Synergistic Hydrocobaltation and Borylcobaltation Enable Regioselective Migratory Triborylation of Unactivated Alkenes

The structural diversity of sp3‐triorganometallic reagents enhances their potentiality in the modular construction of molecular complexity in chemical synthesis. Despite significant achievements on the preparation of sp3 1,1,1‐ and 1,1,2‐triorganometallic B,B,B‐reagents, catalytic approaches that enable the installation of multiple boryl groups at skipped carbons of unactivated alkenes still remain elusive. Herein, we report a cobalt‐catalyzed selective triborylation reaction of unactivated alkenes to access synthetically versatile 1,1,3‐triborylalkanes. This triborylation protocol provides a general platform for regioselective trifunctionalization of unactivated alkenes, and its utility is highlighted by the synthesis of various value‐added chemicals from readily accessible unactivated alkenes. Mechanistic studies, including deuterium‐labelling experiments and evaluation of potential reactive intermediates, provide insight into the experimentally observed chemo‐ and regioselectivity. A regioselective cobalt‐catalyzed triborylation of unactivated alkenes is developed to access synthetically versatile 1,1,3‐triborylalkanes with a catalyst generated from Co(acac)2 and xantphos. Mechanistic studies reveal that this triborylation reaction proceeds through three interdependent catalytic cycles.