Metal ion-mediated diastereoface-selective 1,3-dipolar cycloaddition of nitrile oxides with dipolarophiles bearing an oxazolidinone chiral auxiliary

摘要

Magnesium ion-mediated cycloaddition reactions of nitrile oxides to chiral 3-acryloyl-2-oxazolidinones lead to highly diastereoselective foramtion 2-isoxazolines. The magnesium ion serves to fix the #alpha, #beta#-unsaturated moiety through chelation to effect chiral shielding. These asymmetric reactions provide the first sucessful examples of Lewis acid-mediated stereocontrol of nitrile cycloaddition reactions to electron-deficient dipolarophiles.