A method for synthesizing Salacinol, its stereoisomers, and non-naturally occurring selenium and nitrogen analogues thereof having formula (I). The compounds are potentially useful as glycosidase inhibitors. The synthetic schemes comprise reacting a cyclic sulfate with a 5-membered ring sugar containing a heteroatom (X). The heteroatom preferably comprises sulfur, selenium, or nitrogen. The cyclic sulfate and ring sugar reagents may be readily prepared from carbohydrate precursors, such as D-glucose, L-glucose, D-xylose and L-xylose. The target compounds are prepared by opening of the cyclic sulfates by nucleophilic attack of the heteroatoms on the 5-membered ring sugars. The resulting heterocyclic compounds have a stable, inner salt structure comprising a heteroatom cation and a sulfate anion. The synthetic schemes yield various stereoisomers of the target compounds in moderate to good yields with limited side-reactions. In an alternative embodiment of the invention, the cyclic sulfate may be similarly reacted with a 6-membered ring sugar containing a heteroatom (X) to yield a compound having formula (XII).