Diastereoselective synthesis of deprotectable isoxazolidines

Isoxazolidines are important synthetic targets due to their ability to act as nucleoside analogs. The 1,3-dipolar cycloaddition reaction of nitrones with alkenes is a powerful approach to the synthesis of isoxazolidines with the potential for control over absolute and relative stereoselectivity. However, removal of the most commonly used protecting groups without cleavage of the N–O bond is a significant challenge. The diastereoselective synthesis of benzhydryl protected isoxazolidines and the reductive cleavage of the benzhydryl protecting group with retention of the isoxazolidine ring are reported.