Efficient Enantioselective Ni(0)‐Catalyzed Cascade <i>syn</i> ‐Arylative Cyclization for Five‐Membered Heterocyclics Bearing Chiral Tetrasubstituted Allylic Alcohols

Comprehensive Summary Enantioselective synthesis of five‐membered heterocycles bearing chiral tetrasubstituted allylic alcohols remains challenging due to severe steric hindrance and strict regio‐ and enantio‐control demands. Herein, we report an efficient, highly enantioselective Ni(0)‐catalyzed cascade syn ‐arylative cyclization of hetero‐1,6‐alkynones with arylboronic acids, enabling direct access to chiral pyrrolidines and tetrahydrofurans with chiral quaternary carbon stereocenters. Using Ni(cod) 2 /( S )‐BIDIME, tert ‐butanol, and LiOMe, 35 products were obtained in up to 98% yield and &gt;99 : 1 er. Gram‐scale synthesis proceeded without erosion of reactivity or enantioselectivity. Mechanistic studies and DFT calculations revealed that the cyclization forming the Ni(II) metallacycle is the enantio‐determining step. This work provides a practical strategy for the synthesis of chiral five‐membered heterocycles and valuable mechanistic insights for the design of asymmetric catalysts.