Synthesis of 2,2'-Dihalobiaryls via Cu-Catalyzed Halogenation of Cyclic Diaryliodonium Salts.

We report an efficient method for the preparation of various 2,2'-dihalobiaryls from cyclic diaryliodonium salts. With cheap halogen sources as starting materials, a broad range of 2,2'-diiodobiaryls, 2-bromo-2'-iodobiaryls, and 2-chloro-2'-iodobiaryls were obtained under mild reaction conditions. More importantly, a chiral copper-bisoxazoline catalyst system was further developed for the preparation of axially chiral 2,2'-dihalobiaryls in excellent yields and enantioselectivities, which can serve as versatile precursors for the synthesis of various chiral ligands.