A versatile catalyst system for Suzuki-Miyaura syntheses of sterically hindered biaryls employing a cyclobutene-1,2-bis(imidazolium) salt

The catalyst system consisting of 3,3'-(3,4-bis(dichloro-methylene)-cyclobut-1-ene-1,2-diyl)bis(1-methyl-1H-imidazolium) bis(tetrafluoroborate), Pd(OAc)(2) and NaOtBu in toluene proved to be very effective for a broad variety of Suzuki-Miyaura reactions at room temperature. It is also suited for the synthesis of sterically hindered compounds including 2,6-di-tert-butyl-2'-substituted biaryls at elevated temperatures.