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 I-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. (C) 2000 Elsevier Science Ltd. ALI rights reserved.