A General Palladium–Phosphine Complex To Explore Aryl Tosylates in the N-Arylation of Amines: Scope and Limitations

The scope and limitations of the monoselective N-arylation of various amines by using aryl and hetaryl tosylates are presented. The air-stable and easily accessible Pd(OAc)₂/CM-phos {CM-phos=2-[2-(dicyclohexylphosphino)phenyl]-1-methyl-1H-indole}catalyst system was able to deal with a wide range of aryl tosylate substrates as well as amine nucleophiles, including primary and secondary cyclic/acyclic aliphatic amines and anilines. NH-Bearing heterocycles such as indole, carbazole, pyrrole, 10-phenothiazine, and 10-phenoxazine were shown to be feasible coupling partners under this catalytic system. The described reaction conditions tolerate a wide range of functional groups and allow an array of aromatic amines as well as unsymmetrical amine products to be easily accessed from the various phenolic derivatives. Interestingly, this catalyst system even offers the opportunity to perform the reaction in water medium. We also report the intermolecular coupling of optically active α-central chiral amines with aryl tosylates without erosion of the enantiomeric purity.