Enantioselective Aza-Friedel-Crafts Reaction of Heteroarenes with in situ Generated Isoxazolium Ions via Chiral Phosphoric Acid Catalysis

Abstract

An asymmetric organocatalytic aza-Friedel-Crafts reaction was developed to give the enantioenriched Δ4-isoxazoline scaffold bearing a quaternary-substituted stereogenic centre in good-to-excellent yields and enantioselectivity (50–99%, 55–&gt

99% ee). This protocol involves the in situ generated isoxazolium ions in the presence of a chiral phosphoric acid followed by the heteroarene addition through asymmetric counteranion-directed catalysis. (Figure presented.). © 2021 Wiley-VCH GmbH