Organocatalytic Enantioselective Dipolar [3+2] Cycloadditions of Acetylenic Aldehydes with Nitrones for the Formation of Chiral 4‐Isoxazolines

Abstract

AbstractThe first organocatalytic enantioselective protocol has been developed for the dipolar [3+2] cycloaddition between acetylenic aldehydes and nitrones through an iminium activation pathway. This protocol uses L‐α,α‐bis(3,5‐ditrifluoromethylphenyl)prolinol as catalyst and 3,5‐dinitrobenzoic acid as additive and is friendly for one‐pot operation for the nitrone formation and the subsequent cycloaddition. It also exhibits a broad substrate scope and allows for the highly efficient production of chiral 4‐isoxazolines with various substituents under mild conditions in high yields (68–92%) with high enantioselectivities (up to 96% ee).