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.