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.