Synthesis of Planar‐Chiral [2.2]Paracyclophane‐Based Oxazole‐Pyrimidine Ligands and Application in Nickel‐Catalyzed 1,2‐Reduction of α,β‐Unsaturated Ketones

Comprehensive Summary The planar‐chiral ligands have been widely applied as a class of unique and significant ligands in asymmetric catalysis. Among them, chiral [2.2]paracycyclophane has emerged as a privileged type of planar‐chiral framework and has been utilized as an important toolbox due to their structural stability. Herein, we design and synthesize [2.2]paracyclophane‐derived oxazole‐pyrimidine ligands (abberviated as PYMCOX). These N,N‐ligands with stable properties, rigid structure and large steric hindrance performed successfully in nickel‐catalyzed asymmetric 1,2‐reduction of α,β‐unsaturated ketones, affording the chiral allylic alcohols with up to 99% yield and 99% ee. Meanwhile, this reduction reaction could be conducted on gram‐scale without loss of activity and enantioselectivity, and the chiral ligand could be conveniently recovered with high yield. The [2.2]paracyclophane‐derived oxazole‐pyrimidine ligands with planar chirality (PYMCOX) were designed, synthesized and successfully applied in nickel‐catalyzed asymmetric 1,2‐reduction of α,β‐unsaturated ketones, affording the chiral allyilic alcohols with up to 99% yield and 99% ee. Meanwhile, this reduction reaction could be conducted on gram scale without loss of activity and enantioseletivity, and the chiral ligand could be conveniently recovered with high yield.