清华大学Wei He团队通过Rh催化C-H硅烷化反应的计算和实验综合研究以期为开发一种更有效的催化体系提供见解。 相关研究成果发表在2021年2月23日出版的《美国化学会杂志》。

新型C-H硅烷化试剂及其反应的研究一直是一个重要的课题。

研究人员报道了在Rh催化下，硅环丁烷（SCBs）首次能够与C（sp2）–H和C（sp3）–H键反应，但这种新反应的根本原因尚不清楚。通过计算和实验相结合的研究，研究人员不仅描述了一个充分说明反应性和所有实验结果的反应途径，而且简化了一个更有效的催化剂，大大提高了反应速率和产率。

研究人员的主要发现包括：（1）活性催化物种是[Rh]-H，而不是先前提出的[Rh]-Cl；（2）通过还原消除/β-氢化物（β-H）消除序列生成[Rh]-H，而不是先前提出的内环β-H消除；（3）确定了区域和对映决定步骤；（4） 同样重要的是，离散合成的[Rh]-H被证明是一种更有效的催化剂。

该研究工作表明，[Rh]-H/二膦体系在涉及SCBs的C-H硅烷化反应中有进一步的应用前景。

附：英文原文

Title: A Combined Computational and Experimental Study of Rh-Catalyzed C–H Silylation with Silacyclobutanes: Insights Leading to a More Efficient Catalyst System

Author: Linxing Zhang, Kun An, Yi Wang, Yun-Dong Wu, Xinhao Zhang, Zhi-Xiang Yu, Wei He

Issue&Volume: February 23, 2021

Abstract: The study of new C–H silylation reagents and reactions remains an important topic. We reported that under Rh catalysis, silacyclobutanes (SCBs) for the first time were able to react with C(sp2)–H and C(sp3)–H bonds, however the underlying reasons for such a new reactivity were not understood. Through this combined computational and experimental study on C–H silylation with SCBs, we not only depict a reaction pathway that fully accounts for the reactivity and all the experimental findings but also streamline a more efficient catalyst that significantly improves the reaction rates and yields. Our key findings include: (1) the active catalytic species is a [Rh]–H as opposed to the previously proposed [Rh]–Cl; (2) the [Rh]–H is generated via a reductive elimination/β-hydride (β-H) elimination sequence, as opposed to previously proposed endocyclic β-H elimination; (3) the regio- and enantio-determining steps are identified; (4) and of the same importance, the discretely synthesized [Rh]–H is shown to be a more efficient catalyst. This work suggests that the [Rh]–H/diphosphine system should find further applications in C–H silylations involving SCBs.

DOI: 10.1021/jacs.0c13335

Source: https://pubs.acs.org/doi/10.1021/jacs.0c13335