The elimination of vicinal sulfonyloxy groups fro111 methyl 2,3-di-O-n1ethanesulfonyl-a-~-gIucopyranosides with the formation of hex-2-enopyranosides using potassium iodide, and zinc in refluxing dry dimethyl formamide has been investigated. The specific use of a zinc-copper couple has been found to be highly advantageous to the yield and reproducibility of the reaction, and the elimination proceeds successfully whether acid or base labile groups are present at carbon-4 or -6. Both the 4,6-di-0-benzoyl (3b) and the 6-0-benzoyl (3d) precursors give methyl 6-O-benzoyl-r-~-ery1ht~-11ex-2-enopyrano~ide ( 4 4 as the major product, the latter also being obtainable by selective benzoylation of methyl a-D-eqzrktohex-2-enopyranoside (4c). The reaction of the dibenzoate therefore occurs with some deacylation at carbon-4, but it is noteworthy that this is not accompanied by any epimerization. A sinlilar pattern of reaction apparently occurs with the 4,6-di-0-acetyl derivative (3a). The confornlations of the starting di-0-methanesulfonyl esters are discussed and suggestions for the n.nl.r. assignments of the groups are made.