General Synthesis of Trialkyl- and Dialkylarylsilylboranes: Versatile Silicon Nucleophiles in Organic Synthesis
General Synthesis of Trialkyl- and Dialkylarylsilylboranes: Versatile Silicon Nucleophiles in Organic Synthesis
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DOI：
10.1021/jacs.0c03011
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发表时间：
2020-08-19
影响因子：
15
通讯作者：
Ito, Hajime
中科院分区：
文献类型：
--
作者：
Shishido, Ryosuke;Uesugi, Minami;Ito, Hajime
与碳基亲核试剂相比，目前可用的硅基亲核试剂数量仍然有限，这大大阻碍了可合成的硅基分子的结构多样性。由于碳基硼亲核试剂的合成效率高，易于操作，近年来，硅基硼亲核试剂，即硅基硼烷，作为由过渡金属催化剂或碱活化的亲核硅化试剂引起了人们的极大兴趣。然而，实际可获得的硅基硼烷的范围仍然有限。特别是，空间受阻和官能化的硅基硼烷的制备仍然是一个重大的挑战。在这里，我们报道了在含氢硅烷与双(频那多)二硼的直接硼化反应中使用的Rh和Pr催化剂，这使得我们可以合成带有大量烷基和官能团的新的三烷基硅烷以及用传统方法很难用碱金属合成的新的二烷基芳基硅烷。我们进一步证明了这些化合物可以在有机转化中用作硅亲核试剂，与以前报道的方法相比，这大大扩展了可合成的有机硅化合物的范围。因此，本研究可望为开发新型含硅生物活性分子和具有理想性能的有机材料提供有效的方法。我们还首次报道了I-Pr3Si-B(Pin)与Meli反应生成I-Pr3SiLi的B-11{H-1}和Si-29(H-1)核磁共振谱证据。
Compared to carbon-based nucleophiles, the number of silicon-based nucleophiles that is currently available remains limited, which significantly hampers the structural diversity of synthetically accessible silicon-based molecules. Given the high synthetic utility and ease of handling of carbon-based boron nucleophiles, silicon-based boron nucleophiles, i.e., silylboranes, have attracted considerable interest in recent years as nucleophilic silylation reagents that are activated by transition-metal catalysts or bases. However, the range of practically accessible silylboranes remains limited. In particular, the preparation of sterically hindered and functionalized silylboranes remains a significant challenge. Here, we report the use of rhodium and platinum catalysts for the direct borylation of hydrosilanes with bis(pinacolato)diboron, which allows the synthesis of new trialkylsilylboranes that bear bulky alkyl groups and functional groups as well as new dialkylarylsilylboranes that are difficult to synthesize via conventional methods using alkali metals. We further demonstrate that these compounds can be used as silicon nucleophiles in organic transformations, which significantly expands the scope of synthetically accessible organosilicon compounds compared to previously reported methods. Thus, the present study can be expected to inspire the development of efficient methods for novel silicon-containing bioactive molecules and organic materials with desirable properties. We also report the first B-11{H-1} and Si-29(H-1) NMR spectroscopic evidence for the formation of i-Pr3SiLi generated by the reaction of i-Pr3Si-B(pin) with MeLi.