Enolizable Ketones as Activators of Palladium(II) Precatalysts in Amine Arylation Reactions

Enolizable ketones have been identified as effective activators for palladium­(II) precatalysts in the coupling of aryl bromides and aniline. N-arylation reactions catalyzed by [(DTBNpP)­PdCl2]2 (DTBNpP = (bis­(tert-butyl)­neopentylphosphine) and PEPPSI-IPr precatalysts are activated by the addition of acetone, mesityl oxide, and 3-pentanone. 3-Pentanone was the most effective activator. Mechanistic studies show that acetone, 3-pentanone, and mesityl oxide reduce [(DTBNpP)­PdCl2]2 in the presence of NaO-t-Bu to Pd0(DTBNpP)2.