Boron-Mediated Hydroalkylation of Unactivated Olefins: An <i>Anti</i> -Markovnikov Approach to Congested Carbon Centers

Transition metal-catalyzed hydroalkylations offer efficient routes to install alkyl fragments onto readily available olefins. However, the formation of quaternary carbon centers through olefin hydroalkylations with tertiary alkyl electrophiles remains a formidable synthetic challenge. Difficulty arises as a result of steric congestion, which slows the rate of oxidative addition and promotes deleterious β-hydride elimination. Here, we report a boron-mediated coupling strategy using nickel/photoredox dual catalysis that circumvents these limitations and enables <i>anti</i>-Markovnikov hydroalkylations of unactivated olefins with carboxylic acid derivatives as alkylating partners. Our protocol proceeds via initial hydroboration, followed by a sequence of deboronative and decarboxylative radical generation, radical sorting, and bimolecular homolytic substitution (S_H2). This mild and practical approach allows the construction of densely substituted carbon frameworks, including sterically congested quaternary carbon centers, providing a solution to a long-standing challenge in fragment-coupling chemistry.