Catalytic Asymmetric Synthesis of N-N Biaryl Atropisomers.

Atropisomers have emerged as important structural scaffolds in natural products, drug design, and asymmetric synthesis. Recently, N-N biaryl atropisomers have drawn increasing interest due to their unique structure and relatively stable axes. However, its asymmetric synthesis remains scarce compared to its well-developed C-C biaryl analogs. In this concept, we summarize the asymmetric synthesis of N-N biaryl atropisomers including N-N pyrrole-pyrrole, N-N pyrrole-indole, N-N indole-indole, and N-N indole-carbazole, during which a series synthetic strategies are highlighted. Also, a synthetic evolution is briefly reviewed and an outlook of N-N biaryl atropisomers synthesis is offered.