Synthesis of C₂-Symmetric Benzimidazolium Salts and Their Application in Palladium-Catalyzed Enantioselective Intramolecular α-Arylation of Amides.

A series of C2-symmetric chiral benzimidazolium salts, the precursor of N-heterocyclic carbene ligands, were designed and synthesized from 1,2-dibromobenzene. In situ prepared corresponding carbenes were tested in the asymmetric palladium-catalyzed intramolecular α-arylation of amides, affording chiral diarylmethanols with high yields and moderate enantioselectivities.