A series of phosphine-ligated palladium
precatalysts based on N-methyl- and N-phenyl-2-aminobiphenyl
have been developed. Substitution at the nitrogen center prevents
the presence of traces of aminobiphenyls that contain a free −NH2 group from contaminating cross-coupling products. These precatalysts
produce N-substituted carbazoles upon activation, which cannot consume
starting materials. These precatalysts were efficiently generated
from 2-aminobiphenyl with minimal purification and found to be highly
effective in Suzuki–Miyaura and C–N cross-coupling reactions.