- α-Fluorotricarbonyl Derivatives as Versatile Fluorinated Building Blocks: Synthesis of Fluoroacetophenone, Fluoroketo Ester and Fluoropyran-4-one Derivatives
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Fluorinated acyl-Meldrum's acid derivatives were synthesized by electrophilic fluorination of appropriate phenacyl Meldrum's acid substrates using Selectfluor. Reactions with water, ethanol, Grignard, and alkynyllithium reagents gave rise to the correspon
- Harsanyi, Antal,Lückener, Anne,Pasztor, Hedvig,Yilmaz, Zahide,Tam, Lawrence,Yufit, Dmitry S.,Sandford, Graham
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p. 3872 - 3878
(2020/06/09)
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- Fluorination of α-bromomethyl aryl ketones with fluorohydrogenate-based ionic liquids
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Fluorination of α-bromomethyl aryl ketones using fluorohydrogenate-based ionic liquids as fluorinating reagent is described. Reaction of various α-bromomethyl aryl ketones (1a-g) with fluorohydrogenate-based ionic liquids such as EMIMF·(HF)2.3, PYR13F·(HF)2.3 or PYR14F·(HF)2.3 as a fluoride ion source in anhydrous THF led to the formation of the corresponding α-fluoromethyl aryl ketones (2a-g) in very good yield. Compared to alternative fluorinating agents for this reaction, fluorohydrogenate-based ionic liquids are safer to handle and have the potential to be less expensive and more selective.
- Singh, Rajendra P.,Martin, Jerry L.
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- Synthesis of α-Fluoroketones from Vinyl Azides and Mechanism Interrogation
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An efficient and mild fluorination of vinyl azides for the synthesis of α-fluoroketones is described. The mechanistic studies indicated that a single-electron transfer (SET) and a subsequent fluorine atom transfer process could be involved in the reaction.
- Wu, Shu-Wei,Liu, Feng
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supporting information
p. 3642 - 3645
(2016/08/16)
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- Synthesis of α-fluoroketones and α-fluoroenones in aqueous media
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An efficient synthesis of α-fluoroketones via the nucleophilic fluorination of α-bromoketones in water with TBAF·3H2O as the fluorinating agent was developed in this paper. In addition, a simple and efficient synthesis of α-fluoroenones through the condensation of α-fluoroketones with aldehydes promoted by sodium hydroxide in water was also discovered.
- He, Yan,Zhang, Xinying,Shen, Nana,Fan, Xuesen
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- Synthesis of enantiopure fluorohydrins using alcohol dehydrogenases at high substrate concentrations
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The use of purified and overexpressed alcohol dehydrogenases to synthesize enantiopure fluorinated alcohols is shown. When the bioreductions were performed with ADH-A from Rhodococcus ruber overexpressed in E. coli, no external cofactor was necessary to obtain the enantiopure (R)-derivatives. Employing Lactobacillus brevis ADH, it was possible to achieve the synthesis of enantiopure (S)-fluorohydrins at a 0.5 M substrate concentration. Furthermore, due to the activated character of these substrates, a huge excess of the hydrogen donor was not necessary.
- Borzeicka, Wioleta,Lavandera, Ivan,Gotor, Vicente
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p. 7312 - 7317
(2013/08/23)
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- One-pot α-nucleophilic fluorination of acetophenones in a deep eutectic solvent
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Two methods of nucleophilic fluorination to prepare α-fluoroacetophenones from α-bromoacetophenones by using KF with PEG-400 or TBAF with ZnF2 are described. On the fundamental of nucleophilic fluorination, a novel method of one-pot fluorination to prepare α-fluoroacetophenones directly from acetophenones in DES was developed.
- Chen, Zizhan,Zhu, Wei,Zheng, Zubiao,Zou, Xinzhuo
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experimental part
p. 340 - 344
(2010/06/11)
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- Microwave assisted fluorination: an improved method for side chain fluorination of substituted 1-arylethanones
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A two-step, one-pot microwave (MW) assisted fluorination of 1-arylethanones to their corresponding 1-aryl-2-fluoroethanones has been developed. The first step utilises Selectfluor as a fluorinating agent in methanol forming 1-aryl-2-fluoroethanones and their corresponding dimethyl acetals. In the second step, water is added and Selectfluor acts as a Lewis acid in the hydrolytic cleavage of the dimethyl acetals. Compared to the thermal synthesis, the MW assisted method leads to a reduction in reaction time both in the fluorination and for the dimethyl acetal cleavage. Moreover, the one-pot procedure reduces reagent and solvent consumption. The method is best suited for the preparation of 1-aryl-2-fluoroethanones containing substituents that deactivates electrophilic aromatic substitution, however highly electron deficient ketones such as 1-(3,5-dinitrophenyl)ethanone reacts more slowly. Reactions using electron rich aromatic ketones had a low regioselectivity, and also produced fluoroaromatic products.
- Krane Thvedt, Thor H?kon,Fuglseth, Erik,Sundby, Eirik,Hoff, B?rd Helge
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experimental part
p. 9550 - 9556
(2010/02/27)
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- Ruthenium-catalysed asymmetric transfer hydrogenation of para-substituted α-fluoroacetophenones
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The first examples of asymmetric transfer hydrogenation of α-fluoroacetophenones are reported. Eight para-substituted α-fluoroacetophenones have been reduced using four catalytic systems constructed of [RuCl2(p-cymene)2]2 or [RuCl2(mesitylene)2]2 in combinations with each of the ligands (1R,2R)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine ((R,R)-TsDPEN) and (1R,2R)-N-(p-toluenesulfonyl)-1,2-cyclohexanediamine ((R,R)-TsCYDN). All reactions were performed in both water and formic acid/triethylamine. The highest enantioselectivity was obtained using the (R,R)-TsDPEN ligand in a formic acid/triethylamine mixture, giving the (S)-1-aryl-2-fluoroethanols in high to moderate enantiomeric excess (97.5-84.5%). For this solvent system the presence of electron withdrawing groups in the para position reduced the enantioselectivity. Reactions performed in water generally gave lower enantioselectivity and reaction rate, although RuCl(mesitylene)-(R,R)-TsDPEN yielded the product alcohols with enantiomeric excess in the range of 95.5-76.5%.
- Fuglseth, Erik,Sundby, Eirik,Hoff, B?rd H.
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experimental part
p. 600 - 603
(2009/11/30)
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- Electrophilic and nucleophilic side chain fluorination of para-substituted acetophenones
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para-Substituted α-fluoroacetophenones have been synthesised by three different routes. Electrophilic fluorination of trimethylsilyl enol ethers of acetophenones using Selectfluor (F-TEDA-BF4, 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis-(tetrafluoroborate)) gave high to moderate yield depending on the electronic properties of the substituents. F-TEDA-BF4 mediated fluorination of acetophenones in methanol resulted in a mixture of α-fluoroacetophenones and the corresponding 2-fluoro-1,1-dimethyl acetals. The dimethyl acetals were hydrolysed using trifluoroacetic acid in water to maximise the yield of the product. Nucleophilic fluorination of α-bromoacetophenones using tetrabutylammonium hydrogen bifluoride (TBABF) led to moderate yield when having electron-donating substituents, whereas low yields were experienced when more electron-withdrawing substituents were introduced.
- Fuglseth, Erik,Thvedt, Thor H?kon Krane,M?ll, Maria F?rde,Hoff, B?rd Helge
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p. 7318 - 7323
(2008/12/21)
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- Novel entry to aryl α-fluoromethyl ketones via sodium hydroxide-induced hydrolysis of fluorinated enol tosylates
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Abstract: 1-Aryl-substituted 2,3,3-trifluoro-1-propenyl p-toluene-sulfonate 1 was smoothly hydrolyzed in a mixed solvent of dimethyl sulfoxide-water (1:1) in the presence of sodium hydroxide at 80 °C to afford the corresponding aryl α-monofluoromethyl ketones 2 in fair to good yields.
- Funabiki,Fukushima,Sugiyama,Shibata,Matsui
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p. 1308 - 1310
(2007/10/03)
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- The synthesis of α-fluoroketones by 1,4-additions of mono-fluorinated enamines to Michael acceptors
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Stork enamine reactions are explored with mono-fluorinated enamines derived from α-fluoroacetophenones and pyrrolidine. The resulting enamines react under mild conditions with Michael acceptors (acrylonitrile, methyl acrylate, methyl methacrylate, methyl vinyl ketone and cyclohexenone) to generate a variety of substituted α-fluoroketones.
- Bridge, Colin F.,O'Hagan, David
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