Yi‐Xin Wang, Osamu Kitagawa
Stereoisomers arising from the rotational restriction about a CN single bond, namely CN atropisomers, have recently attracted considerable attention in the field of synthetic organic chemistry. Diverse CN atropisomeric compounds have been prepared with high optical purity through catalytic enantioselective reactions, and they have been used in various asymmetric reactions as chiral building blocks and chiral ligands. CN atropisomers are attractive compounds from the viewpoint of not only synthetic organic chemistry but also medicinal chemistry. Recently, various CN atropisomeric bioactive compounds have been found, and their biological activity, the target selectivity, and the pharmacokinetics have been revealed to differ significantly between atropisomers. On the other hand, we feel that the chemistry community is still not fully aware of the fascinating biological properties of CN atropisomers. This review article comprehensively describes CN atropisomeric compounds exhibiting diverse biological activities as well as the synthesis or separation of atropisomers and their rotational stability.