A new class of glycosidase inhibitor: Synthesis of salacinol and its stereoisomers

Salacinol (4) is one of the active principles in the aqueous extracts of Sa lacia reticulata that are traditionally used in Sri Lanka and India for the treatment of diabetes. The syntheses of salacinol (4), the enantiomer of s alacinol (5), and a diastereomer (7) are described. The synthetic strategy relies on the selective nucleophilic attack of 2,3,5-tri-O-benzyl-1,4-anhyd ro-4-thio- or L-arabinitol at C-l of 2,4-O-benzylidene D- or L-erythritol-1 ,3-cyclic sulfate, The work serves to resolve the ambiguity about the exact structure of salacinol and establishes conclusively the structure of the n atural product.