Enantioselective Protonation of Cyclic Carbonyl Ylides by Chiral Lewis Acid Assisted Alcohols

Chiral Lewis acid‐catalyzed asymmetric alcohol addition reactions to cyclic carbonyl ylides generated from N‐(α‐diazocarbonyl)‐2‐oxazolidinones featuring a dual catalytic system are reported. Construction of a chiral quaternary heteroatom‐substituted carbon center was accomplished in which the unique heterobicycles were obtained in good yields with high stereoselection. The alcohol adducts were successfully converted to optically active oxazolidine‐2,4‐diones by hydrolysis. Mechanistic studies by DFT calculations revealed that alcohols could be activated by Lewis acids, enabling enantioselective protonation of the carbonyl ylides. Enantioselective protonation of cyclic carbonyl ylides by chiral Lewis acid assisted alcohol addition reactions featuring a dual catalytic system is reported. The unique heterobicyclic products bearing a quaternary heteroatom‐substituted carbon center were obtained with high diastereo‐ and enantioselectivities. The alcohol adducts were successfully converted to optically active oxazolidine‐2,4‐diones by hydrolysis. Computational mechanistic studies indicated that a stepwise syn‐addition of alcohols under the influence of a Lewis acid was favored.