Vitamin B12 and hydrogen atom transfer cooperative catalysis as a hydride nucleophile mimic in epoxide ring opening

Epoxide ring-opening reactions have long been utilized to furnish alcohol products that are valuable in many subfields of chemistry. While many epoxide-opening reactions are known, the hydrogena-tive opening of epoxides via ionic means remains challenging because of harsh conditions and reactive hydride nucleophiles. Recent progress has shown that radical chemistry can achieve hy-drogenative epoxide ring opening under relatively mild conditions; however, these methods invariably require oxophilic metal catalysts and sensitive reagents. In response to these challenges, we report a new approach to epoxide ring-opening hydrogenation using bio-inspired Earth-abundant vitamin B12 and thiol-centric hydrogen atom transfer (HAT) co-catalysis to produce Markovnikov alcohols under visible light irradiation. This powerful reaction system ex-hibits a broad substrate scope, including a number of electrophilic and reductively labile functionalities that would otherwise be susceptible to reduction or cleavage by hydride nucleophiles, and preliminary mechanistic experiments are consistent with a radical process.