Dual Photoredox/Cobalt Catalysis Enabled Regiospecific Markovnikov Hydroboration of Unactivated Mono-, Di-, and Trisubstituted Alkenes

Hydroboration of alkenes constitutes an important synthetic tool to assemble valuable alkylboron molecules. Although various protocols have been developed, the regiospecific Markovnikov reactions of unactivated alkenes, in particular for trisubstituted ones, remain a formidable challenge. Here, we report a general method for the Markovnikov hydroborylation of unactivated mono-, di- and trisubstituted alkenes enabled by dual photoredox/cobalt catalysis. The reaction proceeds via a photoinduced metal-hydride hydrogen atom transfer (MHAT) of unactivated alkenes followed by a versatile radical borylation process. This strategy is characterized by its unique Markovnikov selectivity, mild reaction conditions, high catalytic efficiency and broad substrate scope. This method demonstrates a new reaction pattern that achieves the hydroboration of unactivated alkenes through the combination of reductive MHAT and radical borylation. Moreover, this catalytic system could also be applied to complex substrates derived from natural products.