Catalyst-free photoinduced dehalogenation and functionalization of alkyl halides using Lewis bases

Abstract

Alkyl halides are foundational building blocks in organic synthesis and valuable commodity chemicals. While numerous pathways have been developed to functionalize these groups into higher value compounds, most of the methods require the use of transition metals and associated ligands, which increase the footprint of these transformations. Simultaneously, dehalogenation of these materials to their corresponding C(sp3)-H forms has been limited despite the regulatory incentives to phase-out the use of halogenated compounds due to their innate toxicities and environmental impact. As such, the upcycling of alkyl halides and forever chemicals, via functionalization or dehalogenation strategies, needs the development of novel methods that are sustainable and cost-effective. Herein, we present a photoinduced functionalization and defunctionalization of alkyl halides using Hünig's base (diisopropylethylamine). This protocol can successfully reduce, chalcogenate, and borylate a broad range of aliphatic halides. Emphasizing the low footprint of this reaction, the transformation only requires a commodity Lewis base, a green solvent, and light, thereby offering a more sustainable alternative to conventional pathways.