An Electrochemical Strategy to Synthesize Disilanes and Oligosilanes from Chlorosilanes**

Abstract

Silanes are important compounds in industrial and synthetic chemistry. Here, we develop a general approach for the synthesis of disilanes as well as linear and cyclic oligosilanes via the reductive activation of readily available chlorosilanes. The efficient and selective generation of silyl anion intermediates, which are arduous to achieve by other means, allows for the synthesis of various novel oligosilanes by heterocoupling. In particular, this work presents a modular synthesis for a variety of functionalized cyclosilanes, which may give rise to materials with distinct properties from linear silanes but remain challenging synthetic targets. In comparison to the traditional Wurtz coupling, our method features milder conditions and improved chemoselectivity, broadening the functional groups that are compatible in oligosilane preparation. Computational studies support a mechanism whereby differential activation of sterically and electronically distinct chlorosilanes are achieved in an electrochemically driven radical‐polar crossover mechanism.

Deep Electroreductive Chemistry: Harnessing Carbon- and Silicon-Based Reactive Intermediates in Organic Synthesis

“…Electroreductive silyl cross-electrophile coupling . (A) Reaction design of electroreductive disilylation of alkenes and DFT calculations support for the proposed mechanism.…”

“…We were interested in applying the principles of e-XEC to achieve Si–Si cross-electrophile coupling starting from chlorosilanes with distinct redox potentials and steric properties (Figure A) . For example, a chlorosilane with an aromatic stabilizing group ( 11 - 1 ) would preferentially undergo an overall two-electron reduction to form a silyl anion ( 11 - 4 ) in the presence of a di- or trialkylchlorosilane ( 11 - 3 ); the ensuing silyl anion would then selectively attack the sterically less encumbered di- or trialkylchlorosilane to complete the Si–Si bond formation ( 11 - 5 ).…”

Iterative Synthesis of Oligosilanes Using Methoxyphenyl- or Hydrogen-Substituted Silylboronates as Building Blocks: A General Synthetic Method for Complex Oligosilanes

“…Organosilicon compounds − are widely used, indispensable compounds in academic research and industry. Due to the general reaction similarities between the group-14 elements carbon and silicon, it is expected that a wide variety of organosilicon compounds could be synthesized in the same way as organic compounds.…”

“…However, while there are currently over 200 million registered structures for organic compounds, the number of known organosilicon compounds is less than ∼1.4 million (<1%) . This lack of diversity in organosilicon compounds is primarily due to the limited number of synthetic routes to organosilicon compounds compared to other organic compounds. − …”

“…Tamao has reported that the structural constraint of the silicon main chain in polysilanes has a significant effect on their optical properties . Although oligosilanes with simple and repeating units can be synthesized by homocoupling, more complicated organosilane compounds that consist of different substituents with a defined sequence generally require customized synthetic procedures. , If oligosilanes with different side chains could be synthesized more easily, our knowledge of such silicon materials can be expected to advance significantly. General synthetic methods for various oligosilanes comparable to those used in carbon-based organic synthesis are thus strongly desirable for the development of advanced oligosilane-based materials.…”