Cobalt-catalyzed alkene hydrohalogenation via hydrogen atom transfer

Alkene hydrohalogenation is a fundamental transformation for the synthesis of organohalides, key intermediates in organic synthesis, pharmaceuticals, and materials science. Traditional ionic methods with hydrogen halides are limited by harsh conditions, poor functional group tolerance, and regioselectivity issues. Recently, cobalt-catalyzed hydrohalogenation via metal-hydride hydrogen atom transfer (MHAT) has emerged as a versatile and radical-based alternative, enabling mild conditions, broad functional group tolerance, and tunable regioselectivity. This mini-review provides a comprehensive overview of the development in cobalt-catalyzed alkene hydrohalogenation via MHAT, with particular emphasis on methodological innovations, substrate scopes, mechanistic principles, and emerging applications. The continued growth of this field is poised to expand the synthetic utility and sustainability of alkene hydrofunctionalization, opening new avenues for programmable C–X bond formation across diverse chemical contexts.