Isoxazolidines serve as intermediates in the synthesis of natural products. In addition, they can display significant biological activity, much of which derives from their ability to act as nucleoside analogues. As a result, considerable effort has been applied toward the asymmetric synthesis of isoxazolidines. However, a rapid and straightforward method for determination of the absolute configuration of isoxazolidines has not yet been reported. Herein we report the application of Mosher derivatives for the determination of the absolute configuration of substituted isoxazolidines. The Mosher derivatives exhibit conformational behavior similar to the Mosher derivatives of cyclic secondary amines. Interpretation of the chemical shift anisotropy, with these conformational biases in mind, can be used for the assignment of the absolute configuration of substituted 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.