Iodine-hexamethyldisilane (HMDS)-mediated anomerization of peracetylated 1,2-trans-linked alkyl and aryl glycosides.

Treatment of peracetylated alkyl and aryl 1,2-trans-glycosides with iodine in the presence of HMDS has been found to result in the anomerization leading to the formation of the respective 1,2-cis-glycosides. In the case of alkyl glycosides with aglycons of short alkyl chain length complete anomerization to the alpha-glycosides was observed while with those of longer chain length the process was found to be incomplete. The observations have been interpreted mechanistically.