Formation of TEMPO Adducts with Hydrogen Atom Transfer: A New Pathway to Versatile Hydrofunctionalizations of Olefins

Since the seminal work by Mukaiyama, many research groups reported hydrofunctionalization of olefin with different metal hydrides in situ. Despite the rapid development of MHAT (metal-catalyzed hydrogen atom transfer)-derived reactions, the need for using different catalyst systems to accommodate different reactivities makes it not appealing. Here, we describe a two-step process to access a broad range of hydrofunctionalization of olefins. The first step involves a cobalt-catalyzed formation of TEMPO adduct from olefins. The reaction demonstrates a broad substrate scope and functional group tolerance. The second step involves a photocatalytic nucleophilic addition to generate a new C-C, C-N, C-O, C-F, and C-Cl bond. Interestingly with our methodology, nucleophilic fluorination could be achieved with a short reaction time, showing its potential in PET applications. Combining the two steps, a net hydrofunctionalization of olefins with a broad range can be achieved by simply changing the nucleophiles in the second step. Noteworthily, a two-step diastereoselective hydration of olefins was also demonstrated by employing the bulkiness of TEMPO.