Carbon-Carbon Bond Formation by Ligand-free Cross-Coupling Reaction Using Palladium Catalyst Supported on Synthetic Adsorbent

A palladium catalyst supported on a commercial synthetic adsorbent, DIAION HP20, could be employed for the crosscoupling reactions of aryl halides with organoboronic acids (Suzuki–Miyaura reaction), alkenes (Mizoroki–Heck reaction), and alkynes (Sonogashira reaction) in a ligand‐free manner. 10 % Pd/HP20 was highly active as the catalyst at approximately the same level as 10 % palladium on carbon (10 % Pd/C) for many of the reactions, and was especially effective for the Suzuki–Miyaura reaction using bromoaniline derivatives without the N‐protection and Sonogashira reaction of the heteroaryl iodides. As a stable supply and certain quality of HP20 are available as an industrial product, 10 % Pd/HP20 would be in practical use for a variety of cross‐coupling reactions and hydrogenation as the substitute for 10 % Pd/C, which is dependent on charcoal as a natural product. A reaction trident! 10 % Pd/HP 20, palladium supported on a commercial synthetic adsorbent, could efficiently catalyze the Suzuki–Miyaura, Mizoroki–Heck, and Sonogashira reactions without ligands, as well as hydrogenation. As the synthetic adsorbents are prepared with a certain quality under strict regulations, the 10 % Pd/HP20 could be in practical use with the high reliability of a constant stable supply.