A Single Phosphine Ligand Allows for the Palladium-Catalyzed Intermolecular C–O Bond Formation with Secondary and Primary Alcohols**

An efficient, general palladium catalyst for C–O bond-forming reactions of secondary and primary alcohols with a range of aryl halides has been developed. Use of a catalyst based on a single bulky biarylphosphine ligand L4 (RockPhos, soon to be commercially available) has expanded this chemistry to allow the transformation of a variety of heteroaryl halides, and for the first time, allows for the coupling of electron-rich aryl halides with secondary alcohols. Additionally, this new catalyst system provides the ability to effect these reactions with a diverse set of substrate combinations, while employing a single ligand. Thus the need to survey mutiple ligands, as was previously the case, is obviated.