Intermolecular Palladium(0)-Catalyzed Atropo-enantioselective C–H Arylation of Heteroarenes

Atropisomeric (hetero)­biaryls are motifs with increasing significance in ligands, natural products, and biologically active molecules. The straightforward construction of the stereogenic axis by efficient C–H functionalization methods is extremely rare and challenging. An intermolecular and highly enantioselective C–H arylation of relevant heteroarenes providing an efficient access to atropisomeric (hetero)­biaryls is reported. The use of a Pd(0) complex equipped with H8-BINAPO as a chiral ligand enables the direct functionalization of a broad range of 1,2,3-triazoles and pyrazoles in excellent yields and selectivities of up to 97.5:2.5 er. The method also allows for an atroposelective double C–H arylation for the construction of two stereogenic axes with >99.5:0.5 er.