- 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 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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- 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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