Bulky biaryl phosphine ligands facilitate Pd-catalyzed C-O coupling reactions of aryl halides with primary and secondary alcohols by promoting reductive elimination at the expense of beta-hydride elimination. The key to their success is the ability to match the size of the ligand to that of the combination of substrates. The efficient coupling of a number of unactivated aryl chlorides and bromides with cyclic and acyclic secondary alcohols was achieved. This included the coupling of allylic alcohols for the first time in a Pd-catalyzed coupling process.
“Use of Tunable Ligands Allows for Intermolecular Pd-Catalyzed C−O Bond Formation”, J. Am. Chem. Soc., 2005, 127(22), 8146-8149.