Chiral four-membered cyclic nitrones were synthesized by the asymmetric (4+2)-cycloaddition of nitroalkenes 1 and chiral ynamines 2. The subsequent stereoselective addition of nucleophiles to these nitrones enabled the synthesis of chiral N-hydroxyazetidines.
van Elburg, P. A., Honig, G. W. N., & Reinhoudt, D. (1987). Chiral four-membered cyclic nitrones; asymmetric induction in the (4+2)-cycloaddition reaction of chiral ynamines and nitroalkenes. Tetrahedron letters, 28(50), 6397-6400. https://doi.org/10.1016/S0040-4039(01)91385-1