporting information
p. 544 - 547
(2015/03/05)
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- Silver-mediated fluorination of potassium aryltrifluoroborates with Selectfluor Dedicated to Professor Andrea Vasella on the occasion of his 71st birthday
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A simple and practical procedure for the silver-mediated fluorination of aryl- and heteroaryltrifluoroborates with electrophilic fluorine from Selectfluor and LiOH·H2O is presented. The reaction procedure is simple and easy to set up, the process produces fluorinated arenes and heteroarenes in good to excellent yields and a wide range of electronically and structurally diverse substrates are tolerated.
- Dubbaka, Srinivas Reddy,Narreddula, Venkateswara Reddy,Gadde, Satyanarayana,Mathew, Thresen
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p. 9676 - 9681
(2015/01/08)
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- Studying regioisomer formation in the pd-catalyzed fluorination of aryl triflates by deuterium labeling
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Isotopic labeling has been used to determine that a portion of the desired product in the Pd-catalyzed fluorination of electron-rich, non-ortho-substituted aryl triflates results from direct C-F cross-coupling. In some cases, formation of a Pd-aryne intermediate is responsible for producing undesired regioisomers. The generation of the Pd-aryne intermediate occurs primarily via ortho-deprotonation of a L·Pd(Ar)OTf (L = biaryl monophosphine) species by CsF and thus competes directly with the transmetalation step of the catalytic cycle. Deuterium labeling studies were conducted with a variety of aryl triflates.
- Milner, Phillip J.,Kinzel, Tom,Zhang, Yong,Buchwald, Stephen L.
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supporting information
p. 15757 - 15766
(2015/02/02)
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- FLUORINATION OF ARYL COMPOUNDS
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The invention provides compositions and methods of using the compositions in fluorinating aryl precursors containing a leaving group replaceable by a fluorine atom. The compositions include a metal ion source, a electrophilic fluorine source, a base, and a compound, which is an aryl precursor of the aryl fluoride, and which has a leaving group replaceable by the fluorine atom. Exemplary methods of the invention make use of such compositions and methods to prepare an aryl fluoride compound. In an exemplary embodiment, the electrophilic fluorine source is a source of 18F.
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Paragraph 00117
(2014/07/22)
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- Pd-catalyzed nucleophilic fluorination of aryl bromides
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On the basis of mechanism-driven reaction design, a Pd-catalyzed nucleophilic fluorination of aryl bromides and iodides has been developed. The method exhibits a broad substrate scope, especially with respect to nitrogen-containing heteroaryl bromides, and proceeds with minimal formation of the corresponding reduction products. A facilitated ligand modification process was shown to be critical to the success of the reaction.
- Lee, Hong Geun,Milner, Phillip J.,Buchwald, Stephen L.
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supporting information
p. 3792 - 3795
(2014/04/03)
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- Cu-catalyzed fluorination of diaryliodonium salts with KF
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A mild Cu-catalyzed nucleophilic fluorination of unsymmetrical diaryliodonium salts with KF is described. This protocol preferentially fluorinates the smaller aromatic ligand on iodine(III). The reaction exhibits a broad substrate scope and proceeds with high chemoselectivity and functional group tolerance. DFT calculations implicate a CuI/CuIII catalytic cycle.
- Ichiishi, Naoko,Canty, Allan J.,Yates, Brian F.,Sanford, Melanie S.
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supporting information
p. 5134 - 5137
(2013/10/22)
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- Mild copper-mediated fluorination of aryl stannanes and aryl trifluoroborates
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This communication describes a mild copper-mediated fluorination of aryl stannanes and aryl trifluoroborates with N-fluoro-2,4,6-trimethylpyridinium triflate. This protocol demonstrates broad substrate scope and functional group tolerance, and does not require the use of any noble metal additives. The reaction is proposed to proceed via an arylcopper(III) fluoride intermediate.
- Ye, Yingda,Sanford, Melanie S.
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supporting information
p. 4648 - 4651
(2013/05/09)
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- Synthesis of functionalized aryl fluorides using organolithium reagents in flow microreactors
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Flow on: Flow microreactors enable the generation of aryl lithium compounds and subsequent electrophilic fluorination with NFSI and N-fluorosultam. The reaction can be successfully accomplished to synthesize various aryl fluorides involving an electron-withdrawing, an electron-donating, and a sterically hindered functional group in good yields. Copyright
- Nagaki, Aiichiro,Uesugi, Yuki,Kim, Heejin,Yoshida, Jun-Ichi
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supporting information
p. 705 - 708
(2013/05/08)
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- Copper-mediated fluorination of arylboronate esters. Identification of a Copper(III) fluoride complex
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A method for the direct conversion of arylboronate esters to aryl fluorides under mild conditions with readily available reagents is reported. Tandem reactions have also been developed for the fluorination of arenes and aryl bromides through arylboronate ester intermediates. Mechanistic studies suggest that this fluorination reaction occurs through facile oxidation of Cu(I) to Cu(III), followed by rate-limiting transmetalation of a bound arylboronate to Cu(III). Fast C-F reductive elimination is proposed to occur from an aryl-copper(III)-fluoride complex. Cu(III) intermediates have been generated independently and identified by NMR spectroscopy and ESI-MS.
- Fier, Patrick S.,Luo, Jingwei,Hartwig, John F.
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supporting information
p. 2552 - 2559
(2013/03/29)
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- Direct trifluoro-methoxylation of aromatics with perfluoro-methyl- hypofluorite
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The reactivity of CF3OF (FTM) has been widely studied especially in halogenated olefinic systems and its use in pharmaceutical synthesis as a mild radical and electrophilic fluorinating agent is well documented. On the other hand, the chemical behavior of the perfluoro-methyl-hypofluorite with aromatic substrates is much less studied. Up to now few and scattered data regarding its use as electrophilic fluorinating agent of variously substituted aromatic compounds are found in the literature. In this work the reactivity of CF3OF with simple electron rich and electron poor aromatics (α,α,α-trifluoro-toluene, toluene, benzene, chloro-benzene, methoxybenzene) has been investigated. The possibility of selectively bind the trifluoro-methoxy group (via radical mechanism) or the fluorine atom (via electrophilic addition) by varying the reaction conditions has been explored. In particular we have observed that the trifluoro-methoxy free radical substitution can be the main synthetic pathway if the reaction is promoted by an independent and steady source of CF3O radical.
- Venturini, Francesco,Navarrini, Walter,Famulari, Antonino,Sansotera, Maurizio,Dardani, Patrizia,Tortelli, Vito
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experimental part
p. 43 - 48
(2012/08/14)
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- Unprecedented directing group ability of cyclophanes in arene fluorinations with diaryliodonium salts
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For the first time it is shown that exceptionally electron-rich arene rings can be fluorinated exclusively during the reductive elimination reactions of diaryliodonium fluorides. The 5-methoxy[2.2]paracyclophan-4-yl directing group simultaneously reduces unproductive aryne chemistry and eliminates ligand exchange reactions by a combination of steric and electronic effects. Use of the cyclophane directing group permits an unprecedented degree of control in fluorination reactions of diaryliodonium salts.
- Graskemper, Joseph W.,Wang, Bijia,Qin, Linlin,Neumann, Kiel D.,Dimagno, Stephen G.
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body text
p. 3158 - 3161
(2011/08/06)
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- NO-CARRIER-ADDED NUCLEOPHILIC [F-18] FLUORINATION OF AROMATIC COMPOUNDS
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Phenyliodonium ylide derivatives substituted with electron donating as well as electron withdrawing groups on the aromatic ring are shown for use as precursors in aromatic nucleophilic substitution reactions. The iodonium ylide group is substituted by nucleophiles such as halide ions to provide the corresponding haloaryl derivatives. No- carrier-added [F-18]fluoride ion exclusively substitutes the iodonium ylide moiety in these derivatives and provides high specific activity F- 18 labeled fluoro derivatives. Protected L-dopa-6-iodonium ylide derivative have been synthesized as a precursors for the preparation of no-carrier-added 6-[F- 18]fluoro-L-dopa. The iodonium ylide group in this L-dopa.derivative is nucleophilically substituted by no-carrier-added [F-18]fluoride ion to provide a [F-18]fluoro intermediates which upon acid hydrolysis yielded 6-[F- 18]fluoro-L-dopa.
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Page/Page column 11-12
(2010/11/03)
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- Ortho-directed functionalization of arenes using magnesate bases
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Ortho-directed functionalisation of arenes using lithium alkylmagnesate bases were achieved, demonstrating the potential use of arylmagnesates as suitable arylanions, without a further transmetallation step, for challenging functionalizations such as fluorination, hydroxylation, arylation, vinylation and alkylation through epoxide ring-opening.
- Bellamy, Estelle,Bayh, Omar,Hoarau, Christophe,Trecourt, Francois,Queguiner, Guy,Marsais, Francis
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supporting information; experimental part
p. 7043 - 7045
(2010/11/02)
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- Improved arene fluorination methodology for I(III) salts
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(Equation Presented). The use of low polarity aromatic solvents (benzene or toluene) and/or the removal of inorganic salts results in dramatically improved yields of fluorinated arenes from diaryliodonium salts. This methodology is shown to "scale down" to the conditions used typically for radiotracer synthesis.
- Wang, Bijia,Qin, Linlin,Neumann, Kiel D.,Uppaluri, Shriharsha,Cerny, Ronald L.,DiMagno, Stephen G.
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supporting information; experimental part
p. 3352 - 3355
(2010/11/02)
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- Efficient synthesis of aryl fluorides
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Chemical Equation Presented Creating C-F bonds: A novel electrophilic fluorination of aryl and heteroaryl Crignard reagents has been discovered and was used for the efficient synthesis of various aryl fluoride derivatives (see picture; THF = tetrahydrofuran).
- Anbarasan, Pazhamalai,Neumann, Helfried,Beller, Matthias
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experimental part
p. 2219 - 2222
(2010/06/17)
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- Formation of arf from lpdar(f): catalytic conversion of aryl triflates to aryl fluorides
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Despite increasing pharmaceutical importance, fluorinated aromatic organic molecules remain difficult to synthesize. Present methods require either harsh reaction conditions or highly specialized reagents, making the preparation of complex fluoroarenes ch
- Watson, Donald A.,Su, Mingjuan,Teverovskiy, Georgiy,Zhang, Yong,Garcia-Fortanet, Jorge,Kinzel, Tom,Buchwaldf, Stephen L.
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scheme or table
p. 1661 - 1664
(2010/06/16)
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- Fluorination of aromatic compounds with N-fluorobenzenesulfonimide under solvent-free conditions
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Reactions of N-fluorobenzenesulfonimide with methylbenzenes, phenols, and phenol ethers were studied under solvent-free conditions. The rate constant ratio for the reactions with mesitylene and durene indicates polar mechanism of the process. Solvent-free fluorination of aromatic compounds with N-fluorobenzenesulfonimide in some cases is more selective than reactions with other N-F reagents in a solvent.
- Andreev,Borodkin,Shubin
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scheme or table
p. 1468 - 1473
(2010/03/24)
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- SYSTEM FOR FLUORINATING ORGANIC COMPOUNDS
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Described herein are fluorinated organic compounds and methods of making fluorinated organic compounds, for example, using palladium complexes. Also described herein are compositions and kits containing compounds and palladium complexes described herein.
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Page/Page column 171-172; 174
(2009/10/09)
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- Radical scavengers: A practical solution to the reproducibility issue in the fluoridation of diaryliodonium salts
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The addition of radical scavengers to the fluoridation of diaryliodonium salts was demonstrated to improve significantly both the reproducibility of the process and the material yield of the desired fluoroarene products. It was also established that the selectivity of the process was not influenced by the presence of the radical scavengers. TEMPO and galvinoxyl were found to be the most suitable radical scavengers in the fluoridation process allowing the methodology to be used routinely for the first time.
- Carroll, Michael A.,Nairne, James,Smith, Graham,Widdowson, David A.
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p. 127 - 132
(2008/03/13)
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- PHARMACEUTICAL COMPOUNDS
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The invention provides a compound of the formula (I) or a salt, solvate, tautomer or N-oxide thereof; wherein A is a saturated hydrocarbon linker group; E is a monocyclic or bicyclic carbocyclic or heterocyclic group; L1 is a bond or a linker selected from C1-C4 alkenylene, C1-C4 alkynylene, -CONR’, -NR’CO, -S, -C(O)-, -C(NR11)-, -C(S)-, -N(R11)2, C(=CHR11), -SO- and -SO2-; or L1 together with t R16 forms and 8-12 membered fused bicyclic heteroaryl ring system; L3 is a bond or a linker selected from CONH and HNCO; provided that L1 and L3 cannot both be linkers simultaneously; and provided also that L1 and L3 cannot both be a bond simultaneously; R16 is an optionally substituted 5- to 12-membered monocyclic or bicyclic carbocyclic or heterocyclic ring; L2 is absent or is a linker selected from C]-C4 alkylene, Ci-C4 alkenylene, Ci-C4 alkynylene, -CONR’-, -NR’CO-, -O-, -S-, -C(O)-, C(=CHR11), C(S)-, -N(R11)2, C3-4 cycloalkanediyl, -SO- and -SO2-; R17 is absent or is C1-6 alkyl or an optionally substituted 5 to 12 membered carbocyclic or heterocyclic ring; provided that when R17 is absent, then L2 is also absent; and R2, R3, R4, R5, R11 and R’ are as defined in the claims.
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Page/Page column 122-123
(2010/11/25)
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- Electrochemical fluorination of aromatic compounds in anhydrous HF
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Electrochemical fluorination of anisole furnished 2- and 4-fluoroanisoles in a 3:1 ratio, guaiacol, and 4,4′-dimethoxydiphenyl ether. Phenylacetonitrile alongside the fluorination in the ring suffered the transformation of the cyano group into a trifluoromethyl. 4-Bromobenzamide was fluorinated to a high conversion mostly in the ring to afford predominantly 4-bromo-3,3,6,6-tetrafluoro-1,4-cyclohexadienecarboxamide. 4-Bromonitrobenzene in a low yield gave 4-bromofluoronitrobenzene and 3,4-dibromofluoronitrobenzene. 3-Bromo-nitrobenzene and 1,4-dichlorobenzene did not undergo fluorination. In the course of the electrolysis of the 4-bromobenzamide and 4-bromonitrobenzene in anhydrous HF apart the fluorination occurred also the bromination of the substrates. Pleiades Publishing, Inc. 2006.
- Shainyan,Danilevich
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p. 214 - 219
(2007/10/03)
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- Nickel-catalyzed cross-coupling reaction of aryl fluorides and chlorides with Grignard reagents under nickel/magnesium bimetallic cooperation
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Nickel-catalyzed cross-coupling of Grignard reagents with aryl (poly)fluorides or (poly)chlorides can be achieved efficiently in the presence of a new triarylphosphine ligand bearing a nearby hydroxy group. The high reactivity and the unique chemoselectivity (ArF > ArOTf ? ArSR) of the catalysis have been attributed to synergy of nickel and magnesium atoms preorganized on the ligand, as has been surmised on the basis of theoretical modeling of the reaction mechanism. Copyright
- Yoshikai, Naohiko,Mashima, Hiroko,Nakamura, Eiichi
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p. 17978 - 17979
(2007/10/03)
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- Microwave fluorination: A novel, rapid approach to fluorination with Selectfluor
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Fluorination of electron rich aromatic systems with electrophilic fluorination reagents such as Selectfluor and Accufluor is a well-established process. Herein we report results from investigations into the use of such procedures to perform rapid, small-scale fluorinations under microwave irradiation. We have investigated the transformation with a range of different substrates and discuss the effects of two key factors, namely reaction time and choice of fluorination reagent. The use of Selectfluor in acetonitrile at 150°C with microwave heating for 10 min affords products in comparable yields to those obtained by prolonged heating in acetonitrile at its reflux temperature.
- Bluck, Gavin W.,Carter, Neil B.,Smith, Stephen C.,Turnbull, Michael D.
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p. 1873 - 1877
(2007/10/03)
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- 1-Fluoro-2,4,6-trichloro-1,3,5-triazinium tetrafluoroborate: Synthesis, characterization, and ability to effect electrophilic aromatic substitution
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The synthesis of 1-fluoro-2,4,6-trichloro-1,3,5-triazinium tetrafluoroborate, [(ClCN)3F]+[BF4] - (1), from (ClCN)3, BF3 and F2 is reported. Compound 1 was shown to be a useful reagent for the quantitative fluorination of aromatic substrates such as benzene, chlorobenzene, nitrobenzene, and methoxybenzene.
- Banks, R. Eric,Besheesh, Mohamed K.,Fraenk, Wolfgang,Klap?tke, Thomas M.
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p. 229 - 232
(2007/10/03)
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- First application of ionic liquids in electrophilic fluorination of arenes; Selectfluor (F-TEDA-BF4) for "green" fluorination
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The NF fluorinating agent F-TEDA-BF4 dication salt (Selectfluor) 1 dissolves in imidazolium-based ionic liquids [emim][OTf] 7, [emim][BF4] 8, [bmim][PF6] 9 and [bmim][BF4] 10 (assisted by sonication), providing a convenient medium for fluorination of arenes under essentially acid-free conditions in a simple set-up (no volatile solvent; simple extraction of the aromatics without aqueous work-up), from which the ionic liquid can be easily recycled and reused. Comparative studies in [emim][OTf] 7 with anisole as substrate show that 1 is superior to NFTh-BF4 (Accufluor) 2 and that the N-fluoropyridinium salt NFPy-B2F7 4 is least effective. The scope of the reaction has been surveyed. Substrate selectivity (k mesitylene: k durene = 10) measured in competitive experiments in 7 is clearly indicative of a conventional polar mechanism. Substrate selectivity measured without the ionic liquid in MeCN solvent is also indicative of a polar mechanism but exhibits lower magnitude (k mesitylene: kdurene = 6). Addition of dicyclohexano-24-crown-8 to the fluorination reaction mixture (1 and anisole) in 7 reduced the conversion but did not change the isomer distribution. AM1 minimization was used to model the complexation of 1 with this crown. With reactive aromatics optimal fluorination yields in ionic liquids (using 1 equivalent of the NF reagent) are around 50% (higher for naphthalene). A key control experiment suggests that the free base (produced upon transfer-fluorination) could complex to unreacted 1 (generating a bulky dimer complex which may be ineffective for fluorine transfer) in competition to N-protonation.
- Laali, Kenneth K.,Borodkin, Gennady I.
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p. 953 - 957
(2007/10/03)
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- Ring fluorination of non-activated aromatic compounds
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Unsubstituted aromatic compounds and aromatic compounds having one or more electron-withdrawing substituents are fluorinated, preferably in a nitromethane solvent, by contact with tri(halo- or trifluoromethyl) substituted N-fluorotriazinium salts of the following Formula I: wherein three A moieties are independently CR, where each R is independently halogen or trifluoromethyl; two A moieties are independently Z, where each Z is independently nitrogen or a quaternary nitrogen atom and Y is a counterion or group of counterions which are inert to chemical attack by fluorine. Preferably the cation of the salt is 2,4,6-trichloro-1,3,5-triazinium.
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- Electrophilic fluorination
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N-fluorotriazinium salts, especially those of the following Formula I, are electrophilic fluorinating agents useful in fluorinating, preferably in a nitromethane solvent, carbanionic species and/or activated aromatic compounds:wherein three A moieties are independently CR, where each R is, independently, hydrogen, halogen, (primary, secondary or tertiary) amino, hydroxyl, amino, cyano, perfluorothio hydroxysulphonyl, halosulphonyl, hydrocarbyloxysulphonyl,, or a carbon-containing substituent selected from optionally substituted hydrocarbyl, hydrocarbyloxy, hydrocarbyloxycarbonyl, and hydrocarbylthio groups; two A moieties are independently Z, where each Z is independently nitrogen or a quaternary nitrogen atom and Y is a counterion or group of counterions which are inert to chemical attack by fluorine, and oligomers or polymers thereof in which adjacent triazinium moieties are linked by a common R substituent. Preferably the cation of the salt is 2,4,6-trichloro-1,3,5-triazinium.
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- Preparation process of fluorine substituted aromatic compound
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A preparation process of a fluorine substituted aromatic compound comprising reacting an alkali metal or alkali earth metal salt of an aromatic compound having a hydroxy group with an organic fluorinating agent is disclosed. As a representative fluorinating agent, a bis-dialkylamino-difluoromethane compound, for example, 2,2′-difluoro-1,3-dimethylimidazolidine, is exemplified. According to the process, an industrially useful fluorinated aromatic compound, for example, a fluorobenzene, a fluorine substituted benzophenone, a fluorine substituted diarylsulfone can be prepared with ease in economy without specific equipment.
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- Preparation of aromatic fluorides: Facile photo-induced fluorinative decomposition of arenediazonium salts and their related compounds using pyridine-nHF
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By employing pyridine-nHF solution, the photo-induced fluorinative decomposition of arenediazonium salts (ArN2BF4) (fluoro-dediazoniation) and the related compounds, such as quinonediazides and triazenes, has been successfully carried out to produce the corresponding aromatic fluorides (ArF) in good yields. The rate in the fluoro-dediazoniation of para-substituted ArN2BF4 in pyridine-nHF solution did not obey the classical Hammett equation but conformed well to Taft's treatment [dual substituent parameter relationships (DSP)]. In the thermal fluoro-dediazoniation of ArN2BF4 the rate of reaction was significantly influenced by the substituents in the substrates. On the contrary, only a slight effect by the substituents was observed on the rate of the photo-induced fluoro-dediazoniation of ArN2BF4.
- Sawaguchi, Masanori,Fukuhara, Tsuyoshi,Yoneda, Norihiko
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p. 127 - 133
(2007/10/03)
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- 1-Fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate): An electrophilic fluorinating agent
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1-Fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate), NFTh, is a electrophilic fluorinating that can be used to fluorinate aromatic rings, olefins, dienol acetates and enol ethers. When NFTh is reacted with an active methylene compound in the presence of ZnCl2, the corresponding mono- or di-fluoro derivative can be isolated.
- Poss, Andrew J.,Shia, George A.
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p. 2673 - 2676
(2007/10/03)
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- Synthesis, Properties, and Reactivity of N,N'-Difluorobipyridinium and Related Salts and Their Applications as Reactive and Easy-To-Handle Electrophilic Fluorinating Agents with High Effective Fluorine Content
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N,N′-Difluoro-2,2′-, -2,4′-, -3,3′-, -4,4′-bipyridinium and substituted N,N′-difluoro-2,2′-bipyridinmm bis(triflates), bis(tetrafluoroborates), bis(hexafluorophosphates), and bis(hexafluoroantimonates) 1-9 were synthesized in high yields by the direct fluorination of a mixture of a bipyridyl and a Lewis acid, a Br?nsted acid, or the alkali metal salt of an acid. The higher homologues, trimer 10 and polymer 11, were also synthesized. Unsubstituted or electron-donating group-substituted N,N′- difluorobipyridinium salts are stable nonhygroscopic crystals, while the electron-withdrawing group- substituted N,N′-diflurobipyridinium salts 3, 5, and 6 are moisture-sensitive crystals. Hydrolysis of 1b in boiling water gave 3,3′-dihydroxy-2,2′-bipyridyl. The reactivity determination indicated that the fluorinating capability decreased in the order 2,2′- ? 2,4' > 3,3′- ≈ 4,4′-isomer ? N-fluoropyridinium salt and that the two N-F moieties in a molecule were effective for fluorination. This fluorination occurred in a step-by-step manner, and the reactivity difference between the first and second fluorinations was very small. N,N′-Difluoro-2,2′-bipyridinium bis(tetrafluoroborate) (1b) is thus shown to be a highly reactive and easy-to-handle electrophilic fluorinating agent with the high effective fluorine content (103.3 g/kg) for preparing many fluoro organic compounds.
- Umemoto, Teruo,Nagayoshi, Masayuki,Adachi, Kenji,Tomizawa, Ginjiro
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p. 3379 - 3385
(2007/10/03)
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- N-Halogeno compounds part 19: Electrophilic fluorinating agents of the multiple mono-N-fluoro class derived from nitrogen heterocycles
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Bis(4-fluoro-1,4-diazoniabicyclo[2.2.2]oct-1-yl)-ethane and -propane tetratriflates (4, 5), and 1,1′-difluoro-4,4′-bipyridinium ditriflate (6) were prepared by solution-phase direct fluorination of bis(4-aza-1-azoniabicyclo[2.2.2]oct-1-yl)-ethane or -propane ditriflate (10, 11), and 4,4′-bipyridine respectively. The same technique was employed to convert the complex 4,4′-bipyridine · 2BF3 to the mono-NF derivative F3B-NC5H4-C5H4N+-F BF4- (7) and its monomethylated analogue (4-NC5H4)C5H4N+-CH3 TfO- to F-+ NC5H4-C5H4N+-CH3 (TfO- )2 (8). The results of site-specific electrophilic fluorination of some model substrates (1-morpholinocyclohexene, phenol, 2-naphthol, anisole, di-and tri-methoxybenzene) with 5, 7 and 8 are presented.
- Banks, R. Eric,Besheesh, Mohamed K.,Mohialdin-Khaffaf, Suad N.,Sharif, Iqbal
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p. 157 - 161
(2007/10/03)
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- N-Halogeno compounds. Part 15. Synthesis of N-fluoroquinuclidinium salts via direct fluorination of quinuclidine-Lewis acid adducts, and a comparison of their "F+" transfer capabilities
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Fluorine smoothly attacks quinuclidine-trifluoroborane, quinuclidine-pentafluorophosphorane, and quinuclidine-sulfur trioxide in acetonitrile at -35 °C to give the corresponding N-fluoroquinuclidinium salts NFQ+X- (X- =BF4-, PF6-, and FSO3- respectively; Q = quinuclidine). Like its tetrafluoroborate analogue (NFQ+BF4-), the hexafluorophosphate NFQ+PF6- can also be prepared by direct fluorination of quinuclidine in the presence of the appropriate sodium salt (NaPF6). An alternative route to the tetrafluoroborate involves treatment of NFQ+F- with boron trifluoride. A comparative study of site-specific electrophilic fluorination of methoxybenzene [ → 1-fluoro2-and 4-methoxybenzene], 2-hydroxynaphthalene ( → 1-fluoro-2-hydroxynaphthalene and 1,1-difluoro-2-oxo-1,2-dihydronaphthalene), 2-nitropropan-2-yl-lithium ( → 2-fluoro-2-nitropropane) and diethyl sodio (phenyl) malonate [ → diethyl fluoro(phenyl) malonate] with all of the NFQ+X- salts mentioned above, plus the triflate (X- = CF3SO3-), revealed that the hexafluorophosphate and triflate are the most easily-handled and effective reagents.
- Banks, R. Eric,Besheesh, Mohamed K.
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p. 161 - 167
(2007/10/03)
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- N-Halogeno compounds. Part 16. Perfluoro-[N-fluoro-N-(4-pyridyl)acetamide] - A new site-selective electrophilic fluorinating agent
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Perfluoro-[N-fluoro-N-(4-pyridyl)acetamide] (2), prepared via direct fluorination of the sodium salt (4) of perfluoro-[N-(4-pyridyl)-acetamide], readily fluorinates diethyl sodio(phenyl)malonate [→PhCF(CO2Et)2], 1-morpholinocyclohexene(→2-fluorocyclohexanone), anisole (→2-and 4-FC6H4OMe), and phenol (→2-and 4-FC6H4OH) under mild conditions. The sodium salt precursor (4) of this side-chain N-F reagent (2) is easily made from pentafluoropyridine via the trifluoroacetylation of its 4-amino derivative or, more directly, by treating it with two equivalents of the monosodium salt of trifluoroacetamide.
- Banks,Besheesh,Tsiliopoulos
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- N-halogeno compounds. Part 18. 1-Alkyl-4-fluoro-1,4-diazoniabicyclo [2.2.2] octane salts: User-friendly site-selective electrophilic fluorinating agents of the N-fluoroammonium class
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Methods of synthesis are described for a range of 1-alkyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane salts [R-N+(CH2CH2)3N+-F (X-)2, where R = CH3, CH2Cl, C2H5, CF3CH2, C8H17 and (X-)2 = (TfO-)2, (BF4-)2, (PF6-)2, (TfO-, BF4-), (TfO-, PF6-), (TfO-, FSO3-)] by direct fluorination (with neat F2 at ≤20 mmHg or F2-N2 blends at 1 atm pressure) of monoquaternary salts of 1,4-diazabicyclo[2.2.2]octane [R-+N(CH2CH2)3N X-] or their 1:1 adducts with boron trifluoride, phosphorus pentafluoride, or sulfur trioxide in acetonitrile at ca - 35°C. The results of site-selective electrophilic fluorination of diethyl sodio(phenyl)malonate [→ PhCF(CO2Et)2], 1-morpholinocyclohexene (→ 2-fluorocyclohexanone), phenol (→ 2- and 4-FC6H4OH), 1- and 2-hydroxynaphthalene (→ 2- and 4-FC10H6OH, and 1-FC10H6OH and 1,1-difluoro-2-oxo-1,2-dihydronaphthalene, respectively), acetanilide (→ 2- and 4-FC6H4NHCOCH3), anisole (→ 2- and 4-FC6H4OCH3) and sodium benzenesulfinate (→ PhSO2F) with these N-fluoroammonium salts are presented.
- Banks, R. Eric,Besheesh, Mohamed K.,Mohialdin-Khaffaf, Suad N.,Sharif, Iqbal
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p. 2069 - 2076
(2007/10/03)
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- Facile preparation of aromatic fluorides by deaminative fluorination of aminoarenes using hydrogen fluoride combined with bases
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One-pot deaminative fluorination of aminoarenes including heteroaromatics, namely, diazotization of aminoarenes followed by in situ fluoro-dediazoniation of the corresponding diazonium ions, was successfully accomplished to produce fluoroarenes in high yields by using hydrogen fluoride combined with base solutions. The diazotization stage has been found to play the most important part in yielding fluoroarenes effectively. It was greatly influenced by the composition of the HF solution and enhanced by employing appropriate amounts of bases such as pyridine under carefully controlled conditions. The fluoro-dediazoniation stage was effectively accelerated photochemically to afford fluoroarenes having polar substituents such as hydroxyl, nitro and so on in high yields.
- Yoneda,Fukuhara
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- An improved method for fluoro-dediazoniation of arylamines substituted with polar groups
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The addition of SnX2 (SnCl2 or SnF2), as a low redox potential reductant, at the fluoro-dediazoniation step in the deaminative fluorination of aryl amines substituted with polar groups gave high selectivities for the formation of fluoroaromatics under mild conditions. The selectivities were further increased by the addition of a nucleophilic fluoride anion source, i.e. tetrabutylammonium dihydrogen trifluoride nBu4N+ H2F3-, along with the reductants.
- Sasaki, Koshi,Oishi, Mari,Imaki, Naoshi
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- Selective, Electrophilic Fluorinations Using N-Fluoro-o-benzenedisulfonimide
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The synthesis of N-fluoro-o-benzenedisulfonimide (NFOBS, 2) and its use as an "electrophilic" fluorinating reagent with nucleophilic substrates is described and compared with that of N-fluorobenzenesulfonimide (NFSi, 3).NFOBS (2) is prepared in three steps in 81percent overall yield from commercially available o-benzenedisulfonic acid (4) and involves treatment of o-benzenedisulfonimide (6) with dilute fluorine (10percent F2/N2).Reaction of 2 with metal enolates, silyl enol ethers, and 1,3-dicarbonyl compounds affords the corresponding α-fluoro compounds in yields up to 95percent, with good control of mono- and difluorination.Fluorination of ortho-metalated aromatic compounds was achieved in modest to good yields (10-80percent).While the reactivities of 2 and 3 are similar, better yields were observed with the former reagent in the fluorination of metal enolates, Grignard and lithium reagents, while 3 gave better results with the ortho-lithiated aromatic substrates.The available evidence suggests an SN2-type mechanism for the fluorination of nucleophilic substrates by these reagents.
- Davis, Franklin A.,Han, Wei,Murphy, Christopher K.
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p. 4730 - 4737
(2007/10/02)
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- Process for selectively ortho-fluorinating substituted aromatic compounds
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The invention describes a process for selectively preparing ortho-fluorinated substituted aromatic compounds wherein an aromatic compound containing a substituent capable of directing ortho metalation is contacted with a metalating reagent under reaction conditions sufficient to form an ortho-metalated substituted aromatic compound. The ortho-metalated substituted aromatic compound is reacted with an electrophilic fluorinating reagent under reaction conditions sufficient to form the desired ortho-fluorinated substituted aromatic compound which is then recovered from the reaction mixture. The process which utilizes a metalation intermediate prior to effecting the electrophilic fluorination step overcomes problems associated with prior art electrophilic fluorination processes which do not proceed through a regiospecifically controlled intermediate.
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