Unlocking Reductive Iron-Hydride Hydrogen Atom Transfer Catalysis for Silane- and Oxidant-Free Intramolecular Hydroarylation of Alkenes

Reductive metal-hydride hydrogen atom transfer (MHAT) catalysis generates metal hydride species through electron and proton transfer. Recent advances in photocatalytic and electrocatalytic cobalt-based systems offer sustainable alternatives to conventional oxidative MHAT methods. However, reductive MHAT processes involving other transition metals remain underdeveloped, highlighting the need for more versatile and environmentally benign platforms. Herein, we report an intramolecular hydroarylation of unactivated alkenes under an iron/photocatalyst dual catalytic system. In this process, reductive generation of a low-valent iron intermediate, followed by protonation, affords the key iron hydride species, thereby expanding reductive MHAT catalysis beyond the previously established cobalt-based paradigm.