New approach to α-pentafluorosulfanyl-substituted carboxylic acid derivatives via Ireland-Claisen rearrangements
New approach to α-pentafluorosulfanyl-substituted carboxylic acid derivatives via Ireland-Claisen rearrangements
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DOI：
10.1016/j.jfluchem.2014.05.006
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发表时间：
2014-11-01
影响因子：
1.9
通讯作者：
Haufe, Gunter
中科院分区：
文献类型：
--
作者：
Dreier, Anna-Lena;Matsnev, Andrej V.;Haufe, Gunter
提出了一种合成α-五氟硫基羧基化合物的新方法。以含氟或无氟的烯丙基醇与五氟硫烷基乙酰氯酯化制得的烯丙基酯为原料，通过Ireland-Claisen重排反应合成了一系列反式结构的γ，δ-不饱和α-五氟硫烷基羧酸。通过NMR光谱证实了作为关键步骤的中间体（E）-和（Z）-烯醇化物的形成，这也表明仅（Z）-烯醇化物重排，而（E）-烯醇化物在反应条件下是稳定的，并且在水处理期间水解回起始烯丙基酯。因此，观察到起始酯的不完全重排。将形成的酸转化成相应的甲酯允许更容易地分离所需的含五氟硫烷基的产物。(C)© 2014 Elsevier B. V.保留所有权利。
A new synthetic strategy towards alpha-pentafluorosulfanyl carboxyl compounds Was developed. Starting from allylic esters, which were prepared from fluorinated or fluorine free allylic alcohols by esterification with pentafluorosulfanylacetyl chloride, a range of trans-configured gamma,delta-unsaturated alpha-pentafluorosulfanyl carboxylic acids were synthesized via Ireland-Claisen rearrangements. The formation of intermediate (E)- and (Z)-enolates as the key-step was confirmed by NMR spectroscopy, which also indicated that only the (Z)-enolates rearrange, while the (E)-enolates are stable under the reaction conditions and hydrolyze back to the starting allylic esters during aqueous workup. As a consequence an incomplete rearrangement of the starting esters was observed. Transformation of the formed acids into the corresponding methyl esters allowed an easier isolation of the desired pentafluorosulfanyl-containing products. (C) 2014 Elsevier B.V. All rights reserved.