isoxazolidines were synthesized in good to excellent yields by 1,3-dipolar cycloaddition of N-vinylamide dipolarophiles and nitrones. Strikingly, solvent-free conditions gave high conversion and yields, shortened reaction time, and minimized degradation products. N-Vinyloxazolidin-2-one and its analogues used in these cycloaddition reactions were conveniently prepared in excellent yields by a modified