Photocatalytic activation of carbon–halogen bonds

Abstract

Organic halides are important building blocks in synthesis, but their use in (photo)redox chemistry is limited by their highly negative reduction potentials. Nevertheless, they have been activated through Single Electron Transfer strategies, which very often remained limited to reductive dehalogenation reactions. Halogen-atom transfer remains to this date the most reliable approach to exploit these substrates in radical processes despite its requirement for hazardous reagents and initiators such as tin hydride. In recent years, photoredox catalysis driven by visible light has often been used to oxidise carbon centers adjacent to nitrogen atoms. In this study, we demonstrate that the transient radical cation is transformed into the corresponding α-aminoalkyl radicals. Those species are able to promote the homolytic activation of carbon–halogen bonds with a reactivity profile mirroring that of tin radicals, while displaying a better safety profile. This strategy engages alkyl and aryl halides in a wide range of transformations to assemble sp3-sp3, sp3-sp2, and sp2-sp2 carbon-carbon bonds under mild conditions with high chemoselectivity. We also demonstrated the possibility of merging our Halogen Atom Transfer approach with transition metals.

Date of Award	31 Dec 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Guillaume De Bo (Supervisor), Igor Larrosa (Supervisor) & Daniele Leonori (Supervisor)