Efficient palladium-catalyzed Suzuki–Miyaura coupling of aryl chlorides with arylboronic acids using benzoferrocenyl phosphines as supporting ligands

Four monodentate benzoferrocenyl phosphines were studied as supporting ligands in palladium-catalyzed Suzuki–Miyaura coupling of aryl chlorides with arylboronic acids. Of these ligands, the more electron-rich and steric demanding benzoferrocenyl dicyclohexyl phosphine was found highly effective for the reaction followed by the benzoferrocenyl diisopropyl phosphine. The corresponding diethyl and diphenyl phosphines are much less active. When the dicyclohexyl phosphine was used, both electron-rich and electron-poor aryl chlorides were coupled with arylboronic acids within 1 h giving good to excellent yields. Chloro-substituted pyridines were also found highly reactive under these conditions giving excellent yields of biaryl products. Sterically hindered biaryls can also be prepared using the dicyclohexyl phosphine as ligand.