Lewis Acids Promoted 3 + 2 Cycloaddition of Oxaziridines and Cyclic Allylic Alcohols through Carbonyl Imine Intermediates.

Syntheses of isoxazolidines through the carbonyl imine intermediates are currently limited to monosubstituted olefin substrates. Herein, we reported syntheses of novel bicyclic isoxazolidine-containing compounds through 1,3-dipolar cycloaddition reactions using cyclic allylic alcohols as substrates, which proved challenging in previous reports. Generally, the reaction yields range from good to high, and the reaction substrates tolerate various functional groups, including the cyclopropyl and amine groups. Mechanistic studies suggest that an allylic cation and a carbonyl imine intermediate are involved and responsible for the observed stereochemistry and diastereoselectivity.