Visible-Light-Driven Palladium-Catalyzed Cyclocarbonylative Synthesis of Aliphatic Lactones.

We describe herein a palladium-catalyzed carbonylative route for preparing substituted lactones from aliphatic bromoalcohols. This exploits the ability of photoexcited palladium catalysts to activate C(sp3)-bromides in concert with irreversible thermal reductive elimination to access substituted five-membered lactones under mild conditions, from available reagents, and where regioselectivity is defined by the substrate.