Organocatalytic synthesis of 5-hydroxyisoxazolidine catalyzed by camphor sulfonyl hydrazines through aza-Michael addition/cyclization.

A series of chiral 5-hydroxy isoxazolidines has been successfully synthesized through camphor sulfonyl hydrazine-catalyzed asymmetric aza-Michael addition reaction between N,O-protected hydroxyamines and enals. Moderate yields with moderate to good enantioselectivities (up to 96% enantiomeric excess [ee]) were achieved. It provides an alternative asymmetric approach to preparing isoxazolidine derivatives.