Nickel-catalyzed triarylamine synthesis: synthetic and mechanistic aspects.

An improved protocol was described for the amination of chloroarenes with diarylamines under NiCl2(PCy3)(2) catalysis in the presence of a Grignard reagent as base. This method fully suits bromo-/iodoarene substrates as well, and even is expanded to certain aryl tosylates. A preliminary investigation into the mechanism suggests that this amination reaction might proceed through Ni-I and Ni-III intermediates rather than via the usually expected Ni-0-Ni-II cycle.