alkoxyallenes and the enantiopure L-erythrose-derived cyclic nitrone (+)-3 were used as precursors for the preparation of novel bicyclic 2H-1,2-oxazine derivatives, which were formed as single diastereomers. A highly stereoselective hydroboration/oxidation sequence provided key substrates that were suitable for the synthesis of a series of polyhydroxylated bicyclic N-heterocycles, including unique