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Nucleophilic Fluorination of Heteroaryl Chlorides and Aryl Triflates Enabled by Cooperative Catalysis
Aryl and heteroaryl fluorides are growing to be dominant motifs in pharmaceuticals and agrochemicals, yet they are rare in both nature and commodity chemicals. As a consequence, there is an increasingly urgent need to develop mild, cost-effective, and scalable methods for fluorination. The most straightforward route to synthesize aryl fluorides is through the halide exchange "halex"reaction, but conditions, cost, and atom economy preclude most available methods from large-scale manufacturing processes. We report a new approach that leverages the cooperative action of 18-crown-6 ether and tetramethylammonium chloride to catalytically access the reactivity of tetramethylammonium fluoride and achieve halex fluorinations under mild conditions with operational ease. The described methodology readily converts both heteroaryl chlorides and aryl triflates to their corresponding (hetero)aryl fluorides in high yields and purities.
Hong, Cynthia M.,Whittaker, Aaron M.,Schultz, Danielle M.
p. 3999 - 4006
(2021/03/09)

Method for pipeline continuous fluorination with fluorine salt as fluorine source
The method comprises the following steps: dissolving a fluorine salt in an aqueous polar aprotic solvent as reaction liquid A, dissolving an aryl (heterocyclic) chloride in a polar aprotic solvent as reaction liquid B, and reacting a polar aprotic solvent in the reaction liquid A with a polar aprotic solvent of the reaction liquid B. The reaction medium consisting of the preheated reaction liquid A and the preheated reaction liquid B enters the reaction coil for a fluorination reaction, and the resulting product from the reaction coil is subjected to post-treatment to obtain the product. The method has the characteristics of no need of adding a phase transfer catalyst, continuous production, low production cost and the like.
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Paragraph 0056-0061; 0094-0096

(2021/10/27)

PROCESS FOR FLUORINATING COMPOUNDS
Disclosed are mild temperature (e.g., from 0 to 80°C) SNAr fluorinations of a variety of halide and sulfonate substituted aryl and heteroaryl substrates using NMe4F.
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Page/Page column 24

(2017/02/28)

Synthesis, Characterization, and Reactivity of Thermally Stable Anhydrous Quaternary Ammonium Fluorides
The synthesis and properties of a new class of anhydrous quaternary ammonium fluorides, based on the rigid skeleton azabicyclo[2.2.2]octane, is described. Compounds 2a-d were easily prepared by passing the corresponding ammonium iodides over fluoride-based resin followed by drying their hydrated form at 100 or 140 °C under reduced pressure. The stability (experimental and theoretical study), solubility, reactivity, and characterization by solution and solid-state MAS NMR are discussed.
Elias, Shlomi,Karton-Lifshin, Naama,Yehezkel, Lea,Ashkenazi, Nissan,Columbus, Ishay,Zafrani, Yossi
supporting information
p. 3039 - 3042
(2017/06/23)

Selective fluorination of pyridine and its derivatives in the presence of high-oxidation-state transition metals
The oxidative fluorination of pyridine and 4-ethylpyridine under chemical and electro-chemical conditions in the presence of transition metal (high-oxidation-state nickel, cobalt, and silver) salts was studied. The chemical fluorination affords 2-fluoropyridine in all cases, while the electrochemical fluorination results in 2-fluoroor 3-fluoropyridine depending on the catalyst used.
Gryaznova,Khrizanforova,Kholin,Khrizanforov,Budnikova, Yu. H.
p. 1798 - 1804
(2017/03/22)

Dehalogenation degradation method for halogenated pyridine compound
The invention provides a dehalogenation degradation method for a halogenated pyridine compound. The halogenated pyridine compound is adopted as a raw material, alcohol is adopted as a hydrogen source, water is adopted as a solvent, reacting is carried out for 3-10 h under normal pressure at the temperature of 20 DEG C to 120 DEG C under the action of a supported catalyst, and the halogenated pyridine compound is subjected to dehalogenation degradation in situ through water phase hydrogen production. A pyridine ring of the halogenated pyridine compound at least contains an F or Cl or Br or I substituent group. The supported catalyst is composed of an active component and a carrier, the active component is composed of a mixture of transition metal and other metal, the transition metal is one of Rh, Pd, Pt and Ni, and other metal is one of Se, Ca, Ba, La and Ce. The carrier is one of activated carbon, kieselguhr, zeolite, gamma-Al2O3, AlF3 and MgO. H2 is not directly used as a reduction agent, activated hydrogen is prepared through in-situ catalysis to directly participate in reacting, the advantages of being high in reaction activity, high in selectivity, high in safety, environmentally friendly and the like are achieved, and good application prospects are achieved.
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Paragraph 0019; 0020

(2016/12/16)

Anhydrous Tetramethylammonium Fluoride for Room-Temperature SNAr Fluorination
This paper describes the room-temperature SNAr fluorination of aryl halides and nitroarenes using anhydrous tetramethylammonium fluoride (NMe4F). This reagent effectively converts aryl-X (X = Cl, Br, I, NO2, OTf) to aryl-F under mild conditions (often room temperature). Substrates for this reaction include electron-deficient heteroaromatics (22 examples) and arenes (5 examples). The relative rates of the reactions vary with X as well as with the structure of the substrate. However, in general, substrates bearing X = NO2 or Br react fastest. In all cases examined, the yields of these reactions are comparable to or better than those obtained with CsF at elevated temperatures (i.e., more traditional halex fluorination conditions). The reactions also afford comparable yields on scales ranging from 100 mg to 10 g. A cost analysis is presented, which shows that fluorination with NMe4F is generally more cost-effective than fluorination with CsF.
Schimler, Sydonie D.,Ryan, Sarah J.,Bland, Douglas C.,Anderson, John E.,Sanford, Melanie S.
p. 12137 - 12145
(2016/01/09)

Selective C-H fluorination of pyridines and diazines inspired by a classic amination reaction
Fluorinated heterocycles are prevalent in pharmaceuticals, agrochemicals, and materials. However, reactions that incorporate fluorine into heteroarenes are limited in scope and can be hazardous. We present a broadly applicable and safe method for the site-selective fluorination of a single carbon-hydrogen bond in pyridines and diazines using commercially available silver(II) fluoride. The reactions occur at ambient temperature within 1 hour with exclusive selectivity for fluorination adjacent to nitrogen. The mild conditions allow access to fluorinated derivatives of medicinally important compounds, as well as a range of 2-substituted pyridines prepared by subsequent nucleophilic displacement of fluoride. Mechanistic studies demonstrate that the pathway of a classic pyridine amination can be adapted for selective fluorination of a broad range of nitrogen heterocycles.
Fier, Patrick S.,Hartwig, John F.
p. 956 - 960
(2013/12/04)

FLUORINATION OF ORGANIC COMPOUNDS
Methods for fluorinating organic compounds are described herein.
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Page/Page column 25

(2012/11/06)

Deoxyfluorination of phenols
An operationally simple ipso fluorination of phenols with a new deoxyfluorination reagent is presented.
Tang, Pingping,Wang, Weike,Ritter, Tobias
supporting information; experimental part
p. 11482 - 11484
(2011/10/02)

Process for the Synthesis of Highly Active Binary Metal Fluoride as a Fluorinating Agent for Aromatics
The subject invention relates to a process for the synthesis of highly active binary metal fluoride system for the fluorination of aromatic compounds. Fluorinated aromatic compounds are valuable synthons for the chemical synthesis of pharmaceutical drugs and novel polymers. Fluorobenzene is used to control carbon content in steel manufacturing, is an intermediate for pharmaceuticals, pesticides and other organic compounds. Fluorobenzene is typically produced by the reaction of aniline and sodium nitrite in the presence of hydrogen fluoride. The present invention relates to a process for the synthesis of highly active binary metal fluoride system consists of copper (II) fluoride and aluminum (III) fluoride for the fluorination of aromatic compounds in gas phase and recycling of the reagent, in situ, using O2 and HF.
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Page/Page column 5

(2010/02/17)

Highly reactive and regenerable fluorinating agent for oxidative fluorination of aromatics
A newly synthesized copper aluminum fluoride of nominal composition CuAl2F8 exhibits excellent reactivity towards direct oxidative fluorination of aromatic compounds, as well as fluorodechlorination of chloroaromatics. The spent CuAl2F8 reagent can be regenerated by treatment with O2 and HF, and the fluorination process has been demonstrated to retain high conversions through 20 reaction cycles. The main advantages of this new process are safety, minimal waste, and potentially low cost.
Janmanchi, Krishna Murthy,Dolbier Jr., William R.
p. 349 - 354
(2013/01/03)

Room-temperature nucleophilic aromatic fluorination: Experimental and theoretical studies
(Chemical Equation Presented) Taming the reagent: The use of anhydrous tetrabutylammonium fluoride (TBAFanh) in nucleophilic aromatic substitution reactions, including variants of the selective halogen-exchange and fluorodenitration processes (see scheme), was investigated. It was shown that TBAFanh permits these reactions to be performed under surprisingly mild conditions if it is used in relatively nonpolar media.
Sun, Haoran,DiMagno, Stephen G.
p. 2720 - 2725
(2007/10/03)

Oxidative fluorination of aromatic derivatives by copper (II) fluoride and silver (I) fluoride
The subject invention provides methods of fluorinating an aromatic or chloroaromatic compound comprising combining an aromatic compound, a chloroaromatic compound, a mixture of aromatic compounds, a mixture of chloroaromatic compounds, or a mixture of chloroaromatic and aromatic compounds and a fluorinating composition comprising at least one active fluorinating agent selected from the group consisting of CuF2, AgF, HgF2, TeF4, MnF4, FeF3, and CoF2-4 and at least one support selected from the group consisting of activated carbon, ZnF2, CaF2, MgF2, AIF3, and combinations of activated carbon, ZnF2, CaF2, MgF2, or AlF3.
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Page/Page column 6-7

(2008/06/13)

Process for the preparation of fluorinated heterocyclic compounds
A method of fluorinating a heterocyclic organic compound comprises the step of reacting a heterocyclic compound with elemental fluorine in the presence of another halogen. The reaction may be conducted in the presence of a base.
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(2008/06/13)

Elemental fluorine. Part 10.1 Selective fluorination of pyridine, quinoline and quinoxaline derivatives with fluorine-iodine mixtures
Selective fluorination of a range of pyridine and quinoline substrates to give corresponding 2-fluoro-derivatives can be readily achieved in high yield at room temperature using elemental fluorine-iodine mixtures. Reaction of fluorine with iodine forms, in situ, systems that function like sources of both iodonium and fluoride ions and fluorination of heterocyclic derivatives is suggested to proceed by fluoride ion attack on intermediate W-iodo-heterocyclic species. Quinoxaline derivatives react under similar conditions to give either the 2-fluoro- or 2,3-difluoro-quinoxaline derivatives depending on the ratio of fluorine passed through the solution. In related processes, pyridine can be alkoxylated upon reaction of an appropriate alcohol and fluorine.
Chambers, Richard D.,Parsons, Mandy,Sandford, Graham,Skinner, Christopher J.,Atherton, Malcolm J.,Moilliet, John S.
p. 803 - 810
(2007/10/03)

Novel base-initiated reactions of N-substituted pyridinium salts
Reaction of N-fluoropyridinium triflate with a base in dichloromethane gave 2-chloropyridine as the major product along with 2-pyridyl triflate and 2-fluoropyridine, regardless of the nature of the base. This base-initiated reaction was also shown to take place similarly in other halogenated alkanes, ethers, a nitrile, aromatics, a ketone, vinyl ethers, alcohols and trimethylsilyl acetate as solvents to give pyridine derivatives substituted with a solvent molecule (s) at the 2-position. N-(Trifluoromethanesulfonyloxy)-and (benzenesulfonyloxy) pyridinium salts were found to undergo the same base-initiated reaction. These reactions may be explained by a postulated singlet carbene (canonical formula 11b) produced through proton abstraction of N-substituted pyridinium salts. A similar carbene reaction may thus likely occur in the thermal decomposition of thiatriazole 10. Ab initio MO calculations revealed the structure and properties of the labile deprotonated N-fluoropyridinium cation and supported the carbene intermediate reaction mechanism rather than a pyridynium or pyridyl cation mechanism. Quarroz's reports on the reactions of picolinic acid N-oxide and the reported reactions of pyridines with F2, CH3COOF or CsSO4F in solvents may be explained by this carbene mechanism.
Umemoto, Teruo,Tomizawa, Ginjiro,Hachisuka, Hitoharu,Kitano, Masakatsu
p. 161 - 168
(2007/10/03)

Facile preparation of aromatic fluorides by deaminative fluorination of aminoarenes using hydrogen fluoride combined with bases
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
p. 23 - 36
(2007/10/02)

Carboxamidation of pyridines by the system of elemental fluorine- carbonitrile-water: A useful alternative to the chichibabin amination
The title reaction with pyridine, 4-methylpyridine, 3-methylpyridine, 3- bromopyridine, nicotinonitrile, and quinoline yields 2-carboxamido derivatives regioselectively. Isoquinoline is amidated at position 1.
Kiselyov,Strekowski
p. 2387 - 2392
(2007/10/02)

Reaction of N-fluoropyridinium salts with Wittig reagents: A novel and convenient approach to symmetric trans-olefins
N-Fluoropyridinium salts were found to react with Wittig reagents containing electron-withdrawing groups to give olefins in 47-83% yield. The mechanism of this conversion is believed in involve single-electron transfer from Wittig reagent to N-fluoropyridinium cation.
Kiselyov, Alexander S.
p. 8951 - 8954
(2007/10/02)

Halogen-Exchange Fluorination of Aromatic Halides with HF or HF-Base
Heteroatomic halides such as 2-chloropyrimidines and 2-chloropyridines, and 2,4-dinitrochlorobenzene underwent halogen-exchange fluorination with the treatment of HF or HF-base solutions to afford the corresponding fluorides in good yields.
Fukuhara, Tsuyoshi,Yoneda, Norihiko
p. 509 - 512
(2007/10/02)

Synthesis of 2-Substituted Pyridines by the Reaction of N-Fluoropyridinium Fluoride with Trimethylsilyl Derivatives
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Kiselyov, Alexander S.,Strekowski, Lucjan
p. 4476 - 4478
(2007/10/02)

Process for the preparation of fluoroaromatic and fluoroheteroaromatic compounds
Good yields of a range of fluoroaromatic and fluoroheteroaromatic compounds may be obtained by reacting an aromatic or a heteroaromatic amine with a nitrosyl polyfluoro salt in an inert solvent to form an intermediate aryl or heteroaryl diazonium polyfluoro salt and decomposing this aryl or heteroaryl diazonium polyfluoro salt in situ. The process described is especially suitable for the preparation in good yield of fluoroaromatic and fluoroheteroaromatic compounds with ortho substituents.
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(2008/06/13)

Electrochemistry of NADH/NAD+ analogues. A detailed mechanistic kinetic and thermodynamic analysis of the 10-methylacridan/10-methylacridinium couple in acetonitrile
The electrochemical oxidation of 10-methylacridan (AH) at platinum and gold electrodes in acetonitrile containing various pyridine bases is investigated by means of cyclic voltammetric and potential step techniques. The conversion of AH to the 10-methylacridinium ion (A+) proceeds along an electron-proton-electron transfer mechanism, the second electron being abstracted by the initial cation radical, AH?+, rather than by the electrode itself in most cases. The use of ultramicroelectrodes (in the 10 μm diameter range) allows the determination of the standard potential of the AH?+/AH couple and of the rate constant of the deprotonation of AH?+; the latter was measured as a function of the pKa of a series of pyridine bases. Investigation of the reduction of A+ by the same techniques led to the determination of the standard potential of the A+/A? couple and of the dimerization rate constant of A?. The oxidation of AH as well as the reduction of A+ are kinetically controlled by follow-up homogeneous chemical steps rather than by the initial electron transfer, which appears as quite fast in both cases. The combination of an ultraslow spectrometric technique with the ultrafast electrochemical techniques allowed the determination of the pKa of the AH?+/A? couple from that of the standard potential of the overall reaction AH ? A+ + 2e- + H+ and hence the construction of a Br?nsted plot with a known driving force origin for the deprotonation of AH?+.
Hapiot, Philippe,Moiroux, Jacques,Savéant, Jean-Michel
p. 1337 - 1343
(2007/10/02)

Reactions of Caesium Fluoroxysulphate with Pyridine
Pyridine readily reacts with CsSO4F in various solvents at room temperature producing a mixture of up to three products (2-fluoropyridine, 2-pyridyl fluorosulfonate and 2-chloro or 2-alkoxypyridine), their distribution strongly depending on the solvent used.Reaction of 3-chloropyridine with CsSO4F in methanol leads regioselectively to 2-methoxy-3-chloropyridine, while 3-methylpyridine was converted into 2-methoxy-3-methyl and 2-methoxy-5-methylpyridine in a 2:1 relative ratio.
Stavber, Stojan,Zupan, Marko
p. 775 - 776
(2007/10/02)

The reaction of CF with aromatics
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Sztyrbicka, Renata,Moklesur Rahman,D'Aunoy, Mary E.,Shevlin, Philip B.
p. 6712 - 6713
(2007/10/02)

Preparation of 2-Fluoropyridines via Base-Induced Decomposition of N-Fluoropyridinium Salts
N-Fluoropyridinium salts with either BF4-, SbF6-, or PF6- as a counteranion were treated with excess base such as triethylamine at room temperature to give 2-fluoropyridine in good yield.This method was succesfully applied to the preparation of 2-fluoropyridine derivatives possessing electron-donating or -withdrawing substituents using substituted N-fluoropyridinium tetrafluoroborates.Pyridine-F2 compounds produced through reactions of pyridines with molecular fluorine were also treated with base to give 2-fluoropyridines but in low yields.These reactions are considered to occur through a carbene mechanism as follows: a novel N-F-containing cyclic carbene (3), generated from the N-fluoropyridinium salts by 2-proton abstraction, reacts with fluorine atoms from counteranions such as BF4-, SbF6-, or PF6-, followed by elimination of F- from the N-F moiety, to yield 2-fluoropyridines.Previously reported findings in reactions of pyridines with molecular fluorine are explained on the basis of this mechanism.
Umemoto, Teruo,Tomizawa, Ginjiro
p. 1726 - 1731
(2007/10/02)

A Facile Preparation of Fluoropyridines from Aminopyridines via Diazotation and Fluorodediazoniation in HF or HF-Pyridine Solutions
Fluoropyridines were prepared in high yields by dizotation of aminopyridines in HF or HF-pyridine solutions, followed by dediazoniation in situ at 20-60 deg C.
Fukuhara, Tsuyoshi,Yoneda, Norihiko,Suzuki, Akira
p. 435 - 438
(2007/10/02)

BASE-INITIATED REACTIONS OF N-FLUOROPYRIDINIUM SALTS; A NOVEL CYCLIC CARBENE PROPOSED AS A REACTIVE SPECIES
A new type of base-initiated reactions of pyridinium salts was found and a novel cyclic carbene was proposed as the reactive species.
Unemoto, Teruo,Tomizawa, Ginjiro
p. 2705 - 2708
(2007/10/02)

ACTION DU N-BUTYLLITHIUM SUR LES BROMO-3 HALOGENO-2 PYRIDINES FLUOREE, CHLOREE ET BROMEE PRINCIPE ET ETUDE D'UNE POSSIBILITE REACTIONNELLE NOUVELLE: L'HOMOTRANSMETALLATION
Apart from the common bromine-lithium exchange reaction in brominated aromatic compounds, it is possible to obtain a lithio-derivative quite different from the one usually described in such a reaction.This new reaction, which results from a special experimental condition is called 'homotransmetalation', and it occurs when using n-buthyllithium and 3-bromo 2-halogenopyridines (1).Different behaviour is observed with the three similar compounds (1:X = F,Cl,Br).Explanations are proposed of these results.It is then possible to compare the relative stabilities of the proposed lithio-structures.It is evident that nucleophilic substitution of bromine in position 4 of the pyridine ring is easier than is usually recognised.
Mallet, M.,Queguiner, G.
p. 3433 - 3440
(2007/10/02)

IONIC HYDROGEN BOND. 4. INTRAMOLECULAR AND MULTIPLE BONDS. PROTONATION AND COMPLEXES OF AMIDES AND AMINO ACID DERIVATIVES.
The paper examines the proton affinities and ionic hydrogen bonding of some amides and of the N-acetylated amino acid derivative CH//3CONHCH(CH//3)COOCH//3. The thermochemistry of these species can serve as a model for the energetics of protonated intermediates in acid hydrolysis of amides and the energetics of protonated amide groups in proteins.
Meot-Ner (Mautner)
p. 278 - 283
(2007/10/02)

Reactions of Perfluoro-2-methyl-2-pentene with Carboxylic Acids, Alcohols, and Some Cyclic Amides. A New Fluorinating Reagent
Perfluoro-2-methyl-2-pentene (PMP) reacts with carboxylic acids, alcohols, and 2-pyridone, giving Michael-type addition products, 1,1,1,3,4,4,5,5,5-nonafluoro-2-trifluoromethyl-3-acyloxypentane, 1,1,1,3,4,4,5,5,5-nonafluoro-2-trifluoromethyl-3-alkoxypentane, 1,1,1,3,4,4,5,5,5-nonafluoro-2-trifluoromethyl-3(2-pyridyloxy)pentane, respectively, in good yields.In the presence of bases, carboxylic acids give acid fluorides, 1,1,1,4,4,5,5,5-octafluoro-2-trifluoromethyl-3-pentanone, and 1,1,1,4,4,5,5,5-octafluoro-2-trifluoromethyl-3-acyloxy-2-pentene (4), the yields changing with base, solvent, phase-transfer catalyst, and their combination.In the presence of triethylamine, fluorination occurs exclusively, producing acid fluorides in good yields.Alcohols and 2-pyridone are converted into alkyl fluorides and 2-fluoropyridine, respectively, with use of triethylamine as a base with an aprotic solvent.The reaction of PMP with 4-pyridone and 6-chloro-2-ethyl-5-methyl-4(3H)-pyrimidone were also examined.The fluorination reactions were rationalized by preferential replacement of the vinylic fluorine of PMP and a good leaving function of the perfluoro enol group of the intermediates such as 4.
Yanagida, Shozo,Noji, Yukihiro,Okahara, Mitsuo
p. 1151 - 1158
(2007/10/02)

ACTION DU METHYLTRI(N-BUTYL)FLUOROPHOSPHORANE SUR LES HALOGENURES ET LES SULFONATES D'ALKYLE
Monofluorophosphoranes R3MePF are used in exchange reactions to prepare monofluorinated organic compounds.Tri(n-butyl)methylfluorophosphorane (n-Bu3MePF), easily available, is the most reactive.In solvents of low polarity or even in non-polar solvents, it reacts at -70 deg C with alkyl sulphonates and halides activated by ester, ketone, or ether functions.Thus, fluorinated epoxides can be obtained directly by exchange from their chlorinated or brominated homologues.
Leroy, J.,Bensoam, J.,Humiliere, M.,Wakselman, C.,Mathey, F.
p. 1931 - 1936
(2007/10/02)

Diazotization-fluorination in a medium of hydrogen fluoride-containing ammonium ions
Process for diazotization-fluorination of aromatic or heterocyclic amines in a solution of hydrogen fluoride containing ammonium ions.
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(2008/06/13)