Palladium-catalyzed Direct Monoarylation Of Aryl C-H Bond With Iodoarenes

Biaryl compounds play an important role in organic chemistry.They are often found in natural products,pharmaceuticals,pesticides and biological active molecules.Due to their intrinsic physical properties,biaryls have potential applications in the fields of dyes,organic semiconductors and advanced materials.Additionally,biaryls with heteroatoms are important backbones of ligands for some efficient and selective asymmetric catalyses.Therefore,the construction of aryl-aryl bonds has attracted great attentions from the synthesis community,resulting in great progress made.Traditionally,biaryls can be constructed by transition metal catalyzed aryl-aryl coupling reactions,such as Suzuki-Miyaura coupling,Negishi coupling,Stille coupling,Heck coupling reaction and so on.These works suffer from two main disadvantages:1)the use of organometallic reagents in most of the reactions,which not only increase the cost of the reactions,but also require high operative skills;2)the challenge of the monoarylations.Currently,the diarylation products can be obtained unavoidably when there are two identical reaction sites on aromatic substrate.So the development of a low cost,effective method to achieve the monoaryl catalytic system is high desirable.In this paper,we have developed an efficient Pd?OAc?₂/TFA/O₂ catalysis system that could promote direct arylation reactions of a variety of aromatic C-H bonds with diverse iodoarenes under silver-free conditions.The coupling reaction possesses complete monoarylation selectivity.The approach provides a straightforward,facileand economical route to biaryls,facilitating the utilities of biaryls in the areas of pharmaceuticals,pesticides,dyes and functional materials.