Radical Group Transfer of Vinyl and Alkynyl Silanes Driven by Photoredox Catalysis

Abstract

Radical group transfer is a powerful tool for the formation of C–C bonds. These processes typically involve radical addition to C–C π bonds, followed by fragmentation of the cyclic intermediate. Despite the advantageous lability of organosilanes in this context, silicon-tethered radical acceptor groups have remained underexplored in radical group transfer reactions. We report a general photoredox-catalyzed protocol for the radical group transfer of vinyl and alkynyl silanes onto sp3 carbons, using activated and unactivated iodides as radical precursors. Our method displays high diastereoselectivity and excellent functional group tolerance. Mechanistic investigations revealed the key role played by silicon in facilitating a single-electron oxidation step, which leads to direct ring-opening and an overall redox-neutral process.

Radical Group Transfer of Vinyl and Alkynyl Silanes Driven by Photoredox Catalysis

“…This unusual dual catalytic cycle results in an overall redox-neutral radical group transfer reaction that can be performed with catalytic amounts of amine. We expect that this process can also be applied in the initiation of other radical transformations, and that the improved understanding of the reactivity of silicon-based radical acceptors can be exploited in the synthesis of complex molecular scaffolds through radical cyclization/fragmentation strategies …”

“…We expect that this process can also be applied in the initiation of other radical transformations, and that the improved understanding of the reactivity of silicon-based radical acceptors can be exploited in the synthesis of complex molecular scaffolds through radical cyclization/fragmentation strategies. 35 …”