Polymer-Incarcerated (PI) Pd-Catalyzed Semi-Hydrogenation of Alkynes

Significance

The authors demonstrated the selective semi-hydrogenation of alkynes to alkenes catalyzed by phosphinated polymer-incarcerated palladium catalysts (PI Pd catalyst). Thus, hydrogenation of alkynes catalyzed by non-phosphinated PI Pd catalysts 2c and 2d prepared by treatment of non-phosphinated copolymers 1c and 1d with Pd(PPh₃)₄ gave the corresponding alkane exclusively. However, when phosphinated PI Pd catalysts 2a and 2b were used, alkynes were converted into the corresponding semi-hydrogenated products in high yields as major products. Leaching of palladium was not detected in any case.