Electrochemical Radical Silyl‐Oxygenation of Activated Alkenes

Abstract

An efficient electrochemical radical silyl-oxygenation of electron-deficient alkenes is demonstrated, which gives access to a variety of new highly functionalized siliconcontaining molecules, including b-silyl-cyanohydrin derivatives in good yields with excellent chemo-and regio-selectivity. This electrochemical radical silylation process conducts under mild conditions without the use of transition metal catalyst or chemical oxidant and exhibits a wide scope of substrate silanes with high functional-group tolerance. The ability to access silyl radicals using electrochemical SiÀH activation offers new perspectives for the synthesis of valuable organosilicon compounds in a sustainable and green manner. Scheme 1. Radical 1,2-silylfunctionalization of alkenes.

General Concepts and Recent Advances in the Electrochemical Transformation of Chloro‐ and Hydrosilanes

“…Another important function of the supporting electrolyte is the stabilization of the silyl intermediate in the reaction. Anodically generated silyl species, i. e. via the oxidation of hydrosilanes, can be well stabilized by weakly coordinating anions, such as ClO 4 − , [60,69,70] BF 4 − , [71] and PF 6 − [72] . Mg 2+ has been shown to be particularly suitable for the stabilization of cathodically generated intermediates, which has a positive effect on the yield obtained by electrochemical conversion [56,67,73,74] .…”

Electrochemical Difunctionalization of Alkenes

“…He and co-workers developed an efficient electrochemical strategy for the silyl-oxygenation of electron-deficient alkenes to obtain a variety of new highly functional silicon-containing molecules with good chemical selectivity and regional selectivity (Scheme 24 ). 19 Upon the reactive electrolysis of the graphite anode and Pt plate cathode, a wide range of triarylsilanes bearing electronically and sterically varied substituents on the aryl ring underwent the difunctionalization smoothly with various electron-deficient alkenes and N -hydroxyphthalimides in the electrochemical reaction to produce the corresponding silicon-containing molecules. Triarylsilanes with different electronic and spatial substituents on the aryl group and alkylsilanes are suitable for this conversion.…”

Recent advances in photo- and electro-enabled radical silylation

“…In the same year, He and co-workers demonstrated an efficient electrochemical radical silyl-oxygenation of electrondeficient alkenes, giving access to a variety of new highly functionalized silicon-containing molecules in good yields with excellent chemo-and regio-selectivities (Scheme 28). 102 A wide range of triarylsilanes, heterocyclic silanes, methyldiphenylsilanes, and dihydrosilanes all reacted smoothly with acrylonitrile and N-hydroxyphthalimide, delivering the corresponding β-silyl-cyanohydrin products 113a-113c in good to excellent yields. Moreover, a variety of electron-deficient alkenes and N-oxyl species were also tolerated in this transformation (113d-113i).…”