<i>Remote</i> -Markovnikov Hydrobromination and Hydrochlorination of Allyl Carboxylates via Dual Photoredox/Cobalt Catalysis
Arman Khosravi, Yuxin Zhang, Gaoyuan Zhao, Kelton Radefeld, Sahil Sharma, Nuwan Pannilawithana, Yuxiang Zhang, Peng Liu, Ming‐Yu Ngai
Abstract
Alkyl halides are ubiquitous motifs in pharmaceuticals, agrochemicals, and materials, yet direct access to regioisomeric variants remains 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 regioselectivity 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.