德国柏林工业大学Martin Oestreich研究团队开发出芳基离子催化的全烷基化硅烷的卤代脱烷基反应。相关论文于2023年10月11日发表在《自然》杂志上。

在该研究中，研究团队介绍了一种芳基离子催化的卤化脱烷基反应，有效地将Me₄Si和相关的季硅烷转化为各种功能化衍生物。该反应以烷基卤化物和芳烃(共)溶剂为主体：烷基卤化物是卤源，最终与芳烃发生付-克烷基化反应，使催化剂再生，而芳基离子则作为强Bronsted酸用于原脱烷基步骤。

这种自上而下的卤代脱烷基方法比报道的自下而上的方式具有优势，例如在含硅药物前体的合成中得到体现。此外，与烷基链相连的较为惰性的Me₃Si基团的化学选择性氯去甲基化，以及随后的氧化降解，被证明是进入Tamao - Fleming醇合成的一个入口。

研究人员表示，“有机硅”不存在于自然界，但现代化学很难想象没有硅与碳结合的情况。虽然从“直接工艺”中产生的含硅商品化学品看起来很简单，但选择性地制备芳基取代和烷基取代(功能化)的硅化合物(称为硅烷)并非易事。氯硅烷，如Me_4-nSiCl_n (n= 1-3)和SiCl₄ (n= 4)是合成含硅分子的常见起始点。然而，这些方法常常受到分离问题的困扰。相反，四个烷基取代的硅烷过去被认为是合成的尽头。

附：英文原文

Title: Arenium-ion-catalysed halodealkylation of fully alkylated silanes

Author: He, Tao, Klare, Hendrik F. T., Oestreich, Martin

Issue&Volume: 2023-10-11

Abstract: ‘Organic silicon’ is not found in nature but modern chemistry is hard to imagine without silicon bound to carbon. Although silicon-containing commodity chemicals such as those emerging from the ‘direct process’1,2,3,4 look simple, it is not trivial to selectively prepare aryl-substituted and alkyl-substituted (functionalized) silicon compounds, known as silanes. Chlorosilanes such as Me4nSiCln (n=1–3) as well as SiCl4 (n=4) are common starting points for the synthesis of silicon-containing molecules. Yet these methods often suffer from challenging separation problems5. Conversely, silanes with four alkyl groups are considered synthetic dead ends. Here we introduce an arenium-ion-catalysed halodealkylation that effectively converts Me4Si and related quaternary silanes into a diverse range of functionalized derivatives. The reaction uses an alkyl halide and an arene (co)solvent: the alkyl halide is the halide source that eventually engages in a Friedel–Crafts alkylation with the arene to regenerate the catalyst6, whereas the arenium ion acts as a strong Brnsted acid for the protodealkylation step7. The advantage of the top-down halodealkylation methodology over reported bottom-up procedures is demonstrated, for example, in the synthesis of a silicon drug precursor. Moreover, chemoselective chlorodemethylation of the rather inert Me3Si group attached to an alkyl chain followed by oxidative degradation is shown to be an entry into Tamao–Fleming-type alcohol formation8,9.

DOI: 10.1038/s41586-023-06646-9

Source: https://www.nature.com/articles/s41586-023-06646-9