Cobalt‐Catalyzed Stereodivergent Semihydrogenation of Alkynes: Synthesis of E‐ and Z‐Alkenes

Transition metal‐catalyzed semihydrogenation of alkynes is one of the most efficient, sustainable, and environmental‐friendly strategies for accessing stereoisomerically pure olefins. Herein, we report a tridentate nitrogen‐containing ligand (8‐OIQ) promoted cobalt‐catalyzed stereodivergent semihydrogenation of internal alkynes, a series of Z‐ and E‐alkenes could be synthesized with high stereoselectivity. Besides, this protocol exhibits excellent functional group tolerance and operates under mild reaction conditions (1 bar H2, room temperature). A preliminary mechanistic study revealed that acetonitrile plays an important role in suppressing over‐reduction and controlling the stereoselectivity in this transformation.