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 (SuzukiMiyaura reaction), alkenes (MizorokiHeck 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 SuzukiMiyaura 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.