1,3-Dipolar Cycloaddition Reactions of Nitrones with Unsaturated Methylsulfones and Substituted Crotonic Esters

Abstract

The cycloaddition reaction of nitrones to unsaturated methylsulfones and substituted crotonic esters gives a sole product or a mixture of tri- or tetra-substituted isoxazolidines, such that with disubstituted dipolarophiles the regiochemistry is dependent upon the nitrone and the vicinal electron-withdrawing group (CN or CO₂Me) but with trisubstituted olefins, regiospecific cycloadditions are observed.