- Unbalanced-Ion-Pair-Catalyzed Nucleophilic Fluorination Using Potassium Fluoride
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An unbalanced ion pair promoter (e.g., tetrabutylammonium sulfate), consisting of a bulky and charge-delocalized cation and a small and charge-localized anion, greatly accelerates nucleophilic fluorinations using easy handling KF. We also successfully converted an inexpensive and commercially available ion-exchange resin to the polymer-supported ion pair promoter (A26–SO42–), which could be reused after filtration. Moreover, A26–SO42– can be used in continuous flow conditions. In our conditions, water is well-tolerated.
- Hammond, Gerald B.,Li, Wangbing,Lu, Zhichao,Xu, Bo
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supporting information
p. 9640 - 9644
(2021/12/14)
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- Nucleophilic (Radio)Fluorination of α-Diazocarbonyl Compounds Enabled by Copper-Catalyzed H-F Insertion
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The copper-catalyzed H-F insertion into α-diazocarbonyl compounds is described using potassium fluoride (KF) and hexafluoroisopropanol. Access to complex α-fluorocarbonyl derivatives is achieved under mild conditions, and the method is readily adapted to
- Gray, Erin E.,Nielsen, Matthew K.,Choquette, Kimberly A.,Kalow, Julia A.,Graham, Thomas J. A.,Doyle, Abigail G.
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supporting information
p. 10802 - 10805
(2016/09/09)
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- Diastereoselective Addition of Metal α-Fluoroenolates of Carboxylate Esters to N-tert-Butylsulfinyl Imines: Synthesis of α-Fluoro-β-amino Acids
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We report a diastereoselective addition reaction of fluoroacetate and α-alkylated fluoroacetate to N-tert-butylsulfinyl imines. This method provides a concise route to α-fluoro-β-amino acids containing fluorinated quaternary stereogenic carbon centers with very good yields and high diastereoselectivities. This protocol has the benefit of using abundant and readily accessible starting materials and is operationally simple. Additionally, the stereochemical outcome of the present reaction was different from that of the previously known addition of comparable nonfluorinated, brominated, and chlorinated enolates to N-sulfinyl imines, suggesting that an open transition state (rather than a closed one) is involved in the current fluoroalkylation reaction.
- Shang, Huaqi,Li, Ya,Li, Xiang,Ren, Xinfeng
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supporting information
p. 8739 - 8747
(2015/09/15)
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- PyFluor: A low-cost, stable, and selective deoxyfluorination reagent
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We report an inexpensive, thermally stable deoxyfluorination reagent that fluorinates a broad range of alcohols without substantial formation of elimination side products. This combination of selectivity, safety, and economic viability enables deoxyfluorination on preparatory scale. We employ the [18F]-labeled reagent in the first example of a no-carrier-added deoxy-radiofluorination.
- Nielsen, Matthew K.,Ugaz, Christian R.,Li, Wenping,Doyle, Abigail G.
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supporting information
p. 9571 - 9574
(2015/08/18)
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- Mild copper-catalyzed fluorination of alkyl triflates with potassium fluoride
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A chemoselective catalytic fluorination of alkyl triflates is described using potassium fluoride as a fluoride source. Excellent yields of the desired alkyl fluorides are obtained after one hour at 45°C using 2 mol% of the copper catalyst. With 10 mol% of the catalyst, full conversion can be achieved in less than 10 minutes at 45°C, and thus makes this procedure potentially suited for the preparation of 18F-labeled PET probes. As a result of the mild reaction conditions, only the substitution products are observed with no evidence of common side reactions, such as elimination. Reported is a preliminary study of the reaction scope, which demonstrates that the fluorination can be performed in the presence of a wide range of functional groups. Evidence suggests an unusual role of the [IPrCuOTf] catalyst as a phase-transfer catalyst and points to [IPrCuF] as the active fluorinating reagent (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene).
- Dang, Hester,Mailig, Melrose,Lalic, Gojko
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p. 6473 - 6476
(2014/06/24)
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- Dihaloiodoarenes: α,α-dihalogenation of phenylacetate derivatives
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A hypervalent iodine reagent-based α-carbonyl dihalogenation reaction is reported. Treating diazoacetate derivatives with either iodobenzene dichloride or iodotoluene difluoride results in gem-dichlorination or gem-difluorination products, respectively. The reaction is catalyzed by either Lewis acid or Lewis base activation of the aryl-λ3-iodane (ArIX2) species and proceeds rapidly and chemoselectively to the desired gem-difunctionalized products in good to excellent yield.
- Tao, Jason,Tran, Richard,Murphy, Graham K.
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supporting information
p. 16312 - 16315
(2013/12/04)
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- Design, synthesis and biological evaluation of novel fluorinated docetaxel analogues
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A series of novel fluorinated docetaxel analogues have been synthesized and evaluated in vitro and in vivo. Incorporated one, two or three fluorine atom(s) either at both meta position on C-2 benzolate and 3′-N-tert-butyloxyl group or only at 3′-N-tert-butyloxyl group has resulted in potent analogues which have comparable or superior in vitro and in vivo cytotoxicity to docetaxel. Among them, compounds 14d and 14e have displayed more potent cytotoxicity than docetaxel both in human cancer cell line SK-OV-3 in vitro and in human non-small cell lung cancer A549 xenografts in vivo. Preliminary data show that compound 14a has reduced acute animal toxicity in mice compared with docetaxel.
- Lu, Hong-Fu,Sun, Xun,Xu, Liang,Lou, Li-Guang,Lin, Guo-Qiang
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experimental part
p. 482 - 491
(2009/09/06)
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- N-Fluorobisimide: An Efficient Reagent for the α-Fluorination of Functionalized Carbonyl Compounds
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The N-fluorobisimide (1) has been used in the electrophilic fluorination of the lithium enolate of esters, amides, and ketones.The corresponding α-fluorocarbonyl compounds have been obtained in good yields.The α-fluorination of β-diesters, β-diamides, β-keto esters, and β-diketones has been performed either on the neutral compounds or on the metal enolates.In this way some geminal azafluoro, chlorofluoro, fluorooxy compounds have been prepared in nearly quantitative yields.Also some α-keto esters and acids have been selectively monofluorinated in the β-position by simple treatment of the neutral compound with 1.
- Resnati, Giuseppe,DesMarteau, Darryl D.
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p. 4925 - 4929
(2007/10/02)
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- THE STEREOSELECTIVE ALDOL CONDENSATION OF α-FLUOROACETATES
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2,6-Di-t-butyl-4-methylphenyl(BHT) and benzyl α-fluoroacetates were converted to their lithium enolates and were utilized in the aldol condensation.The improved diastereoselectivity found with the BHT esters is thought to arise from of equilibration of th
- Welch, John T.,Plummer, Janet S.
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p. 1081 - 1090
(2007/10/02)
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