Cobalt Hydride-Catalyzed Hydroalkynylation of Alkenes with Alkynyl Trifluoroborates

A cobalt-catalyzed hydroalkynylation of alkenes with alkynyl trifluoroborates is described, proceeding through a cobalt hydride-mediated radical-polar crossover metal hydrogen-atom-transfer process. This method affords structurally diverse alkynyl-containing compounds in high yields under mild conditions and features a wide substrate scope, good functional group tolerance, and suitability for late-stage functionalization of relatively complex natural products and bioactive molecules. Expanding the scope to alkenyltrifluoroborate salts further increases the utility of the developed methodology. This approach paves an alternative route for radical-involved alkynylation and alkenylation reactions of alkenes with nucleophilic alkynyl/alkenyl reagents.