Novel bulky pyrazolylphosphine ligands for the Suzuki coupling of aryl chlorides

Bulky 1-(3,5-di-tert-butyl)pyrazolyl-dicyclohexylphosphine and 1-(3,5-di-tert-butyl)pyrazolyl-di-tert-butylphosphine were prepared from the reactions of 3,5-di-tert-butylpyrazolide and corresponding chlorodialkylphosphines. They were successfully employed as ligands in the Suzuki coupling reactions of phenylboronic acid and various aryl bromides and chlorides.