A series of beta-phenyl-2-isoxazolidineethanols having cis-disposed substituents at C(4) and C(5) has been prepared by asymmetric nitrone cycloaddition reactions and their NMR spectra recorded over a wide range of temperatures. The spectra in CDCl3 at low temperatures indicate the presence of two interconverting invertomers for some of the tri-substituted isoxazolidines. The effect of H-bonding--intramolecular in CDCl3 and intermolecular in CD3OD--on the population ratio of the nitrogen invertomers has been investigated. The nitrogen inversion barriers are determined using complete line-shape analysis, and their dependence on solvent is discussed.
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