Double Ligands Enabled Ruthenium Catalyzed ortho‐C−H Arylation of Dialkyl Biarylphosphines: Straight and Economic Synthesis of Highly Steric and Electron‐Rich Aryl‐Substituted Buchwald‐Type Phosphines

A double‐ligands enabled ruthenium catalyzed C(sp2)−H arylation of dialkyl phosphines is described, which provides a straight access to aryl‐substituted dialkyl phosphine ligands. The combination of 1,3‐diketone and amino acid ligands is essential for this transformation. An important six‐membered cycloruthenium intermediate was successfully isolated and characterized by X‐ray diffraction. Mechanistic studies showed that the 1,3‐diketone promoted the process of oxidative addition of cycloruthenium intermediate. Some of modified CyJohnPhos ligands exhibited highly catalytic activity in palladium catalyzed C−N bond formation.