Table 1. Catalytic Semihydrogenation of Alkynes^a.

^aReaction conditions: 1 (0.3 mmol), Mg-1 (3 mol %), H₂ (5 bar), toluene (0.5 mL), 120 °C, 24 h. Reaction yields were determined by ¹H NMR using 1,3,5-trimethoxybenzene as the internal standard. Isolated yields are in parentheses. The Z/E ratio was determined by ¹H NMR of the crude solution. The over-reduction products were less than 3% in all cases unless noted otherwise.

^bYield in parenthesis was obtained from a 6 mmol scale reaction.

^c5 mol % catalyst, 8 bar of H₂, and 36 h reaction time.

^dWith 5% over-reduction product.

^eWith 7% over-reduction product, the isolated yield in parenthesis contains 7% over-reduction product.