2010 年 68 巻 9 号 p. 920-929
In an effort to create reusable, Pd-leach-free catalysts, many heterogeneous catalysts have been developed with Pd immobilized on supports such as activated carbon, inorganic solids and polymers. Yet few of these immobilized Pd catalysts for C-C bond formations can claim both high recyclability (>10 times) and low Pd-leaching (<1 ppm).
We successfully developed a practical Pd material, SGPd (Sulfur-modified GaAs(001) supported Pd) and SAPd (Sulfur-modified Au supported Pd) whose Pd was immobilized on sulfur-modified GaAs(001) or Au, respectively. With the lowest Pd-releasing levels and high recyclability, this is one of the best Pd materials thus far developed. It became clear that actual active species is released Pd in the reaction mixture through detailed mechanistic experiments. Because it leaches extremely low levels of Pd into reaction mixtures, removal of the residual Pd is unnecessary especially using SAPd, even in syntheses involving pharmaceutical ingredients.