Evidence for the Formation and Structure of Palladacycles during Pd‐Catalyzed CN Bond Formation with Catalysts Derived from Bulky Monophosphinobiaryl Ligands

The structural origins of the differences in catalytic activity observed between catalysts containing 2′‐substituted and 2′,6′‐disubstituted biaryl monophosphane ligands for a Pd‐catalyzed CN bond‐forming reaction are discussed. It is shown that palladacycle formation is avoided and optimal catalyst activity is achieved through the use of the 2′,6′‐disubstituted ligands. ( t Am= tert ‐amyl, dppe=1,2‐bis(diphenylphosphanyl)ethane).