Site-selective aliphatic C-H bromination using N-bromoamides and visible light.

Transformations that selectively functionalize aliphatic C-H bonds hold significant promise to streamline complex molecule synthesis. Despite the potential for site-selective C-H functionalization, few intermolecular processes of preparative value exist. Herein, we report an approach to unactivated, aliphatic C-H bromination using readily available N-bromoamide reagents and visible light. These halogenations proceed in useful chemical yields, with substrate as the limiting reagent. The site selectivities of these radical-mediated C-H functionalizations are comparable (or superior) to the most selective intermolecular C-H functionalizations known. With the broad utility of alkyl bromides as synthetic intermediates, this convenient approach will find general use in chemical synthesis.