Nickel-Catalyzed Regioselective Hydroalkynylation of Nitrogen Heterocycle-Tethered Unactivated Alkenes

The hydroalkynylation of unactivated olefins presents a significant challenge, primarily due to difficulties in controlling the regioselectivity and competing reaction pathways. Herein, we report a practical NiH-catalyzed γ-selective hydroalkynylation of unactivated alkenes tethered to nitrogen heterocycles performed under external ligand-free conditions. This method provides structurally diverse alkynes in good to excellent yields with high regioselectivity and broad functional group tolerance. The synthetic utility of this approach is demonstrated through facile transformations of the products into other valuable scaffolds. Additionally, regioselectivity can be switched to the β position by employing DPPB/(TolSO₃)₂Ni·6H₂O as a catalyst. Preliminary mechanistic studies offer insight into the reaction pathway.