Remote-Markovnikov Hydrobromination and Hydrochlorination of Allyl Carboxylates via Dual Photoredox/Cobalt Catalysis

Alkyl halides are ubiquitous motifs in pharmaceuticals, agrochemicals, and materials, yet direct access to regioisomeric variants re-mains limited. Conventional hydrohalogenation of alkenes proceeds via ionic or radical pathways and is generally confined to 1,2-addition. Here, we report a dual cobalt/photoredox catalytic platform that enables remote-Markovnikov-selective 1,3-hydrobromination and hydrochlorination of allyl carboxylates. The transformation proceeds via a metal–hydride hydrogen atom transfer (MHAT) from a Co–H species, 1,2-radical acyloxy migration (1,2-RAM), and halogen atom transfer (XAT) from a Co–X complex. This strategy delivers β-acyloxy alkyl halides under mild conditions, with broad functional group tolerance, compatibility with complex molecules, and scalability. Mechanistic experiments support a radical relay sequence that diverges from classical regi-oselectivity to access formal 1,3-addition products. This work establishes a general approach to regioselective C–X bond formation via programmable radical migration and expands the synthetic toolbox for alkene hydrofunctionalization.