Stereoselectivity of 1,3-dipolar cycloadditions of D-erythrose and D-threose derived nitrones with methyl acrylate

1,3-Dipolar cycloadditions between the D-erythrose and D-threose derived ni trones and methyl acrylate proceed in a regiospecific manner to afford the corresponding 3,5-disubstituted diastereomeric isoxazolidines in good yield s. The stereoselectivity was dependent on the steric hindrance of the nitro ne. The major products were found to have the C-3/C-4' erythro and C-3/C-5 cis relative configuration. Its formation can be rationalized by less hinde red endo attack of the Z-nitrone in an antiperiplanar manner with respect t o the largest group of the cyclic acetal.