Copper‐Catalyzed Asymmetric Büchner Reaction of Diynes to Access Chiral Cyclohepta[ b ]indoles

Comprehensive Summary Transition‐metal catalyzed asymmetric Büchner reaction has emerged as one of the efficient ways for the synthesis of diverse chiral seven‐membered ring compounds. However, most of the established methods rely on the noble metal catalysts and are generally limited to the diazo approach. Herein, we report a copper‐catalyzed asymmetric Büchner reaction of diynes with aryl amines through vinyl cations. This approach allows practical and atom‐economic construction of valuable chiral cyclohepta[ b ]indoles in moderate to excellent yields and excellent enantioselectivities. In addition, this cyclization is also successfully extended to the synthesis of the related cyclohepta[ b ]benzofuran in moderate yield with high enantioselectivity. Particularly, this research not only constitutes the first example of accessing such valuable chiral frameworks via non‐noble metal catalyzed Büchner reaction, but also represents a rare example of asymmetric Büchner reaction based on alkynes.