- High Chemo-/Stereoselectivity for Synthesis of Polysubstituted Monofluorinated Pyrimidyl Enol Ether Derivatives
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A novel intramolecular Smiles rearrangement of α-fluoro-β-keto-pyrimidylsulfones (usually used as a carbon nucleophile) was developed, providing a versatile avenue for synthesis of tri/tetra-substituted monofluorinated pyrimidyl enol ethers. Among these, diverse (Z)-monofluorovinylsulfones and sulfinates were efficiently assembled by adding extra electrophile and fine-tuning reaction conditions. The process is triggered by a keto-enol tautomerism from enol oxyanion to pyrimidine 2-carbon, completely different from the classical carbon nucleophilic addition reaction approach.
- Kang, Lei,Wang, Fang,Zhang, Jinlong,Yang, Huameng,Xia, Chungu,Qian, Jinlong,Jiang, Gaoxi
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supporting information
p. 1669 - 1674
(2021/03/08)
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- α,α-Alkylation-Halogenation and Dihalogenation of Sulfoxonium Ylides. A Direct Preparation of Geminal Difunctionalized Ketones
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A one-pot alkylation–halogenation of ketosulfoxonium ylides in the presence of alkyl halides is described. The method furnishes several gem-difunctionalized haloketones (an alkyl and F, Cl, Br, or I) in good yields. Replacing alkyl halides with a mixture of electrophilic halogen species and various halide anions led to gem-dihalogenated ketones containing a combination of the same or two different halogens. Kinetic isotopic effects as well as reaction kinetic experiments give insight to the mechanism of these reactions.
- Gallo, Rafael D. C.,Ahmad, Anees,Metzker, Gustavo,Burtoloso, Antonio C. B.
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p. 16980 - 16984
(2017/11/27)
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- Detrifluoroacetylative Generation of Halogenated Enolates: Practical Access to Perhalogenated Ketones and Alkenes
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Sequential chlorination/fluorination of aromatic trifluoroacetylated ketones gives 1-aryl 2-chloro-2,4,4,4-tetrafluorobutan-1,3-dione hydrates that are used for the synthesis of ketones and alkenes exhibiting a terminal bromochlorofluoromethyl group. The
- Balaraman, Kaluvu,Moskowitz, Max,Liu, Yang,Wolf, Christian
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p. 2376 - 2384
(2016/07/28)
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- Hypervalent iodine-promoted α-fluorination of acetophenone derivatives with a triethylamine·hf complex
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The direct fluorination reaction of acetophenone using iodosylarenes and TEA·5HF was conducted under mild conditions except for use of a HF reagent. The fluorination reaction was applied to acetophenone derivatives, acetonaphthones, benzyl phenyl ketone, propiophenone, butyrophenone, 1-indanone, and phenacyl chloride, giving selectively the corresponding α-fluoroketone derivatives in good yields.
- Kitamura, Tsugio,Muta, Kensuke,Muta, Kazutaka
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p. 5842 - 5846
(2014/07/08)
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- Expanding the scope of alcohol dehydrogenases towards bulkier substrates: Stereo- and enantiopreference for α,α-dihalogenated ketones
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Alcohol dehydrogenases (ADHs) were identified as suitable enzymes for the reduction of the corresponding α,α-dihalogenated ketones, obtaining optically pure β,β-dichloro- or β,β-dibromohydrins with excellent conversions and enantiomeric excess. Among the different biocatalysts tested, ADHs from Rhodococcus ruber (ADH-A), Ralstonia sp. (RasADH), Lactobacillus brevis (LBADH), and PR2ADH proved to be the most efficient ones in terms of activity and stereoselectivity. In a further study, two racemic α-substituted ketones, namely α-bromo- α-chloro- and α-chloro-α-fluoroacetophenone were investigated to obtain one of the four possible diastereoisomers through a dynamic kinetic process. In the case of the brominated derivative, only the (1R)-enantiomer was obtained by using ADH-A, although with moderate diastereomeric excess (>99 % ee, 63 % de), whereas the fluorinated ketone exhibited a lower stereoselectivity (up to 45 % de). Bulking up: A series of β,β-dihalohydrins are obtained through alcohol dehydrogenase (ADH) catalyzed bioreduction of the synthesized α,α-dihalogenated ketones. Two racemic acetophenone derivatives are also subjected to this protocol to obtain stereoenriched alcohols through dynamic kinetic resolution (DKR).
- Kedziora, Kinga,Bisogno, Fabricio R.,Lavandera, Ivan,Gotor-Fernandez, Vicente,Montejo-Bernardo, Jose,Garcia-Granda, Santiago,Kroutil, Wolfgang,Gotor, Vicente
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p. 1066 - 1072
(2014/05/06)
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- Laccase/TEMPO-mediated system for the thermodynamically disfavored oxidation of 2,2-dihalo-1-phenylethanol derivatives
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An efficient methodology to oxidize β,β-dihalogenated secondary alcohols employing oxygen was achieved in a biphasic medium using the laccase from Trametes versicolor/TEMPO pair, providing the corresponding ketones in a clean fashion under very mild conditions. Moreover, a chemoenzymatic protocol has been applied successfully to deracemize 2,2-dichloro-1-phenylethanol combining this oxidation with an alcohol dehydrogenase-catalyzed bioreduction. the Partner Organisations 2014.
- Kedziora, Kinga,Diaz-Rodriguez, Alba,Lavandera, Ivan,Gotor-Fernandez, Vicente,Gotor, Vicente
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supporting information
p. 2448 - 2453
(2014/05/06)
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- Unusual reactions of Grignard reagents toward fluoroalkylated esters
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Fluorine-containing esters were demonstrated to be convenient substrates for construction of the corresponding ketones by low temperature reaction with Grignard reagents followed by warming up to 0 °C, while heating the mixture up to 80 °C readily promoted the reduction of the ketones obtained by the generated magnesium alkoxides whose mechanism was speculated as Meerwein-Ponndorf-Verley type reduction by computational technique.
- Yamazaki, Takashi,Terajima, Tsukasa,Kawasaki-Taskasuka, Tomoko
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p. 2419 - 2424
(2008/09/18)
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- New synthetic routes towards various α-fluorinated aryl ketones and their enantioselective reductions using baker's yeast
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Highly electrophilic dichlorofluoromethyl aryl ketones were obtained by oxidation of dichlorofluoromethyl aryl alcohols. Subsequent dechlorination of these ketones using sodium formaldehyde sulfoxylate (Rongalite) and reductive dehalogenating system SnCl2/Al led to various fluoromethyl aryl ketones and chlorofluoromethyl aryl ketones, respectively. Asymmetric reductions of these fluorinated ketones using the inexpensive baker's yeast produced the corresponding fluoromethyl aryl alcohols with different enantioselectivities.
- Barkakaty, Balaka,Takaguchi, Yutaka,Tsuboi, Sadao
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p. 970 - 976
(2007/10/03)
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- Reactions of 1-aryl-2,2-dihalogenoethanone oximes with tetrasulfur tetranitride (S4N4): A general method for the synthesis of 3-aryl-4-halogeno-1,2,5-thiadiazoles
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1-Aryl-2,2-dichloro-7, 1-aryl-2,2-dibromo-8, 1-aryl-2-bromo-2-fluoro-9 and 1-aryl-2-chloro-2-fluoroethanone oximes 10 have been prepared by allowing the corresponding ketones to react with hydroxylamine hydrochloride in EtOH at room temperature. Stereoche
- Yoon, Sung Cheol,Cho, Jaeeock,Kim, Kyongtae
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p. 109 - 116
(2007/10/03)
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