Asymmetric synthesis of saddle-shaped eight-membered azaheterocycles via (dynamic) kinetic resolution

Chiral molecules have played prominent roles in various domains, including pharmaceuticals, agrochemicals, and functional materials. However, the scope of chiral molecules has mostly been limited to central chirality, with recent advancements in axial chirality. The synthesis and application of chiral molecules with other types of chiral elements remain scarce. 9,10-Dihydrotribenzoazocines, a type of eight-membered azaheterocycle, display intriguing saddle-shaped inherent chirality. Herein, we disclose the asymmetric synthesis of these saddle-shaped chiral azaheterocycles through two alternative protocols: kinetic resolution (KR) and dynamic kinetic resolution (DKR). A series of racemic substituted dihydrotribenzoazocines were kinetically resolved with chiral phosphoric acid (CPA)-catalyzed C-H amination reaction with azodicarboxylates, which gave excellent KR performances. In addition, a more efficient DKR protocol was developed by CPA-catalyzed asymmetric transfer hydrogenation of their corresponding imine-type analogous. The facile derivatization of these saddle-shaped chiral azaheterocycles, combined with their remarkable configurational stability, exemplifies the potential applications of these methods.