Iodocyclization of Homoallylic Hydroxylamines Derived from D‐Glyceraldehyde

The reaction of allylmagnesium chloride with nitrone 1 derived from D ‐glyceraldehyde affords two diastereoisomeric homoallylic hydroxylamines 2a and 3a which, after separation and O ‐silylation, are subjected to iodocyclization using N ‐iodosuccinimide. The stereochemical outcome of the cyclization reaction was found to be different; thus, the hydroxylamine 2b is converted into a mixture of cis ‐ and trans ‐isoxazolidines 10 and 11 in which the trans product prevails, whereas 3b is stereoselectively converted into the cis product 12 . The final 5‐(iodomethyl)isoxazolidines 10–12 may be easily subjected to further studies; for example they undergo iodine displacement by treatment with azide, phthalimide, and acetate ions to give 13–16 , formal precursors of deoxy‐amino‐hexitols. As an example, 1‐ O ‐acetyl‐3,4‐dideoxy‐5,6‐ O ‐(1‐methylethylidene)‐4‐[(phenylmethyl)amino]‐ D ‐lyxo‐hexitol ( 17 ) is synthesized.