Synthesis of substituted (trifluoromethyl)alkenes: (Trifluoromethyl)alkylidenation of thioketones via CF3-thiiranes

IF 1.7 4区化学 Q3 CHEMISTRY, INORGANIC & NUCLEAR

Journal of Fluorine Chemistry Pub Date : 2024-03-23 DOI:10.1016/j.jfluchem.2024.110273

Kohei Fuchibe , Tomoya Matsunobu , Junji Ichikawa

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Abstract

The synthesis of (trifluoromethyl)alkenes, including fully substituted variants, was achieved from thioketones with in situ-generated (trifluoromethyl)diazoalkanes [CF₃C(R)=N₂] (the Barton–Kellogg reaction). In the presence of sodium methoxide and a catalytic amount of tetrabutylammonium chloride, trifluoromethylated N-tosylhydrazones [CF₃C(R)=NNHTs] derived from trifluoroacetaldehyde hemiacetal (R = H) or trifluoromethyl ketones (R = aryl or alkyl) were employed in the reactions with thioketones. The resulting (trifluoromethyl)diazoalkanes reacted with thioketones, forming (trifluoromethyl)thiirane intermediates. Treatment of these intermediates with trimethyl phosphite readily afforded the substituted (trifluoromethyl)alkenes. Theoretical calculations (DFT, B3LYP/6-31G*) showed that (trifluoromethyl)thiiranes, with less distortion than 2,2-difluorothiiranes, exhibited lower reactivity. Consequently, the involvement of a reducing agent was deemed necessary for the desulfurization step.

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取代的（三氟甲基）烯的合成：通过 CF3-环烷对硫酮进行（三氟甲基）亚烷基化反应

利用原位生成的（三氟甲基）重氮烷烃 [CF3C(R)=N2]（巴顿-凯洛格反应），从硫酮中合成了（三氟甲基）烯，包括完全取代的变体。在甲醇钠和一定量的四丁基氯化铵催化下，由三氟乙醛半缩醛（R = H）或三氟甲基酮（R = 芳基或烷基）衍生的三氟甲基化 N-对甲苯磺酰肼[CF3C(R)=NNHTs]被用于与硫酮的反应。生成的（三氟甲基）重氮烷与硫酮反应，形成（三氟甲基）硫烷中间体。用亚磷酸三甲酯处理这些中间体，很容易得到取代的（三氟甲基）烯。理论计算（DFT，B3LYP/6-31G*）表明，(三氟甲基)硫环烷的畸变小于 2,2-二氟硫环烷，反应活性较低。因此，脱硫步骤需要还原剂的参与。

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来源期刊

Journal of Fluorine Chemistry 化学-无机化学与核化学

CiteScore

3.80

自引率

10.50%

发文量

审稿时长

33 days

期刊介绍： The Journal of Fluorine Chemistry contains reviews, original papers and short communications. The journal covers all aspects of pure and applied research on the chemistry as well as on the applications of fluorine, and of compounds or materials where fluorine exercises significant effects. This can include all chemistry research areas (inorganic, organic, organometallic, macromolecular and physical chemistry) but also includes papers on biological/biochemical related aspects of Fluorine chemistry as well as medicinal, agrochemical and pharmacological research. The Journal of Fluorine Chemistry also publishes environmental and industrial papers dealing with aspects of Fluorine chemistry on energy and material sciences. Preparative and physico-chemical investigations as well as theoretical, structural and mechanistic aspects are covered. The Journal, however, does not accept work of purely routine nature. For reviews and special issues on particular topics of fluorine chemistry or from selected symposia, please contact the Regional Editors for further details.