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

Abstract

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.