Synthesis of Dibenzosiloles through Electrocatalytic Sila‐Friedel‐Crafts Reaction

Abstract

A novel electrocatalyzed method for the preparation of dibenzosiloles was developed through intramolecular C−H/Si−H dehydrogenative coupling strategy starting from biarylhydrosilanes. Both electro‐donating and electro‐withdrawing substitution groups were tolerated for this transformation, and the desired dibenzosilole products could be obtained in moderate to excellent yields. A sila‐Friedel‐Crafts reaction mechanism was proposed on the basis of previous literature and our controlled experiments.

Organoelectrophotocatalytic C–H Silylation of Heteroarenes

“…Electrochemical generation of silyl radicals has been reported via a stoichiometric NHPI-promoted HAT process and the cleavage of a Si–Cl bond or Si–B bond . However, the silyl radicals are easily further oxidized to silyl cations under electrooxidative conditions, in which the latter can be used to synthesize silanols and silicon-containing cyclic compounds . Merging the electrochemistry and photochemistry, the group of Zeng and Xu developed a photoelectrochemical method for the generation of silyl radicals by using a CeCl 3 /MeOH system, achieving the formation of silicon-functionalized benzimidazo-fused isoquinolinones …”

Recent advances in photo- and electro-enabled radical silylation

“…Later, Han, Jing, and co-workers demonstrated an electro-catalyzed method for the synthesis of dibenzosiloles through the intramolecular C–H/Si–H dehydrogenative coupling from biarylhydrosilanes (Scheme 30). 103 Both the electron-donating and electron-withdrawing substituted groups were tolerated in this reaction, delivering the desired products in moderate to good yields. Moreover, the substrate with the 3-pyridinyl group would react at the 4-position with high selectivity ( 117d ).…”

Photocatalytic Synthesis of Diarylmethyl Silanes via 1,6-Conjugate Addition of Silyl Radicals to p-Quinone Methides

“…On the other hand, photoredox catalysis has become a powerful tool for the construction of carbon–carbon and carbon–heteroatom bonds in the past decades owing to its mild, green, and high-efficient characteristics, and many excellent photocatalytic works have been reported . In 2017, Wu and co-workers developed an elegant silyl radical strategy for the hydrosilylation of electron-deficient and electron-rich alkenes through photoredox and hydrogen atom transfer (HAT). − Inspired by these studies and combined with our research interest in the construction of carbon–silicon bonds, we herein disclose a photoredox catalytic 1,6-addition of silyl radicals to p -QMs for the convenient preparation of diarylmethyl silanes (Scheme , 3).…”