Highly reactive catalysts based on palladium and dialkylbiarylphosphino ligands provide unprecedented reactivity and selectivity in C–N bond-forming processes. The bulky monophosphine catalyst system Pd/1 was effective for the reaction of aryl/heteroaryl halides bearing primary amides and 2-aminoheterocycles (see scheme; dba=dibenzylideneacetone, R=CONH2, NH2), thus showing that monodentate phosphines are viable alternatives to, and sometimes superior to, chelating ligands.
“Monodentate Phosphines Provide Highly Active Catalysts for Pd-Catalyzed C–N Bond-Forming Reactions of Heteroaromatic Halides/Amines and (H)N-Heterocycles”, Angew. Chem. Int. Ed., 2006, 45(39), 6523-6527.