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.

目前，通过羰基亚胺中间体合成异恶唑啉的过程主要局限于单取代烯烃底物。本研究中，我们报道了通过使用环状烯丙醇作为底物，通过1,3-偶极环加成反应合成新型双环异恶唑啉类化合物的合成方法，该方法在以往的报道中颇具挑战性。通常，该反应的产率从良好至高，反应底物能够容忍多种官能团，包括环丙基和胺基。机制研究表明，烯丙基阳离子和羰基亚胺中间体参与了反应，并对观察到的立体化学和光学选择性负责。