Iodocyclization of homoallylic hydroxylamines derived from D-glyceraldehyde

Abstract

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.