The Deoxygenation of Some Carbohydrate Diols Via the Derived Cyclic Thiocarbonate

Abstract

The treatment of methyl 2,6-di-O-methyl-3,4-O-thiocarbonyl-β-D-galactoside with methyl iodide gives mainly the 3-deoxy-3-iodo-D-guloside , whereas the α- anomer of the above and methyl 2-O-methyl-3,4- O- thiocarbonyl-β-L-arabinoside give mainly the 4-deoxy-4-iodo-D- glycosides. An explanation is given for these and some previously reported results. As well, two of the above cyclic thiocarbonates (β-D-galacto and β-L- arabino), together with two cyclic thiocarbonates derived from methyl α-D- mannopyranoside, when treated with tributyltin hydride, gave mixtures (nearly 1:1) of products resulting from deoxygenation . Single-crystal X-ray diffraction structure determination of the β-D- galacto and the β-L- arabino cyclic thiocarbonates showed both pyranose rings to be in the 4C1 conformation.