Wiesemann Markus, Klösener Johannes, Neumann Beate, Stammler Hans-Georg, Hoge Berthold
Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany.
Chemistry. 2018 Feb 6;24(8):1838-1843. doi: 10.1002/chem.201704807. Epub 2017 Dec 11.
Pentafluoroethyllithium, LiC F , has been established as an efficient and versatile reagent for the transfer of the pentafluoroethyl unit to a number of electrophiles. Here, the stability of this species up to -40 °C is of advantage, particularly in comparison to its smaller congener LiCF . The usual production of LiC F , however, from gaseous HC F or IC F and strong bases requires specially designed apparatuses, which severely impeded its value as a laboratory reagent. In this contribution we communicate an alternative gas-free and highly efficient protocol for the synthesis of LiC F from the already commercialized stannate salt [PPh ][Sn(C F ) ]. The [Sn(C F ) ] anion represents not only the first example of a structurally characterized hypervalent pentaalkylstannate but also serves as a precursor for the synthesis of the homoleptic tetrakis(pentafluoroethyl)stannane, Sn(C F ) . The reaction of the latter with n-butyllithium provides an insight into the mechanism of LiC F generation.
五氟乙基锂（LiCF₂CF₃）已被确立为一种高效且通用的试剂，可将五氟乙基单元转移至多种亲电试剂上。在此，该物种在高达 -40°C 时的稳定性具有优势，特别是与其较小的同系物 LiCF₃ 相比。然而，通常由气态 HC₂F₄ 或 IC₂F₄ 与强碱制备 LiCF₂CF₃ 需要专门设计的仪器，这严重限制了其作为实验室试剂的价值。在本论文中，我们报道了一种替代的无气且高效的方法，用于从已商业化的锡酸盐 [PPh₄][Sn(C₂F₅)₅] 合成 LiCF₂CF₃。[Sn(C₂F₅)₅]⁻ 阴离子不仅代表了结构表征的高价五烷基锡酸盐的首个实例，还用作合成均配四（五氟乙基）锡烷（Sn(C₂F₅)₄）的前体。后者与正丁基锂的反应为 LiCF₂CF₃ 的生成机理提供了见解。
