Atroposelective Synthesis of Heterobiaryls through Ring Formation.

Atropisomeric heterobiaryls play a vital role in natural products, chiral ligands, organocatalysts, and other research fields, which have aroused great interest from chemists in recent years. Until now, a growing number of optically active heterobiaryls based on indole, quinoline, isoquinoline, pyridine, pyrrole, azole, and benzofuran skeletons have been successfully synthesized through metal or organic catalytic cross-coupling, functionalization of prochiral or racemic heterobiaryls, and ring formation. Among different strategies for the atroposelective synthesis of heterobiaryls, the strategy of ring formation has become a vital tool toward this goal. In this review, we summarize the enantioselective synthesis of axially chiral heterobiaryls through ring formation approaches, such as cycloaddition, cyclization, and chirality conversion. Meanwhile, the reaction mechanism and the corresponding applications of the chiral heterobiaryls are also discussed.