- Anodic fluorination of 4-methoxy-1-naphthol and 4-nitroanisole using Et3N · 5 HF in mixed nonaqueous solvent
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Anodic fluorination of 4-methoxy-1-naphthol and 4-nitroanisole has been investigated in a mixed nonaqueous solvent using Et3N · 5 HF as supporting electrolyte as well as fluorine source. In order to avoid the formation of polymer on the anode,
- Saraswat,Sharma,Singh,Siddiqui,Singh
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Read Online
- Base-promoted nucleophilic fluoroarenes substitution of C–F bonds
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With the use of KOH/DMSO as the superbase medium, the nucleophilic fluoroarene substitution for C–F bonds is presented. The transformation proceeds smoothly with the use of fluoroarenes bearing not only electron-withdrawing group, but also electron-donating group and a variety of nucleophiles such as alcohols, phenols, amines, amides and nitrogen-heterocyclic compounds. The double nucleophilic substitution using ortho-difluoroarenes and nucleophiles bearing ortho-dinucleophilic groups results in the formation of 2,3-dihydro-1,4-benzodioxins, dibenzo[b,e][1,4]dioxins and 10H-phenoxazines in moderate to good yields.
- Su, Ji,Chen, Qian,Lu, Le,Ma, Yuan,Auyoung, George Hong Lok,Hua, Ruimao
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supporting information
p. 303 - 307
(2017/12/11)
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- Method for preparing alkyloxy aromatic compound from fluoroaromatic compound
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The invention discloses a method for preparing an alkyloxy aromatic compound from a fluoroaromatic compound. The alkyloxy aromatic compound is highly-efficiently prepared through a reaction of the fluoroaromatic compound, a strong alkali, dimethyl sulfoxide and alcohol under certain conditions. The method has the advantages of no metal catalyst, mild and controllable reaction, simple process, good universality, and suitableness for large-scale industrial production.
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Paragraph 0037; 0038
(2017/05/18)
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- Constructing a catalytic cycle for c-f to c-x (x = o, s, n) bond transformation based on gold-mediated ligand nucleophilic attack
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A tricoordinated gold(I) chloride complex, tBuXantphosAuCl, supported by a sterically bulky 9,9-dimethyl-4,5-bis(di-Tert-butylphosphino)xanthene ligand (tBuXantphos) was synthesized. This complex features a remarkably longer Au?Cl bond length [2.632(1) ?] than bicoordinated linear gold complexes (2.27-2.30 ?) and tricoordinated XantphosAuCl [2.462(1) ?]. Single-crystal Xray diffraction analysis of a cocrystal of tBuXantphosAuCl and pentafluoronitrobenzene (PFNB) and UV-vis spectroscopic titration experiments revealed the existence of an anion-φ interaction between the Cl anion ligand and PFNB. Stoichiometric reaction between PFNB and tBuXantphosAuOtBu, after replacement of Cl by a more nucleophilic tBuO anion ligand, showed higher reactivity and para selectivity in the transformation of C-F to C-OtBu bond, distinctively different from that when only KOtBu was used (ortho selectivity) under the identical condition. Mechanistic studies including density functional theory calculations suggested a gold-mediated nucleophilic ligand attack of the C?F bond pathway via an SNAr process. On the basis of these results, using trimethylsilyl derivatives TMS-X (X = OMe, SEt, NEt) as the nucleophilic ligand source and the fluorine acceptor, catalytic transformation of the C-F bond of aromatic substrates to the C-X (X = O, S, N) bond was achieved with tBuXantphosAuCl as the catalyst (up to 20 turnover numbers).
- Hu, Ji-Yun,Zhang, Jing,Wang, Gao-Xiang,Sun, Hao-Ling,Zhang, Jun-Long
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supporting information
p. 2274 - 2283
(2017/01/16)
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- Fluorination of aromatic compounds with xenon difluoride in the presence of boron trifluoride etherate
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Fluorination of benzene with the XeF2 - BF3?Et2O system in acetonitrile at low temperatures affords fluorobenzene in 18% yield, the conversion of benzene being 92%. The rest products are di-, tri-, tetra-, and polyphenyls with different fluorination pattern. Toluene and chloro- and bromobenzenes are fluorinated predominantly at the ortho and para positions. Fluorination of 4-nitroanisole affords 2-fluoro-4-nitroanisole in 73% yield.
- Fedorov,Zubarev,Mortikov, V. Yu.,Rodinovskaya,Shestopalov
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p. 1049 - 1052
(2016/02/09)
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- Silver(I)-Promoted ipso-Nitration of Carboxylic Acids by Nitronium Tetrafluoroborate
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A novel and efficient method for the regioselective nitration of a series of aliphatic and aromatic carboxylic acids to their corresponding nitro compounds using nitronium tetrafluoroborate and silver carbonate in dimethylacetamide has been described. This transformation is believed to proceed via the alkyl-silver or aryl-silver intermediate, which subsequently reacts with the nitronium ion to form nitro substances. Mild reaction conditions, tolerant of a broad range of functional groups, and formation of only the ipso-nitrated products are the key features of this methodology when compared to known methods for syntheses of nitroalkyls and nitroarenes.
- Natarajan, Palani,Chaudhary, Renu,Venugopalan, Paloth
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p. 10498 - 10504
(2015/11/18)
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- Elemental fluorine. Part 20. Direct fluorination of deactivated aromatic systems using microreactor techniques
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Continuous flow microreactor technology has been used for the direct fluorination of a range of deactivated di- and tri-substituted aromatic systems.
- Chambers, Richard D.,Fox, Mark A.,Sandford, Graham,Trmcic, Jelena,Goeta, Andres
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- Tandem of nucleophilic substitution of hydrogen and cyclocondensation with participation of nitro group in the synthesis of fluorine-containing 3-amino-1,2,4-benzotriazines
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Reactions of 3-fluoro-1-nitrobenzenes with guanidine hydrochloride in THF in the presence of ButOK gave isomeric 5-and 7-fluoro-containing 3-amino-1,2,4-benzotriazines. Springer Science+Business Media, Inc. 2006.
- Zhumabaeva,Kotovskaya,Perova,Charushin,Chupakhin
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p. 1243 - 1247
(2008/02/03)
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- Novel bicyclic heterocyclic compounds, process for their preparation and compositions containing them
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The present invention provides, among other things, new bicyclo heterocyclic compounds, compositions comprising these heterocyclic compounds, methods of making the heterocyclic compounds, and methods of using these heterocyclic compounds for treating a variety of conditions and disease states associated with, for example, cellular proliferation, inflammation, glycosidase expression, or the low expression of Perlecan.
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Page/Page column 77
(2008/06/13)
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- Elemental fluorine Part 12. Fluorination of 1,4-disubstituted aromatic compounds
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Direct fluorination of a series of 1,4-disubstituted benzene derivatives in acid reaction media at convenient temperature leads, in many cases, to selectively fluorinated aromatic products in preparatively useful conversions and yields.
- Chambers, Richard D.,Hutchinson, John,Sparrowhawk, Matthew E.,Sandford, Graham,Moilliet, John S.,Thomson, Julie
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p. 169 - 173
(2007/10/03)
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- Effect of ring fluorination on the pharmacology of hallucinogenic tryptamines
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A series of fluorinated analogues of the hallucinogenic tryptamines N,N-diethyltryptamine (DET), 4-hydroxy-N,N-dimethyltryptamine (4-OH-DMT, psilocin), and 5-methoxy-DMT was synthesized to investigate possible explanations for the inactivity of 6-fluoro-DET as a hallucinogen and to determine the effects of fluorination on the molecular recognition and activation of these compounds at serotonin receptor subtypes. The target compounds were evaluated using in vivo behavioral assays for hallucinogen-like and 5-HT(1A) agonist activity and in vitro radioligand competition assays for their affinity at 5-HT(2A), 5-HT(2C), and 5-HT(1A) receptor sites. Functional activity at the 5-HT(2A) receptor was determined for all compounds. In addition, for some compounds functional activity was determined at the 5-HT(1A) receptor. Hallucinogen-like activity, evaluated in the two-lever drug discrimination paradigm using LSD-trained rats, was attenuated or abolished for all of the fluorinated analogues. One of the tryptamines, 4-fluoro-5-methoxy-DMT (6), displayed high 5-HT(1A) agonist activity, with potency greater than that of the 5-HT(1A) agonist 8-OH-DPAT. The ED50 of 6 in the two-lever drug discrimination paradigm using rats trained to discriminate the 5-HT(1A) agonist LY293284 was 0.17μmol/kg, and the K(i) at [3H]8-OH-DPAT-labeled 5-HT(1A) receptors was 0.23 nM. The results indicate that fluorination of hallucinogenic tryptamines generally has little effect on 5-HT(2A/2C) receptor affinity or intrinsic activity. Affinity at the 5-HT(1A) receptor was reduced, however, in all but one example, and all of the compounds tested were full agonists but with reduced functional potency at this serotonin receptor subtype. The one notable exception was 4-fluoro-5-methoxy-DMT (6), which had markedly enhanced 5-HT(1A) receptor affinity and functional potency. Although it is generally considered that hallucinogenic activity results from 5-HT(2A) receptor activation, the present results suggest a possible role for involvement of the 5-HT(1A) receptor with tryptamines.
- Blair,Kurrasch-Orbaugh,Marona-Lewicka,Gumbay,Watts,Barker,Nichols
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p. 4701 - 4710
(2007/10/03)
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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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- Fluorination process
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According to the present invention there is provided a process for the selective introduction of one or more fluorine atoms into a disubstituted aromatic compound in an acid medium with fluorine gas characterized in that the acid medium has a dielectric constant of at least 20 and a pH of less than 3. The present process provides a cost effective means of selectively introducing one or more fluorine atoms into an aromatic compound in good overall yield.
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- A novel method for the nitration of simple aromatic compounds
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Simple aromatic compounds such as benzene, alkylbenzenes, halogenobenzenes, and some disubstituted benzenes are nitrated in excellent yields with high regioselectivity under mild conditions using zeolite β as a catalyst and a stoichiometric quantity of nitric acid and acetic anhydride. The zeolite can be recycled, and the only byproduct is acetic acid, which can be separated easily from the nitration product by distillation; the process is inexpensive and represents an attractive method for the clean synthesis of a range of nitroaromatic compounds. For example, nitration of toluene gives a quantitative yield of mononitrotoluenes, of which 79% is 4-nitrotoluene; fluorobenzene gives a quantitative yield of mononitro compounds, of which 94% is 4-nitrofluorobenzene; and 2-fluorotoluene gives a 96% yield of mononitro products, of which 90% is the 5-nitro isomer and 10% is the 4-nitro isomer.
- Smith, Keith,Musson, Adam,DeBoos, Gareth A.
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p. 8448 - 8454
(2007/10/03)
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- Charge control in the S(N)Ar reaction. Meta substitution with respect to the activating nitro group in 3,4-dihalogenonitrobenzenes
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The reactions of 3-fluoro-4-chloronitrobenzene and of 3,5-difluoro-4-chloronitrobenzene with thiophenoxide anion lead to predominant substitution of the chlorine atom through S(N)Ar orbital-controlled processes. However, when harder nucleophiles (methoxide anion) are used, the substitution of a fluorine atom meta with respect to the activating nitro group becomes apparent in the reaction of 3-fluoro-4-chloronitrobenzene, predominant in the reaction of 5-fluoro-4-chloro-3-methyoxynitrobenzene, and almost exclusive in the reaction of 3,5-difluoro-4-chloronitrobenzene. Kinetic measurements and theoretical calculations indicate that the observed meta substitution of a fluorine atom is a S(N)Ar charge-controlled reaction with a loosely bonded transition state.
- Cervera,Marquet,Martin
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p. 2557 - 2564
(2007/10/03)
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- Electrophilic Fluorination Using Elemental Fluorine
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Electrophilic fluorination by elemental fluorine is promoted by the use of protonic acids; formic and sulfuric acids are especially effective.
- Chambers, Richard D.,Skinner, Christopher J.,Thomson, Julie,Hutchinson, John
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- A Novel Electrophilic Fluorination of Activated Aromatic Rings Using Acetyl Hypofluorite, Suitable also for Introducing (18)F into Benzene Nuclei
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Acetyl hypofluorite (1) is a new compound that serves as a novel electrophilic fluorinating agent.It is special in the sense that, while it is very reactive, it is still a milder reagent than other fluoroxy compounds such as CF3OF or CF3COOF.It is synthesized directly from elemental fluorine and is used without any isolation or purification.The hypofluorite 1 reacts efficiently and selectively with activated aromatic rings,particularly phenol and aniline derivatives after suitable protection of the hydroxyl and the amino groups.The net result of the reaction is partly according to classical aromatic electrophilic substitution.Unlike such a substitution, however, the electrophilic fluorine atom of 1 substitutes mainly an ortho hydrogen and only occasionally small amounts of p-fluoro derivatives are found.Evidence supports the mechanism for this aromatic fluorination as being mainly an addition-elimination one.In many cases the electrophilic aromatic fluorinations can replace the classical 60-year-old Balz-Schiemann method, which until today is probably the most used procedure.Since aromatic fluorination with 1 is a very fast reaction and since 1 is produced directly from elemental fluorine, this is probably one of the best ways for introduction of the short-living radioisotope (18)F into activated aromatic rings.This will greatly encourage the synthesis of compounds suitable for use in the rapidly developing field of positron emitting transaxial tomography, which in itself depends on the efficient and easy supply of compounds possessing positron emitting isotopes.
- Lerman, Ori,Yitzhak, Tor,Hebel, David,Rozen, Shlomo
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p. 806 - 813
(2007/10/02)
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- 4-Methyl-5-(unsubstituted and substituted phenoxy)-6-methoxy-8-(aminoalkylamino)quinolines
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Compounds of the class including 4-methyl-5-(unsubstituted and substitutedhenoxy)-6-methoxy-8-(aminoalkylamino)quinolines as the free bases and pharmaceutically acceptable acid amine salts are described. The compounds are highly effective antimalarial agents which possess, surprisingly, both tissue schizonticidal (radical curative) and blood schizonticidal (suppressive) activity. In addition, these drugs have significantly better therapeutics indices than primaquine which is the current tissue schizonticidal drug of choice. Primaquine possesses no useful blood schizonticidal activity at tolerated dose levels.
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- Acetyl Hypofluorite as a Taming Carrier of Elemental Fluorine for Novel Electrophilic Fluorination of Activated Aromatic Rings
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The new fluorinating reagent CH3COOF, which is prepared in situ from F2, is used for electrophilic aromatic fluorinations of activated aromatic rings.
- Lerman, Ori,Tor, Yitzhak,Rozen, Shlomo
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p. 4629 - 4631
(2007/10/02)
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- The Kinetics of the Reactions of Picryl Chloride with Some Substituted Anilines. Part 6. 4-Substituted and 3,4-Disubstituted Anilines
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Arrhenius parameters have been measured for the reactions of picryl chloride with the following substituted anilines in acetonitrile: 4-X- (X = F, Cl, Br, I, Me, or OMe); 3,4-X2- (X = Cl, Br, Me, or OMe); 4-X-3-nitro- (X = F, Cl, or Me); 3-X-4-methoxy- (X = F, Cl, Br, or I); 3-fluoro-4-nitro-; and 3,4,5-trimethoxy-aniline.In the 3,4-disubstituted series the effect of two methyl groups on the free energy of activation is strictly additive, but for the rest the measured rate constants are greater than those calculated on the assumption of additivity.The results are rationalized in terms of the positions of the transition state on the reaction co-ordinate.
- Emokpae, Thomas A.,Eguavoen, Osa,Khalil-Ur-Rahman,Hirst, Jack
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p. 832 - 834
(2007/10/02)
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