Acid-Mediated Transformations of Enantiopure 3,6-Dihydro-2H-1,2-oxazines into Functionalised Aminotetrahydrofuran Derivatives

Two new routes to substituted aminotetrahydrofuran derivatives have been investigated. Treatment of 3,6-dihydro-2H-1,2-oxazines with hydrochloric acid in the presence of zinc provided 4-benzylamino-5-hydroxy furanose derivatives which contain a quaternary anomeric centre with a vinyl unit. Upon mesylation and subsequent heating in aqueous media 5-hydroxy-3,4,5,6-tetragydro-1,2-oxazines were converted into novel bicyclic 1,2-oxazines with complete regio- and stereoselectivity. Cleavage of the N-O bond and subsequent debenzylation furnished enantiopure polyhydroxylated aminotetrahydrofuran derivatives which are promising ligands for selectin inhibition studies.