Anionic inverse electron-demand 1,3-dipolar cycloaddition of nitrones with ynolates. Facile stereoselective synthesis of 5-isoxazolidinones leading to beta-amino acids.

[reaction: see text] The inverse electron-demand 1,3-dipolar cycloaddition of nitrones with ynolates, followed by quenching with t-BuOH, produced substituted 5-isoxazolidinones with good trans-selectivity. These products were easily converted into beta-amino acids.