Xanthate-mediated synthesis of (E)-alkenes by semi-hydrogenation of alkynes using water as the hydrogen donor.

Semi-hydrogenation of alkynes is one of the most widely used methods for obtaining alkenes in laboratory preparation and in industry. Transition metal catalysts have been extensively studied for this transformation, but the tolerance of functional groups, such as pyridine, -OH, -NH2, -Bpin, and halides, and the toxicity of the trace amount of transition metal catalysts are still highly challenging. In this study, we report a general and robust strategy to achieve the semi-hydrogenation of alkynes using inexpensive and commercially available xanthate as the mediator. Mechanism studies support a non-radical process and H2O acts as the hydrogen donor.