Selective Hydrogenation of Functionalized Alkynes to ( E )-Alkenes, Using Ordered Alloys as Catalysts

Intermetallic Pd 3 Pb acts as a highly selective alkyne semihydrogenation catalyst that is greatly superior to the conventional Lindlar catalyst. Density functional theory (DFT) calculations demonstrate an ideal adsorption property of Pd 3 Pb, where the surface holds alkynes while releasing alkenes. A tandem catalytic system that is comprised of Pd 3 Pb/SiO 2 for alkyne semihydrogenation and RhSb/SiO 2 for alkene isomerization allows one-pot ( E )-alkene synthesis from a functionalized alkyne, which is the first success using heterogeneous catalysts. A variety of functionalized alkynes with aldehyde, ketone, carboxylic acid, and ester moieties are hydrogenated into the corresponding ( E )-alkene in good to excellent yields under 1 atm H 2 at room temperature.