observed in the reduction of hinderedketones such as isopropyl ketone, while the stereoselectivity was inverted in the reduction of ketones with electron-withdrawing atoms such as chlorine. The mechanism for the inversion in stereochemistry was investigated by enzymatic studies. Several enzymes with different stereoselectivities were isolated; one of them catalyzed the reduction of methyl ketones, and another
Chemoselective Trifluoromethylation of Methyl Esters Using an Et<sub>3</sub>GeNa/C<sub>6</sub>H<sub>5</sub>SCF<sub>3</sub> Combination: Efficient Synthesis of Trifluoromethyl Ketones
作者:Yasuo Yokoyama、Kunio Mochida
DOI:10.1055/s-1997-961
日期:1997.8
Various trifluoromethyl ketones were synthesized from the corresponding methyl esters by effective nucleophilic trifluoromethylation using an Et3GeNa/C6H5SCF3 combination. This trifluoromethylation proceeded chemoselectively. When, cyclohexyl, i-propyl and t-butyl esters coexisted in the reaction system, only the methyl ester was easily transformed to the desired compounds in excellent yield. Furthermore, some protective groups were remained under this reaction condition.
detection of the elusive trifluoromethylradical. In contrast, long-chain TFMKs did not provide clues to prove formation of the trifluoromethylradical but instead to radicals derived by abstraction of one alpha-methylene proton to the carbonyl. Although TFMKs are quite stable to photodegradation in the absence of initiator, methyl ketone 2b and phenyl ketone 3 produce radicals resulting from abstraction
Reduction of trifluoromethyl ketones by a crude alcohol dehydrogenase from Geotrichum afford (S)-trifluoromethyl carbinols in excellent ee, whereas the reduction of methyl ketones gives the corresponding alcohols of the opposite configuration in excellent ee.
A new entry for the oxidation of fluoroalkyl-substituted methanol derivatives: Scope and limitation of the organoiodine(V) reagent-catalyzed oxidation
作者:Yusuke Tanaka、Takashi Ishihara、Tsutomu Konno
DOI:10.1016/j.jfluchem.2012.03.002
日期:2012.5
Oxidation of various fluoroalkyl-substituted methanol derivatives under the influence of a catalytic amount of sodium 2-iodobenzenesulfonate and Oxone® in CH3CN or CH3NO2 was investigated in detail. The efficiency of the newly developed oxidation was also evaluated by comparison to other oxidations, such as Dess–Martin, PDC, and Swern oxidation.
钠2-碘和过硫酸氢钾的催化量的影响下的各种氟烷基取代甲醇衍生物的氧化®在CH 3 CN或CH 3 NO 2详细进行了研究。通过与其他氧化方法(如Dess-Martin,PDC和Swern氧化方法)进行比较,还评估了新开发的氧化方法的效率。