Highly Efficient Ligands for the Palladium‐Assisted Double N‐Arylation of Primary Amines for One‐Sep Construction of Carbazoles

A highly efficient one‐pot synthesis of carbazoles via palladium‐catalyzed double N ‐arylation of primary amines with 2,2′‐dihalobiphenyls is described using a catalyst system comprised of tris(dibenzylideneacetone)dipalladium(0) (Pd 2 dba 3 ) and the proazaphosphatrane P( i ‐BuNCH 2 CH 2 ) 3 N ( 8 ) or its derivative ( t‐ Bu) 2 PNP( i‐ BuNCH 2 CH 2 ) 3 N ( 9a ) as the ligand. The process is effective for double N ‐arylation of 2,2′‐biphenyl dibromide, diiodide, and even dichloride with a variety of primary amines including neutral, electron‐rich, electron‐deficient, and sterically hindered anilines as well as aliphatic amines.