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

Abstract

AbstractA 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) (Pd2dba3) and the proazaphosphatrane P(i‐BuNCH2CH2)3N (8) or its derivative (t‐Bu)2PNP(i‐BuNCH2CH2)3N (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.