Abstract
The cycloaddition between (E)- or (Z)-1,4-dichloro-2-butene and a menthone-derived nitrone as a glycine equivalent afforded dichlorinated isoxazolidine-based cycloadducts. The stereochemistry of these adducts was controlled by the configuration of the starting alkene and nitrone. An amino group was generated either by reductive cleavage of the isoxazolidine N-O bond or by azidation and a subsequent reduction, which triggered in both routes a cyclization reaction that proceeded through a chloride displacement. This approach afforded unprecedented 3-substituted 4-hydroxyproline derivatives and (alpha S,3R,4S)-3-glycinyl-4-hydroxypyrrolidine. Both enantiomers of the reported products can be prepared by using one or the other nitrone enantiomer.