Synthesis of salacinol

Salacinol, a new type of α-glucosidase inhibitor discovered from the antidiabetic herb, was synthesized for the first time. Under the strategy that salacinol would be synthesized by the coupling reaction between 1,4-epithio-d-arabinitol and the cyclic sulfate of an erythritol derivative, the model coupling reactions between tetrahydrothiophene and versatile cyclic sulfate derivatives were undertaken. These experiments indicated that the 1,3-diol of the cyclic sulfate should be protected with the isopropylidene group, otherwise, even the benzylidene-protected cyclic sulfate decomposed during the reaction. Thus, the salacinol was synthesized using the cyclic sulfate of 1,3-O-isopypropylidene-d-erythritol. The resulting coupling product was deisopropylidenated to afford salacinol. A diastereomer of salacinol was also synthesized.