Synthesis and Cycloaddition Reactions of 2,3,4,5-Tetrahydropyrazine 1-Oxide

The stereochemistry and reactivity of the cycloaddition reactions of a heterocyclic nitrone, 2,3,4,5,-tetrahydropyrazine 1-oxide, have been studied. The heterocyclic nitrone is found to be more reactive than its carbocyclic counterpart. The nitrone underwent regio- and stereo-selective cycloaddition reaction with several alkenes to afford bicyclic isoxazolidines efficiently. Barriers to nitrogen inversion in the cycloadducts have been determined.